热处理对TC4薄板组织与性能的影响

Influence of Heat-treatment Process on Microstructure and Performance of TC4 Alloy Sheet

研究了退火温度、保温时间、退火方式及冷却方式等热处理制度对TC4薄板室温力学性能和显微组织的影响。结果表明,在单片式退火方式下,温度从720℃升高到820℃时,板材的抗拉强度和屈服强度先降低后升高,但其伸长率先升高后降低,退火温度为780~800℃时板材的强度和塑性得到了良好的匹配;当保温时间从30 min延长到120 min时,板材的抗拉强度变化不明显,屈服强度显著下降,但保温时间超过60 min后屈服强度趋于定值。随退火温度的升高和保温时间的延长,初生α和β转变组织的晶粒尺寸都增大,且β转变组织的比例增大。采用真空垛式退火＋炉冷方式,退火温度为780℃、保温时间为7 h时板材可获得良好的综合力学性能。

The influences of heat treatment, such as annealing temperature and time, annealing way, cooling rates on the microstructure and room temperature mechanical properties of TC4 titanium alloy sheet were studied. The experimental results show that the tensile strength and yield strength of the alloy sheet decrease at first and then increase with the increase of annealing temperature from 720 ℃ to 820 ℃ under the condition of monolithic annealing, but elongation has taken on an opposite change. And the strength and elongation get a well match at temperature of 780-800 ℃. When the holding time changes from 30 min to 120 min, the tensile strength has a little change, while the yield strength has a significant decrease before 60 min, and then it is up to a fixed value. The grain size of primary α and transformed β increase with the increase of annealing temperature and annealing time. And the amout of transformed β raises at the same time. The predominant comprehensive mechanical properties of TC4 alloy can be obtained under the conditions of 780 ℃ of annealing temperature and 7 h of annealing time with vacuum stack annealing and furnace cooling treatment.