Abstract
Energy density of selected laser melting technology (SLM) has an important effect on the microstructure and properties of alloy steel parts. In this paper the 24CrNiMoY alloy steel samples were prepared by SLM technology, the effects of different laser energy densities (102 J/mm3, 120 J/mm3, 138 J/mm3, 156 J/mm3) on microstructure and mechanical properties of alloy steel samples were investigated. The results show: when the lap width was 0.07 mm, the scanning angle was 67°, the scanning line length was 10 mm, the scanning speed was 800 mm/s, while the laser power was changed to form different energy density, the internal defects of the sample first decrease and then increase with the increasing energy density, while the hardness and tensile properties also appeared similar trends as internal defects. The measurements when the energy density was 138 J/mm3, the defects of the alloy steel sample were the least, the microstructure was mainly ultra-fine grain lath martensite, the mechanical properties achieved well. The average hardness was 386 HV0.2, the tensile strength was 1252 MPa, while the elongation was 12.00% after fracture. This 24CrNiMoY alloy steel sample has excellent matching properties between strength and toughness.
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