锌基镀层热成形钢裂纹的产生、扩展机理及高温力学性能研究
Crack generation,propagation mechanism and thermal property of Zn-coated hot stamping steel
李学涛 1朱国森 1马闻宇 1邵蓉 1张永强 1郑学斌1
作者信息
- 1. Research Institute of Technology of Shougang Group Co.,Ltd.,Beijing 100043,China;Beijing Key Laboratory of Green Recycling Process for Iron&Steel Production Technology,Beijing 100043,China;Beijing Engineering Research Centre of Energy Steel,Beijing 100043,China
- 折叠
摘要
本文通过锌基镀层热成形钢的Gleeble试验和实际零件热冲压试验,在材料高温性能分析的基础上,建立了材料模型,用于高精度地拟合真应力和真应变之间的关系,进而研究成形温度、铁素体形成和弯曲变形对液态锌致基板脆裂(LMIE)的影响.结果表明,真应力随着变形温度的下降而增加.当变形温度为820℃时,LMIE导致真应变较低,约为0.13.根据Gleeble热模拟测试和实际零件试验结果,建议成形温度为720℃,可以避免LMIE并保证材料的力学性能.在实际应用中,拉应力容易导致微裂纹的产生,而压应力可以抑制微裂纹的产生.随着成形温度的降低,镀层中微裂纹的数量和宽度降低,同时镀层厚度增加.镀层主要为固态α-Fe(Zn)相.通过减少在加热保温和成形过程中的液态相可以减少甚至避免LMIE裂纹的产生.
Abstract
In this study,the Gleeble tests and hot stamping of practical part of Zn-coated hot stamping steel were conducted.Based on the analysis of thermal properties,a material model was employed to fit the relationship between true stress and true strain with high accuracy.The effect of forming temperature,ferrite formation and bending on the liquid metal induce embrittlement(LMIE)was researched.The results show that the true stress increases as forming temperature decreases.LMIE occurs,leading to a low true strain of about 0.13,as the forming temperature reaches 820℃.According to the Gleeble simulation test and the actual test results,the forming temperature is suggested to be 720℃.So,LMIE is avoided and the mechanical properties are guaranteed.In practical application,the tensile stress is easy to produce microcrack while the compressive stress constrains it.With the decrease of stamping temperature,the number and width of the microcrack in the coating layer decrease,and the thickness of the coating layer increases.The coating layer is composed of solid α-Fe(Zn)phase.Decreasing the liquid phase in heating,soaking and forming period tends to reduce and even avoid the LMIE cracks.
关键词
热成形钢/锌基镀层/断裂/直接热冲压/微观组织Key words
hot stamping steel/Zn-coated layer/crack/direct hot stamping/microstructure引用本文复制引用
出版年
2024
NETL
NSTL
万方数据