The work aims to quantitatively elucidate the specific effects of the ALCF on the surface morphology, the cross-sectional geometrical characteristics, and the microstructures of both the weld zone and heat-affected zone in 5052 aluminum alloy welds, to provide a theoretical basis for the precise control of CMT welding quality and joint microstructure. An automated robotic CMT welding platform was employed. Welding joints were fabricated by systematically varying only the ALCF (from -25% to +25%), while keeping the welding current (125 A), voltage (19.2 V), and speed (90 cm/min) constant. The weld surface morphology was documented via macroscopic photography. Stereomicroscopy was used to measure the weld penetration depth, width, and reinforcement height. Microstructural analysis, including the observation of equiaxed grains in the weld center, heat-affected zone width, and columnar grain width, was conducted systematically through metallurgical microscopy. With positive ALCF values, the weld surface exhibited uniform fish-scale patterns and superior formation quality, whereas negative values led to spatter, oxidation, and degraded quality. The ALCF significantly affected penetration depth, with greater penetration observed in the negative ALCF range, reaching a maximum (at ALCF= -10%) that was 86.8% greater than the minimum value. The weld width variation was more moderate, with a maximum increase of 12.9%. As the ALCF increased from 0% to 25%, the average grain size of the equiaxed crystals in the weld center decreased from 102.8 μm to 90.5 μm. The maximum variation in the average width of the heat-affected zone was 279.8 μm. The maximum variation in the average width of columnar grains was 341.9 μm. The ALCF, by modulating the arc length and its stability, effectively alters the welding heat input and its distribution, thereby serving as an important means for controlling the macroscopic formation and microscopic microstructure of CMT aluminum alloy welds. The study findings confirm that increasing the positive ALCF can refine the equiaxed grains in the weld center and reduce the extent of the heat-affected zone, but it also leads to a decrease in penetration depth and may promote the coarsening of columnar grains. This study is expected to provide theoretical guidance and fundamental data for the precise design of CMT welding processes tailored to different performance requirements, such as deep penetration, superior surface quality, or a fine-grained microstructure.
Key words
CMT /
arc length correction factor /
weld formation /
weld penetration /
welding parameters
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
References
[1] 周星宇, 刘红伟, 田甜. 冷金属过渡(CMT)技术综述[J]. 材料导报, 2024, 38(S1): 422-430.
ZHOU X Y, LIU H W, TIAN T.A Review of Cold Metal Transition(CMT)Technologies[J]. Materials Reports, 2024, 38(S1): 422-430.
[2] SRINIVASAN D, SEVVEL P, SOLOMON I J, et al.A Review on Cold Metal Transfer (CMT) Technology of Welding[J]. Materials Today: Proceedings, 2022, 64: 108-115.
[3] 黄相山, 孟宇驰, 赵岩, 等. 新能源电池托盘用5083/6061异种铝合金搅拌摩擦焊接工艺研究[J]. 精密成形工程, 2025, 17(9): 103-114.
HUANG X S, MENG Y C, ZHAO Y, et al.Friction Stir Welding Process of 5083/6061 Dissimilar Aluminum Alloys for New Energy Battery Trays[J]. Journal of Netshape Forming Engineering, 2025, 17(9): 103-114.
[4] KOLI Y, ARAVINDAN S, RAO P V.Influence of Heat Input on the Evolution of δ-Ferrite Grain Morphology of SS308L Fabricated Using WAAM-CMT[J]. Materials Characterization, 2022, 194: 112363.
[5] ZHANG Z Q, YAN J P, LU X C, et al.Optimization of Porosity and Surface Roughness of CMT-P Wire Arc Additive Manufacturing of AA2024 Using Response Surface Methodology and NSGA-Ⅱ[J]. Journal of Materials Research and Technology, 2023, 24: 6923-6941.
[6] HU Y N, CHEN F R, CAO S L, et al.Preparation and Characterization of CMT Wire Arc Additive Manufacturing Al-5%Mg Alloy Depositions through Assisted Longitudinal Magnetic Field[J]. Journal of Manufacturing Processes, 2023, 101: 576-588.
[7] KARIM M A, JADHAV S, KANNAN R, et al.Investigating Stainless Steel/Aluminum Bimetallic Structures Fabricated by Cold Metal Transfer (CMT)-Based Wire-Arc Directed Energy Deposition[J]. Additive Manufacturing, 2024, 81: 104015.
[8] GAO Z N, LI Y F, SHI H Z, et al.Microstructure Characteristics under Varying Solidification Parameters in Different Zones during CMT Arc Additive Manufacturing Process of 2319 Aluminum Alloy[J]. Vacuum, 2023, 214: 112177.
[9] HUANG Y N, YANG L, XIN Q C.Novel Geometrical Model and Design Mechanical Parameters for CMT-WAAM Stainless Steel[J]. Journal of Constructional Steel Research, 2023, 210: 108071.
[10] SINGH S, PALANI I A, DEHGAHI S, et al.Influence of the Interlayer Temperature on Structure and Properties of CMT Wire Arc Additive Manufactured NiTi Structures[J]. Journal of Alloys and Compounds, 2023, 966: 171447.
[11] YANG S H, YANG X Y, LU X, et al.Strength Calculation and Microstructure Characterization of HAZ Softening Area in 6082-T6 Aluminum Alloy CMT Welded Joints[J]. Materials Today Communications, 2023, 37: 107077.
[12] YIN C X, SHEN J Q, HU S S, et al.Microstructure and Mechanical Properties of AZ91 Magnesium Alloy Fabricated by Multi-Layer and Multi-Pass CMT Based WAAM Technique[J]. Results in Engineering, 2023, 18: 101065.
[13] ZHANG L, WANG S T, WANG H X, et al.Investigate the Effect of Arc Characteristic on the Mechanical Properties of 5A56 Al Alloy in CMT Arc Additive Manufacturing[J]. CIRP Journal of Manufacturing Science and Technology, 2023, 40: 102-113.
[14] ZHANG Z Q, LI H X, HE S W, et al.Improving Forming Quality and Corrosion Resistance of CMT-P Additive Manufactured 2024 Aluminum Alloy Using Assisted Laser[J]. Journal of Manufacturing Processes, 2024, 124: 1025-1036.
[15] LIU L, CHEN H B, CHEN S B.Quality Analysis of CMT Lap Welding Based on Welding Electronic Parameters and Welding Sound[J]. Journal of Manufacturing Processes, 2022, 74: 1-13.
[16] LIU Y, LIU Z Z, ZHOU G S, et al.Microstructures and Properties of Al-Mg Alloys Manufactured by WAAM-CMT[J]. Materials, 2022, 15(15): 5460.
[17] KHAJURIA A, MISRA A, SHIVA S.On the Heat-Affected Zone Role for Mechanical Properties of Structural-Steel MIG and CMT-MIG Weldments[J]. Transactions of the Indian Institute of Metals, 2024, 77(11): 3905-3913.
[18] HE S, YANG D Q, HUANG Y, et al.Effect of the Current Waveform on the Droplet Transfer in CMT Welding High-Nitrogen Steel[J]. Journal of Manufacturing Processes, 2022, 75: 41-48.
[19] SINGH I J, MURTAZA Q, KUMAR P.Effect of Welding Speed on Metallurgical Characterization of CMT Welding of Dissimilar Aluminium Alloys of AA6061 and AA8011[J]. Silicon, 2024, 16(9): 3891-3903.
[20] KUMAR T, KIRAN D V, ARORA N, et al.Study of Steel-Aluminium Joining under the Influence of Current Waveforms Using Advanced CMT Process Variants[J]. Materials and Manufacturing Processes, 2022, 37(13): 1578-1595.
[21] SHANKER H, WATTAL R.Comparative Study of Microstructural and Mechanical Properties of Robotic CMT and GMAW Welded 7475-T7351 Aluminium Alloy Joints[J]. Materials Today Communications, 2023, 37: 106994.
[22] TAN C W, WANG B Q, ZHOU X H, et al.Improving the Formability and Quality of CMT Additively Manufactured Aluminum Thin-Wall Parts via Laser Stabilization Effect[J]. Optics & Laser Technology, 2025, 180: 111453.
[23] ZHANG X Y, DAI H J, WANG X Y, et al.Effect of Droplet Transition on Arc Morphology, Mn Evaporation and Microstructure during the CMT Welding with High Nitrogen Cr-Mn Steel[J]. Journal of Manufacturing Processes, 2023, 85: 527-543.
[24] GOU Q Z, ZHANG Z Q, XU L Y, et al.Heat and Mass Transfer Behavior in CMT Plus Pulse Arc Manufacturing[J]. International Journal of Mechanical Sciences, 2024, 281: 109638.
[25] 陈卫, 刘斌, 张琪飞, 等. CMT+P焊接行为及其AE特征频率[J]. 焊接学报, 2024, 45(6): 89-96.
CHEN W, LIU B, ZHANG Q F, et al.CMT+P Welding Behavior and AE Characteristic Frequency[J]. Transactions of the China Welding Institution, 2024, 45(6): 89-96.
[26] 朱轩, 杨晓益, 陆鑫, 等. 电弧脉冲对6005A-T6铝合金CMT-P焊接接头组织和性能的影响[J]. 材料导报, 2024, 38(23): 219-225.
ZHU X, YANG X Y, LU X, et al.Effect of Arc Pulse on Microstructure and Properties of 6005A-T6 Aluminum Alloy CMT-P Welded Joint[J]. Materials Reports, 2024, 38(23): 219-225.
Funding
The National Natural Science Foundation of China (51605201)
PDF(32072 KB)
