在始锻温度1120℃, 终锻温度1050℃的近等温锻造条件下,通过工程应变量75%的变形获得晶粒细小的喷射成形FGH4095高温合金组织.合金经热处理调节晶粒尺寸, 平均晶粒直径约为8 μm,其室温和650℃拉伸强度(σ_b)分别为1565和1552 MPa,屈服强度(σ_0.2)分别达1231和1130 MPa. 利用OM, SEM和TEM对不同状态坯料进行微观组织观察.结果表明, 经较大累积变形量后, 合金组织由尺寸1-3 μm的细小再结晶晶粒和较大尺寸狭长变形晶粒组成,细小再结晶晶粒为后续静态再结晶提供了形核核心, 小角度晶界为静态再结晶提供了晶格畸变能作为驱动力储备.对比沉积态组织, 喷射成形高温合金经锻造后晶界洁净度更高、碳化物破碎、微观孔洞等缺陷更少,细小的三次γ＇相弥散分布于基体之中, 具有较好的力学性能.

Spray forming is a rapid solidification technology.The metal melts are atomized by inert gas into droplets of 10—100 μm in size, and fly at subsonic speed onto a deposition substrate during the spray forming process. The main features of spray formed material are free from macro-segregation, the well fine grain size and uniform distribution of the strengthening phase, leading to improvement of mechanical property at acceptable costs compared to the conventional techniques. Spray forming is an inexpensive alternative to powder metallurgy (PM) for the production of High－alloyed materials, finer microstructures and better mechanical properties than conventional materials. The spray forming route is trying to manufacture superalloy turbine components in the aerospace field. FGH4095 superalloy is generally used to manufacture powder metallurgy turbine disc for high working temperature of 650℃ in aerospace industries of China. The microstructure features of spray formed FGH4095 superalloy after isothermal forging and heat treatment process are studied in thework. Spray formed FGH4095 superalloy with grain size of 8 μm was prepared by 75% engineering deformation near isothermal forging under beginning temperature 1120℃ and finish temperature 1050℃. The tensile strengths (σ_b) of isothermal forged FGH4095 superalloy at room temperature and 650℃ reach 1565 and 1552 MPa, respectively, and the yield strengths (σ_0.2) at room temperature and 650℃ reach 1231 and 1130 MPa, respectively. Meanwhile, the microstructure evolution was observed by OM, SEM and TEM. The results indicate that alloy microstructure are composed of fine recrystallization grains and larger deformed grains. Fine recrystallization grains  provide nucleation core, and then small—angle grain boundaries provide lattice distortion energy for static recrystallization. Compared with spray formed material, isothermal forged superalloy possesses fine tertiary γ′ phases dispersed in the matrix, cleaner boundary, crushed carbides, and less defects such as micropores, which has better mechanical properties.