纯钼板坯热变形行为研究

发布时间：2018-01-02 11:55

  本文关键词：纯钼板坯热变形行为研究　出处：《河南科技大学》2015年硕士论文　论文类型：学位论文

  更多相关文章： 纯钼板坯 热变形 流变应力 动态再结晶 热加工图

【摘要】：Mo具有高熔点、良好导电导热性能、较小的比电阻和膜应力、低的热膨胀系数,以及良好的环保性能,越来越受到人们的关注。近年来随着纯钼在钼靶材领域的应用进展,对钼靶材要求越来越严格,要求较高的纯度和一定的晶粒度,且致密度高,表面质量好。通常采用粉末冶金法制备钼板靶坯,经热轧制获得性能满足要求的钼靶材。课题以粉末冶金法制备的钼板坯为研究对象,研究钼板坯在热轧制过程中的动态再结晶及热变形行为,具有重要理论意义和工程价值。本文采用Gleeble-1500型热模拟实验机,设计变形温度1060~1300℃,变形速率0.01~10s-1,变形量为80%时,对粉末冶金法制备的纯钼板坯进行压缩实验。绘制高温压缩真应力应变曲线,并分析真应力与变形温度、变形速率的之间关系。利用Olympus光学显微镜及JSM-5600型扫描电子显微镜对试验材料的微观组织进行了表征,研究变形前后的组织变化规律,动态再结晶情况以及晶粒平均尺寸长大规律、建立晶粒平均尺寸模型及动态再结晶体积分数模型。运用Arrhenius模型,结合真应力-应变曲线分析计算了纯钼板坯的变形激活能,构建了本构方程。采用THV-50MDX高级维氏硬度检测仪检测实验材料热变形后的显微硬度,研究硬度与应变温度、变形速率、真应力之间的关系。建立了纯钼板坯热加工图,形成了热加工工艺准则。研究结果表明:1.在热变形条件下,纯钼板坯流变应力应变曲线中,变形速率为0.01s-1时的流变应力有明显峰值,其他变形速率下峰值不明显;当变形速率为10s-1,流变应力呈波浪状。2.流变应力与变形温度和变形速率有关,真应力随变形温度升高而降低,随变形速率增加而增加。计算此纯钼板坯的本构方程为:[( )] [ ]/(RT)10343.3exp0.0092sinh106.4477.113ε′-′= s3.变形温度越高,变形速率越小时,动态再结晶晶粒平均尺寸越大;变形温度越低,变形速率越大时,发生动态再结晶晶粒越细小,且内部裂纹也越多。4.此纯钼板坯最佳热加工工艺变形温度为1250~1300℃,变形速率为0.01~0.22s-1。
[Abstract]:Mo has high melting point, good thermal conductivity, small specific resistance and film stress, low coefficient of thermal expansion, and good environmental performance. In recent years, with the development of the application of pure molybdenum in the field of molybdenum target, the requirements of molybdenum target are more and more strict, high purity and certain grain size, and high density. The surface quality is good. Usually the molybdenum plate target is prepared by powder metallurgy and the molybdenum target which can be acquired by hot rolling is made. The molybdenum slab prepared by powder metallurgy method is taken as the research object. The study of dynamic recrystallization and hot deformation behavior of molybdenum slab during hot rolling process is of great theoretical significance and engineering value. In this paper, Gleeble-1500 thermal simulation machine is used to study the dynamic recrystallization and hot deformation behavior of molybdenum slab. The design deformation temperature is 1060,1300 鈩，

本文编号：1369101