Effect of post heat treatment on the microstructure and properties of as-annealed TC4 ELI alloy
The effects of post heat treatment on the microstructure and mechanical properties of an-nealed TC4 ELI alloy investigated by optical microscopy(OM),transmission electron microscopy(TEM),scanning electron microscopy(SEM),tensile and Charpy impact test at room temperature.The results show that the"bimodal → equiaxed"reverse transformation occurs in the annealed TC4 ELI al-loy after aging at 520-720 ℃,and the strength increases first and then decreases.The impact toughness of the annealed TC4 ELI alloy decreases to the lowest value at 560 ℃,then increases slightly with the increase of temperature.The appearance of aging α phase is the main reason for the deterioration of im-pact toughness,while the precipitation of α2 phase has little effect.The strength of TC4 ELI alloy aged at 620 ℃ increases slightly after high temperature treatment.When the temperature rises to the β phase region,the coarsening of the microstructure causes a sudden drop in yield strength,and the appearance of the α phase at the grain boundary causes a sudden drop in plasticity.After high temperature treat-ment,the aging α phase disappears,and the impact toughness is recovered to a greater extent.
annealed TC4 ELI titanium alloypost heat treatmentmicrostructurestrengthimpact toughness
NETL
NSTL
万方数据
