ABSTRACT

During spheroidizing annealing of steels, the carbide shape is modified from lamellar to spheroidal for increasing cold deformability. The aim of this work is to study the kinetics and the mechanical properties of a C–Mn–B steel grade after spheroidizing annealing, varying the prior microstructure produced by industrial conventional and thermo-mechanical hot rolling with different Stelmor cooling rates. Moreover, different prior microstructures were also produced by laboratory heat treatments. Microstructural analysis, hardness tests, and tensile tests were carried out at different soaking times. The results show that a better distribution of the carbon in the metal matrix obtained in bainitic and martensitic microstructures results in a more uniform dispersion of the carbides with higher mechanical resistance and deformability. The ferritic and pearlitic microstructures obtained by thermo-mechanical hot rolling are able to produce more homogeneous carbides when compared with the traditional hot rolling.

摘要

在钢的球化退火过程中，碳化物形状从层状变为球状，以增加冷变形能力。这项工作的目的是研究 C-Mn-B 钢种在球化退火后的动力学和机械性能，改变由不同 Stelmor 冷却速率的工业常规和热机械热轧产生的先前微观结构。此外，不同的先前微观结构也通过实验室热处理产生。在不同的浸泡时间进行显微组织分析、硬度测试和拉伸测试。结果表明，碳在贝氏体和马氏体微观结构中获得的金属基体中更好的分布导致碳化物更均匀的分散，具有更高的机械阻力和变形能力。