摘要
针对目前热成形钢冲压过程中零部件局部强度较低与塑性较低问题,设计了2种不同Cr-Mn含量的微合金化热成形用钢。并采用热膨胀仪、光学显微镜、扫描电镜与硬度计等研究了实验钢的相变温度、组织演变与性能。结果表明:1号实验钢(0.27C-2.03Mn-0.12Si-1.5Cr-0.011Nb)的相变温度低于2号实验钢(0.21C-1.66Mn-1.21Cr-0.034Nb)。实验条件下1号实验钢的CCT曲线仅包含贝氏体与马氏体转变,在冷速为0.2℃/s时即发生马氏体转变。然而2号实验钢的CCT曲线包含铁素体、珠光体、贝氏体与马氏体转变,在冷速大于等于10℃/s时才发生全马氏体转变。1号实验钢有较宽的成形工艺范围,即使在冷速为1℃/s时,零部件强度也能达1500 MPa级,对模具设计要求低且具有较高的生产效率;而2号实验钢成形工艺相对较窄,成形后冷速需大于20℃/s其零部件强度才能达到1500 MPa。
Aiming at the problems of low local strength and low plasticity during stamping process of hot forming steel, two kinds of microalloyed Cr-Mn steel with different compositions were designed. The phase transformation temperature, microstructure evolution and mechanical properties of the experimental steels were studied by means of thermal dilatometer, optical microscope, scanning electron microscopy and hardness tester. The results show that the phase transformation temperature of the experimental steel No.1(0.27 C-2.03 Mn-0.12 Si-1.5 Cr-0.011 Nb) is lower than that of No.2(0.21 C-1.66 Mn-1.21 Cr-0.034 Nb). Under experimental conditions, the CCT curves of the experimental steel No.1 only contain bainite and martensite transformation, and the martensite transformation occurs when the cooling rate is 0.2 ℃/s. However, the CCT curves of the experimental steel No.2 contain ferrite, pearlite, bainite and martensite transformation, and the martensite transformation occurs only when the cooling rate is greater than or equal to 10 ℃/s. The steel No.1 has a wide forming process range, even when the cooling rate is 1 ℃/s, the strength of the parts can reach 1500 MPa, and also the process has a low die design requirement and a high production efficiency. The forming process range of the steel No.2 is relatively narrow, and the strength of the parts can reach 1500 MPa only when the cooling rate after forming is greater than 20 ℃/s.
作者
牟秀婷
陈其伟
潘红波
黄飞
MOU Xiu-ting;CHEN Qi-wei;PAN Hong-bo;HUANG Fei(School of Metallurgical Engineering,Anhui University of Technology,Ma'anshan 243002,China;Key Laboratory of Metallurgical Emission Reduction and Resources Recycling of Ministry of Education,Anhui University of Technology,Ma’anshan 243002,China)
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2020年第7期111-118,共8页
Transactions of Materials and Heat Treatment
基金
国家自然科学基金(51774006,U1860105)
安徽省科技重大专项(18030901085)。
