GH4738高温合金高通量双锥试样设计及晶粒组织演变

Design of high-throughput double cone sample and grain structure evolution of GH4738 superalloy

在高温合金领域,双锥试样被广泛用于高通量研究热加工工艺与组织关系。针对GH4738高温合金,本文通过有限元分析,设计了一种在压缩过程中具有较小等效应变速率波动的双锥试样,并研究了其对晶粒尺寸的影响及其温度依赖性,进而研究了在变形温度为1000~1160℃、应变速率为2 s^(-1)和14 s^(-1)、工程应变为30%、50%、70%的条件下合金的晶粒演变。结果表明:等效应变速率的波动会影响变形后合金的晶粒尺寸,并且具有变形温度依赖性。所设计的双锥试样有利于精确研究等效应变与晶粒组织关系。热压缩实验表明,合金的软化以非连续动态再结晶为主,热加工窗口为变形温度1030~1080℃、应变速率14 s^(-1)、工程应变50%~70%。

In the field of superalloys,double cone sample has been widely used for high-throughput study on the relationship between processing parameters and microstructures.This article designed a double cone sample for GH4738 superalloy with a small effective strain rate(εˉ̇)fluctuations during compression through finite element simulation,and studied the impact ofεˉ̇fluctuations in grain size and its temperature dependence.Moreover,the grain structure evolution of GH4738 superalloy was studied under the conditions of deformation temperatures of 1000−1160℃,strain rates of 2 s^(−1)and 14 s^(−1),and engineering strains of 30%,50%,and 70%.The results indicate that the fluctuation ofεˉ̇strongly affects the grain size of the deformed alloy,and has a temperature dependence.The designed double-cone sample is beneficial for accurate research on the relationship between effective strain and grain structure.The hot compression experiments on the double cone sample show that discontinuous dynamic recrystallization is the main softening mechanism of GH4738 alloy.The hot working window for this alloy is the deformation temperature of 1030−1080℃,the strain rate of 14 s^(−1),and the engineering strain of 50%−70%.