詳細描述

鈦及鈦合金具有眾多優異(yi)的(de)性能，如(ru)高的(de)比強度、優良的(de)耐腐蝕性、良好(hao)的(de)低溫(wen)性能以及無磁等特點(dian)，廣泛應用于航(hang)空、航(hang)天(tian)、海(hai)洋(yang)、汽車和生物醫藥產(chan)業。

其(qi)應用(yong)(yong)水(shui)平(ping)日(ri)益成(cheng)為衡(heng)量(liang)一個國家(jia)或(huo)地區的(de)(de)經濟水(shui)平(ping)、社會發展和(he)戰略(lve)地位(wei)的(de)(de)重要(yao)指標。TA15鈦合金(jin)是一種通用(yong)(yong)型高(gao)鋁含量(liang)的(de)(de)近α型鈦合金(jin)，兼有α型和(he)α+β型鈦合金(jin)的(de)(de)優點，具有中等室溫和(he)高(gao)溫強度，良好的(de)(de)熱穩定性和(he)焊接(jie)性能，長(chang)時工作溫度可達(da)500℃，主(zhu)要(yao)用(yong)(yong)于飛機(ji)(ji)結構件和(he)發動機(ji)(ji)上，是一種重要(yao)的(de)(de)航空材料。

研(yan)究(jiu)(jiu)發現，晶粒細(xi)化可(ke)以有(you)(you)(you)效提升鈦合(he)金(jin)(jin)的(de)(de)(de)(de)強度(du)及塑(su)性(xing)(xing)，進一步提高其(qi)使(shi)用壽(shou)命。大(da)(da)塑(su)性(xing)(xing)變(bian)(bian)(bian)形(xing)(xing)(xing)技術(shu)（SPD）通過(guo)對金(jin)(jin)屬(shu)施加(jia)大(da)(da)的(de)(de)(de)(de)塑(su)性(xing)(xing)應變(bian)(bian)(bian)，有(you)(you)(you)效細(xi)化金(jin)(jin)屬(shu)組(zu)織(zhi)，從而(er)獲(huo)得(de)亞微米甚至(zhi)納(na)米尺寸(cun)的(de)(de)(de)(de)晶粒，提高合(he)金(jin)(jin)的(de)(de)(de)(de)綜合(he)性(xing)(xing)能(neng)(neng)(neng)。多(duo)向鍛壓工(gong)(gong)(gong)(gong)(gong)藝(yi)（MDF）是一種典型的(de)(de)(de)(de)大(da)(da)塑(su)性(xing)(xing)變(bian)(bian)(bian)形(xing)(xing)(xing)方法，變(bian)(bian)(bian)形(xing)(xing)(xing)過(guo)程(cheng)中對塊狀(zhuang)(zhuang)金(jin)(jin)屬(shu)材(cai)(cai)料(liao)沿(yan)三個(ge)不同的(de)(de)(de)(de)軸(zhou)向進行反復(fu)壓縮，其(qi)工(gong)(gong)(gong)(gong)(gong)藝(yi)原(yuan)理(li)如(ru)圖 1 所(suo)示。多(duo)向等(deng)溫(wen)(wen)(wen)鍛壓不僅工(gong)(gong)(gong)(gong)(gong)藝(yi)簡單、成(cheng)(cheng)本(ben)低，而(er)且(qie)可(ke)使(shi)用現有(you)(you)(you)的(de)(de)(de)(de)工(gong)(gong)(gong)(gong)(gong)業裝(zhuang)備實現制備大(da)(da)塊致(zhi)密材(cai)(cai)料(liao)并使(shi)材(cai)(cai)料(liao)性(xing)(xing)能(neng)(neng)(neng)得(de)到改善(shan)等(deng)目的(de)(de)(de)(de)，可(ke)直接用于工(gong)(gong)(gong)(gong)(gong)業生(sheng)產(chan)。目前，對初始組(zu)織(zhi)為片狀(zhuang)(zhuang)或雙態組(zu)織(zhi)的(de)(de)(de)(de) TA15 鈦合(he)金(jin)(jin)大(da)(da)變(bian)(bian)(bian)形(xing)(xing)(xing)量的(de)(de)(de)(de)熱(re)加(jia)工(gong)(gong)(gong)(gong)(gong)組(zu)織(zhi)演變(bian)(bian)(bian)的(de)(de)(de)(de)研(yan)究(jiu)(jiu)多(duo)有(you)(you)(you)報道。對初始組(zu)織(zhi)為等(deng)軸(zhou)狀(zhuang)(zhuang)的(de)(de)(de)(de)TA15鈦合(he)金(jin)(jin)熱(re)加(jia)工(gong)(gong)(gong)(gong)(gong)變(bian)(bian)(bian)形(xing)(xing)(xing)的(de)(de)(de)(de)研(yan)究(jiu)(jiu)多(duo)在(zai)近β或β單相(xiang)區(qu)溫(wen)(wen)(wen)度(du)區(qu)間，但存在(zai)變(bian)(bian)(bian)形(xing)(xing)(xing)后冷卻速(su)率不夠(gou)快易造成(cheng)(cheng)晶粒尺寸(cun)迅(xun)速(su)長大(da)(da)和(he)材(cai)(cai)料(liao)不均勻問題，且(qie)高溫(wen)(wen)(wen)β相(xiang)組(zu)織(zhi)難以保(bao)留。由于TA15合(he)金(jin)(jin)鍛壓溫(wen)(wen)(wen)度(du)區(qu)間窄(zhai)，在(zai)β轉變(bian)(bian)(bian)溫(wen)(wen)(wen)度(du)下成(cheng)(cheng)形(xing)(xing)(xing)具有(you)(you)(you)較(jiao)低的(de)(de)(de)(de)延展性(xing)(xing)。因此，研(yan)究(jiu)(jiu)在(zai)相(xiang)變(bian)(bian)(bian)點以下溫(wen)(wen)(wen)度(du)區(qu)間內大(da)(da)塑(su)性(xing)(xing)變(bian)(bian)(bian)形(xing)(xing)(xing)參數對組(zu)織(zhi)性(xing)(xing)能(neng)(neng)(neng)的(de)(de)(de)(de)影響具有(you)(you)(you)較(jiao)大(da)(da)的(de)(de)(de)(de)實際意義。本(ben)實驗通過(guo)等(deng)溫(wen)(wen)(wen)多(duo)向鍛壓實驗，結合(he)組(zu)織(zhi)觀察和(he)室溫(wen)(wen)(wen)拉(la)伸(shen)性(xing)(xing)能(neng)(neng)(neng)測試，對在(zai)α+β相(xiang)區(qu)溫(wen)(wen)(wen)度(du)加(jia)熱(re)后在(zai)不同變(bian)(bian)(bian)形(xing)(xing)(xing)條件下變(bian)(bian)(bian)形(xing)(xing)(xing)水冷后的(de)(de)(de)(de)初始組(zu)織(zhi)為等(deng)軸(zhou)狀(zhuang)(zhuang)的(de)(de)(de)(de)TA15鈦合(he)金(jin)(jin)的(de)(de)(de)(de)顯微組(zu)織(zhi)演變(bian)(bian)(bian)和(he)室溫(wen)(wen)(wen)拉(la)伸(shen)性(xing)(xing)能(neng)(neng)(neng)進行研(yan)究(jiu)(jiu)，探明初生(sheng)α隨變(bian)(bian)(bian)形(xing)(xing)(xing)道次和(he)溫(wen)(wen)(wen)度(du)的(de)(de)(de)(de)演化規律，以獲(huo)得(de)組(zu)織(zhi)均勻、綜合(he)性(xing)(xing)能(neng)(neng)(neng)優異(yi)的(de)(de)(de)(de)TA15合(he)金(jin)(jin)材(cai)(cai)料(liao)。

TA15鈦鍛件鍛壓的組織變化特(te)點：

1) TA15 鈦合(he)金(jin)經多(duo)向鍛壓變形(xing)后(hou)，晶(jing)粒(li)(li)主(zhu)要通(tong)過機械(xie)破(po)碎和動態再(zai)結晶(jing)細化(hua)。700 ℃變形(xing)條件下隨著變形(xing)道次(ci)(ci)的增加，晶(jing)粒(li)(li)細化(hua)的主(zhu)要方式由機械(xie)破(po)碎轉向連續動態再(zai)結晶(jing)，組織(zhi)中粗大的初生α晶(jing)粒(li)(li)得(de)到明顯(xian)細化(hua)，3道次(ci)(ci)后(hou)細化(hua)至6.0μm，等軸(zhou)α晶(jing)粒(li)(li)增多(duo)，顯(xian)微組織(zhi)均勻性(xing)得(de)到有效(xiao)提(ti)高(gao)。

2) 3 道(dao)次變形條(tiao)件下，隨(sui)著變形溫度的(de)升(sheng)高，材料中的(de)動(dong)態再結(jie)晶(jing)現象明顯(xian)，合金(jin)中位(wei)錯等(deng)缺陷減少(shao)，900 ℃，3道(dao)次變形條(tiao)件下初生(sheng)α晶(jing)粒細(xi)化效果不(bu)明顯(xian)。

3) 多向鍛壓變(bian)(bian)形(xing)(xing)后(hou)，隨著鍛壓道次(ci)的(de)(de)增加，材(cai)料的(de)(de)強塑(su)性(xing)提高，700 ℃，3道次(ci)變(bian)(bian)形(xing)(xing)條(tiao)件下抗拉強度(du)(du)提高到1443 MPa，延(yan)伸率(lv)增加到13.6%，變(bian)(bian)形(xing)(xing)溫(wen)度(du)(du)的(de)(de)提高保(bao)證了材(cai)料的(de)(de)良好塑(su)性(xing)，強度(du)(du)得到改善，材(cai)料綜(zong)合(he)性(xing)能(neng)得到明(ming)顯提高。