预应变对汽车双相钢材料成形性的影响  

Influence of pre-strain on formability of dual-phase steel material for automobile

作　　者：乔书杰[1] 张晓莹[2] Qiao Shujie;Zhang Xiaoying(College of Mechanical Electrical and Automotive Engineering,Zhengzhou Institute of Finance and Economics,Zhengzhou 450000,China;College of Mechanical Engineering,Zhengzhou University of Science and Technology,Zhengzhou 450064,China)

机构地区：[1]郑州财经学院机电与汽车工程学院,河南郑州450000 [2]郑州科技学院机械工程学院,河南郑州450064

出　　处：《锻压技术》2020年第11期181-186,共6页Forging & Stamping Technology

基　　金：教育部产学协同育人项目(201802048105)。

摘　　要：双相钢在成形过程中的相变情况复杂,单独采用普通拉伸性能对其成形性进行评价的误差较大。选取DP780双相钢,根据实际的生产参数和实验条件,采用单向拉伸过程预应变的方式,对单轴拉伸试样实施不同大小的预应变(0%,5%,10%和15%),再进行拉伸实验,直至试样断裂失效,分别对预拉伸后材料的力学性能和加工硬化进行评价。结果可知:DP780双相钢具有良好的抗拉强度、高加工硬化指数和低屈强比的特征,但塑性较低,伸长率仅为20.7%;随着预应变的增大,屈服强度和抗拉强度均相应增大,但是抗拉强度的变化较小,预应变主要影响了DP780双相钢的伸长率;经过预拉伸的试样在继续拉伸的过程中,加工硬化指数n值在拉伸开始阶段降低至最小值后,随着拉伸的继续,n值缓慢增大,这与未经过预拉伸试样的n值的变化规律明显不同,预应变后DP780双相钢在拉伸过程中的加工硬化主要表现在大应变区。The phase transformation of dual-phase steel is complicated during the forming process,and the error in evaluating its formability by ordinary tensile properties alone is relatively large.Therefore,for DP780 dual-phase steel,according to the actual production parameters and experimental conditions,different pre-strains(0%,5%,10%and 15%)were applied to uniaxial tensile samples,and the tensile tests were conducted until the samples broke.Then,the mechanical properties and work hardening of materials after pre-stretching were evaluated.The results show that DP780 dual-phase steel has the characteristics of good tensile strength,high work hardening index and low yield ratio,but the plasticity is low,and the elongation is only 20.7%.With the increasing of pre-strain,both yield strength and tensile strength increase correspondingly,but the change of tensile strength is small,and the pre-strain mainly affects the elongation of DP780 dual-phase steel.After the pre-stretched sample continues to be stretched,the value of work hardening index n decreases to the minimum value at the beginning of stretch.With the stretch continues,the n value slowly increases,which is obviously different from that of the tensile specimen without pre-stretching.Furthermore,the work hardening of DP780 dual-phase steel after pre-strain is mainly manifested in the large strain area.

关 键 词：预应变 双相钢 力学性能 加工硬化 成形性 

分 类 号：TF76[冶金工程—钢铁冶金] TG142.1[一般工业技术—材料科学与工程]