CAJ | 학술논문

对AZ31镁合金在3种温度(523,573和673 K)下进行了单向压缩变形.在523 K,当真应变ε达到0.22时真应力-真应变曲线出现尖锐的应力峰值,在应力峰值之前先后经历了缓慢加工硬化(0.02≤ε<0.06)和急剧加工硬化(0.06≤ε<0.22)2个阶段.利用SEM/EBSD技术分析了这2个阶段对应的显微组织.结果表明,在缓慢加工硬化阶段(ε=0.03),仅有少量孪晶出现;在急剧加工硬化阶段(ε=0.06),产生了大量{101~-2}孪晶,孪晶间的相互交叉导致材料产生急剧加工硬化.AZ31镁合金{101~-2}孪晶间交叉有5种可能存在的形式,孪晶的形成和交叉与压缩应力方向有密切关系.在基体应力方向分别为近似<112~-0>和<101~-0>方向时确认了(101~-2)-(011~-2)和(101~-2)-(01~-12)2种交叉形式.
대AZ31미합금재3충온도(523,573화673 K)하진행료단향압축변형.재523 K,당진응변ε체도0.22시진응력-진응변곡선출현첨예적응력봉치,재응력봉치지전선후경력료완만가공경화(0.02≤ε<0.06)화급극가공경화(0.06≤ε<0.22)2개계단.이용SEM/EBSD기술분석료저2개계단대응적현미조직.결과표명,재완만가공경화계단(ε=0.03),부유소량련정출현;재급극가공경화계단(ε=0.06),산생료대량{101~-2}련정,련정간적상호교차도치재료산생급극가공경화.AZ31미합금{101~-2}련정간교차유5충가능존재적형식,련정적형성화교차여압축응력방향유밀절관계.재기체응력방향분별위근사<112~-0>화<101~-0>방향시학인료(101~-2)-(011~-2)화(101~-2)-(01~-12)2충교차형식.
Though electron backscattering diffraction (EBSD) is widely employed for the ori-entation analysis of deformed microstructures in many metallic materials, its applications to Mg and its alloys are not widespread because of the difficulties involved in sample preparation. In this work, uniaxial compression tests were performed on samples cut along the extrusion direction from AZ31 Mg alloy bars, and then the twins and their intersections were analyzed by SEM/EBSD microscopy. Deformation and deformation mechanisms operating in Mg alloy depend sensitively on temperatures. Flow curve at 523 K shows a sharper and larger stress peak following slow strain hardening and rapid strain hardening. At slow hardening stage (0.02 ≤ε < 0.06) a few of {101~-2} twinning was commonly observed, but at rapid hardening stage (0.06 ≤ε < 0.22) more twins and twin intersections appeared. There are five possible types of twin intersections, which are strongly depended on the stress direction. The two types of (101~-2)-(011~-2) and (101~-2)-(01~-12) twin intersections were observed at stress axis near to <112~-0> and <10~-10> in the samples compressed to a true strain of 0.06.