15Cr-25Ni-Fe基合金高温塑性变形行为的加工图

THE PROCESSING MAP OF HOT PLASTIC DEFORMATION OF A 15Cr-25Ni-Fe BASE SUPERALLOY

在Gleeble-1500热模拟机上对15Cr-25Ni-Fe基合金GH2674进行了热压缩实验,采用动态材料模型的加工图研究了其在950—1200℃和0．001—10 s^(-1)条件下的热变形行为,结果表明：GH2674合金在热变形时呈现两个微观机制不同的动态再结晶峰区,再结晶Ⅰ区：功率耗散效率峰值为38％,峰值对应的温度和应变速率分别为1040℃与10 s^(-1)；再结晶Ⅱ区：功率耗散效率峰值为40％,峰值对应的温度和应变速率分别为1075℃与0．04 s^(-1),在1075—1100℃温度区间内,可能是晶界相M_38_2的溶解造成该合金的晶粒粗化,这在一定程度上会影响合金的热加工性能,在应变速率小于0．01 s^(-1)、形变温度高于1050℃条件下,合金呈现晶粒急剧粗化现象,进而导致在热变形过程中楔形裂纹的产生；在应变速率高于0．1 s^(-1)、形变温度低于1000℃条件下,合金有出现剪切变形带的趋势,根据上述加工图对GH2674合金的热变形工艺进行了初步设计。

The hot deformation behaviors of 15Cr-25Ni-Fe base alloy GH2674 in the temperature range of 950-1200 ℃ and strain rate range of 0.001-10 s^-1 have been studied by using hot compressing testing on a Gleeble-1500 simulator. A processing map is developed on the basis of these data and by using the principles of dynamic material modeling. The map exhibits two domains： one at 1040 ℃ and 10 s^-1, with a peak efficiency of power dissipation of 38%, the second at 1075 ℃ and 0.04 s^-1, with a peak efficiency of 40%. Optical microscopic observations show they represent two dynamic recrystallization （DRX） domains with different mechanisms. The map also exhibits a long concave band in the temperature range of 1075-1100 ℃, which may be related to the solutionizing of M3B2 phase. At temperatures lower than 1000 ℃ and strain rates higher than 0.1 s^-1, the material may be subjected to potential instabilities, while at temperatures higher than 1050 ℃ and strain rates lower than 0.01 s^-1, the material exhibits significant grain coarsening, furthermore, the wedge cracking would appear at 1200 ℃ and 0.001 s^-1. On the basis of the above processing map, the hot working schedules have been designed primarily.