Effect of Interface Form on Creep Failure and Life of Dissimilar Metal Welds Involving Nickel-Based Weld Metal and Ferritic Base Metal

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外文摘要：For dissimilar metal welds(DMWs)involving nickel-based weld metal(WM)and ferritic heat resistant steel base metal(BM)in power plants,there must be an interface between WM and BM,and this interface suffers mechani-cal and microstructure mismatches and is often the rupture location of premature failure.In this study,a new form ofWM/BM interface form,namely double Y-type interface was designed for the DMWs.Creep behaviors and life of DMWs containing double Y-type interface and conventional l-type interface were compared by finite element analysis and creep tests,and creep failure mechanisms were investigated by stress-strain analysis and microstructure characterization.By applying double Y-type interface instead of conventional l-type interface,failure location of DMW could be shifted from the WM/ferritic heat-affected zone(HAZ)interface into the ferritic HAZ or even the ferritic BM,and the failure mode change improved the creep life of DMW.The interface premature failure of Ⅰ-type interface DMW was related to the coupling effect of microstructure degradation,stress and strain concentrations,and oxide notch on the WM/HAZ interface.The creep failure of double Y-type interface DMW was the result of Type Ⅳ fracture due to the creep voids and micro-cracks on fine-grain boundaries in HAZ,which was a result of the matrix soften-ing of HAZ and lack of precipitate pinning at fine-grain boundaries.The double Y-type interface form separated the stress and strain concentrations in DMW from the WM/HAZ interface,preventing the trigger effect of oxide notch on interface failure and inhibiting the interfacial microstructure cracking.It is a novel scheme to prolong creep life and enhance reliability of DMW,by means of optimizing the interface form,decoupling the damage factors from WM/HAZ interface,and then changing the failure mechanism and shifting the failure location.

外文关键词：

Dissimilar metal weldNickel-based weld metalFerritic heat resistant steelInterfaceCreep strainMicrostructureFailure mechanismCreep life

作者：

Xiaogang Li、Junfeng Nie、Xin Wang、Kejian Li、Haiquan Zhang

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作者单位：

Institute of Nuclear and New Energy Technology,Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education,Tsinghua University,Beijing 100084,China

Department of Mechanical Engineering,Tsinghua University,Beijing 100084,China

基金：

Youth Elite Project of CNNC and Modular HTGR Supercritical Power Generation Technology Collaborative Project between CNNC and Ts

项目编号：

ZHJTIZYFGWD20201

出版年：

2024

DOI：

10.1186/s10033-024-01005-9

中国机械工程学报

中国机械工程学会

中国机械工程学报

CSTPCD

影响因子：0.765

ISSN：1000-9345

年,卷(期)：2024.37(1)