EBSD技术在研究高强马氏体不锈钢氢脆机理中的应用

Application of EBSD technique in research of hydrogen embrittlement mechanism for high strength martensite stainless steel

用EBSD技术研究了在恒定应力和长期氢扩散作用下马氏体不锈钢的氢脆断裂机制。结果表明,氢脆在初期阶段萌生沿晶裂纹,晶界开裂有选择性和倾向性,高能量的大角晶界易发生开裂,低能量的CSL晶界抑制氢脆裂纹。沿晶裂纹两侧的塑性应变宽度仅为微米或亚微米量级,宏观下表现出典型的脆性开裂特征。扩展阶段氢脆裂纹沿特定的滑移系和解理面穿晶扩展,穿越不同晶粒时,裂纹随解理或滑移晶面的取向变化而发生弯折。氢脆断裂机制符合结合力降低和氢促进局部塑性变形模型。

The hydrogen brittle fracture mechanism of martenite stainless steel with the effect of constant stress and long time hydrogen diffusivity was analyzed by EBSD. The results show that the hydrogen brittle is beginning with inter-granular crack,and it is found that the high energy random grain boundary is easy to fracture while the CSL is resistant to hydrogen brittle. The plastic deformed thickness near the hydrogen brittle is micrometer or sub-micrometer,which is the character of macro brittle fracture. The crack propagates by transgranular along the specified slip system and cleavage plane during propagating,and the crack alters with the change of crystal orientation.The hydrogen brittle fracture mechanism is conformed to with decohesion and hydrogen enhanced plastic flow model.