加热温度对34MnB5热成形钢组织性能的影响

以经酸连轧后的34MnB5钢为原料，采用Gleeble3500热模拟试验机模拟退火试验，分析最佳退火温度，并进行不同热冲压工艺的平模淬火试验。研究退火温度、淬火温度对热成形钢组织与性能的影响。结果表明，退火温度为790℃时，条带状组织已基本消失，晶粒的等轴化程度较高，混晶现象明显改善，贝氏体晶粒组织细化，在基体内部均匀分布铁贝两相。退火温度为790℃,淬火温度为930℃,保温5 min时，显微组织为细小均匀的板条马氏体，综合力学性能最好，其屈服强度达到1353 MPa,抗拉强度达到2018 MPa,伸长率达到7.5%,且横纵向三点弯曲角均可以达到50°以上。

Effect of heating temperature on microstructure and properties of 34MnB5 hot forming steel

Gleeble3500 thermal simulation machine was used to simulate annealing of 34MnB5 steel after continuous acid rolling. The optimum annealing temperature was analyzed and the flat die quenching test of different hot stamping processes was carried out. The effect of annealing temperature and quenching temperature on microstructure and properties of the hot formed steel was studied. The results show that when the annealing temperature is 790 ℃, the banded structure is almost disappeared, the equiaxation degree of grains is higher, the mixed grain phenomenon is improved obviously, the bainite grain structure is refined, and the two phases of ferrite and bainite are evenly distributed in the matrix. When annealing temperature is 790 ℃, quenching temperature is 930 ℃ and holding time is 5 min, the microstructure is fine and uniform lath martensite, and the comprehensive mechanical properties are the best. Yield strength reaches 1353 MPa, tensile strength reaches 2018 MPa, elongation reaches 7.5%, and the transverse and longitudinal three-point bending angle reach more than 50°.