9%Ni钢焊接熔合区的氢致裂纹与马氏体带的关系

RELATIONSHIP BETWEEN MARTENSITE LAYER AND HYDROGEN-INDUCED CRACKING IN THE WELD BOND OF 9%Ni STEEL

利用金相法、超高温显微镜及超高压透射电子显微镜技术,对9%Ni 钢焊接熔合区马氏体带的特性,拉应力对9%Ni 钢焊接熔合区组织,性能的影响进行了探讨。试验得出用Cr17Ni13Mn8W3奥氏体钢焊条焊接9%Ni 钢时,熔合区马氏体带中包含具有孪晶精细结构的马氏体,该马氏体带的相变滞后于热影响区的马氏体,其中的残余奥氏体稳定性不高,在拉应力作用或低温条件下易于转变成马氏体,从而增加了熔合区氢致裂纹倾向。提出了9%Ni 钢焊接熔合区氢致裂纹形成的模型。

Characteristics of martensite layer in the weld bond of 9% Ni steel,effectsof tensile stress on the microstructure and mechanical properties of the weld bondwere investigated with metallography,ultra-high temperature microscopy and tran-smission electronic microscopy.It is revealed that the weld bond contains twinmartensite;martensite transformation in the weld bond lags behaind that inHAZ;tensile stress or low temperature may induce the residual austenite in thewartensite layer to transform into martensite,which enhances the tendency tohydrogen-induced cracking.A model of the formation of hydrogen-induced crackingin the weld bond of 9%Ni steel is proposed.