CAJ | 학술논문

对AZ31B镁合金焊接接头和热影响区的疲劳裂纹扩展行为进行研究,分析了焊接接头[L-T(W)]和热影响区的紧凑拉伸试验[C(T)],其中热影响区的C(T)试验包括焊缝平行于挤压方向[T-L(H)]和垂直于挤压方向[L-T(H)]两种.结果表明:对于L-T(W)试样,裂纹沿挤压方向扩展,裂纹扩展经历先快后慢的扩展过程；T-L(H)试样裂纹平行于缺口方向扩展,L-T(H)试样裂纹为平行于缺口方向和与缺口成一定角度两种扩展方向,裂纹扩展经历先慢后快的扩展过程.裂纹尖端扩展为穿晶和沿晶的混合模式,疲劳断口为准解理特征的脆性断口.
대AZ31B미합금한접접두화열영향구적피로렬문확전행위진행연구,분석료한접접두[L-T(W)]화열영향구적긴주랍신시험[C(T)],기중열영향구적C(T)시험포괄한봉평행우제압방향[T-L(H)]화수직우제압방향[L-T(H)]량충.결과표명:대우L-T(W)시양,렬문연제압방향확전,렬문확전경력선쾌후만적확전과정；T-L(H)시양렬문평행우결구방향확전,L-T(H)시양렬문위평행우결구방향화여결구성일정각도량충확전방향,렬문확전경력선만후쾌적확전과정.렬문첨단확전위천정화연정적혼합모식,피로단구위준해리특정적취성단구.
The fatigue crack propagation behavior of as-extruded AZ31B magnesium alloy welded joint and heat affected zone have been studied.Compact tensions [C(T)] of welded joint [L-T(W)] and heat affected zone(welded joint is parallel [T-L(H)]and vertical [L-T(H)] to the extruded direction) were researched.Results indicate that the crack propagation direction is parallel to the extrusion direction for L-T(W); fatigue crack propagation rate is a rapid-slow process.T-L(H) is parallel to the notch direction and L-T(H) can be divided into two states (i.e.,parallel to or angularly deflected towards the notch direction);crack propagation rate initially goes through a rapid course before it slows down.The fracture modes of crack tip remain a mixed-mode of transgranular and intergranular fractures.The fatigue fracture consists of quasi-cleavage and is a brittle fracture.