Microstructural evolution and mechanical properties of a low-carbon quenching and partitioning steel after partial and full austenitization  

作　　者：Wan-song Li Hong-ye Gao Hideharu Nakashima Satoshi Hata Wen-huai Tian 

机构地区：[1]School of Materials Science and Engineering, University of Science and Technology Beijing [2]Interdisciplinary Graduate School of Engineering Sciences, Kyushu University

出　　处：《International Journal of Minerals,Metallurgy and Materials》2016年第8期906-919,共14页矿物冶金与材料学报（英文版）

基　　金：funded by China Scholarship Council (No. 201406460053)

摘　　要：In this work, low-carbon steel specimens were subjected to the quenching and partitioning process after being partially or fully austenitized to investigate their microstructural evolution and mechanical properties. According to the results of scanning electron microscopy and transmission electron microscopy observations, X-ray diffraction analysis, and tensile tests, upper bainite or tempered martensite appears successively in the microstructure with increasing austenitization temperature or increasing partitioning time. In the partially austenitized specimens, the retained austenite grains are carbon-enriched twice during the heat treatment, which can significantly stabilize the phases at room temperature. Furthermore, after partial austenitization, the specimen exhibits excellent elongation, with a maximum elongation of 37.1%. By contrast, after full austenitization, the specimens exhibit good ultimate tensile strength and high yield strength. In the case of a specimen with a yield strength of 969 MPa, the maximum value of the ultimate tensile strength reaches 1222 MPa. During the partitioning process, carbon partitioning and carbon homogenization within austenite affect interface migration. In addition, the volume fraction and grain size of retained austenite observed in the final microstructure will also be affected.In this work, low-carbon steel specimens were subjected to the quenching and partitioning process after being partially or fully austenitized to investigate their microstructural evolution and mechanical properties. According to the results of scanning electron microscopy and transmission electron microscopy observations, X-ray diffraction analysis, and tensile tests, upper bainite or tempered martensite appears successively in the microstructure with increasing austenitization temperature or increasing partitioning time. In the partially austenitized specimens, the retained austenite grains are carbon-enriched twice during the heat treatment, which can significantly stabilize the phases at room temperature. Furthermore, after partial austenitization, the specimen exhibits excellent elongation, with a maximum elongation of 37.1%. By contrast, after full austenitization, the specimens exhibit good ultimate tensile strength and high yield strength. In the case of a specimen with a yield strength of 969 MPa, the maximum value of the ultimate tensile strength reaches 1222 MPa. During the partitioning process, carbon partitioning and carbon homogenization within austenite affect interface migration. In addition, the volume fraction and grain size of retained austenite observed in the final microstructure will also be affected.

关 键 词：low-carbon steel quenching partitioning microstructure mechanical properties interfaces 

分 类 号：TG142.1[一般工业技术—材料科学与工程] TG156.3[金属学及工艺—金属材料]