目的 研究马氏体耐热钢在蠕变-疲劳载荷下的失效行为,为超超临界机组的高温失效行为提供理论指导。方法 系统开展了G115钢在650 ℃高温环境下的蠕变-疲劳行为研究。采用应力控制模式进行试验,应变幅值范围为180~230 MPa,应力比为0。在峰值拉伸应力处设置0~3 600 s的保载时间。在试验过程中,采用90 kN/min的恒定加载速率,并针对G115钢在蠕变-疲劳载荷下的断裂机制以及微观损伤演化开展研究。结果 延长保载时间及增大保载应力均会导致G115钢蠕变-疲劳寿命下降。通过对断后试样进行表征,发现所有试样断口表现出明显的蠕变颈缩特征。断口截面的孔洞形态与数量统计分析结果显示,在较低应力水平下,孔洞主要呈硬币状且易于聚合形成微裂纹;而在较高应力水平下,则以孤立的蠕变孔洞为主。同时,孔洞密度随保载时间的延长而增大。G115钢蠕变-疲劳试验中析出物包括M23C6相、Laves相以及富Cu相。结论 G115钢蠕变-疲劳微观断裂模式表现为马氏体裂纹与马氏体断裂;Laves相的快速粗化削弱了沉淀强化效应,进而促进了孔洞与微裂纹的形核及扩展,这构成了G115钢在该条件下的核心失效机制。
Abstract
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.
关键词
G115钢 /
蠕变-疲劳 /
断裂机制 /
孔洞和微裂纹 /
微观组织演化
Key words
G115 steel /
creep-fatigue /
fracture mechanism /
cavities and microcracks /
microstructural evolution
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参考文献
[1] 米大为, 沈天阔, 宿希慧, 等. 核电站控制棒驱动机构Canopy焊缝焊接温度场和应力-应变场模拟[J]. 精密成形工程, 2024, 16(2): 182-189.
MI D W, SHEN T K, SU X H, et al.Simulation of Welding Temperature Field and Stress-Strain Field of Canopy Welded Seam in Control Rod Drive Mechanism of Nuclear Power Plant[J]. Journal of Netshape Forming Engineering, 2024, 16(2): 182-189.
[2] 赵雷, 冯国才, 徐连勇, 等. 新型马氏体耐热钢蠕变-疲劳性能与寿命预测[J]. 焊接学报, 2022, 43(5): 1-7.
ZHAO L, FENG G C, XU L Y, et al.Creep-Fatigue Properties and Life Prediction Method of New Martensitic Heat Resistant Steel[J]. Transactions of the China Welding Institution, 2022, 43(5): 1-7.
[3] 何焕生, 余黎明, 刘晨曦, 等. 新一代马氏体耐热钢G115的研究进展[J]. 金属学报, 2022, 58(3): 311-323.
HE H S, YU L M, LIU C X, et al.Research Progress of a Novel Martensitic Heat-Resistant Steel G115[J]. Acta Metallurgica Sinica, 2022, 58(3): 311-323.
[4] 刘正东, 陈正宗, 何西扣, 等. 630~700 ℃超超临界燃煤电站耐热管及其制造技术进展[J]. 金属学报, 2020, 56(4): 539-548.
LIU Z D, CHEN Z Z, HE X K, et al.Systematical Innovation of Heat Resistant Materials Used for 630- 700 ℃ Advanced Ultra-Supercritical(a-USC)Fossil Fired Boilers[J]. Acta Metallurgica Sinica, 2020, 56(4): 539-548.
[5] 万夫伟, 郭新芳, 马志宝, 等. G115大壁厚管道GTAW+ TIP TIG焊接工艺[J]. 焊接技术, 2021, 50(12): 71-74.
WAN F W, GUO X F, MA Z B, et al.GTAW+TIP TIG Welding Process of G115 Large Wall Thickness Pipeline[J]. Welding Technology, 2021, 50(12): 71-74.
[6] XIAO B, YADAV S D, ZHAO L, et al.Deep Insights on the Creep Behavior and Mechanism of a Novel G115 Steel: Micromechanical Modeling and Experimental Validation[J]. International Journal of Plasticity, 2021, 147: 103124.
[7] XIAO B, XU L Y, CAYRON C, et al.Solute-Dislocation Interactions and Creep-Enhanced Cu Precipitation in a Novel Ferritic-Martensitic Steel[J]. Acta Materialia, 2020, 195: 199-208.
[8] XIAO B, XU L Y, TANG Z X, et al.A Physical-Based Yield Strength Model for the Microstructural Degradation of G115 Steel during Long-Term Creep[J]. Materials Science and Engineering: A, 2019, 747: 161-176.
[9] 周任远, 翟国丽, 朱丽慧, 等. G115钢650 ℃蠕变试验不同时间后的微观组织和硬度[J]. 上海金属, 2021, 43(4): 7-12.
ZHOU R Y, ZHAI G L, ZHU L H, et al.Microstructure and Hardness of G115 Steel after Creep Testing at 650 ℃ for Different Lengths of Time[J]. Shanghai Metals, 2021, 43(4): 7-12.
[10] 罗振轩. G115马氏体耐热钢高温低周疲劳行为及微观组织研究[D]. 天津: 天津大学, 2018.
LUO Z X.Study on Low Cycle Fatigue Behavior and Microstructure of G115 Martensite Heat Resistant Steel at High Temperature[D]. Tianjin: Tianjin University, 2018.
[11] SONG K, WANG K M, ZHAO L, et al.A Combined Elastic-Plastic Framework Unifying the Various Cyclic Softening/Hardening Behaviors for Heat Resistant Steels: Experiment and Modeling[J]. International Journal of Fatigue, 2022, 158: 106736.
[12] SONG K, ZHAO L, XU L Y, et al.A Modified Energy Model Including Mean Stress and Creep Threshold Stress Effect for Creep-Fatigue Life Prediction[J]. Fatigue & Fracture of Engineering Materials & Structures, 2022, 45(5): 1299-1316.
[13] LI K S, WANG R Z, XU L, et al.Life Prediction and Damage Analysis of Creep-Fatigue Combined with High-Low Cycle Loading by Using a Crystal Plasticity-Based Approach[J]. International Journal of Fatigue, 2022, 164: 107154.
[14] ZHANG T Y, WANG X W, ZHOU D W, et al.A Universal Constitutive Model for Hybrid Stress-Strain Controlled Creep-Fatigue Deformation[J]. International Journal of Mechanical Sciences, 2022, 225: 107369.
[15] SONG K, WANG K M, ZHAO L, et al.A Physically-Based Constitutive Model for a Novel Heat Resistant Martensitic Steel under Different Cyclic Loading Modes: Microstructural Strengthening Mechanisms[J]. International Journal of Plasticity, 2023, 165: 103611.
[16] ZHANG T Y, WANG X W, XIA X X, et al.A Robust Life Prediction Model for a Range of Materials under Creep-Fatigue Interaction Loading Conditions[J]. International Journal of Fatigue, 2023, 176: 107904.
[17] ZHANG T Y, WANG X W, JI Y N, et al.P92 Steel Creep-Fatigue Interaction Responses under Hybrid Stress-Strain Controlled Loading and a Life Prediction Model[J]. International Journal of Fatigue, 2020, 140: 105837.
[18] ZHANG T Y, WANG X W, JI Y N, et al.Cyclic Deformation and Damage Mechanisms of 9%Cr Steel under Hybrid Stress-Strain Controlled Creep Fatigue Interaction Loadings[J]. International Journal of Fatigue, 2021, 151: 106357.
[19] ZHANG T Y, WANG X W, ZHANG C N, et al.Revealing the Influences of Strain Amplitudes on Hybrid Stress-Strain Controlled Creep-Fatigue Interaction Responses for 9% Cr Steel[J]. Engineering Fracture Mechanics, 2023, 289: 109415.
[20] ZHOU D W, WANG X W, WANG R Z, et al.An Extended Crystal Plasticity Model to Simulate the Deformation Behaviors of Hybrid Stress-Strain Controlled Creep-Fatigue Interaction Loading[J]. International Journal of Fatigue, 2022, 156: 106680.
[21] XIAO B, XU L Y, ZHAO L, et al.Tensile Mechanical Properties, Constitutive Equations, and Fracture Mechanisms of a Novel 9% Chromium Tempered Martensitic Steel at Elevated Temperatures[J]. Materials Science and Engineering: A, 2017, 690: 104-119.
[22] CAI H Y, XU L Y, ZHAO L, et al.Microstructure and Mechanical Properties of 9Cr-3Co-2.9W-CuNbV Steel Welded Joints Processed by Different Tungsten Inert Gas (TIG) Welding[J]. Materials Characterization, 2023, 199: 112840.
[23] XIAO B, XU L Y, ZHAO L, et al.Microstructure Evolution and Fracture Mechanism of a Novel 9Cr Tempered Martensite Ferritic Steel during Short-Term Creep[J]. Materials Science and Engineering: A, 2017, 707: 466-477.
[24] LIU Z, LIU Z D, WANG X T, et al.Investigation of the Microstructure and Strength in G115 Steel with the Different Concentration of Tungsten during Creep Test[J]. Materials Characterization, 2019, 149: 95-104.
[25] GAO Q Z, YUAN Z, MA Q S, et al.Strengthening and Toughening Optimizations of Novel G115 Martensitic Steel: Utilizing Secondary Normalizing Process[J]. Materials Science and Engineering: A, 2022, 852: 143621.
[26] ZHANG J W, YU L M, GAO Q Z, et al.A New Strategy to Improve the Creep Strength of a Novel G115 Steel by Accelerating the Precipitation of Nano-Sized MX and Cu-Rich Particles[J]. Scripta Materialia, 2022, 220: 114903.
基金
国家能源投资集团有限责任公司科技项目（GJNY, 22-97）
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