电子束选区熔化TC4合金固溶时效后组织及力学性能研究

Study on Microstructure and Mechanical Properties of TC4 Alloy by Electron Beam Melting after Solid Solution and Aging

研究了不同工艺参数的固溶时效处理对电子束选区熔化的TC4合金微观组织及力学性能的影响。结果表明,热处理前的试样组织内含有众多大小和取向不一致的条状α晶粒交叉排列,它们与少量的β晶粒共同组成网篮结构。经固溶时效热处理后,α相尺寸增大,固溶温度到达960℃时,组织由网篮组织转变为片层组织。随着固溶温度的升高,TC4合金的强度增加而塑性降低;TC4合金经过930℃固溶处理后并在不同温度时效时,随着时效温度的增加,马氏体α’相的分解的细小的次生α相不断被周围初生α相合并,使TC4合金的组织发生粗化长大,合金强度先增加后降低,塑性增加;并在550℃处理时抗拉强度达到最大的1144.5 MPa,伸长率达到8.7%。

The influence of different solid solution and aging heat treatment on the microstructure and mechanical properties of TC4 alloy fabricated by electron beam melting were investigated.The results show that the untreated structure is made up of crosswise arrangedα-grains with different sizes and orientations,theα-grains and a small amount ofβ-grains form the net basket structure.After solution and aging heat treatment,the size ofαphase increases,when the solution temperature reaches 960℃,the microstructure changes from basket microstructure to lamellar microstructure.With the increase of solution temperature,the strength of TC4 alloy increases while the plastic decreases.When the TC4 alloy is treated at the solution temperature of 930℃ and then aging at different temperatures,with the increase of aging temperature,the fine secondaryαphase decomposed by martensiteα'phase is merged with the surrounding primaryαphase,and the microstructure of the TC4 alloy becomes coarse,the strength of the alloy increases first and then decreases while the plastic increases.When the aging temperature reaches 550℃,the tensile strength reaches the maximum of 1144.5 MPa,and the elongation reaches 8.7%.