Effect of Heat Treatment Temperature on Microstructure and Impact Performance of TC18 Titanium Alloy AITranslate

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Chinese Library Classification Number:TG156.1[金属学及工艺—热处理]

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TC18 titanium alloy bars were heat treated at different temperatures,and then cooled in the fur-nace.The effects of heat treatment temperature on the microstructure,phase composition,impact perfor-mance and impact fracture micromorphology of the alloy were analyzed by optical microscope,scanning e-lectron microscope,X-ray diffractometer and impact tester.The results show that the size,distribution and morphology ofαphase in TC18 titanium alloy have different degrees of change after heat treatment at dif-ferent temperatures.In the process of increasing the heat treatment temperature,the large blockαphase gradually disappears,the long stripαphase becomes finer,and more fine needleαphase precipitates.The microstructure of the alloy after heat treatment at different temperatures and furnace cooling formsαphase andβphase,and with the increase of heat treatment temperature,the diffraction peak intensity of someαphase andβphase increases.The equiaxed and strip-shapedαphase can make the crack propagation path smoother,while the needleαphase andβphase can disperse the stress of the alloy when it is impacted and avoid brittle fracture caused by stress concentration.The impact performance of the alloy gradually decrea-ses with the increase of heat treatment temperature.When the heat treatment temperature is 835℃,the al-loy has the best impact performance with an impact absorption energy of 46 J and an impact toughness of 57 J/cm².When the heat treatment temperature is low(835℃and 855℃),the impact fracture micromor-phology of the alloy is mainly characterized by large dimples,which contain a large number of small dim-ples.When the heat treatment temperature is high(875℃and 895℃),the fracture dimple size becomes smaller,tearing edges appear,and the void size increases.