选区激光熔化成形Ti31钛合金显微组织与力学性能研究OA

Ti31 titanium alloy was fabricated using selective laser melting(SLM).The microstructures of both the as-deposited and annealed conditions were examined,and room-temperature tensile tests along with fracture morphology analy-sis were conducted.The results show that the SLM-formed Ti31 exhibits a dense structure without significant defects.In the as-deposited state,primary β grains with an average width of approximately 110 μm were observed,within which a basket-weave interlacing pattern of acicular α′ martensite was present.The α′ martensite displayed distinct hierarchical characteris-tics and maintained an approximately 45° angle relationship with the β grain boundaries.After annealing at 800℃for 4 h,the primary β grains remained relatively stable,while the α′ phase coarsened and transformed into lamellar α phase.The la-mellar structure retained the basket-weave interlacing arrangement.The as-deposited material achieved a tensile strength ex-ceeding 969 MPa and an elongation above 15.5%.Following the 800℃/4 h annealing treatment,the tensile strength de-creased to about 795 MPa,while the elongation increased to over 19%.Both the as-deposited and annealed conditions of SLM-formed Ti31 exhibited higher strength than forged counterparts,and the elongation of the annealed condition reached a level comparable to that of forged material.Tensile fracture of the as-deposited condition exhibited a mixed brittle and duc-tile mode,whereas the annealed condition showed ductile fracture characteristics.This study provides theoretical support for the application of additively manufactured residual heat removal heat exchangers in nuclear power systems.