热处理对高温钛合金TG6铸造组织及性能的影响

对熔模精铸TG6合金进行了热等静压和退火热处理试验,研究了其铸态、热等静压态和退火态的显微组织和力学性能。结果表明,该合金在铸态下为晶粒粗大的魏氏组织,组织中存在缩松缺陷,合金抗拉强度为871.3MPa,塑性0.8%,合金组织中的疏松缺陷为断裂的裂纹起始源;通过热等静压后该合金抗拉强度及伸长率提高到950.7 MPa和3.7%;经过750℃退火热处理后,组织中β板条部分溶解,并析出(TiZr)6Si3硅化物,合金的室温拉伸延伸率提高到5%以上,强度相对于热等静压未发生明显改变,断口表现为解理断裂。

Effect of Annealing on Microstructure and Tensile Property of Cast TG6 High-temperature Ti-based Alloy

The microstructure and mechanical properties of high temperature titanium alloy TG6 under different conditions such as cast state,hot isostatic pressing and annealing treatment were studied.The resuits shows that the microstructure of the as-cast alloy is coarse Widmanstaten with shrinkage porosity,and the resulting tensile strength is 871.3 MPa,while the elongation is only O.8％.It is found out that shrinkage porosity acts as crack initiation source.The tensile strength and elongation increase to 871.3 MPa and 0.8％ respectively after HIP.The banded and granular (TiZr)6Si3 silicide phase precipitate in β lathes after annealing at 750 ℃,and β lathes dissolve partially.The ductility at room temperature improves to more than 5％ after annealing,with no significant change of tensile strength compared to that of HIP,and the tensile fracture surface indicates the characteristics of cleavage fracture.