新型镍基粉末高温合金的热变形行为

采用Gleeble-1500热模拟试验机对新型镍基粉末高温合金FGH98Ⅰ进行了单向热压缩变形试验,研究了其在变形温度为950～1150℃,应变速率为0.0003～1s-1条件下的热变形行为,建立和对比了不同应变量下的应变速率敏感因子m图和功率耗散效率因子η图,并对热加工图进行了组织验证。结果表明:合金的流变应力随着变形温度的升高和应变速率的降低而降低;不同应变量下的η图与m图相似,随着应变量的增大,峰区的η与m值逐渐升高;当真应变为0.5时,在变形温度为1050℃,应变速率为0.0003s-1条件下,η与m达到峰值,分别为40%和25%,合金发生了动态再结晶,晶粒细化且无内裂纹。该结果为FGH98Ⅰ合金实际热加工工艺的优化提供了理论依据。

Hot Deformation Behavior of a New Type Nickel-Based P/M Superalloy

Uniaxial hot compression deformation experiments for a new type nickel-based powder metallurgy (P/M) superalloy FGH98 I have been performed on Gleeble-1500 thermal simulator, and the hot deformation behavior has been investigated under the conditions of deformation temperatures of 950-1150 oC and strain rates of 0.0003-1 s-1. The strain rate sensitivity m maps and the power dissipation efficiency η maps have been established and compared at different strains. The microstructural validation of processing maps also has been done. The results show that the flow stress decreases with the deformation temperature increasing and strain rate decreasing. The maps of m and η are similar at different strains, and the values of m and η in the peak zones gradually increase with the strain increasing. When the true strain is 0.5, the alloy has peak η of 40% and peak m of 25% at 1050 oC and 0.0003 s-1, which corresponds to dynamic recrystallization and grain refinement without inner cracks. The above results can be used as a theoretical reference for the optimization of actual hot working processing of FGH98 I alloy.