700℃超超临界转子用617基合金镦粗工艺研究

Study on Upsetting Process of 617-Based Superalloy for A-USC Turbine Rotor Application

对617基合金覫375 mm吨级电渣锭镦粗工艺开展研究,通过对铸态试料进行高温拉伸、Gleeble压缩,以及对覫60 mm×100 mm试样进行等比例锭模拟镦粗等试验,对617基合金的高温强度及塑性、锻造完整性、流变状况及动态再结晶行为等进行分析,确定617基合金开坯锻造温度区间应为950-1 180℃,变形速率应为0.01-0.1 s^-1。通过包覆保温棉解决了617基合金可锻温区狭窄的问题,通过数值模拟预测覫375 mm电渣锭在1 180℃出炉镦粗时所需最大压机吨位约为3 000 t,并在实际生产中得到验证。通过试验证明模拟镦粗件进行1 180℃×2 h再结晶热处理能够得到较均匀的等轴晶组织,有利于下一火次的锻造工艺。试验结果表明,实际操作中需要多火次镦拔才能实现617基合金微观组织的均匀化。

Studs was performed on the upseuing process of one-tonnage φ375 mm ESR ingot in 671-based superalloy,High-temperature tensile test, Gleeble compression test and geometric-proportion simulating upsetting on a φ60 mm×100 mm test sample were carried out to analyze the elevated-temperature strength and plasticity, forging integrity, flow pattern and dynamic recrystallization behavior of 617-based superalloy. The resuhs show that 617-based superalloy is cogged at temperatures between 950℃ and 1 180 ℃ under strain rate of 0.01-0.1 s^-1. Covering the ingot with thermal insulating asbestos solved the problem about forging temperature limitation. The numerical simulation predicts the maximum hydraulic press capacity required by the upsetting of φ375 mm ESR ingot with lapping temperature of 1 180℃ is about 3 000 MT. This has been proven in the actual production. The metallographic test revealed that even equiaxial microstructure can form when the upset ingot is subject to recrystallization heat treatment at 1180 ℃ for 2 hours, which is good for subsequent forging operation. The homogeneous microstrueture of 617-based superalloy can be obtained with multiple upsetting and drawing-out operations.