材料科学
等温过程
马氏体
猝灭(荧光)
铁氧体(磁铁)
极限抗拉强度
相(物质)
奥氏体
等温转变图
冶金
微观结构
贝氏体
复合材料
热力学
化学
荧光
物理
量子力学
有机化学
作者
Xixi Cui,Derek O. Northwood,Cheng Liu
标识
DOI:10.1002/srin.201800207
摘要
A 55Mn2SiCr steel is developed by a novel multiple‐step process, which involves austenitizing at 900 °C for 30 min, rapid quenching to 210 °C, then holding at 170 °C for 5 min, and isothermally holding at 250 °C for different times, and finally cooling in air. The mixed microstructure consists of lenticular prior martensite (PM), fine needle bainitic ferrite (BF), and filmy retained austenite (RA). The results show that the highest tensile strength of 2030 MPa with a bending strength of 4000 MPa is achieved at 250 °C for 120 min. This is attributed to a synergistic multi‐phase strengthening effect. The presence of martensite formed during the quenching process prior to the isothermal treatment, accelerates the kinetics of subsequent nano‐scaled super bainitic transformation by bainitic laths nucleating quickly at the martensite‐austenite interfaces. The product of austenite fraction and its carbon content is found to be another important factor for controlling the strength. In addition, the phase evolution as well as carbon partitioning mechanism during isothermal treatment is discussed.
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