铸态GH4175合金高温变形行为及热加工图研究

High Temperature Deformation Behavior and Hot Processing Map of As-Cast GH4175 Alloy

目的建立铸态GH4175合金的本构模型以预测材料变形过程中的流动应力,绘制其热加工图,用于优选铸态GH4175合金热变形的工艺参数。方法采用Gleeble-3500热模拟压缩试验机对铸态GH4175合金试样在不同的变形温度和应变速率下进行热模拟压缩试验,获得流动应力-应变曲线。结果 GH4175合金的流动应力随变形温度的上升和应变速率的下降而下降;计算结果表明建立的本构模型第1道次的流动应力试验值与预测值的最大相对误差为13.54%,最小相对误差为0.38%,平均相对误差为5.1%;第2道次的最大相对误差为25.6%,最小相对误差为0.09%,平均相对误差为6.8%。热加工图中对应的可加工区域:变形温度为1160~1170℃,应变速率为0.01~0.1 s^(-1)。结论建立了GH4175合金预测精度较高的本构模型,在热加工图中高能量耗散率区域所对应的工艺参数下变形后获得了γ+γ′双相细晶组织。

The work aims to establish the constitutive model of as-cast GH4175 alloy to predict the flow stress during deformation and prepare hot processing map, so as to optimize the deformation parameters of the alloy. The isothermal compression tests were carried out to the as-cast GH4175 alloy by Gleeble-3500 simulated machine at different deformation temperature and strain rates, to obtain the flow stress-strain curve. The flow stress of GH4175 alloy decreased with increase of deformation temperature and decrease of strain rate. The calculation results showed that the maximum relative error between the flow stress test value and the predicted value by the constitutive model in the first pass was 13.54%, the minimum relative error was 0.38%,and the average relative error was 5.1%. The maximum relative error in the second pass was 25.6%, the minimum relative error was 0.09%, and the average relative error was 6.8%. In the processable area of the hot processing map, of the deformation temperature was 1160-1170 ℃ and the strain rate was 0.01-0.1 s^(-1). The constitutive model of GH4175 alloy with high prediction accuracy is established, and the γ+γ′ dual-phase fine grain structure is obtained after deformation under the process parameters corresponding to the high power dissipation rate region in the hot processing map.