铸态ER8车轮钢的热变形行为及本构模型研究  

Study on hot deformation behavior and constitutive model of as-cast ER8 wheel steel

作　　者：任劲宇 陈飞[1] 张晓峰 陈慧琴[1] 贾晓斌 赵晓东[1] Ren Jinyu;Chen Fei;Zhang Xiaofeng;Chen Huiqin;Jia Xiaobin;Zhao Xiaodong(College of Material Science and Engineering,Taiyuan University of Science and Technology,Taiyuan 030024,China;Technique Center,Taiyuan Heavy Industry Transit Equipment Co.,Ltd.,Taiyuan 030032,China)

机构地区：[1]太原科技大学材料科学与工程学院,山西太原030024 [2]太原重工轨道交通设备有限公司技术中心,山西太原030032

出　　处：《锻压技术》2021年第1期202-207,共6页Forging & Stamping Technology

基　　金：太原科技大学博士科研启动基金项目(20172011);山西省重点研发计划重点项目(201703D111005);山西省重点学科建设经费资助。

摘　　要：采用Gleeble-1500D热模拟试验机,在变形温度为900~1250℃、应变速率为0.001~1 s^-1的条件下对铸态ER8车轮钢进行热压缩试验,得到真应力-真应变曲线。结果发现:其真应力-真应变曲线符合动态再结晶型软化机制,变形初始阶段,材料发生硬化,真应力快速增加,随着变形的继续,材料发生动态回复,加工硬化速率减缓;在材料变形过程中,材料畸变的应变储存能增加,动态再结晶激活,真应力迅速降低,后硬化及软化达到动态平衡。并分析了变形温度和应变速率对该材料高温下真应力的影响,发现真应力的大小随着变形温度的升高及应变速率的降低而减小。通过对试验数据的归纳整理得出,铸态ER8车轮钢的热变形激活能为258.4 k J·mol^-1。建立了Arrhenius双曲正弦本构方程,用作图法求解加工硬化速率,找出峰值应变及临界应变,基于此建立动态再结晶体积分数模型。其能精准地预测此材料的高温软化行为,为有限元数值模拟提供了理论基础。The hot compression experiment of as-cast ER8 wheel steel under deformation temperature of 900-1250℃ and strain rate of 0.001-1 s^-1 was conducted by Gleeble-1500 D thermal simulation testing machine,and the true stress-true strain curve was obtained.The results show that the true stress-true strain curve conforms to the dynamic recrystallization softening mechanism.At the initial stage of deformation,the hardening of material occurs,and the true stress increases rapidly.However,as the deformation continues,the dynamic recovery of material occurs,and the work hardening rate slows down.Furthermore,in the material deformation process,the distortion strain storage energy of metarial increases,the dynamic recrystallization is activated,the true stress decreases rapidly,and the post-hardening and softening reach dynamic balance.Finally,the influences of deformation temperature and strain rate on the true stress of material at high temperature were analyzed.The true stress decreases with the increasing of deformation temperature and the decreasing of strain rate.By summarizing the experimental data,the hot deformation activation energy of as-cast ER8 wheel steel is 258.4 k J·mol^-1,and the Arrhenius hyperbolic sine constitutive equation was established.In addition,the work hardening rate was solved by the graphing method to find the peak strain and critical strain,and the dynamic recrystallization volume fraction model was established,which accurately predicted the high-temperature softening behavior of this material and provided the theoretical basis for finite element numerical simulation.

关 键 词：铸态ER8车轮钢 热变形 本构模型 变形温度 应变速率 

分 类 号：TG314[金属学及工艺—金属压力加工]