LZ50钢的热变形行为及热加工图  

Hot deformation behavior and processing maps of LZ50 steel

作　　者：杜诗文[1] 陈双梅[1] 

机构地区：[1]太原科技大学材料科学与工程学院,金属材料成形理论与技术山西省重点实验室,山西太原030024

出　　处：《材料热处理学报》2016年第3期223-229,共7页Transactions of Materials and Heat Treatment

基　　金：国家自然科学基金(51305289,51405325);山西省国际科技合作项目(2013081030);太原科技大学博士启动基金(20122052)

摘　　要：利用Gleeble-3500D热模拟试验机,在变形温度为870-1170℃,应变速率为0.05-3 s^-1,最大变形量为60%的条件下,对LZ50钢进行等温恒应变速率的热压缩实验,研究应变速率和变形温度对流变应力的影响,建立LZ50钢热变形时的本构方程和热加工图。结果表明：LZ50钢的流变应力随变形温度的升高和应变速率的降低而减小,其动态再结晶型流变应力曲线可表述为加工硬化、过渡、软化和稳态流变4个阶段;热变形激活能为304.265 k J/mol,根据双曲正弦方程建立包含Z参数的峰值流变应力本构方程;将LZ50钢的热加工图与快锻液压机的技术参数及通过Deform模拟获得的优化工艺参数相结合可得,当压下量为15%-20%,在开始锻造的高温阶段1050-1150℃,可采用较高的应变速率0.5-3 s^-1,随着锻件温度降低至870-1050℃,应适当降低应变速率至0.5-1.5 s^-1以避开失稳区,整个变形过程的微观组织演变机制为动态回复。Isothermal and constant strain rate hot compression tests of LZ50 steel were studied on a Gleeble-3500 D thermal simulation machine at 870 to 1170 ℃,strain rates from 0. 05 to 3 s^-1,and the maximum deformation of 60%. The influence of strain rate and deformation temperature on flow stress was studied,and the constitutive equation and thermal process maps of LZ50 steel during hot deformation were established. The results show that the peak stress of LZ50 steel can decrease with increasing of deformation temperature and decreasing of strain rate. The hot compression flow stress curve of dynamic recrystallization can be described as four stages of work hardening,transition,softening and steady-state. The deformation activation energy is 304. 265 k J / mol. A peak flow stress constitutive equation with parameter Z was established,which is based on the hyperbolic sine equation. According to the processing maps of LZ50 steel and considering the technical parameters of fast forging hydraulic press and the optimized process parameters obtained by Deform simulation,while the deformation is 15%-20%,suitable strain rate was chosen. At the beginning of high temperature forging stage from1050 to 1150 ℃,a higher strain rate of 0. 5-3s^-1can be taken. When the forging temperature decreases to 870-1050 ℃,in order to avoid the instability zone,the strain rate should be reduced to 0. 5-1. 5 s^-1,and the corresponding microstructure evolution mechanism is dynamic recovery.

关 键 词：LZ50钢 热变形激活能 本构方程 热加工图 

分 类 号：TG142.3[一般工业技术—材料科学与工程]