应变速率及温度对GH3230镍基高温合金力学性能的影响（英文）

Effects of Strain Rate and Temperature on Mechanical Property of Nickel-based Superalloy GH3230

对航空发动机用新型镍基高温合金GH3230在不同温度和应变速率下进行了高温拉伸-断裂试验,分析了应变速率和温度对该合金高温力学性能的影响。结果表明,随着应变速率的增加和温度的下降,合金的塑性流动应力有所提高,加工硬化指数n下降。从流变应力、应变速率和温度的相关性,得到应变速率敏感系数m是一个独立于温度的常量,并计算出GH3230合金的变形激活能Q=441kJ/mol。GH3230合金的热变形温度在1273 K左右时,合金在变形过程中能够充分再结晶,并得到晶粒细小、均匀的组织。SEM断口分析表明GH3230合金在高温下(1144~1273 K)应变率范围为10^(-3)~10^(-1)s^(-1)时的拉伸断裂都是由损伤引起的韧性断裂,且温度对断口形貌影响不大,但应变速率增大会使韧窝尺寸和深浅变小。

High temperature tensile tests of nickel-based superalloy GH3230 were carried out at various strain rates from 10-3 s-1 to10-1 s-1 over temperature range from 1144 K to 1273 K.The emphasis has been put on the effect of strain rate and temperature on the plastic flow stress.The results show that flow stress increases and the hardening exponent n decreases with the strain rate increasing or temperature decreasing.The strain rate sensitivity exponent m is a constant independent of temperature according to the interdependencies of flow stress,strain rate and temperature.The thermal deformation activation energy of GH3230 was calculated as 441 kJ/mol.The full recrystallization will occur when the temperature is about 1273 K and the microstructures with uniform and fine grains can be obtained.The SEM result shows that the fracture mode of all specimens is micro-porous aggregation ductile fracture caused by damage,the variation of temperature has not much effect on fracture morphology at various temperatures,but fracture dimple becomes deeper and larger while the strain rate decreasing.