Abstract
Selective laser melting (SLM) is an important advanced additive manufacturing technology. The existing SLM products cannot fully meet the requirements of high-precision and strength of the mechanical component because of their defects. The TiAlN/TiN multilayer coating can improve the surface property of SLM products. The present work aims to explore the influences of different process parameters of SLM on the property of TiAlN/TiN multilayer coating plating on the 361L specimen and the mechanism of these influences. Taking laser power, scanning speed, and scanning space as factors, an orthogonal experiment was designed. The TiAlN/TiN multilayer coating specimens can be obtained by plating on the 361L specimen, fabricated by the process parameters of SLM on the orthogonal experiment. The surface topographies and properties of TiAlN/TiN multilayer coating were tested, the influences of SLM process parameters on TiAlN/TiN multilayer coating were analyzed, and the optimal process parameter was obtained. The electron microscope images revealed that the surface morphology of TiAlN/TiN multilayer coating plating on the SLM specimen was relatively flat, and there were some macro-particles in different sizes and pin holes dispersed on it. The thickness of the TiAlN/TiN multilayer coating was 2.77–3.29 μm. The microhardness value of coating SLM specimen was more than four times that of the uncoated SLM specimen and the wear rates of the uncoated specimen were 2–4 times that of the corresponding coating specimen. The comprehensive analysis shows that the laser power had the greatest influence on the comprehensive property of the coating. The primary cause of the influence of SLM process parameters on the properties of the TiAlN/TiN multilayer coating was preliminarily discussed. When the laser power was 170 W, the scanning speed was 1,100 mm/s, and the scanning space was 0.08mm, the TiAlN/TiN multilayer coating plating on the SLM specimen had the best comprehensive property.
Highlights
The surface of mechanical components should have good abrasion resistance, high strength, and other surface properties to extend their service lifetime
Through the analysis of the obtained data, it can be known that the primary cause of the process parameter of selective laser melting (SLM) affecting the property of the TiAlN/TiN multilayer coating plating on the 361L specimen is that the internal structure of substrate with different process parameter of SLM is different
Using smaller scanning spacing when printing is beneficial to improve the internal organization of the SLM specimen and beneficial to improve the adhesion and thickness of the coating. This is because the laser can penetrate the molten metal powder and the powder melts more fully and the fluidity of the molten pool is better when the laser power is large, the liquid spatter in the molten pool decreases when the scanning speed is moderate, and the scanning spacing is moderate, which is beneficial to fuse fusion, reducing the gross defects of the sample and making the high-density defects reasonable. The influences and their mechanism of SLM process parameters on the surface morphology and selected mechanical properties of the TiAlN/TiN multilayer coating plating on SLM 361L substrate were studied by an orthogonal experiment
Summary
The surface of mechanical components should have good abrasion resistance, high strength, and other surface properties to extend their service lifetime. There are many methods to improve the surface property of a component such as plasma techniques, shoot penning, chemical vapor deposition and physical vapor deposition, and so on. There are many methods to improve the mechanical and surface properties of SLM specimens. The main way to improve the quality of SLM specimens are to change the process parameters of SLM, such as laser power, scanning strategy [3], scanning speed, scanning space [4], layer thickness [5], particle size of powder, materials, and so on. Ortner et al [7] found that residual stress could improve the fracture toughness of steel
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