Nano WC powder cold surface enhancing of aluminium alloy 5A06 via laser shock peening

Abstract

Aluminum alloy 5A06 has many superior properties such as high strength, good corrosion resistance and welding performance. It is widely used in aerospace, ship craft and transportation areas. Unfortunately, poor surface hardness and wear resistance and shorter life time limit its applications in industries. Many hardfacing processes such as heat treatment, plasma spray, micro-arc oxidation, laser cladding and laser alloying can increase the wear resistance of the 5A06 alloy. However, almost all of these processes are thermal process which may induce lighter element melting loss, porosity and cracking. Nano-materials have unique acoustic, optic, electric, magnetic and thermodynamic characteristics because of their quantum size and surface effect. It can play an important role in hardfacing of the light metal alloys. However, nano powders will completely melted into the melt pool due to their relative low melt points, this will lose many of their unique properties.We have recently developed a novel process: nano powder cold enhancing of light metal surface via laser shock peening process. This is a cold process, by which the nano powders are squeezed into the surface of the light metal alloys by the very high pressure (up to Giga or even tens of Giga Pascal) induced by the laser shock peening process.This paper reports our research work one nano WC powder cold surface enhancing of 5A06 alloy by using a 50J Q switch Nd:YAG laser system for shock peening, focusing on the influences of the processing conditions such as surface roughness of the aluminium sample, the powder layer thickness, the absorbing layer, the constrain layer and the single pulse energy on the enhanced nano powder percentage and nanopowder dispersion degree in the enhanced nano WC coatings. The paper will also report the hardness, tribology property, wear resistance of the as-enhanced layers. The results confirm that nano powder cold surface enhancing vis laser shock peening can dramatically improve the surface performance of the aluminium alloy by the combined strengthening mechanism of laser shock peening, nano-particles and nano-particle intensified shock peening.Aluminum alloy 5A06 has many superior properties such as high strength, good corrosion resistance and welding performance. It is widely used in aerospace, ship craft and transportation areas. Unfortunately, poor surface hardness and wear resistance and shorter life time limit its applications in industries. Many hardfacing processes such as heat treatment, plasma spray, micro-arc oxidation, laser cladding and laser alloying can increase the wear resistance of the 5A06 alloy. However, almost all of these processes are thermal process which may induce lighter element melting loss, porosity and cracking. Nano-materials have unique acoustic, optic, electric, magnetic and thermodynamic characteristics because of their quantum size and surface effect. It can play an important role in hardfacing of the light metal alloys. However, nano powders will completely melted into the melt pool due to their relative low melt points, this will lose many of their unique properties.We have recently developed a novel process:...