Experimental Study Of Laser Melting And Laser Shock On Magnesium Alloys

The density of magnesium is the lowest compared with all of the structural metals and alloys. The specific strength of the magnesium alloys is very high, and the magnesium alloys will be widely used in Auto,computer and communications. Many advantages as the magnesium alloys have, while the strength of the common one exists between 50-70% of the same aluminium alloys of the craftwork preparation, and the anti-corrosion property is very poor. Although some types of the magnesium alloys have high intensity, it is much more expensive. In this way, the application of the magnesium alloys now is narrowed. In this case, it is significant to develop the new-type magnesium alloys of the low cost and high intensity.The experiment of my research is based on the AZ91 magnesium alloy which was most widely used in the industry. The surface of the magnesium alloys was treated through laser melting and laser shock. We are in hope of altering the organizing appearance, and improve the mechanical and anti-corrosion properties furthermore. The analysis methods, such as OM,XRD,SEM,EDS and micro-hardness tests were carried out during the research process. We studied the microstructure,mechanical and anti-corrosion properties of the samples which treated by laser melting and laser shock systematically.The study of laser melting showed that the grains of magnesium alloy AZ91 were refined after laser melting. The solid solubility of Al in the magnesium alloy substrate was increased that compared with untreated samples. With the increase of laser scanning speed, and the grains are refined increasingly, while the inter-metallic all over the surface decreased. The content of Al in each area of melted zone becomes much closer. The surface mechanical and anti-corrosion properties of the magnesium alloy can be enhanced through these ways. The result of micro-hardness test showed that the micro-hardness value of the melted zone was much higher than the substrate. The result of electrochemical measurement showed that the anti-corrosion property of treated surface was improved.The result of research on laser shock showed that apparent plastic deformation generated on the area which treated by laser shock. There is much waves on the surface of the pit. Compared with untreated samples, the surface roughness of the pit was increased, and the micro-hardness value of laser shocked area was enhanced. The micro-hardness increased from border to center along the radius direction. The anti-corrosion property of the treated surface was improved compared with untreated samples.