Control of Solidification Structure of Stainless Steel in Additive Manufacturing Process

Abstract

Additive metal manufacturing-has been attracting attention for various applications such as aircraft parts. However, the parts manufactured exhibit anisotropy characteristics due to the columnar crystal structure induced by rapid melting and solidification. In this work, an equiaxed solidification structure is obtained by adding Zr to promote nucleation. Samples were fabricated by additive manufacturing using Zr-added SUS304L powder. Their microstructures were observed by scanning electron microscopy and transmission electron microscopy. The mechanical and corrosion resistance properties were evaluated by comparison with samples fabricated by additive manufacturing using SUS316L. The microstructure observation revealed that the formation of columnar crystals in the SUS304L-Zr-3DP samples was suppressed compared with the SUS316L-3DP samples and that the average grain size was reduced to 1/3 or less. The transmission electron microscopy revealed a ZrN crystallized substance, which may have contributed to the suppression of columnar crystal formation. Tensile test results showed that the SUS304L-Zr-3DP exhibited isotropic mechanical properties. Corrosion resistance tests using electrochemical methods showed that they exhibited higher corrosion resistance than the SUS316L-3DP. These results demonstrate that the solidification structure formed during additive manufacturing can be controlled by adding Zr into the alloy matrix as nucleation sites.

Austenite Reversion Behavior of Maraging Steel Additive-manufactured by Laser Powder Bed Fusion

“…The L-PBF process enables the manufacturing of complex-shaped parts of steel and is expected to be applied not only to lightweight structural parts but also to fabricate molds for press-forming and injection processes. The L-PBF process [6][7][8] for steel powders has been reported for SUS316L 9,10) , SUS304L 10) , and maraging steel 11,12) , and it has been recently reported for various ferrous alloys including duplex stainless steels 13) , 17-4PH steel 14) (SUS630 equivalent), tool steels 15) and high-strength steels 16) .…”

Microstructure Control of Continuous Casting Slab of Grain Oriented Silicon Steel

“…By optimizing the chemistry composition Sb, Cu, 12,13) Cr, 14) mechanical vibration 15) and continuous casting process, 1620) the equiaxed crystal ratio can be increased, and it is critical to obtain the optimal process parameters for specific steel composition. The patent 17) can applied to increase the equiaxed crystal ratio of grain oriented silicon steel slab to more than 80% by controlling the molten steel superheat of the caster and the dynamic soft reduction under the premise of bypassing the electromagnetic stirring in segments.…”