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

• Published in: International journal of minerals, metallurgy and materials Vol. 23; no. 8; pp. 906 - 919
• Main Authors: Li, Wan-song, Gao, Hong-ye, Nakashima, Hideharu, Hata, Satoshi, Tian, Wen-huai
• Format: Journal Article
• Language: English
• Published: Beijing University of Science and Technology Beijing 01.08.2016; Springer Nature B.V; School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China%Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Fukuoka 8168580, Japan
• Subjects: Austenitizing; Bainite; Carbon; Carbon content; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composites; Corrosion and Coatings; Electron microscopy; Elongation; Evolution; Glass; Grain size; Heat treating; Heat treatment; High strength steels; Low carbon steels; low-carbon; Materials Science; Mechanical properties; Metallic Materials; Microscopy; Microstructure; Natural Materials; Partitioning; properties;interfaces; Quenching; Retained austenite; Room temperature; steel;quenching;partitioning;microstructure;mechanical; Surfaces and Interfaces; Tempered martensite; Tensile strength; Tensile tests; Thin Films; Tribology; Ultimate tensile strength; X-ray diffraction; Yield strength; Yield stress; partitioning; interfaces; microstructure; quenching; low-carbon steel; mechanical properties
• ISSN: 1674-4799; 1869-103X
• DOI: 10.1007/s12613-016-1306-0

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.