Effects of Process Parameters on Morphologies and Microstructures of Laser Melting Deposited V-5Cr-5Ti Alloys

Abstract

V-Cr-Ti alloys are promising structural materials for future nuclear systems. In this study, a laser melting deposition process has been applied to the fabrications of V-5Cr-5Ti alloys. Laser powers of 1200W, 1400W and 1600W, scanning speeds of 400 mm/min and 600 mm/min, and scanning strategies of single directional scanning and dual directional scanning have been applied to investigate the effects on the morphologies and microstructures of formed individual deposits and thin walls. The dual directional scanning is favored for fabricating thin walls with regular shape, comparing to the single directional scanning. Microstructures of the deposits and walls consist of columnar grains and equiaxed grains. Due to the effects on temperature gradients, both the laser powers and deposition duration show significant effects on the microstructural evolutions of the thin wall samples. As the laser power and deposition duration increase, columnar to equiaxed transitions have been observed. The regions containing columnar grains and equiaxed grains have a <100> fiber texture and a random texture, respectively.