热加工工艺对TC6钛合金棒材组织与性能的影响

Effect of hot working process on microstructure and properties of TC6 titanium alloy bars

研究了热加工工艺对TC6钛合金棒材组织与力学性能的影响。结果表明,TC6钛合金在β相变点以下50℃热加工,ϕ160 mm锻坯与ϕ60 mm大规格棒材组织主要为等轴α相+含片状α相的转变β相。与心部相比,表层等轴α相含量较高,片层α数量及尺寸较小,且一火轧制后ϕ60 mm棒材心部存在沿原始β晶界分布的连续或断续的晶界α相。在经二火轧制后ϕ25 mm细棒变形充分,组织中未出现连续的晶界α相,且在900℃退火后,出现了更多的新形成的初晶,α相晶粒全部等轴化,但晶粒尺寸分布不均匀。ϕ60 mm大规格棒材表层强度高于心部,随着退火温度的升高,强度逐渐降低,伸长率变化较小。对于ϕ25 mm细棒,热轧态至800℃退火,随着退火温度的升高,强度逐渐降低,伸长率增加,而当继续升温至900℃退火,强度开始逐渐增加,伸长率逐渐降低。

Effect of hot working process on microstructure and mechanical properties of TC6 titanium alloy bars was studied.The results indicate that theϕ160 andϕ60 mm bars are composed of equiaxedαphase+transformedβincluding plateletαphase when the TC6 titanium alloy is hot worked within 50℃below theβphase transformation point.Compared with the core,more equiaxedαgrains are found and the number and size of the plateletαphase are smaller in the surface.Furthermore,the continuous and discontinuous grain boundaryαalong priorβgrain boundary occurs in core of theϕ60 mm bar produced by the first hot rolling while that isn't found in theϕ25 mm bar deformed fully due to the secondary hot rolling.When annealed at 900℃,more primaryαand most of equiaxedαgrains occur,but the grain size distribution is uneven in theϕ25 mm bar.The strength of theϕ60 mm bar in the surface is greater than in the core,and the strength decreases greatly and elongation varies slightly with the annealing temperature increasing.The strength of theϕ25 mm bar decreases and the elongation increases gradually when the annealing temperature increases from as-rolled to 800℃,while the strength increases and the elongation decreases gradually with the continuous increase of annealing temperature to 900℃.