Abstract: GH3128 alloy samples with carbon content of 0.031% and 0.015% are forged from Φ500 mm ingots to 350 mm × 350 mm square billet by the same open-die forging process，then forge the 350 mm × 350 mm square billet to Φ200 mm round bar by using the heating temperature 1 180 ℃ and 1 100 ℃ and the deformation rate of 27.5% and 36% per operation respectively. The results show that the forging process of 1 100 ℃ heating temperature and 27.5% deformation rate per operation lead to optimal grain size；At the same time the amount of carbide and microstructure is closely related to C content， but has little relationship with forging process； Compared 0.031%C with 0.015%C ， the tensile strength of room temperature is increased by 5%-10%， and the 950 ℃ high temperature stress-rupture time increased by 30%.

Key words: High-temperature Alloy GH3128, Open-die Forging, Carbon Content, Grain Size

摘要： 针对C含量分别为0.031%和0.015%的GH3128合金锭，采用相同自由锻锻造工艺由Φ500 mm铸锭锻制成350 mm × 350 mm方坯，再分别采用1 180 ℃和1 100 ℃的加热温度以及27.5%和36%的每火次变形率将350 mm × 350 mm方坯锻成Φ200 mm圆棒。结果表明，1 100 ℃加热并采用27.5%每火次变形率可以获得最佳晶粒组织；同时显微组织及碳化物数量与C含量关系密切，而与锻造工艺关系较小；0.031%C相较于0.015%C，室温拉伸强度提升5%~10%，950 ℃高温持久时间提升30%。

关键词: 高温合金GH3128, 自由锻, 碳含量, 晶粒度