(1. 合肥工業(yè)大學(xué)材料科學(xué)與工程學(xué)院，合肥 230009；
2. 合肥工業(yè)大學(xué)機(jī)械工程學(xué)院，合肥 230009)
摘 要: 在600~800 ℃溫度區(qū)間對TA15合金進(jìn)行多向等溫鍛造，利用金相顯微鏡(OM)、透射電子顯微鏡(TEM)以及拉伸試驗(yàn)研究了變形溫度對微觀組織與力學(xué)性能的影響。結(jié)果表明：經(jīng)3道次多向等溫鍛造后，TA15合金發(fā)生細(xì)化和球化，隨變形溫度的升高，等軸α機(jī)械破碎細(xì)化效應(yīng)受到抑制，而片狀α細(xì)化更加明顯，不連續(xù)動態(tài)再結(jié)晶(dDRX)機(jī)制逐漸被激發(fā)。在800 ℃時，變形體內(nèi)同時發(fā)生連續(xù)動態(tài)再結(jié)晶(cDRX)和dDRX，且在試樣局部劇烈形變區(qū)域發(fā)生了形變誘導(dǎo)α→β相的轉(zhuǎn)變。隨變形溫度的升高，材料抗拉強(qiáng)度和斷后伸長率的變化趨勢相反，且相比于伸長率，其抗拉強(qiáng)度下降更為顯著，在600 ℃多向鍛造條件下其抗拉強(qiáng)度最高。最后，通過經(jīng)典強(qiáng)化模型的定量分析，證實(shí)了TA15合金多向等溫鍛造時其強(qiáng)度的提高除受細(xì)晶強(qiáng)化和位錯強(qiáng)化外，晶粒形態(tài)、亞結(jié)構(gòu)及大塑性變形(SPD)形成的特殊晶界結(jié)構(gòu)也將對材料的屈服強(qiáng)度產(chǎn)生影響。
關(guān)鍵字: TA15合金；變形溫度；大塑性變形；顯微組織；力學(xué)性能
（1. School of Materials Science and Engineering, Hefei University of
Technology, Hefei 230009, China;
2. School of Mechanical Engineering, Hefei
University of Technology, Hefei 230009, China）
Abstract:The multi-directional isothermal forging (MDIF) experiments of TA15 alloy was carried out at 600-800 ℃. The effects of deformation temperature on microstructure and mechanical properties were studied by metallographic microscopy, transmission electron microscope and quasi-static tensile test. The results show that the grains of TA15 alloy are refined and spheroidized after three cycles of MDIF. With the increase of deformation temperature, the refinement effect of equiaxed α is restrained, while the refinement of lamellar α is more obvious. Additionally, the discontinuous dynamic recrystallization (dDRX) mechanism was gradually dominated. At 800 ℃, both continuous dynamic recrystallization (cDRX) and dDRX occur during deformation, and the deformation induced α→β phase transition occurs in the severely deformed region. The tensile strength and elongation of TA15 alloy show the opposite trend with the increase of deformation temperature, and the tensile strength decreases significantly compared with the elongation. Resultantly, the comprehensive mechanical properties of TA15 alloy are the best at 600 ℃. Through quantitative analysis, it is found that the increase of yield strength is affected not only by Hall-Petch strengthening and dislocation strengthening, but also by grain morphology, substructure and special grain boundary structure induced by SPD.
Key words: TA15 alloy; deformation temperature; severe plastic deformation; microstructures; mechanical properties
