Study on the forming efficiency, microstructure and properties of GH3536 alloy prepared by SLM with large layer thickness

 To address the high number of layers and limited efficiency associated with the commonly used small layer thickness (20-40 μm) in Selective Laser Melting (SLM) of GH3536 alloy, this study designed and validated an efficient processing parameter window for GH3536 alloy using an 80 μm powder layer thickness. A total of 16 parameter sets (T1–T16) were established by varying the hatch spacing (0.11/0.12 mm), laser power (400/430/450 W), and scanning speed (950-1250 mm∙s⁻¹). Two post-heat treatment conditions, namely solution treatment and hot isostatic pressing plus solution treatment, were applied. The phase constitution, microstructure, and mechanical properties were evaluated using SEM, EDS, XRD, micro-Vickers hardness testing, and room-temperature tensile testing. The results indicate that after solution treatment, melt pool boundaries disappear, and recrystallization-related microstructural features emerge, with porosity reduced compared to the as-built condition. As the scanning speed increases, the grain structure gradually refines, exhibiting a heterogeneous "small grains associated with large grain surfaces" characteristic; precipitates transition from a granular to a linear morphology. The elongation after fracture remains stable around 50%, while yield strength, ultimate tensile strength, and microhardness show a slight increase. With increasing laser power, the grains gradually coarsen, precipitates show minimal change, and elongation after fracture remains stable at approximately 50%; however, yield strength, ultimate tensile strength, and microhardness exhibit a slight decrease. The fracture mechanism of the specimens is primarily a complex mixed mode involving intergranular fracture with dimples present. Within the conditions of this study, the optimal printing parameters identified are: layer thickness of 80 μm, hatch spacing of 0.12 mm, laser power of 430 W, and scanning speed of 1150 mm∙s⁻¹