β-manganese Transformation in High Manganese Low-density Steels

摘要：

　　Weight reduction of automotive vehicles is getting more important for reduction of carbon dioxide emission and enhancement of fuel efficiency.There have been research activities for development of low-density steels.The low-density steels usually contain aluminum which provides density reduction effect by substitution and lattice expansion.The low-density steels can be classified into ferritic alloys and austenitic or multi-phase alloys based on constitutional phase.The austenitic or multi-phase alloys contain manganese content higher than 15 mass%.These alloys can have β-manganese phase in the microstructure depending on chemical composition and heat treatment condition 1,2.In this work,formation and growth behavior of β-manganese phase in Fe-30Mn- (9,12)Al-0.9C alloys aged at 550℃ were investigated.The microstructure was observed using electron backscatter diffraction (EBSD) analysis and transmission electron microscopy (TEM).β-manganese phase formed at austenite grain boundaries or ferrite/austenite boundaries during aging treatment.The morphology of β-manganese phase depended on aluminum content.In case of the alloy containing 9 mass% of aluminum,the β-manganese phase formed colonies with newly-formed ferrite at austenite grain boundaries.In case of the alloy containing 12 mass% of aluminum,the β-manganese phase grew extensively into austenite grains showing Widmanstatten-type morphology (Fig.1).Lattice expansion of austenite and carbon enrichment in austenite caused by β-manganese formation was examined using X-ray diffractometry (XRD) and electron probe micro-analyzer (EPMA).The intrinsic mechanical properties of constitutional phases were obtained by nanoindentation.Changes in hardness of constitutional phases could be attributed to partitioning of alloying elements due to β-manganese transformation.

关键词： low-density steel β-manganese nanoindentation

作者: PARK Seong-Jun KANG Jun-Yun MOON Joonoh PARK Jun Young LEE Keunho HAN Heung Nam

作者单位: Ferrous Alloy Department, Korea Institute of Materials Science, Republic of Korea Department of Materials Science and Engineering, Seoul National University, Republic of Korea

会议类型: 国际会议

会议名称: the 1st International Conference on Automobile Steel & The 3rd International Conference on High Manganese Steels (第一届国际汽车用钢大会暨第三届高锰钢国际会议)

会议地点: 成都

会议语种:英文

页码: 742-742

在线出版日期: 2016-11-16（万方平台首次上网日期，不代表论文的发表时间）