22MnB5超高强度热冲压成形钢的开发及应用

Development and application of 22MnB5 ultra high strength hot stamping steel

通过成分设计、轧制、退火及热冲压成形过程关键工艺参数的调控,研究分析了冷轧压下率、退火温度及热冲压成形冷却速度对22MnB5超高强度热冲压成形钢(22MnB5钢)微观组织及力学性能的影响。结果表明,22MnB5钢的冷轧压下率控制在50%~60%范围时可实现酸连轧的稳定轧制,退火温度控制在780~820℃范围时退火态22MnB5钢的金相组织为均匀细小的铁素体和珠光体,且性能均匀稳定。热冲压成形淬火在冷却速度不低于30℃·s^(-1)时可获得板条尺寸均匀的全马氏体组织。本产品通过了热冲压成形生产线的工业试用,结果表明:热冲压成形后22MnB5钢的屈服强度为1030~1113 MPa、抗拉强度为1480~1520 MPa、伸长率在8.0%以上、硬度HV10不低于500、表面总脱碳层深度均在35μm以下,热冲压成形后零件的尺寸精度、外观均满足客户需求。

The influence of cold rolling reduction rate,annealing temperature and hot stamping cooling velocity on the microstructure and mechanical properties of 22MnB5 ultra high strength hot stamping steel(22MnB5 steel)was studied and analyzed by means of composition design,rolling,annealing and the control of key process parameters in hot stamping process.The results show that the stable rolling of acid continuous rolling of 22MnB5 steel can be achieved when the cold rolling reduction rate is controlled within the range of 50%-60%.The metallographic structure of annealed 22MnB5 steel is uniform and fine ferrite and pearlite,and the properties are uniform and stable when the annealing temperature is controlled within the range of 780-820℃.When the cooling velocity of hot stamping quenching is not less than 30℃·s^(-1),the whole martensitic structure with uniform size of slats can be obtained.This products passed the industrial trial of hot stamping production line,and the results show that after hot stamping,the yield strength of 22MnB5 steel is 1030-1113 MPa,the tensile strength is 1480-1520 MPa,the elongation is more than 8.0%,the hardness HV10 is not less than 500,the depth of the total decarburization layer on the surface is below 35μm,and the dimension accuracy and appearance of the parts meet the requirements of customers.