电子束熔丝成形TC17钛合金显微组织与拉伸性能研究

针对电子束熔丝(EBWD)成形TC17钛合金开展了显微组织调控与力学性能研究。成形态EBWD TC17钛合金的成分均匀性较好,具有沿z方向外延生长并贯穿多个沉积层的粗大β柱状晶组织,柱状晶内部为细密的网篮状组织。经过热等静压后,β柱状晶内部呈现粗短棒状α网篮组织。经过固溶时效处理后,β基体中同时存在粗短棒状α相和细小的次生α相。成形态EBWD TC17材料的抗拉强度为935MPa,延伸率为9.0%;热等静压态材料的抗拉强度为904MPa,延伸率为18.0%;二重固溶+时效后,由于析出的细小次生α相起到了沉淀强化的作用,材料的抗拉强度较热等静压态提高了18%(至1066MPa),但塑性显著下降(至7.5%),其拉伸断口的韧窝数量也大幅减少。

Investigation of Microstructure and Tensile Properties of TC17 Alloy Fabricated by Electron Beam Wire Deposition

The microstructure and tensile properties of TC17 alloy fabricated by electron beam wire deposition(EBWD)were investigated.The as-built EBWD TC17 alloy exhibited a homogeneous element distribution,and the coarse columnarβgrains grew epitaxially through many deposited layers along the z direction.Inside each columnar grain there was fine basket-waved microstructure.After hot isostatic pressing(HIP),smallαrods formed in theβmatrix.In the solution treated and aged material,rod-likeαphase and fineαprecipitates both existed.The tensile strength and elongation of as-built EBWD TC17 alloy were 935MPa and 9.0%,respectively.The tensile strength and elongation after HIP were 904MPa and 18.0%.After solution treating and aging,the tensile strength increased 18%(to 1066MPa)compare with the HIP condition due to the strengthening effect of fineαprecipitates.However,the elongation decreased significantly(to 7.5%)and the ductile dimples on the tensile fracture surface also decreased.