(煙臺(tái)大學(xué) 精準(zhǔn)材料高等研究院，煙臺(tái) 264010)
摘 要: 鎳基粉末高溫合金的變形抗力大、熱塑性較差、熱加工窗口窄，而且在熱加工過程中易產(chǎn)生裂紋和流動(dòng)不穩(wěn)定等缺陷。本文采用Gleeble-3500熱模擬實(shí)驗(yàn)機(jī)對擠壓態(tài)新型鎳基粉末高溫合金進(jìn)行熱壓縮，壓縮溫度為1050~1150 ℃、應(yīng)變速率為0.001~1 s-1，壓縮真實(shí)應(yīng)變?yōu)?.69。基于雙曲正弦型Arrhenius函數(shù)，計(jì)算該合金的熱激活能Q、構(gòu)建本構(gòu)方程，采用多項(xiàng)式擬合摩擦、溫度變化、應(yīng)變補(bǔ)償?shù)挠绊懀瑢?yīng)力-應(yīng)變曲線及本構(gòu)方程進(jìn)行修正，繪制能量耗散圖和熱加工圖。結(jié)果表明：該合金的熱激活能Q為536.36 kJ/mol，其在變形溫度為1075~1150 ℃、應(yīng)變速率為10-3~10-1.5 s-1的條件下有較好的加工性能，但當(dāng)應(yīng)變速率為0.001 s-1時(shí)，晶粒組織較為粗大，γ′相溶入基體。
關(guān)鍵字: 擠壓態(tài)鎳基粉末高溫合金；熱變形行為；本構(gòu)方程；應(yīng)力應(yīng)變曲線修正；熱加工圖
（Institute for Advanced Studies in Precision Materials, Yantai University, Yantai 264010, China）
Abstract:Nickel-based powder superalloys have high deformation resistance, poor thermoplasticity, narrow hot working window, and are prone to crack and flow instability during hot working. In this paper, thermal compression experiments were carried out on the extruded novel nickel-base powder superalloy by Gleeble-3500 thermal simulator, where the compression temperature was 1050-1150 ℃, the strain rate was 0.001-1 s-1 and the true strain was 0.69. Based on the hyperbolic sinusoidal Arrhenius function, the thermal activation energy Q was calculated and the constitutive equation was built, then the stress-strain curve and constitutive equation were modified by combining friction, temperature change and strain compensation by polynomial fitting. The energy dissipation diagrams and hot processing maps were plotted to determine the suitable thermal processing temperature and strain rate. The results show that the thermal activation energy Q is 536.36 kJ/mol, and the alloy has good processing performances at the deformation temperature ranging from 1075 ℃ to 1150 ℃ and the strain rate ranging from 10-3 s-1 to 10-1.5 s-1, but the grain microstructure is coarse and the γ′ phase dissolves into the matrix at the strain rate of 0.001 s-1.
Key words: extruded nickel-base powder superalloy; thermal deformation behavior; constitutive equation; stress-strain curve correction; hot processing map
