(西北工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院， 西安 710072)
摘 要: 在等溫恒應(yīng)變速率壓縮過程中，隨著等效應(yīng)變速率的增大，變形熱效應(yīng)對流動應(yīng)力的影響程度增大。當(dāng)?shù)刃?yīng)變速率很小時(shí)，變形熱效應(yīng)對流動應(yīng)力的影響可忽略不計(jì)，壓縮過程可近似認(rèn)為是等溫過程；當(dāng)?shù)刃?yīng)變速率較大時(shí)，變形熱效應(yīng)對流動應(yīng)力的影響相當(dāng)顯著，壓縮過程基本上成為絕熱過程。提出了一種考慮變形熱效應(yīng)對流動應(yīng)力影響的本構(gòu)關(guān)系建立方法。用該方法建立的本構(gòu)關(guān)系能客觀地反映材料在熱態(tài)變形過程中的動態(tài)響應(yīng)特性，為提高塑性加工過程數(shù)值模擬的精度創(chuàng)造了必要的前提。
關(guān)鍵字: 本構(gòu)關(guān)系； 變形熱效應(yīng)； 非線性回歸； 熱力參數(shù)
（College of Materials Science & Engineering， Northwestern Polytechnical University Xi′an 710072， P.R.China）
Abstract:During the isothermal constant strain rate compression process, the effectof deformation heating on flow stress increases with increasing equivalent strain rate. When the equivalent strain rate is relatively low， this influence can beneglected and the compression process can be considered as an isothermal process. While the equivalent strain rate is high， this influence is of importance and the compression process can be approximately considered as an adiabatic process. In this paper a method is proposed for taking the effect of deformation heating into consideration and the constitutive relationship for GH4169 alloy was formulated by using the method based on the results of isothermalconstant strain rate compression test. The proposed constitutive relationship is capable of revealing the dynamical characteristics of materials during hot deformation processes， creating an essential prerequisite for improvement of numerical simulation accuracy of metal forming processes.
Key words: constitutive relationship； deformation heating； nonlinear regression； thermomechanical parameters
