研究目的
To control the crystallographic texture of 316L austenitic stainless steel via selective laser melting (SLM), a powder bed fusion-type metal AM using a laser as the heat source.
研究成果
The study successfully controlled the crystallographic texture of 316L SS via SLM, achieving a single crystalline-like texture with {001} orientation in the build direction, a crystallographic lamellar texture with {011} and {001} orientations alternately stacked, and polycrystalline with relatively random orientation. The melt pool shape and solidification behavior were identified as important controlling factors for the evolution of the crystallographic texture under the SLM process.
研究不足
The study acknowledges that for different product sizes, the optimal laser conditions for obtaining such textures will vary, because temperature distribution is largely affected by the product size. Additionally, the transition of the microstructure observed cannot be fully explained without quantitative determination of the transition point in 316L SS and the actual G and R experienced in this study.
1：Experimental Design and Method Selection:
The study employed selective laser melting (SLM) with an 'X-scan strategy' to control the crystallographic texture of 316L austenitic stainless steel. The laser beam was scanned bidirectionally along the x-axis without rotation.
2：Sample Selection and Data Sources:
Gas atomized 316L SS powder was used, with a nominal composition of 18Cr-14Ni-
3：5Mo-03C (wt.%), and the powder size was under 53 μm. List of Experimental Equipment and Materials:
An EOS M290 printer equipped with a Yb-fiber laser was used for SLM fabrication. The densities were measured using the Archimedes method. Microstructures were observed by optical microscopy (OM) and field-emission scanning electron microscopy (FE-SEM). The crystallographic texture was examined by electron backscatter diffraction (EBSD).
4：Experimental Procedures and Operational Workflow:
Products of 10 mm × 10 mm × 10 mm were fabricated by changing the laser scan speed (v) to control the energy density (E), while keeping the laser power (P) constant. The hatching distance (h) and layered thickness (t) were set to 80 μm and 40 μm, respectively.
5：Data Analysis Methods:
The crystallographic texture was analyzed using AZtecHKL software. The degree of orientations (p) of {001} and {011} with respect to the build direction were calculated based on the Euler angles obtained by EBSD.
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