过时效温度对低成本冷轧双相钢组织性能的影响

Effects of Over-Aging Temperatures on Microstructure and Mechanical Properties of Low Cost Cold Rolled Dual Phase Steels

通过建立合理的热处理工艺窗口,将低附加值的钢种升级为具有高强塑性的高附加值双相钢产品.以常规C-Mn钢热轧板坯为原料,经过热轧及冷轧后,进行连续退火实验.实验钢经过不同的冷却后过时效制度,形成了铁素体和马氏体组成的微观组织.当过时效温度在320℃以下时,避免了贝氏体组织的出现,并且马氏体相的体积分数随温度的降低而增加.实验钢的抗拉强度与马氏体相含量成正比,屈服强度和延伸率与其成反比,在320℃过时效处理下可获得最佳的综合力学性能,强塑积为18 254.6 MPa%.

A high strength and ductility dual phase steel was developed from the traditional steel via establishing reasonable processing parameter windows, which transferred from low to high additional values. The continuous annealing specimen was prepared from C-Mn steels by hot and cold rolling. The microstructure contained ferrite and martensite was obtained by the intercritical anneal, controlled cooling and the subsequent different over-aging procedures. The bainite transformation was avoided when the over-aging temperature was lower than 320 ℃. The volume fraction of the martensite increased with the decrease of temperatures. The tensile strength was proportional to the volume fraction of the martensites, whereas the yield strength and elongation performanced an inverse relationship. The strength-ductility balance was 18 254.6 MPa% in the 320 ℃ over-aging procedure as a better mechanical property.