GH690合金热加工图及管材热挤压实验研究

采用Gleeble-3500热模拟试验机进行高温等温压缩实验,研究了GH690合金在变形温度为950～1200℃、应变速率为0.001～10.000 s-1条件下的热变形行为,利用动态材料模型构建了GH690合金热加工图,并基于加工图进行GH690合金管材热挤压实验。结果表明:GH690合金有应力峰和动态再结晶软化的特征,在ε≥0.4时,流动应力趋于稳定状态;在热加工图中变形温度为1100～1150℃、应变速率为1.0～2.5 s-1时功率耗散效率达到0.34～0.39,该区域对应的工艺参数适合于进行GH690合金管材热挤压;在热加工图中变形温度为950～1000℃,应变速率在0.94～10.00 s-1之间的区域为不稳定变形区域,热加工时应该避开这一区域。

Processing Map and Tube Hot Extrusion of GH690 Alloy

The hot deformation behavior of GH690 alloy was studied by isothermal compression tests in the temperature range of 950~1200 ℃ and strain rate range of 0.001~10.000 s-1 on Gleeble-3500 thermo-simulation machine.The processing map of this alloy was established on the basis of dynamic material model,and the hot extrusion process of GH690 alloy tube based on the processing map was investigated.The results showed that there existed stress peak and dynamic recrystallization softening characteristics in GH690 alloy,in which the flow stress tended to be stable when the strain was more than 0.4.A region with efficiency of power dissipation of 0.34~0.39 could be observed in the processing map in the temperature range of 1100~1150 ℃ and strain rate range of 1.0~2.5 s-1,and the process parameters of this region was suitable for the hot extrusion of GH690 alloy tube.There was a flow instability region in the processing map which occurred roughly in temperature range of 950~1000 ℃ and strain rate range of 0.94~10.00 s-1,and this region should be avoided in the hot deformation process of GH690 alloy.