In this article, the microstructure, micro-hardness and low-cycle fatigue property of a 12Cr/30Cr2Ni4MoV welded joint have been studied. The results show that the microstructure of the 12Cr is lath tempered martensite, 30Cr2Ni4MoV is lath tempered martensite and granular tempered bainite. The microstructure of the buttering layer (BL) and weld metal (WM) is granular tempered bainite. WM is composed of columnar grain regions and equiaxed grain regions alternately. 30Cr2Ni4MoV has higher micro-hardness than 12Cr, and the BL is the lowest. Micro-hardness in the heat-affected zone (HAZ) is gradient change. 12Cr, 30Cr2Ni4MoV and BL show cyclic softening characteristics, while WM has initial cycle hardening and subsequent cyclic softening characteristics. BL has the highest fatigue transition life; the 12Cr/BL interface is the weakest link of the low-cycle fatigue of the entire heterogeneous welded joint. The second phase particles distributed in the grain boundary or sub-grain boundary of the columnar grains have uncoordinated deformation with the matrix of WM, which result in the initiation of fatigue cracks in second phase
XIONG Jiankun
,
SHANG Chunqiang
,
WU Haifeng
,
Wang Wenke
,
CAO Tainlan
,
ZHANG Jianxun
. Study on low-cycle fatigue property of 12Cr/30Cr2Ni4MoV heterogeneous joint[J]. Transactions of The China Welding Institution, 2021
, 42(2)
: 16
-23
.
DOI: 10.12073/j.hjxb.20200708003
[1] 朱明亮, 轩福贞, 梅林波. 汽轮机高、低压一体化转子材料及性能的研究进展[J]. 动力工程, 2008, 28(5): 664 ? 671
Zhu Mingliang, Xuan Fuzhen, Mei Linbo. Progression of investigation on high-low-pressure combined rotor materials and properties of the steam turbine[J]. Journal of Power Engineering, 2008, 28(5): 664 ? 671
[2] 庞庆, 彭建强, 孙秀萍. 高参数大容量汽轮机焊接转子[J]. 汽轮机技术, 2014, 56(6): 478 ? 480
Pang Qing, Peng Jianqiang, Sun Xiuping. Welded rotor for large power rating steam turbine with high steam parameters[J]. Turbine Technology, 2014, 56(6): 478 ? 480
[3] Timo D P, Designing turbine components for low-cycle fatigue[C]//International Conference on Thermal Stress and Thermal Fatigue, Berkeley, USA, 1969: 453 − 469.
[4] Liu X. Investigation on mechanical properties of 9%Cr-CrMoV dissimilar steels welded joint[J]. Materials Engineering and Performance, 2015, 24(4): 1434 ? 1440.
[5] Wu Q J, Lu F, Cui H, et al. Role of butter layer in low-cycle fatigue behavior of modified 9Cr and CrMoV dissimilar rotor welded joint[J]. Materials and Design, 2014, 59: 165 ? 175.
[6] 杨百勋, 丁玲玲, 田晓, 等. FB2转子钢低周疲劳断口分析[J]. 中国电力, 2018, 51(11): 20 ? 25
Yang Baixun, Ding Lingling, Tian Xiao. Analysis of the fracture morphology of FB2 under low-cycle fatigue[J]. Electric Power, 2018, 51(11): 20 ? 25
[7] 张建勋. 金属焊接性能的不均匀性及其尺度效应研究[J]. 电焊机, 2008, 39(1): 24 ? 29
Zhang Jianxun. Unevenness of metal welding performance and its scale effect study[J]. Electric Welding Machine, 2008, 39(1): 24 ? 29
[8] Wang W K, Liu Y, Zhang Q B, et al. Microstructure and local mechanical properties of a dissimilar metal welded joint with buttering layer in steam turbine rotor[J]. Materials Science & Engineering: A, 2019, 747: 244 ? 254.
[9] Tan L, Zhang J X, Zhuang D, et al. Influences of lumped passes on welding residual stress of a thick-walled nuclear rotor steel pipe by multipass narrow gap welding[J]. Nuclear Engineering and Design, 2014, 273: 47 ? 57.
[10] Manson S S, Behavior of materials under conditions of thermal stress[C]//Washington, USA: National Advisory Committee for Aeronautics, 1953: 1 − 105.
[11] Coffin L F. A study of the effects of cyclic thermal stresses on a ductile metal[J], Trans. ASTM, 1954, 76: 931.
[12] Zhou H W , He Y Z , Zhang H , et al. Influence of dynamic strain aging pre-treatment on the low-cycle fatigue behavior of modified 9Cr–1Mo steel[J]. International Journal of Fatigue, 2013, 47(FEB.): 83 ? 89.
[13] 郑修麟, 张钢柱. 应变疲劳公式的探讨[J]. 西北工业大学学报, 1984(2): 223 ? 229
Zheng Xiulin, Zhang Gangzhu. On fatigue formula under strain cycling[J]. Journal of Northwestern Polytechnical University, 1984(2): 223 ? 229
[14] Ramberg W, Osgood W R. Description of stress-strain curves by three parameters[C]//Technical note no. 902, National Advisory Committee on Aeronautics, 1943: 1 − 6.
[15] 师田田, 周晓, 沈寅忠. 11%Cr铁素体/马氏体钢蠕变前后的析出相研究[J]. 金属热处理, 2018, 43(7): 1 ? 6
Shi Tiantian, Zhou Xiao, Shen Yanzhong. Precipitate phases in 11%Cr ferritic/martensitic steel before and after creep[J]. Heat Treatment of Metals, 2018, 43(7): 1 ? 6
