316L不锈钢抗氢脆性能研究

Hydrogen Embrittlement Resistance of 316L Austenitic Stainless Steel

用光学显微镜、电子显微镜、俄歇电子谱 /二次离子质谱表面分析仪等结合拉伸试验 ,研究了 316L奥氏体不锈钢及其电子束焊缝在 6 5 0℃充氘后组织、微区成分变化与性能的关系 ,以及拉伸应力与氘分布的关系。结果表明 ,高温气相充氘后 ,316L奥氏体不锈钢及其电子束焊缝抗氢脆性能明显下降。晶界、孪晶界析出大量碳化物 ,但拉伸断口形貌并未呈沿晶断裂 ;晶界上未发现S、P等痕量元素的偏聚 ,却产生了富Cr、Mo的贫Ni层 ,这表明晶界成分的变化减弱了晶界析出物对氢脆的影响。电子束焊缝塑性下降 ,拉伸时从该处断裂。

The effects of the microstructure change and grain boundary composition change in 316L austenitic stainless steel on its resistance to hydrogen embrittlement are investigated by optical microscopy, SEM, AES and SIMS. The deuterium distribution dependence of tension stress is also studied. The hydrogen embrittlement susceptibility of 316L stainless steel and its electron beam welding seam with charged D 2 at 650°C is increased. The tensile fracture surface shows both ductile dimples and secondary cracks, although an amount of carbide precipitates along the grain and twin boundaries. Meanwhile, no segregation of trace elements S, P and C occurs at grain boundary, but a Ni depleted and Cr, Mo rich layer is formed. This indicates that the grain boundary composition change impairs interaction of the precipitates on carbide matrix interface with hydrogen, and then this improves the resistance to hydrogen embrittlement. The plasticity of electron beam welding charged at 650°C is decreased, and the tension samples rupture from welding seam. Moreover, the deuterium richens in fractures of the tension samples because of static stress.