Li Shaohua, Feng Haibo, Wang Shuize, Gao Junheng, Zhao Haitao, Wu Honghui, Xu Shuai, Feng Qingxiao, Li Hualong, Liu Xinyuan, Wu Guilin
Innovation Research Institute for Carbon Neutrality, University of Science and Technology Beijing, Beijing 100083, China.
Institute of Research of Iron and Steel, Shasteel, Zhangjiagang 215625, China.
Materials (Basel). 2023 Feb 28;16(5):1980. doi: 10.3390/ma16051980.
Medium carbon steels have been widely used in the fields of tool and die manufacturing due to their outstanding hardness and wear resistance. In this study, microstructures of 50# steel strips fabricated by twin roll casting (TRC) and compact strip production (CSP) processes were analyzed to investigate the influences of solidification cooling rate, rolling reduction, and coiling temperature on composition segregation, decarburization, and pearlitic phase transformation. The results show that a partial decarburization layer with a thickness of 13.3 μm and banded C-Mn segregation were observed in the 50# steel produced by CSP, leading to the banded distributions of ferrite and pearlite in the C-Mn poor regions and C-Mn rich regions, respectively. For the steel fabricated by TRC, owing to the sub-rapid solidification cooling rate and short processing time at high temperatures, neither apparent C-Mn segregation nor decarburization was observed. In addition, the steel strip fabricated by TRC has higher pearlite volume fractions, larger pearlite nodule sizes, smaller pearlite colony sizes and interlamellar spacings due to the co-influence of larger prior austenite grain size and lower coiling temperatures. The alleviated segregation, eliminated decarburization and large volume fraction of pearlite render TRC a promising process for medium carbon steel production.
中碳钢因其出色的硬度和耐磨性而在工具和模具制造领域得到广泛应用。在本研究中，对通过双辊铸轧（TRC）和紧凑带钢生产（CSP）工艺制备的50#钢带的微观组织进行了分析，以研究凝固冷却速率、压下率和卷取温度对成分偏析、脱碳和珠光体相变的影响。结果表明，在CSP生产的50#钢中观察到厚度为13.3μm的部分脱碳层和带状C-Mn偏析，分别导致铁素体和珠光体在贫C-Mn区和富C-Mn区呈带状分布。对于TRC制备的钢，由于亚快速凝固冷却速率和高温下较短的加工时间，未观察到明显的C-Mn偏析和脱碳现象。此外，由于较大的原始奥氏体晶粒尺寸和较低的卷取温度的共同影响，TRC制备的钢带具有更高的珠光体体积分数、更大的珠光体球粒尺寸、更小的珠光体团尺寸和片层间距。偏析减轻、脱碳消除以及珠光体的大量体积分数使TRC成为中碳钢生产的一种有前景的工艺。
