GH761变形高温合金的热变形行为

HOT DEFORMATION BEHAVIOR OF GH761 WROUGHT Ni BASE SUPERALLOY

镍基GH761合金热模拟压缩实验表明,当变形温度T_d一定时,随应变速率(?)的降低,变形峰值应力σ_p和稳态流动开始应力σ_s及与它们对应的应变ε_p和ε_s均降低;当应变速率一定时,随T_d的升高,σ_p和σ_s以及ε_s均降低,但ε_p基本不变.细化原始晶粒可提高再结晶形核率,在此基础上降低变形温度和提高变形速率是细化最终晶粒的重要途径.当应变达到完全再结晶时,合金具有最均匀且细小的组织;超过这一应变值,晶粒开始长大.GH761合金的热变形本构方程为:(?)=6.5×10~6σ_P^(4.86)exp(-461×10~3/RT).

The flow stress-strain behavior of GH761 alloy was investigated via hot compression testing. The peak stress σp, starting steady-state stress σs, and corresponding strain εp, εs decrease with decreasing strain rate ε at constant temperature. At constant strain rate, σp, σs and εs drop with rising temperature, but εp does not change obviously. On the basis of reducing original grain size, lowering deformed temperature and enhancing strain rate can well refine structure. The microstructure will be most homogenous and finest when the strain reaches the level that DRX is finished exactly. Further increasing the strain will promote the grain growth. The hot deformation constitutive equation obtained is as follows： ε = 6.5 × 10^6σp^4.86（-461 ×10^3/RT）.