双重退火对TA10钛合金组织与拉伸性能的影响

Effect of Double Annealing on Microstructure and Tensile Properties of TA10 Titanium Alloy

对TA10钛合金进行了双重退火,即分别在840℃、860℃、880℃和900℃保温1h空冷,随后在560℃保温4 h空冷。退火后采用光学显微镜、扫描电子显微镜及拉伸试验机检测了合金的显微组织、拉伸性能和拉伸断口形貌。结果表明:当首次退火温度在两相区时,合金的微观组织由初生α相和β转变组织构成,且随着首次退火温度的升高,初生α相数量减少,β转变组织增多,次生α相体积明显增大;当首次退火温度在单相区时,合金中初生α相完全消失,组织以粗大β晶粒为主,晶界有明显的α相;随着首次退火温度的升高,合金的强度升高,塑性降低;当首次退火温度在两相区时,拉伸断口有大量等轴状韧窝,首次退火温度升高至单相区后,拉伸断口呈岩石状,并有明显的撕裂棱。

TA10 titanium alloy was double annealed,that is,it was heated at 840,860,880 and 900℃for 1 h,respectively,air cooled,and then was heated at 560℃for 4 h and air cooled.After this,the alloy was tested for microstructure,tensile properties and pattern of tensile fracture via optical microscope,scanning electron microscope and tensile testing machine.The results showed that(a)when the first annealing temperature of the double annealing was in two-phase region,the microstructure of the alloy was composed of primaryαphase andβ-transformed structure,with the increase in the first annealing temperature,amount of the primaryαphase decreased,amount of theβ-transformed structure increased,and volume of the secondaryαphase increased significantly;(b)when the first annealing temperature was in single-phase region,the primaryαphase in the alloy disappeared completely,the structure was mainly composed of coarseβgrains,and there were obviousαphases at grain boundary;(c)with the increase in the first annealing temperature,the alloy increased in strength and decreased in plasticity;and(d)the tensile fracture exhibited a large number of equiaxed dimples when the first annealing temperature was in the two-phase region,and was rock-like and exhibited obvious tearing edges when the first annealing temperature was increased to the single-phase region.