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10 July 2025, Volume 17 Issue 7
    

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    Composite Material Rolling Technology and Equipment
  • Short-time Heat Bearing Capacity of Thick Gauge Steel/Aluminum/Aluminum Composite Plate Rolled at Different Temperature
    LI Junquan, LIU Wenwen, CHEN Ke, SHI Yujie, ZHANG Peng
    Journal of Netshape Forming Engineering. 2025, 17(7): 1-8. https://doi.org/10.3969/j.issn.1674-6457.2025.07.001
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The work aims to investigate the effects of short-term thermal load treatment on the distribution of Fe and Al elements and microstructure at the interface of thick steel/aluminum/aluminum alloy clad plates, and reveal the effect of thermal load on the interfacial bonding properties of the clad plates. Firstly, the steel/aluminum/aluminum alloy composite plate with a thickness of 15.32 mm was prepared by the two-pass different temperature rolling composite method. Secondly, the composite plate was subject to short-term thermal load treatment at different temperature by box resistance furnace. Finally, by analyzing the element diffusion, bonding properties and matrix microstructure properties of the composite plate interface, the effect of short-term thermal load temperature parameters on the mechanical properties and microstructure of the thick steel/aluminum/ aluminum alloy composite plate was studied. After the composite plate was subject to thermal loads at different temperature, there was no significant difference in the thickness of the Fe and Al element diffusion layer, which was between 1.5 μm and 1.6 μm, and no continuous intermediate compound layer was formed. With the increase of thermal load temperature, the interfacial shear and pull-out strength of the composite plate gradually decreased from 77 MPa and 153 MPa to 61 MPa and 95 MPa. The fracture position was located in the middle aluminum layer, which was ductile fracture, while the side bending performance was good and no obvious defects appeared. At the same time, the grain size of the steel side and the aluminum side at the interface of the composite plate also gradually increased from 9.56 μm and 4.89 μm to 12.54 μm and 10.39 μm, and the dislocation density at the aluminum side of the composite plate also decreased. In conclusion, when the thick steel/aluminum/aluminum alloy composite plate is subject to short-term thermal load, the grain size of the bonding interface increases with the increase of temperature, and the dislocation density decreases obviously, which leads to the decrease of the interfacial shear and pull-off strength of the composite plate.
  • Microstructure of Ti-42Al-9V Alloy Sheets and Impact of Single Pass and Multiple Pass Rolling
    TANG Peng, LIANG Guozheng, XU Xiaokun, ZHANG Shuzhi, ZHANG Xinyu, LIU Riping
    Journal of Netshape Forming Engineering. 2025, 17(7): 9-20. https://doi.org/10.3969/j.issn.1674-6457.2025.07.002
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    The work aims to conduct single-pass and multi-pass high strain rate rolling processes on forged Ti-42Al-9V alloy and systematically investigate the microstructural characteristics and deformation mechanisms of the sheets under these two processing conditions, along with an in-depth analysis of the fracture mechanisms of the rolled alloy. Through the application of high strain rate rolling technology, the evolution laws of microstructures and the associated deformation mechanisms for both single-pass and multi-pass rolled sheets were thoroughly discussed. In the case of single-pass rolled sheets, the microstructure primarily consisted of a needle-like β/γ mixed structure and blocky α2/γ lamellar clusters, forming a dual-phase structure. Twinning occurred within the α phase at elevated temperatures. For multi-pass rolled sheets, the microstructure was predominantly composed of (α/α2+γ) lamellar clusters, along with residual β and γ phases distributed at the boundaries of these clusters. The microstructural evolution in multi-pass rolling was mainly attributed to the fragmentation and decomposition of (α/α2+γ) lamellar clusters, which led to dynamic recrystallization behavior. During single-pass high strain rate rolling, stress concentration occurs at the boundaries of massive α phases, resulting in dislocation accumulation. Consequently, dynamic recrystallization preferentially initiates at these boundaries, leading to the formation of fine recrystallized grains. The deformation mechanisms of lamellar clusters during the dynamic recrystallization process in multi-pass high strain rate rolled sheets can be categorized into three primary modes of spheroidization of laminates, twinning-induced nucleation, and bending/twisting.
  • Numerical Simulation on Flat-corrugated Cross Wedge Rolling of 42CrMo4/45 Steel Hollow Laminated Shaft
    LEI Haitao, LI Zixuan, SHU Xuedao, PATER Zbigniew
    Journal of Netshape Forming Engineering. 2025, 17(7): 21-30. https://doi.org/10.3969/j.issn.1674-6457.2025.07.003
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    The work aims to enhance the interfacial bonding strength of dissimilar metal hollow laminated shafts and achieve high-strength, lightweight, and low-cost shaft components for new energy vehicles and other industrial applications. A flat-corrugated cross wedge rolling process for 42CrMo4/45 steel hollow laminated shafts was proposed. Numerical simulation models were constructed using Simufact.forming software to analyze the effects of different layer thickness ratios (1.7∶1, 1.25∶1, and 1.08∶1) and rolling temperature (1 000, 1 100, 1 200 ℃) on forming quality. By comparing equivalent plastic strain distribution, equivalent stress distribution, and z-axis force between corrugated and traditional cross wedge rolling processes, the effect of corrugated wedges on deformation behavior and interfacial corrugation transfer mechanisms were investigated. The maximum rolling force during the corrugated die rolling stage reached approximately 70 kN, while the master die rolling stage peaked at about 290 kN, representing a 45% increase compared with traditional dies. The symmetrically distributed corrugated wedges progressively penetrated the outer shaft surface, forming regular spiral corrugations on the outer shaft surface and complementary corrugated structures at the inner-outer shaft interface. At a 1.7∶1 layer thickness ratio, the outer shaft exhibited distinct and uniform plastic deformation distribution in the early rolling stage, with optimal coordination between inner and outer shafts, effective corrugation interface transfer, and suppression of ovalization during rolling. At a 1.25∶1 ratio, deformation concentrated in the middle section, showing a “middle bulging” phenomenon. At a 1.08∶1 ratio, by the middle stage of the rolling process, the inner shaft displayed large areas of high equivalent strain values, indicating potential risks of interface separation and flattening. Regarding temperature effects, at 1 100 ℃, the interfacial normal stress distribution was uniform and generally exceeded the yield strength of 45 steel, ensuring good interfacial bonding. In conclusion, the flat-corrugated cross wedge rolling process successfully creates corrugated bonding interfaces in 42CrMo4/45 steel hollow laminated shafts, improving axial shear resistance and circumferential torsional ability. The research results provide a new approach to addressing the insufficient interfacial bonding strength problem in traditionally manufactured laminated shafts.
  • Hot Roll Bonding Fabrication and Interfacial Microstructure and Properties of Titanium/Steel Clad Plates with Corrugated Interface
    LIU Jinhua, LIU Peng, LUAN Qianqian, CHEN Zejun, XIA Xiangsheng, CHEN Qiang
    Journal of Netshape Forming Engineering. 2025, 17(7): 31-40. https://doi.org/10.3969/j.issn.1674-6457.2025.07.004
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    The work aims to investigate the effect of corrugated-flat rolling reduction ratio on the interfacial morphology, microstructure, and bonding strength of high-strength titanium/steel clad plates. Titanium/steel clad plates with corrugated interfaces were fabricated through corrugated-flat rolling process under varying reduction ratios. The interfacial microstructure was characterized with Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction (EBSD), and the interfacial shear strength was evaluated through compression-shear testing. The titanium/steel clad plates prepared by corrugated-flat rolling exhibited good interfacial bonding. Elemental diffusion occurred at the Ti-Fe interface, forming a diffusion layer of measurable thickness. Microstructural analysis of typical regions of the corrugated interface indicated that the wave valleys underwent more severe plastic deformation. On both sides of the interface, EBSD analysis revealed that the α phase in TC4 titanium alloy developed different preferred orientation distributions after hot rolling, exhibiting a clear texture. With the increasing reduction ratio, the pole density and dislocation density in the titanium side gradually increased, while those in the steel side gradually decreased. Compression-shear tests showed that the shear strength of titanium/steel clad plates with reduction ratios of 44%, 54%, and 64% was 359 MPa, 403 MPa, and 442 MPa, respectively. These results indicate that increasing the reduction ratio during corrugated-flat rolling intensifies plastic deformation at the interface, thereby improving the interfacial bonding quality of the titanium/steel clad plates.
  • Influence of Surface Treatment Methods on Bonding Strength of Hot-rolled Steel-aluminum Composite Plates
    GUO Yunchang, LU Minghao, QI Zichen, REN Zhongkai, YU Chao, XIAO Hong
    Journal of Netshape Forming Engineering. 2025, 17(7): 41-51. https://doi.org/10.3969/j.issn.1674-6457.2025.07.005
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    The work aims to clarify the effects of two commonly used surface treatment methods, namely sandpaper grinding and steel wire brush grinding, on the bonding properties of hot-rolled steel-aluminum composite plates after rolling and heat treatment, as well as the fracture mechanism of the composite plates prepared by different grinding methods after annealing. Steel-aluminum composite plates were prepared through surface treatment methods of 3000#, 180# sandpaper grinding and steel wire brush grinding. Bonding property tests and microstructure observations were carried out on the obtained three types of composite plates. The fracture morphologies and fracture mechanisms of the composite plates before and after annealing were characterized. The rough surface prepared by sandpaper grinding could improve the bonding strength of the composite plates after rolling. In contrast, the smooth surface ground by sandpaper showed a lower bonding strength after rolling. However, the bonding strength of the steel-aluminum composite plates with a smooth surface ground by sandpaper increased rapidly after annealing. After annealing for 120 min, intermetallic compounds with a granular and spaced distribution were formed at the interface, and at this time, the composite plates had the highest bonding strength. Through in-situ tensile-shear experiments, it was observed that the granular intermetallic compounds could hinder the crack propagation and force the crack to turn. For the steel-aluminum composite plates prepared by steel wire brush grinding, the surface work-hardened layer peeled off after rolling. However, after annealing, the surface work-hardened layer and the steel matrix were re-healed, and the composite plates exhibited a high bonding strength. In conclusion, the steel-aluminum composite plates prepared by 180# sandpaper grinding have a high bonding strength after rolling; the steel-aluminum composite plates prepared by 3000# sandpaper grinding show excellent bonding properties after heat treatment; and the steel-aluminum composite plates prepared by steel wire brush grinding exhibit high bonding strength both after rolling and heat treatment.
  • Effect of Rolling and Heat Treatment Process on Mechanical Properties of Extra-thick 3Cr2NiMo Steel Plate
    KONG Lingyi, LUO Zongan, FENG Yingying, WU Zaoqin
    Journal of Netshape Forming Engineering. 2025, 17(7): 52-61. https://doi.org/10.3969/j.issn.1674-6457.2025.07.006
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    The work aims to fabricate extra-thick 3Cr2NiMo steel plate, in order to solve the problems of weld cracking, poor interface strength and toughness and uneven hardness of 3Cr2NiMo steel during welding. After preheating of 2 pieces of 3Cr2NiMo steel, the blank edges were sealed by vacuum electron beam welding under 5×10-2 Pa vacuum condition, and then the composite billets were combined by different rolling processes. Next, tempering heat treatment was carried out to solve the problem of uneven hardness. With the increase of the rolling reduction rate, the size of the oxide at the composite interface became smaller. At a reduction rate of 70%, there was no obvious oxide at the interface, and the matrix structure on both sides of the interface was lower bainite. After tempering at 630 ℃ for 3 h and cooling with the furnace, the microstructure on both sides of the interface was relatively uniform, and the oxide size of the composite interface decreased, which was conducive to the improvement of the interface strength. After tempering, the hardness of the blank with the reduction rate at 50% and 70% was between 28HRC-32HRC along the thickness direction, meeting the requirements of the mold industry. After tempering, the z-tensile fracture position of the specimen with the reduction rate at 70% was not at the interface and the neck shrinkage appeared, which was ductile fracture. The tensile strength reached 971 MPa and the elongation reached 22.5%, showing good metallurgical bonding quality. The problems of poor interface strength and toughness and uneven hardness of 3Cr2NiMo steel are solved successfully by the rolling process with 70% reduction rate and the furnace cooling method after tempering at 630 ℃ for 3 h.
  • Synergistic Mechanisms of Electropulsing-induced Dynamic Recrystallization and Low-temperature Dissolution of β-Mg17Al12 Phase in AZ31 Magnesium Alloy
    GAO Xiangyu, YAN Renjie, ZHANG Tao, WANG Yanyan, GUO Yinglong, ZOU Jinchao
    Journal of Netshape Forming Engineering. 2025, 17(7): 62-68. https://doi.org/10.3969/j.issn.1674-6457.2025.07.007
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    The work aims to systematically investigate the effect of electropulsing treatment (EPT) on the microstructural evolution and mechanical properties of rolled AZ31 magnesium alloy. By regulating current density and frequency, combined with metallographic observation, XRD analysis, mechanical testing, and fractography characterization, the synergistic mechanisms of EPT-induced dynamic recrystallization and low-temperature dissolution of the β-Mg17Al12 phase were revealed. The combined effects of Joule heating and electron wind force significantly promoted equiaxed grain refinement. Under optimized parameters (37.5 A/mm2, 200 Hz), the grain size was refined from 24.59 μm (as-rolled) to 18.65 μm, accompanied by a 133% increase in elongation and a marginal 7.2% reduction in tensile strength. XRD analysis revealed that the β phase underwent athermal dissolution below 250 ℃. This phenomenon was attributed to the electron wind force driving the diffusion of Al atoms, while the pulsed current-induced dislocation multiplication generated interfacial defects, providing additional diffusion pathways for atoms and thereby promoting the dissolution of the β phase. Fracture morphology transitioned from a mixed brittle-ductile mode to a fully ductile mode, with dimple density and size exhibiting significant optimization as recrystallization progressed. Microhardness testing indicated a gradual decline in hardness with the increasing current density and frequency, which was consistent with reduced dislocation density and enhanced recrystallization. EPT effectively improves the strength-ductility balance of AZ31 alloy through grain refinement, dissolution of brittle phases, and dislocation elimination, offering critical theoretical insights and technical guidance for advancing short-process precision forming technologies in magnesium alloy applications.
    • Iron and Steel Forming
  • Microstructure and Properties of Laser Tailor Welded Joints of QP1180/DP1180 Steel Plates with Different Thicknesses
    LI Wenjuan, WANG Jinfeng, SU Wenchao, CHE Yajun, WANG Jing, GUO Yi, WANG Hailin, ZHANG Yuanhao
    Journal of Netshape Forming Engineering. 2025, 17(7): 69-78. https://doi.org/10.3969/j.issn.1674-6457.2025.07.008
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    In order to solve the welding problems of heat affected zone softening of high strength steel QP1180 and DP1180 in automobile lightweight application, the work aims to study the microstructure and properties of laser tailor welded joints of heterogeneous QP1180/DP1180 steel plates with different thicknesses. 1.6 mm thick QP1180 steel and 1.2 mm thick DP1180 steel were welded by laser. The effects of heat input on the microstructure and mechanical properties of welded joints were studied by scanning electron microscopy, hydraulic tensile testing machine and Vickers hardness tester. Under different welding process parameters, the laser welded joints were in full penetration state, and the weld surface was well. With the increase of heat input, the transition from the weld metal zone to the base metal zone gradually became gentle, the depression became smaller, and the width of the weld face and back of weld increased. The lath martensite beam in the weld metal zone became longer with the increase of heat input, and the beam spacing became wider, and the width distribution was not uniform. The effects of heat input on the change of grain size in the heat affected zone of QP1180 side and DP1180 side were basically the same. The higher the heat input, the coarser the grain size of the coarse-grain zone and the fine-grain zone, and the more the ferrite content in the inter-critical heat affected zone. There were more carbide particles precipitated in the sub-critical heat affected zone on the QP1180 side, but the effect on the microstructure of the sub-critical heat affected zone on the DP1180 side was not obvious. There were obvious softening zones on both sides of the welded joint, and the softening of DP1180 side was more significant. Under the welding heat input conditions used in this study, the fracture of the samples in the uniaxial tensile test was located in the base metal area. Through fractography, the samples under all process parameters had ductile fracture. In the welding process window that can form full penetration bead, the welded joints with tensile strength of more than 95% of the base metal strength and the elongation of more than 30% of the base metal are obtained.
  • Forming of Double Spot Laser Welded Joints of Heterogeneous DP780/DP590 Dual Phase Steel with Different Thicknesses
    WANG Jiahao, LIU Yan, LIU Xiaoang, ZHANG Wenguang
    Journal of Netshape Forming Engineering. 2025, 17(7): 79-88. https://doi.org/10.3969/j.issn.1674-6457.2025.07.009
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    The work aims to reduce the welding defects by double spot laser welding process and investigate the effects of different process parameters on the macroscopic morphology of welded joints of unequal-thickness heterogeneous dual phase steels DP780 and DP590. Two kinds of dual phase steels, DP780 and DP590, were laser welded with Trudisk 5000 dual spot laser from TRUMPF. The macroscopic morphology of the front and back faces of welded joints and the depth and width of melt in the weld cross-section under different parameters were investigated by metallographic microscope. With the increase of laser power from 3 000 W to 5 000 W, the welding heat input gradually increased, the melt width of the weld increased, and when the laser power was 5 000 W, the melt width of the weld at front and back was the largest, and the welded joints were well formed. With the increase of the welding speed from 100 mm/min to 300 mm/min, the welding heat input decreased with the increasing temperature, the melt width of the weld showed an overall trend of decrease, and the depth of fusion firstly increased and then decreased. As the core-ring ratio increased from 55% to 75%, the melt depth and melt width firstly increased and then decreased. As the defocusing amount increased from -2 mm to 2 mm, the spot focusing plane rose gradually from the inside of the workpiece, the melt width of the weld firstly decreased and then increased, and when the defocusing amount was 2 mm, the weld width was the largest, with the optimal forming. In summary, the effects of laser speed and the core-ring ratio on the formation of welded joints are more significant. Under the welding parameters of laser power of 5 000 W, welding speed of 200 mm/min, core-ring ratio of 65%, and defocusing amount of 2 mm, the best forming results are obtained for the double spot laser welded joints of DP780 dual phase steel sheet with a thickness of 1.2 mm and DP590 dual phase steel sheet with a thickness of 1.4 mm.
  • Temperature and Deformation Distribution during Hot Continuous Rolling Process of WP720 Super Weathering Resistant Steel
    SU Zexing, LI Menglin, LI Liren, LIU Chengzhi, CHENG Shengwei, LIU Xifeng, KANG Jianguang, LI Taotao
    Journal of Netshape Forming Engineering. 2025, 17(7): 89-95. https://doi.org/10.3969/j.issn.1674-6457.2025.07.010
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    The work aims to study the temperature and deformation distribution during the hot continuous rolling process of WP720 super weathering resistant steel, to provide theoretical guidance for optimizing the hot continuous rolling process of super weathering resistant steel. A thermo-mechanical coupled finite element model for the hot continuous rolling process of WP720 super weathering resistant steel was established. The multi-pass rolling process was numerically simulated, and the distribution characteristics of temperature and effective strain during the rolling process were analyzed. The finite element simulation results showed that the temperature of the surface changed drastically, while the internal temperature changed relatively slowly. The surface temperature of the rolled plate first decreased and then increased; the internal temperature of the rolled plate first increased and then decreased. The temperature distribution along the width of the rolled plate was high value at the center and low at the edge. The final rolling temperature differed by 30 ℃ between the center and the edge. Due to the frictional effect in the contact area between the rolling plate and the rolling mill, the plastic strain concentrated on the surface region of the rolled plate, and gradually expanded toward the interior as the number of passes increased, and the surface still maintained the maximum value. The surface plastic strain eventually stabilized at 4.07, while the internal plastic strain stabilized at 3.11. During the rolling process, the temperature difference between the surface and the core of the rolled plate is significant, but there is an overall decreasing trend. In the direction of the plate width, the temperature at the center is higher than that at the edges. The equivalent plastic strain of the rolled plate accumulates significantly with each pass, especially with more pronounced strain accumulation in the contact region.
  • Resistance Spot Welding and Laser Spiral Spot Welding Processes for Q235 Steel with Phosphide Coating
    XU Ping, CHEN Ming, WANG Chongrui, ZHOU Aobo, GUO Tao, XIE Dianbao, FAN Donghui
    Journal of Netshape Forming Engineering. 2025, 17(7): 96-101. https://doi.org/10.3969/j.issn.1674-6457.2025.07.011
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    The work aims to investigate the effects of resistance spot welding and laser spiral spot welding on the microstructure and mechanical properties of Q235 steel with phosphide coatings. Two different welding technologies of resistance spot welding and laser spiral spot welding were used to conduct spot welding tests on Q235 steel specimens with phosphide coatings. Then, the appearance, microstructure, microhardness, and shear strength of the two types of spot welding joints were compared. Based on this, the process and mechanical properties of laser spiral spot welding joints under different test piece spacing were studied. The laser spiral spot welding process had better adaptability to working conditions. The melting situation of the laser spiral spot welding joint test piece was better than that of the resistance spot welding, and it had a higher shear strength. However, resistance spot welding joints had higher microhardness, which could reach up to about 350HV. The spacing of laser spiral spot welding had a significant impact on the mechanical properties of the welding joint. As the spacing increased, the microhardness improved which could reach up to 240HV. Appropriately increasing the spacing was also beneficial to improving the maximum tensile force, which could reach 15.27 kN. The fracture mode of the laser spiral spot welding joint was tear-out, while that of the resistance spot welding joint was pull-out. The maximum tensile strength of the laser spiral spot welding was greater than that of the resistance spot welding. By comparing the two welding processes, it is known that the tensile and shear performance of laser spiral spot welding is better than that of resistance spot welding, and the process adaptability is better, but the resistance spot welding joint has higher microhardness.
  • Microstructure Evolution of Fe-3.5%Si Non-oriented Silicon Steel Prepared by Double Cold Rolling
    WANG Yi'nan, LU Huihu, LIN Yuan, GU Xiangyu, QIAO Weidong, YANG Shengchao, QI Chengzhe, LI Zeyang
    Journal of Netshape Forming Engineering. 2025, 17(7): 102-109. https://doi.org/10.3969/j.issn.1674-6457.2025.07.012
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    The work aims to take the 3.5wt.% Si non-oriented silicon steel as the research object and investigate the evolution of microstructure and texture of the 0.25 mm thick non-oriented silicon steel by double cold rolling. The microstructure and properties of the non-oriented silicon steel during preparation were studied through cold rolling, heat treatment, EBSD and tensile test at room temperature. The surface layer of the hot rolled plate was partially recrystallized and consisted of shear bands, recovery structures and fine equiaxed crystals, and there were a lot of shear bands and deformation bands in the center layer. The surface layer was mainly composed of Goss texture, and the central layer was composed of Fan-sharp α fiber texture. Complete recrystallization occurred after normalization at 950 ℃×3 min, and the average grain size was (147.6±1.9) μm. α fiber texture was transformed into α* fiber texture. The α-fiber texture and γ-fiber texture of the first cold rolled plate were completely recrystallized after annealing at 950 ℃×3 min. The average grain size was (119.3±6.9) μm. In the secondary cold rolled plate, there were sharp $\{001\}\langle 1 \overline{1} 0\rangle$ texture and γ-fiber texture. After recrystallization and annealing at 960 ℃×3 min, the average grain size was (145.4±4.4) μm. The texture groups were divided into cubic, rotating cubic and Goss textures. The yield strength and elongation after annealing were 515.6 MPa and 11.6%. The high-strength non-oriented silicon steel was obtained by double cold rolling. The strengthening mechanism of yield strength is mainly solid solution strengthening, and the contribution value is 357.63 MPa, accounting for 67.63%. The magnetic inductance B5000 of the final annealed sample is 1.690 T and the iron loss P1.0/400 is 13.37 W/kg.
  • Creep-fatigue Fracture Mechanism and Microscopic Damage Behavior of New Martensitic Heat-resistant Steel
    ZHOU Chao, HUANG Jun, MA Dongliang, SU Kailong, DU Jinfeng, ZHAO Lei
    Journal of Netshape Forming Engineering. 2025, 17(7): 110-118. https://doi.org/10.3969/j.issn.1674-6457.2025.07.013
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    The work aims to investigate the failure behavior of martensitic heat-resistant steel under creep-fatigue loading conditions, to provide theoretical guidance for the high-temperature failure behavior of ultra-supercritical (USC) power plant units. The creep-fatigue behavior of G115 steel at 650 ℃ was systematically investigated. Tests were conducted under a stress-controlled mode with a stress amplitude range of 180-230 MPa and a stress ratio (R) of 0. A hold time ranging from 0 to 3 600 s was applied at the peak tensile stress. During the tests, a constant loading rate of 90 kN/min was employed, and the fracture mechanism and microstructural damage evolution of G115 steel under creep-fatigue loading were investigated. Prolonging the hold time and increasing the hold stress both led to a decrease in the creep-fatigue life of G115 steel. Characterization of the fractured specimens revealed that all fractured surfaces exhibited distinct creep necking characteristics. Statistical analysis of the morphology and quantity of cavities on the fracture cross-sections showed that at lower stress levels, cavities were predominantly coin-shaped and tended to coalesce to form microcracks, while at higher stress levels, isolated creep cavities were dominant. Additionally, the cavity density increased with longer hold time. Precipitates observed in G115 steel during creep-fatigue tests included M23C6 phase, Laves phase, and Cu-rich phase. The creep-fatigue micro-fracture mode of G115 steel is characterized by martensitic cracking and martensitic fracture. The rapid coarsening of the Laves phase weakens the precipitation strengthening effect, thereby promoting the nucleation and propagation of cavities and microcracks, which constitutes the primary failure mechanism of G115 steel under these conditions.
    • Light Alloy Forming
  • Preparation Technology, Application Status, and Development Trends of Copper-clad Aluminum Laminated Materials
    LIU Yujiang, DU Wenyu, WANG Yan, ZHOU Yisong, HU Hongjun, YI Zhihao, WANG Xingdong, ZHONG Tao
    Journal of Netshape Forming Engineering. 2025, 17(7): 119-137. https://doi.org/10.3969/j.issn.1674-6457.2025.07.014
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    With the rapid development of modern industry, copper-clad aluminum laminated materials have shown important application value in many fields due to the advantages of both copper's excellent conductivity and aluminum's light weight and low cost. This paper reviews the current status of the preparation technology, application areas and development trend of copper-clad aluminum laminated materials. In terms of preparation technology, copper-clad aluminum laminated material preparation methods are diverse, including horizontal continuous casting direct composite forming, horizontal core-filling continuous casting composite method, cladding casting, solid-liquid composite method, casting-cold extrusion technology, friction mixing welding, cumulative rolling bonding, triple-layer composite plate rolling, corrugated rolling and so on. These technologies have their own characteristics, respectively, for different production needs and material properties. For example, horizontal continuous casting direct composite forming technology, through continuous casting, directly composites copper and aluminum together, improving production efficiency and material consistency; Friction stir welding technology, through solid-state connection, avoids the defects of the traditional fusion welding, achieving high-strength, low heat-affected zone of the welding effect. Application areas cover electrical conductivity, heat dissipation signal transmission, electromagnetic shielding and so on. Copper-clad aluminum composite materials have become a key material in power transmission, electronic equipment, new energy vehicles, 5G communications and other fields, and show significant advantages especially in the need for lightweight design and requires high performance occasions. Looking to the future, the development trend of copper-clad aluminum laminated materials is mainly reflected in the optimization of preparation technology, performance improvement and the expansion of application areas. With the progress of science and technology and changes in market demands, copper-clad aluminum laminated materials are expected to play a more important role in the future.
  • Thermal Deformation Behavior and Microstructure Properties Evolution of LAZ931 MG-Li Alloy
    LYU Yunxiang, LU Zhen, WU Lianmei, LI Fei, YI Manman, GAO Shiqing, XIA Xiangsheng
    Journal of Netshape Forming Engineering. 2025, 17(7): 138-144. https://doi.org/10.3969/j.issn.1674-6457.2025.07.015
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    The work aims to investigate the thermal deformation behavior of LAZ931 MG-Li alloy, the impact of thermal deformation on its microstructure, and the influence of thermal deformation parameters on its mechanical properties. A hot compression deformation test was conducted on LAZ931 MG-Li alloy within a temperature range of 150-300 ℃ and strain rates of 10-3 to 1 s-1, yielding its hot compression curve. Its constitutive model and hot working diagram were established. The effect of hot deformation on the microstructure was examined. As-cast MG-li alloy was prepared by isothermal forging. The influence of deformation parameters on mechanical properties was explored. The microstructure of LAZ931 MLi-Laz931 alloy was significantly refined through dynamic recrystallization during the hot deformation process, and the grain size of the two phases gradually increased with the rise of deformation temperature and the decrease of the strain rate. Isothermal forging could significantly improve the mechanical properties of the alloy. As the deformation temperature increased and the strain rate decreased, the alloy's tensile strength and elongation exhibited a gradual decline. After forging at 250 ℃ and 10-2 s-1, the yield strength, tensile strength, and elongation reached 175 MPa, 195 MPa, and 21.8%, respectively. These values represent increases of 28%, 18%, and 82% compared with the original material. In conclusion, LAZ931 MG-Li alloy exhibits excellent hot working performance.
  • Effect of Different Heat Input on Microstructure and Properties of 7A52 Aluminum Alloy Oscillating MIG Welding Joints
    JIANG Chengyun, ZHU Jialei, WANG Chengyuan, QI Shikong, ZHANG Ziyue, LIU Ting, LI Zhehui
    Journal of Netshape Forming Engineering. 2025, 17(7): 145-152. https://doi.org/10.3969/j.issn.1674-6457.2025.07.016
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    The work aims to study the effects of oscillating MIG welding technology on the microstructural changes and weld joint formation. The research method involved conducting groove oscillating MIG welding experiments on 7A52 aluminum alloy plates with varying heat inputs and analyzing the resulting weld joints for microstructure and mechanical properties, including hardness and tensile tests. The results indicated that at a heat input of 8.56 kJ/mm, the weld joint demonstrated optimal formation and mechanical attributes. It had an average Vickers hardness of 111.7HV and the lowest hardness of 104.7HV was found in the weld area, whereas the heat affected zone (HAZ) exhibited the highest hardness, reaching 114.52HV. Tensile testing indicated that the specimen broke in the weld area with a strength of 361 MPa, which corresponded to 72% of the base material's tensile strength. In conclusion, as the heat input increases, there is a gradual decrease in the hardness of the weld zone. Furthermore, the right amount of heat input is beneficial for the development of slender, equiaxed grains, reducing recrystallization, and thus enhancing the tensile strength of the weld joint.
    • Additive Manufacturing
  • Selective Laser Melting Additive Manufacturing, Heat Treatment and Property Study of Fe-20Cr-5Al Alloy
    NI Xiaonan, MING Liang, HU Zijian, YANG Wenxin, WANG Ansen, DENG Xin
    Journal of Netshape Forming Engineering. 2025, 17(7): 153-163. https://doi.org/10.3969/j.issn.1674-6457.2025.07.017
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    The work aims to explore the application potential of FeCrAl alloys in additive manufacturing, particularly through optimizing process parameters with Selective Laser Melting (SLM) technology, in order to improve the microstructure, mechanical properties, and oxidation resistance of the alloy, thereby providing theoretical support and practical guidance for engineering applications. Based on the Response Surface Methodology (RSM), the SLM process parameters were optimized to determine the best processing conditions, and the Fe-20Cr-5Al alloy was printed with SLM technology. Under the optimized processing conditions, the relative density of the Fe-20Cr-5Al alloy printed by SLM reached 98.6%. The as-printed alloy exhibited a tensile strength of 824.8 MPa and an elongation of 12.3%. After heat treatment, the tensile strength slightly decreased, but the elongation increased to 20.5%. Furthermore, the alloy demonstrated complete oxidation resistance at 800 ℃, with an oxidation rate of 0.042 g/(m²·h) at 1 000 ℃, and maintained good oxidation resistance even after 80 hours of oxidation. Through the optimization of SLM process parameters, this study provides important theoretical and practical guidance for the application of FeCrAl alloys in additive manufacturing, demonstrating the superior performance of the alloy in high-temperature environments and its promising prospects for engineering applications.
  • Structure of Hydrogel Support for Graphene/SiC Composite Prepared by Dual Extruder 3D Printer
    WU Xuexue, LIU Hongjun, LI Yajun, TANG Run, YATSKOVSKYI Dmytro, LI Yamin
    Journal of Netshape Forming Engineering. 2025, 17(7): 164-174. https://doi.org/10.3969/j.issn.1674-6457.2025.07.018
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    The work aims to provide reference for designing the structure of hydrogel support for preparation of graphene/SiC composite by dual extruder 3D printer. Firstly, the starch-based hydrogel was prepared and its rheological properties, ablative properties, formability of extruded filaments and load capacity were analyzed. Then, the effects of structural pattern, printing direction and filling ratio on the accuracy of hydrogel support were investigated through the printing of 3D grid samples, and the matching span between support composites was optimized. Finally, the optimized parameters were applied to hydrogels and parts with complex structures were prepared. When the inclination angle of graphene/SiC composites was lower than 70°, the wedge-shaped parts were obviously deformed, and the hydrogel showed obvious shear thinning characteristics. After ablation at 800 ℃, there was almost no residue, and the extruded filaments were complete and uniform, which could independently load 8 mm high composites. Different structural patterns were rectilinear, honeycomb, wiggle and triangular in order of support height deviation from small to large. The deviation in the height direction for the rectilinear pattern was the smallest ((+0.08±0.23) mm) at printing direction 0° and the largest at printing direction 30°, and the range of error line was widest ((+0.48±0.3) mm). With the increase of filling ratio, the effect of filling ratio on height deviation first decreased and then increased. When the filling ratio was 50%, the height deviation of hydrogel support was the smallest. There should be a certain span between graphene/SiC composite and hydrogel support, but when the span exceeded 1 mm, the suspended position was obviously deformed. The trial-production results of parts showed that the optimized hydrogel support structure could be used to prepare graphene/SiC composites with complex structures. Hydrogel has low cost, good extrusion forming, less sintering residue, simple removal process and certain load capacity, and can be used as a support material for preparation of graphene/SiC composites by dual extruder 3D printer. The optimized parameters of hydrogel support structure are linear mode, printing direction 0°, filling ratio of 50%, and matching span of the two materials of 1 mm.
    • Composites Forming
  • Effects of Solid Solution and Cryogenic Deformation on AlCoCrFeNi-HEAp/2219Al Composites
    YANG Yilong, ZHANG Yun
    Journal of Netshape Forming Engineering. 2025, 17(7): 175-182. https://doi.org/10.3969/j.issn.1674-6457.2025.07.019
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    The work aims to address the issue of coarse Al-Cu crystalline phases and mismatched strength and toughness in AlCoCrFeNi HEAp/2219Al composites. Three deformation processes of high temperature rolling, cryorolling, and solution treatment+cryorolling were used to study the microstructure and mechanical properties of AlCoCrFeNi-HEAp/2219Al composites. It was found that the composites after the high temperature rolling process had the lowest Al-Cu crystalline phase content, only 0.68%. The large amount of broken crystalline phases presented in the matrix after cryorolling and solution treatment+cryorolling further promoted the diffusion of the Cu element. The composite had the highest ultimate tensile strength (361.63 MPa) after high temperature rolling at 90% thickness reduction. Under the same deformation conditions, the composites obtained the highest strength increment (56.95 MPa) after solution treatment+cryorolling with almost no loss of fracture elongation. In conclusion, a large number of dislocations are generated in the composites, with the highest dislocation density observed in the solution treatment+cryorolling process after three deformation processes. High density dislocations accumulate around the Al-Cu phase, leading to the fragmentation of the primary Al-Cu phase. The combination of solution treatment and cryorolling caused significant element diffusion in the crystalline phase, resulting in a decrease in the Al-Cu content in the matrix. The high-density dislocations accumulated during cryorolling also break and disperse along the grain boundaries of the elongated crystalline phase. The ultimate tensile strength and yield strength of the composites increase with the increase of deformation, but the fracture elongation shows a gradual decreasing trend. Through comparative research, the solution treatment+cryorolling forming process can effectively improve the mechanical properties of composites.
  • Research Status of Cold Pressing Sintering Technique in Dielectric Composites
    WANG Xu, WU Yong, LI Jiang, CHENG Zaiqi, LI Chongxiu, LIU Ben, QIAO Zhengyang
    Journal of Netshape Forming Engineering. 2025, 17(7): 183-192. https://doi.org/10.3969/j.issn.1674-6457.2025.07.020
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    With the burgeoning advancement of modern technology, the demand for dielectric composites in electronics, energy storage, sensors, and other fields continues to rise. Their dielectric properties play a critical role, particularly in energy storage applications such as capacitors and sensing technologies. Traditional sintering techniques for fabricating ceramic materials typically require high-temperature processing, which not only consumes significant energy but may also induces detrimental phase transformation and excessive grain growth. To address these challenges, cold pressing sintering has emerged as a novel ultra-low-temperature processing method. This approach not only significantly enhances the dielectric property of composites but also preserves the flexibility and other advantageous properties of polymer matrices, thereby demonstrating substantial potential for diverse applications. In this review, the work systematically elucidates the fundamental principles of cold pressing sintering, with a focus on its mechanisms for optimizing dielectric properties (e.g., dielectric constant, breakdown strength, and thermal stability) at low temperature. It further examines recent advances in cold pressing sintering for enhancing dielectric properties and discusses the current challenges and future prospects for practical implementation.
    • Superalloy Forming
  • Hot Deformation Behavior and Dynamic Recrystallization Modeling and Simulation of GH6159 Superalloy
    ZENG Xiang, LIAO Runze, XU Xuefeng, TU Qiqi, CHEN Xiaoxiao, LUO Jie, FAN Xu, HUANG Leheng, LIU Jie
    Journal of Netshape Forming Engineering. 2025, 17(7): 193-205. https://doi.org/10.3969/j.issn.1674-6457.2025.07.021
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    The work aims to obtain the deformation behavior and microstructure evolution laws of GH6159 superalloy through hot compression experiments and microstructure analysis, to provide theoretical support for optimizing the hot working process. Thus, a study on microstructure evolution laws of GH6159 was carried out. Thermal compression experiments were carried out on GH6159 superalloy with a Thermecmastor-Z thermal simulation tester to obtain the stress-strain curves of the alloy at 0.1-10 s-1 and 900-1 100 ℃. True stress-true strain curves were modified using frictional and deformation-thermal corrections formulae, and modified Arrhenius model and dynamic recrystallization (DRX) model were established. Meanwhile, the microstructure characteristics of specimens at different temperature and strain rates were analyzed by Electron Backscatter Diffraction (EBSD). Then, a finite element compression model of GH6159 superalloy was established. DRX behavior of GH6159 superalloy in the hot working process was predicted with the established DRX model. GH6159 superalloy exhibited an obvious flow softening phenomenon and a large amount of DRX appeared during hot deformation. Via simulation prediction and experimental comparison, DRX volume fractions were 81.3%, 83.7%, 78.5%, and 82.7% at 900 ℃-0.01 s-1, 1 100 ℃- 0.01 s-1, 900 ℃-10 s-1, and 1 100 ℃-10 s-1, respectively, which agreed well with the results of EBSD. The DRX volume fraction is sensitive to deformation temperature and strain rates. High strain rates and low temperature show low dynamic recrystallization volume fraction and poor microstructure homogeneity, while the dynamic recrystallization volume fraction is high and microstructure homogeneity is good at low strain rates and high temperature. The established dynamic recrystallization model has a high accuracy by comparison of experiment and finite element simulation.
  • Research Progress on Precision Rolling Technology of Nickel Based High-temperature Alloy Ultra-thin Strip
    XU Chao, WU Wei, WU Yong, MENG Gang, WANG Fangjun, LIU Haiding, WANG Dongzhe, XIAO Jun
    Journal of Netshape Forming Engineering. 2025, 17(7): 206-218. https://doi.org/10.3969/j.issn.1674-6457.2025.07.022
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    Nickel based high-temperature alloy ultra-thin strips are widely used in the field of high-end equipment manufacturing. Compared with traditional rolling, precision rolling technology has more advantages in controlling the surface/shape quality, mechanical properties, and size accuracy of nickel based high-temperature alloy ultra-thin strips. In this article, the processing capabilities and shape control methods of 6-high, 12-high, and 20-high precision rolling equipment are introduced; the reasons for the limited width of precision rolling of nickel based alloys are discussed; the formation mechanism of surface and plate shape defects during the rolling process of ultra-thin strips are discussed; the key control factors of ultra-thin strips precision rolling forming, including roll shape control, feature size, and rolling process are analyzed, focusing on the influence of convexity, intermediate rolls shifting, width, thickness, width to thickness ratio and other factors on the shape/performance control of nickel based high-temperature alloy ultra-thin strips; current application status of precision rolling forming technology for nickel based high-temperature alloy ultra-thin strips, including equipment design and manufacturing, application of online and offline detection technology, and comparison of domestic and foreign manufacturing levels, are summarized; the future research trend of ultra-thin strip rolling are analyzed, deriving a new method for ultra-thin strip rolling based on the crystal plastic deformation behavior by combining the study of ultimate rollable thickness with ultra-thin strips rolling technology. Finally, common conclusions and limitations are proposed, and precision rolling technology of nickel based high-temperature alloys ultra-thin strips will develop towards intelligence and greenness in the future.
    • Advanced Manufacturing Technology and Equipment
  • Design and Process Parameter Optimization of Double Helix Flow Channel for Polar Hot Rollers
    YAN Huajun, ZHOU Xuhang, YANG Guang, DAI Xuerui, YUAN Zhen'ge, WANG Baoyu, LIU Jinping, ZHOU Xingbang
    Journal of Netshape Forming Engineering. 2025, 17(7): 219-227. https://doi.org/10.3969/j.issn.1674-6457.2025.07.023
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    In order to achieve precise and uniform control of roller surface temperature, the work aims to carry out systematic research on the arrangement of flow channels and fluid velocity. The effect of the arrangement of single and double helix flow channels on the surface temperature of the roller was analyzed. Three equal pitch double flow channel schemes with pitch values of 40, 50, and 60 mm, as well as three non-uniform double flow channel schemes, were designed. Three hot oil velocities of 1, 2, and 3 mm/s were set, and a total of 18 hot flow channel working conditions were constructed. The ANSYS simulation software was used to simulate 18 working conditions and the effect of equal pitch, unequal pitch, and flow velocity on the temperature of the roller was analyzed. The optimal solution for uniform temperature was obtained with the equal difference analysis method. The flow velocity had a significant impact on the surface temperature of the roller. With the increasing flow velocity, both convective heat transfer and thermal conduction resistance were enhanced. However, the enhancement of thermal conduction resistance was more significant. When the velocity reached a near value, the temperature increase reached its maximum. Therefore, a reasonable flow velocity was an important factor in ensuring the surface temperature of the roller. Under the condition of equal spacing flow channels, the smaller the channel spacing, the higher the temperature uniformity of the roller surface. Under the premise of satisfying channel strength and interference, the minimum channel spacing was taken as 40 mm. Under the condition of unequal spacing flow channels, the temperature uniformity of the roller surface was better than that of the equal pitch flow channel scheme. The optimal value for the flow channel spacing P2 in the mid-section of the roller was 70 mm, with a smallest temperature difference on the roller surface. When the flow velocity is 2.2 m/s, the temperature uniformity on the roller surface is the best. Under the condition of a minimum pitch of 40 mm, the minimum temperature difference on the roller surface is ±1.55 ℃. Under the unequal spacing condition with a mid-section channel pitch of P2=70 mm in the roller, the temperature difference on the roller surface is ±0.71 ℃, further improving the uniformity of roller surface temperature.
  • Study on the Compound Extrusion Process of Automobile Steering Knuckle Shaft Sleeve
    ZHANG Liangying, ZHAN Yanran, LU Jintao
    Journal of Netshape Forming Engineering. 2025, 17(7): 228-235. https://doi.org/10.3969/j.issn.1674-6457.2025.07.024
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    The work aims to study the compound extrusion process of automobile steering knuckle shaft sleeve, in order to improve the material utilization rate in the processing of automobile steering knuckle shaft sleeves and achieve ideal dimensional accuracy as well as better fatigue strength. Based on the cup-rod structural characteristics of automobile steering knuckle shaft sleeve, a method combining theoretical process analysis and forming simulation analysis was adopted. After comparison between the one-pass compound extrusion forming process scheme and the pre-processed compound extrusion process scheme, the final process scheme was determined. The metal flow law and equivalent strain distribution during compound extrusion were analyzed, and an extrusion die was designed for experimental verification. The compound extrusion process scheme for automobile steering knuckle shaft sleeve was as follows: machining, annealing and oxalate treatment, compound extrusion, and drilling. Under this scheme, the load borne by the punch exhibited a trend of “increasing-stabilizing-increasing again-slightly decreasing-significantly increasing”, with a lower maximum load and better die filling effect. During compound extrusion, the proportion of forward extrusion was much larger than that of backward extrusion. The diversion plane was mainly distributed from the lower section of the cup wall to the 35° cone angle, and the interface exhibited a trend of “blurry-clear-blurry” as the punch descended. The maximum equivalent strain was mainly distributed in the area where the dimensions of the part changed. The laws of metal flow and equivalent strain distribution during compound extrusion can provide a certain theoretical basis for the promotion and application of compound extrusion technology for similar parts. The pre-processed compound extrusion process for forming automobile steering knuckle shaft sleeves is reasonable and can fulfill the requirements of actual mass production.
  • Influence of Decorative Film Thickness on Molding Quality of MIM-IMD Products
    JIN Xin, LIANG Xiangjing, HUANG Changyi, HUANG Zhenmin, YAN Kui, GUO Wei
    Journal of Netshape Forming Engineering. 2025, 17(7): 236-245. https://doi.org/10.3969/j.issn.1674-6457.2025.07.025
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    The work aims to investigate the regulation mechanism of polypropylene (PP) decorative film thickness on the properties of microcellular foaming-in-mold decorating (MIM-IMD) injection molded products, to optimize the bubble structure, surface quality and mechanical properties. Using the MIM-IMD process, mechanical tests were conducted on samples with different film thicknesses by controlling the thickness of the decorative film (0.10-0.30 mm), and combined with scanning electron microscopy (SEM) to observe the blister hole structure and the surface morphology. When the thickness of the decorative film increased, the maximum diameter of core layer vesicles rose perpendicular to the direction of the melt flow, the average diameter and density of vesicles rose and then fell; and parallel to the direction of the melt flow, the thickness of the core layer decreased, the average diameter of vesicles rose, the density of vesicles rose and then fell, and the average diameter and density of vesicles on the coated side was higher than that on the non-film side; When the film thickness was 0.1 mm, the surface defects of the foamed parts were fewer and the surface roughness was the lowest, and the pores and depressions increased with the increase of the film thickness. The tensile strength, bending strength and impact strength of the foamed part surface showed an upward trend as the film thickness increased. Decorative film thickness significantly affects the asymmetric distribution of the bubble structure. When the thickness of the decorative film increases, the hysteresis effect is enhanced, the melt temperature on the coated side increases, providing more time for the growth of the vesicles. When the film thickness is more than 0.2 mm, the gas escape is intensified, and the quality of the vesicles decreases. The decorative film is effective in improving the surface quality. But after the increase in the thickness of the film, the film can be heated to higher temperatures by the melt, resulting in the increase of the surface defects in the foamed parts. The decorative film improves the mechanical properties of the foamed parts by improving the internal structure of the vesicles, and the increased thickness of the film can further enhance the protection of the substrate.
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