Enhanced strength, hardening and ductility under low temperature condition of an ultra-high strength quenching and partitioning steel

作者：Yong Hou, Zeran Hou, Yi Liu, Nan Guo, Yuhang Xia, Yushi Yang, Yannis P. Korkolis, Zhou Wang, Jianfeng Wang, Junying Min · 发表于：Journal of Materials Research and Technology · 年份：2025 · DOI：10.1016/j.jmrt.2025.02.166 · 被引用次数：9 · 研究领域：Microstructure and Mechanical Properties of Steels、Metal Alloys Wear and Properties、Metallurgy and Material Forming

As the strength of high-strength steels increases, ductility becomes a critical concern, especially at low temperatures (LT). However, LT ductility of high-strength steels, especially the third-generation advanced high-strength steels, is often under-evaluated. In this study, a VDA 238–100 tight radius bending (VDA bending) test at LT was introduced to assess the ductility of QP1500, a quenching and partitioning steel with a strength of 1500 MPa. Uniaxial tensile and VDA bending tests were performed on QP1500 steel at room temperature (20 °C) and LT (−40 °C). To understand the mechanisms behind the observed behavior, X-ray diffraction (XRD), electron backscatter diffraction (EBSD), and finite element analysis (FEA) were employed. The results showed that QP1500 steel exhibited enhanced strength and hardening at LT compared to RT, with a 56 MPa (3.7%) increase in tensile strength and a 3.5% (38.5%) enhancement in uniform elongation. In the LT VDA bending test, peak force increased by 1.10 kN (10.2%), and the bending angle rose by 2.4° (3.4%). XRD and EBSD analyses revealed that the gradual transformation of retained austenite at LT enhanced strain hardening, leading to improved strength and ductility. FEA further indicated that a more uniform strain distribution along the circumference was key to increasing the bending ductility of QP1500 steel.