临界区退火温度对Nb-Cr-RE系微碳DP钢组织及性能的影响

实验室设计了Nb-Cr-RE系微碳DP钢，利用扫描电镜以及拉伸试验机，观察与分析了退火温度对微碳DP钢组织与性能的影响.结果表明:微碳DP钢退火板主要由铁素体及其晶界上附着的细小马氏体所构成；随退火温度的上升，DP钢的抗拉强度先升后降，屈服强度逐渐降低，伸长率先增加后降低；铁素体再结晶越充分，晶粒尺寸分布越均匀，等轴化越明显，DP钢屈服强度越小，伸长率越高；另外高温退火时的较大尺寸短棒状碳化物会明显恶化伸长率. 

Effects of intercritical annealing temperature on the microstructure and properties of Nb-Cr-RE micro-carbon DP steel

Nb-Cr-Re micro-carbon DP steel was designed in the laboratory. The effects of annealing temperature on its microstructure and properties were observed and analyzed by means of scanning electron microscope (SEM) and tensile testing machine. The results showed that the annealed sheet of micro-carbon DP steel was mainly composed of ferrite and fine martensite attached on its grain boundary; with the increase of annealing temperature, the tensile strength of DP steel first increased and then decreased, its yield strength decreased gradually, and its elongation increased first and then decreased; the more the ferrite recrystalized, the more uniform the grain size distribution was and the more obviously it's equiaxed, the smaller the yield strength of DP steel and the higher its elongation rate were; in addition, short rod carbides of larger size could significantly deteriorate the elongation during high temperature annealing.