基于22MnB5钢的铌钒微合金化热成形钢的研发

基于现有热成形零件冷弯性能不足、氢脆敏感性强等共性技术问题,在22MnB5钢的基础上采用Nb、V微合金化的设计思路,对试验钢的显微组织、淬透性和极限尖冷弯性能进行研究。结果表明:微合金化前后22MnB5热成形钢的显微组织均为全马氏体,但是微合金化后的试验钢组织更为细小;Nb-V微合金化能有效提高22MnB5热成形钢的淬透性,其淬硬层深度达到13～14 mm,并且试验钢的极限尖冷弯角达到58°～72°,进一步拓宽了热冲压成形的工艺窗口。综合分析试验钢微观组织、淬透性能及极限尖冷弯性能的检测结果,添加0.04%Nb和0.04%V实现复合微合金化,提升材料的综合强塑性,满足了高冷弯性能汽车零部件用材需求。

Development of Nb-V microalloyed hot forming steel based on 22MnB5

Based on the common technical problems of insufficient cold bending performance and strong hydrogen embrittlement sensitivity of existing hot forming steel parts,the design idea of Nb and V microalloying was adopted on the basis of 22 MnB5 steel,and the microstructure,hardenability and extreme tip cold bending performance of the tested steels were studied.The results show that the microstructure of hot forming steel 22 MnB5 before and after microalloying is all martensite,while becomes finer after microalloying;Nb-V microalloying can effectively improve the hardenability of the 22 MnB5 hot forming steel,the depth of hardened layer reaches 13-14 mm,and the extreme tip cold bending angle of the tested steels reaches 58°-72°,which further widens the processing window of hot forming forming.Based on the test results of microstructure,hardenability and extreme tip cold bending performance of the tested steels,the comprehensive strength and plasticity of the steel are improved by adding 0.04%Nb and 0.04%V,and meet the requirements of automotive parts with high extreme tip cold bending performance.