Microstructure of TA2/TA15 graded structural material by laser additive manufacturing process
(Engineering Research Center of Ministry of Education on Laser Direct Manufacturing for Large Metallic Components,
School of Materials Science and Engineering, Beihang University, Beijing 100191, China)
School of Materials Science and Engineering, Beihang University, Beijing 100191, China)
Abstract: TA2/TA15 graded structural material (GSM) was fabricated by the laser additive manufacturing (LAM) process. The chemical composition, microstructure and micro-hardness of the as-deposited GSM were investigated. The results show that the TA2 part of exhibiting near-equiaxed grains was Widmanst？tten α-laths microstructure. The TA15 part containing large columnar grains was fine basket-weave microstructure. The graded zone was divided into four deposited layers with 3000 μm in thickness. As the distance from the TA2 part increases, the alloy element contents and the β phase volume fraction increase, the α phase volume fraction decreases and the microstructure shows the evolution from Widmanst？tten α-laths to basket-weave α-laths gradually. The micro-hardness increases from the TA2 part to the TA15 part due to the solid solution strengthening and grain boundary strengthening.
Key words: laser additive manufacturing; TA2/ TA15; graded structural material; microstructure; chemical composition