(中南林业科技大学 机电工程学院，长沙 410004)
摘 要: 基于挤压态FGH4096合金双圆锥台试样热压缩变形及过固溶热处理试验，结合DEFORM有限元软件数值模拟，确定试样中各等效应变范围内临界晶粒长大分布规律，研究热加工工艺对挤压态FGH4096合金临界晶粒长大的影响。结果表明：在温度980~1060 ℃、应变速率0.003~0.03 s-1条件下，双圆锥台试样热变形后再经过固溶热处理，合金临界晶粒长大的窗口条件从低温低应变速率向高温高应变速率转变，其中(980 ℃、0.03 s-1)、(1060 ℃、0.003 s-1)条件下可以避免出现临界晶粒长大，并获得均匀晶粒组织。当变形温度为980 ℃时，随着应变速率的增加，异常晶粒长大程度减小，且合金临界晶粒长大位置的临界等效应变数值降低；当应变速率为0.03 s-1时，随着变形温度的升高，异常晶粒长大程度增大，且试样发生临界晶粒长大的等效应变区域扩大。
关键字: FGH4096合金；挤压态；热压缩；过固溶热处理；临界晶粒长大
（College of Mechanical and Electrical Engineering, Central South University of Forestry and Technology, Changsha 410004, China）
Abstract:Based on the hot compression deformation and supersolvus heat treatment of extruded FGH4096 alloy double-cone specimens, with the DEFORM numerical simulation, the distribution of critical grain growth (CGG) in different effective strain ranges was determined. The effect of hot working process on CGG of extruded FGH4096 alloy was studied. The results show that the window conditions for the CGG of the alloy range change from low strain rate at low temperature to high strain rate at high temperature, after the double-cone specimens deformed at temperature of 980-1060 ℃ and strain rate of 0.003-0.03 s-1 and treated by supersolvus heat treatment. Then the CGG can be avoided and uniform grain structure can be obtained at (980 ℃, 0.03 s-1) and (1060 ℃, 0.003 s-1).With the increase of strain rate, the degree of abnormal grain growth and the critical effective strain of CGG decreases at 980 ℃. On the other hand, with the increase of deformation temperature, the degree of abnormal grain growth increases and the effective strain region of CGG enlarges at strain rate of 0.03 s-1.
Key words: FGH4096 superalloy; hot extrusion; thermal compression; supersolvus heat treatment; critical grain growth
