本文關(guān)鍵詞：純鉬板坯熱變形行為研究　出處：《河南科技大學》2015年碩士論文　論文類型：學位論文

  更多相關(guān)文章： 純鉬板坯 熱變形 流變應(yīng)力 動態(tài)再結(jié)晶 熱加工圖

【摘要】：Mo具有高熔點、良好導(dǎo)電導(dǎo)熱性能、較小的比電阻和膜應(yīng)力、低的熱膨脹系數(shù),以及良好的環(huán)保性能,越來越受到人們的關(guān)注。近年來隨著純鉬在鉬靶材領(lǐng)域的應(yīng)用進展,對鉬靶材要求越來越嚴格,要求較高的純度和一定的晶粒度,且致密度高,表面質(zhì)量好。通常采用粉末冶金法制備鉬板靶坯,經(jīng)熱軋制獲得性能滿足要求的鉬靶材。課題以粉末冶金法制備的鉬板坯為研究對象,研究鉬板坯在熱軋制過程中的動態(tài)再結(jié)晶及熱變形行為,具有重要理論意義和工程價值。本文采用Gleeble-1500型熱模擬實驗機,設(shè)計變形溫度1060~1300℃,變形速率0.01~10s-1,變形量為80%時,對粉末冶金法制備的純鉬板坯進行壓縮實驗。繪制高溫壓縮真應(yīng)力應(yīng)變曲線,并分析真應(yīng)力與變形溫度、變形速率的之間關(guān)系。利用Olympus光學顯微鏡及JSM-5600型掃描電子顯微鏡對試驗材料的微觀組織進行了表征,研究變形前后的組織變化規(guī)律,動態(tài)再結(jié)晶情況以及晶粒平均尺寸長大規(guī)律、建立晶粒平均尺寸模型及動態(tài)再結(jié)晶體積分數(shù)模型。運用Arrhenius模型,結(jié)合真應(yīng)力-應(yīng)變曲線分析計算了純鉬板坯的變形激活能,構(gòu)建了本構(gòu)方程。采用THV-50MDX高級維氏硬度檢測儀檢測實驗材料熱變形后的顯微硬度,研究硬度與應(yīng)變溫度、變形速率、真應(yīng)力之間的關(guān)系。建立了純鉬板坯熱加工圖,形成了熱加工工藝準則。研究結(jié)果表明:1.在熱變形條件下,純鉬板坯流變應(yīng)力應(yīng)變曲線中,變形速率為0.01s-1時的流變應(yīng)力有明顯峰值,其他變形速率下峰值不明顯;當變形速率為10s-1,流變應(yīng)力呈波浪狀。2.流變應(yīng)力與變形溫度和變形速率有關(guān),真應(yīng)力隨變形溫度升高而降低,隨變形速率增加而增加。計算此純鉬板坯的本構(gòu)方程為:[( )] [ ]/(RT)10343.3exp0.0092sinh106.4477.113ε′-′= s3.變形溫度越高,變形速率越小時,動態(tài)再結(jié)晶晶粒平均尺寸越大;變形溫度越低,變形速率越大時,發(fā)生動態(tài)再結(jié)晶晶粒越細小,且內(nèi)部裂紋也越多。4.此純鉬板坯最佳熱加工工藝變形溫度為1250~1300℃,變形速率為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，

本文編號：1369101