固溶温度对Ti-62A合金拉伸性能和断裂韧性的影响

Effects of Solution Temperature on Tensile Properties and Fracture Toughness of Ti-62A Alloy

Ti-62A合金是一种新型高强高韧损伤容限型钛合金,研究了固溶温度对Ti-62A合金30 mm厚板材的显微组织、拉伸性能以及断裂韧性的影响规律。研究结果表明:Ti-62A合金Φ720 mm铸锭经单相区和两相区多道次大变形轧制后所得的30 mm厚板材组织为典型的片层组织,由片层状的α相和β转变组织构成,组织均匀,片层状α相平均宽度约为2.5μm,长度在40～65μm之间。两相区固溶+时效处理后,合金的组织类型为片层状组织,即片层状的初生α相(αp)相与β转变组织,随固溶温度升高,合金中的初生α相(αp)相含量显著减少,β转变组织逐渐增多,次生α相(αs)片层宽度增大,同时合金的强度下降,塑性上升,当接近相变点时这种趋势变缓。单相区固溶+时效处理获得魏氏组织,晶粒粗大,晶界平直而清晰,其拉伸强度高于920℃和940℃固溶时的片层组织,但塑性显著降低;与900℃固溶时相比强度和塑性均降低。合金的断裂韧性随固溶温度的上升而逐渐升高,单相区固溶并时效后的魏氏组织的断裂韧性明显优于两相区固溶并时效后的片层组织。

Effects of solution temperature on microstructure,tensile properties and fracture toughness of Ti-62A alloy were discussed.The results showed that typical microstructure in α/β solution and aging condition was lamellar structure.With increasing solution temperature,the αp phase content decreased,and the thickness of αs phase increased.The tensile strength decreased,whereas a slightly increase was observed in the tensile ductility.The microstructure in β solution and aging condition was widmanstatten structure.Compared with the lamellae structure in solution temperature of 920 ℃ and 940 ℃,the tensile strength increased,but the ductility decreased sharply.Compared with the structure at the solution temperature of 900 ℃,the tensile strength and the ductility decreased.With increasing solution temperature,the fracture toughness increased.Compared with bi-model structure,the fracture toughness of widmanstatten structure was higher.