Morawiec Mateusz, Wojtacha Anna, Opiela Marek
Department of Engineering Materials and Biomaterials, Silesian University of Technology, 18A Konarskiego Street, 44-100 Gliwice, Poland.
Materials (Basel). 2021 Mar 30;14(7):1698. doi: 10.3390/ma14071698.
This work presents the results of phase transformation kinetics during continuous cooling in newly developed high strength low-alloy steel (HSLA). Initial theoretical calculations for the determination of heat treatment parameters were conducted. To determine the structural constituents formed due to the austenite decomposition the dilatometry approach was used. The material was cooled down from the austenitization temperature of 1000 °C with cooling rates between 0.1 °C/s to 60 °C/s. Then, light and scanning electron microscopy investigations were carried out. The microstructure after cooling at rates between 0.1 °C/s up to 1 °C/s is mainly ferritic with some fraction of granular bainite. Increasing the cooling rate led to formation of a higher fraction of bainitic ferrite. At 60 °C/s the microstructure was mainly bainite with some fraction of ferrite. To determine the presence of retained austenite, color etching using Klemm solution was used. The results show that the increase of cooling rate decreases the amount of retained austenite in the microstructure of the steel. Hardness measurements were made to determine the changes in the mechanical properties as a function of the cooling rate.
本文介绍了新开发的高强度低合金钢（HSLA）在连续冷却过程中的相变动力学结果。进行了用于确定热处理参数的初始理论计算。为了确定由奥氏体分解形成的结构成分，采用了热膨胀法。材料从1000℃的奥氏体化温度以0.1℃/s至60℃/s的冷却速率冷却。然后，进行了光学和扫描电子显微镜研究。在0.1℃/s至1℃/s的冷却速率下冷却后的微观结构主要是铁素体，并含有一定比例的粒状贝氏体。冷却速率的增加导致贝氏体铁素体比例更高。在60℃/s时，微观结构主要是贝氏体，并含有一定比例的铁素体。为了确定残余奥氏体的存在，使用了Klemm溶液进行彩色蚀刻。结果表明，冷却速率的增加会降低钢微观结构中残余奥氏体的含量。进行硬度测量以确定作为冷却速率函数的力学性能变化。
