时效对Ti-6Cr-5Mo-5V-4Al合金组织与拉伸性能的影响

Effect of Aging on Microstructure and Tensile Properties of Ti-6Cr-5Mo-5V-4Al Alloy

研究了时效对一种新型Ti-6Cr-5Mo-5V-4Al合金组织与拉伸性能的影响。研究发现:Ti-6Cr-5Mo-5V-4Al合金在α/β固溶+时效处理后的典型组织为:β晶粒破碎,β晶界处有连续和不连续的项链状初生α相,晶内有不连续的球状初生α相及时效过程析出纵横交错的细小次生α相。β固溶+时效处理后的典型组织为:等轴β晶粒晶界处析出沿着一定取向的次生α相薄片层,晶内弥散分布着平行交错的细小次生α相;在本研究范围内,Ti-6Cr-5Mo-5V-4Al合金经β固溶+时效处理时,低于500℃长时间时效和高于500℃短时间时效有利于合金强化;α/β固溶+时效处理时,低于500℃短时间时效有利于合金强化,而高于500℃或长时间都会降低合金强度,而且在较宽的时效温度范围内都具有良好的强度塑性匹配。Ti-6Cr-5Mo-5V-4Al合金在低于500℃时效时,α/β固溶+时效处理的合金其强度塑性匹配优于β固溶+时效处理处理后的合金;高于500℃时效时,β固溶+时效处理后合金其强度塑性匹配优于α/β固溶+时效处理后的合金。另外,短时间直接时效可以迅速提高合金强度,同时保持优良的塑性,500℃/2h直接时效后强度达1590MPa,同时保持6.5%的延伸率。

Effect of aging on microstructure and tensile properties of a new type Ti-6Cr-5Mo-5V-4Al Alloy was studied.The experimental results showed that the typical microstructure of Ti-6Cr-5Mo-5V-4Al alloy with α/β solution and aging treatment was broken β grains,continuous and discontinuous necklace-like primary α phase at the β grain boundary,discontinuous spherical primary α phase in the intragranular,and small crossing secondary α phase precipitated during the aging treatment.And the typical microstructure of Ti-6Cr-5Mo-5V-4Al alloy with β solution and aging treatment was equiaxed β grain and secondary α phase precipitated at the equiaxed β grain boundary with a certain orientation,and small crossing secondary α phase homogeneous distributed in the intragranular.Ti-6Cr-5Mo-5V-4Al alloy dissolved in the β area and aging treatment,would be helpful to reinforce alloys when aging at temperature higher than 500 ℃ for a long time,or aging at lower than 500 ℃ for a short time.When dissolved in the α/β area and aging treatment,it would be useful to reinforce alloy aged at temperature lower than 500 ℃ for a short time;aging at temperature higher than 500 ℃ or for a long time would reduce the strength of the alloy,and also,there was is a good strength and plastic match for the alloy in a quite wide range of aging temperature.Ti-6Cr-5Mo-5V-4Al alloy,when aged at temperature lower than 500 ℃,the strength and plastic matched with α/β solution and aging was much better than that with β solution and aging,and when aged at temperature higher than 500 ℃,the results might be inverse.In addition,the short time direct aging treatment could rapidly increase the strength of the alloys,meanwhile,maintaining excellent ductility,such as the alloy directly aged at 500 ℃/ 2h,strength reached to 1590 MPa,while the elongation maintained 6.5%.