(1. 哈爾濱工業(yè)大學(xué) 金屬精密熱加工國家級重點實驗室，哈爾濱 150001； 2. 中國核工業(yè)二三建設(shè)有限公司，北京 101300)
摘 要: 運用Gleeble-1500D型動態(tài)熱模擬試驗機對Ti-47Al-2Nb-2Cr(摩爾分數(shù)，%)合金在溫度為950~1150 ℃、應(yīng)變速率為0.001~1 s-1進行熱模擬壓縮試驗，通過對變形開裂后試樣斷口裂紋形貌的分析，闡明TiAl合金高溫變形過程的開裂損傷機理。結(jié)果表明：在低溫(＜1000 ℃)、高應(yīng)變速率(＞0.1 s-1)條件下，TiAl合金高溫變形開裂方式為沿45°剪切開裂，隨著變形溫度的升高和應(yīng)變速率的降低，材料發(fā)生縱向自由表面開裂。采用二分法確定TiAl合金不同溫度和應(yīng)變速率下的臨界變形量，引入考慮溫度和應(yīng)變速度參量的Zener-Hollomon因子，構(gòu)建TiAl合金高溫變形過程臨界損傷模型。
關(guān)鍵字: TiAl合金；高溫變形；臨界損傷
（1. National Key Laboratory for Precision Processing of Metals, Harbin Institute of Technology, Harbin 150001, China; 2. China Nuclear Industry 23 Construction Co., Ltd, Beijing 101300, China）
Abstract:The hot deformation behaviors of Ti-47Al-2Nb-2Cr (mole fraction, %) alloys were studied by Gleeble-1500D at the temperature range of 950-1150 ℃ and strain rate of 0.001-1 s-1. By true stress-strain curve analysis, fracture thermomechanical simulator appearance analysis, the results indicate that shear cracking along the direction of 45° with respect to the compression axis occurs at lower temperature (＜1000 ℃) and higher strain rate (＞0.1 s-1), then it is attributed free surface cracking along longitude with increasing deformation temperature and decreasing strain rate. The critical strain is obtained by bisection method at various temperature and strain rates. The Zener-Hollomon parameter, which considers the effect of temperatures and strain rate, is employed to establish the correlation among critical strain and hot processing parameters in the present investigation. Finally, a fracture criterion of Ti-47Al-2Nb-2Cr alloy during hot deformation is successfully developed and verified by experiment.
Key words: TiAl alloy; hot deformation behavior; critical damage
