IN718高温合金的新型热控凝固工艺优化  

New Thermally Controlled Solidification Optimization of IN718 Superalloy

作　　者：介子奇[1,2] 张军 刘鼎元[1] 郭敏 JIE Ziqi;ZHANG Jun;LIU Dingyuan;GUO Min(State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi'an 710072,China;School of Materials Science and Chemical Engineering,Xi'an Technological University,Xi'an 710021,China)

机构地区：[1]西北工业大学凝固技术国家重点实验室,西安710072 [2]西安工业大学材料与化工学院,西安710021

出　　处：《机械工程材料》2024年第10期9-15,共7页Materials For Mechanical Engineering

基　　金：国家自然科学基金资助项目(52031012,51904218)。

摘　　要：针对高温合金复杂薄壁铸件易出现欠铸、晶粒粗大和疏松等问题,开发了一种以“低温浇注、高温充型、顺序凝固”为特征的新型热控凝固工艺,研究了在1 380℃浇注温度下模壳温度(1 260~1 350℃)和抽拉速度(6~48 mm·min^(-1))等工艺参数对IN718高温合金圆柱试样组织的影响,并在优化工艺下进行了复杂薄壁特征结构件的成形试验。结果表明:随着模壳温度升高,试样的晶粒尺寸从2.33 mm增加到7.46 mm,且组织均匀性变差,断面等轴晶比例由98%降低到41%,疏松数量减少,尺寸减小。随着抽拉速度增大,晶粒尺寸从3.66 mm减小到2.69 mm,疏松数量增加,尺寸增大;当抽拉速度不小于24 mm·min^(-1)时,组织均匀性较好。最优工艺为模壳温度1 290℃、抽拉速度24 mm·min^(-1),采用该工艺可制备得到晶粒尺寸为0.81 mm、疏松面积分数仅为0.2%、最小壁厚为1.8 mm的IN718高温合金大面积薄壁特征结构件。A new thermally controlled solidification characterized by“low-temperature pouring,high-temperature filling,and sequential solidification”had been developed to address the problems of misrun,coarse grain and microporosity in complex thin-walled castings of superalloys.The influence of mold temperature (1 260?1 350℃) and withdrawal rate(6?48 mm·min^(-1)) on the microstructure of IN718 superalloy cylindrical samples was studied at a pouring temperature of1 380℃,and the forming test of complex thin-walled characteristic structural parts was carried out under the optimized process.The results show that with the increase of mold temperature,the grain size increased from 2.33 mm to 7.46 mm,the uniformity of the microstructure was deteriorated,the proportion of equiaxed grains in the cross-section decreased from 98%to 41%,and the quanity and size of microporosity decreased.With the increase of the withdrawal rate,the grain size decreased from 3.66 mm to 2.69 mm,and the quanity and size of microporosity in creased.When the withdrawal rate was not less than 24 mm·min^(-1),the microstructure uniformity was good.The optimized process was the mold temperature of 1 290°C and the withdrawal rate of 24 mm·min^(-1).A large area thin-walled structural part of IN718 superalloy with a minimum wall thickness of 1.8 mm,grain size of 0.81 mm and microporosity area fraction of only 0.2%was prepared by this process.

关 键 词：新型热控凝固工艺 IN718高温合金 晶粒尺寸 组织均匀性 疏松 

分 类 号：TG21[金属学及工艺—铸造]