Abstract
This paper presents the effects of laser treatment (fiber laser YLS-4000) on the microstructure and selected mechanical properties of the surface layer of AlMg (AlMg9) foundry alloy obtained by alloying with boron carbide (B4C). The correlation between laser alloying process parameters and selected properties of the formed layer was discussed. The studies were supported by microstructural analysis of the remelted zone (RZ), heat affected zone (HAZ), undissolved carbide particles, substrate material, and precipitates formed during rapid solidification. Metallographic investigations of the laser-treated layer were performed using optical microscopy and scanning electron microscopy (SEM). The elemental composition and a detailed analysis of chemical composition in micro-areas were carried out using energy dispersive X-ray spectroscopy (EDS). The remelting thickness, heat-affected zone (HAZ), and amount of base material in surface layers were determined. Microhardness tests were performed on transverse cross-sections of the remelted zone to obtain the hardness profiles in the base material (BM), remelted zone (RZ), and heat affected zone (HAZ). The hardness, roughness, and wear resistance measurements showed that the highest tribological properties of the obtained surface layer were achieved using 0.5 Bar protective gas (Ar) during alloying with B4C powder.
Highlights
The good ductility and lightweight nature of aluminium and its alloys have permitted their broad use in aerospace, automotive, and transportation industries
On the basis of preliminary experimental research regarding the impact of the shielding gas used on the depth and depth of the melted zone and the heat-affected zone for further studies, the best parameters were selected
On the basis of the analysis performed here, the surface layer obtained owing to alloying an aluminium alloy with B4 C powder was composed of three zones: a laser remelting zone (RZ), an enriched in boron carbide zone, a melted and rapidly solidified zone, and a heat-affected zone (HAZ)
Summary
The good ductility and lightweight nature of aluminium and its alloys have permitted their broad use in aerospace, automotive, and transportation industries. One of the primary methods to obtain materials with better mechanical properties is surface treatment technology. Laser surface alloying (LSA) is used for lightweight metals to improve their properties because the surface layer formed on the metal has different properties than the substrate material, for example, higher hardness, fatigue, and corrosion resistance; the surface is usually rougher than the original alloyed material [2]. LSA consists of enriching the surface layer with alloying elements, accompanied by structural changes. Owing to convection and gravitation movements and the pressure of the laser beam, the materials are intensively mixed, and the properties of the formed layer depend on the microstructure, porosity, and chemical composition of the base material [11,12,13,14,15,16]
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