Simulation Of Thermal Effect And Experimental Research Of Laser Surface Processing On Aluminum Alloy

As Aluminum has a low density, high strength, low coefficient of thermal expansion, good thermal conductivity and electrical conductivity, low cost, etc. So it’s widely used in industrial production and manufacturing. However, as the development of science and technology, higher demand is put for the performance of aluminum. But the common aluminum has low hardness, poor wear resistance and can’t meet technical requirements. Laser surface processing techniques can significantly improve the surface properties of aluminum alloy. However, the laser processing is very fast. It is difficult to test the transient laser processing completely and accurately. To solve this problem, the simulation of thermal effect and experimental study of laser processing on the surface of aluminum alloy are carried out as follows:A theoretical model of temperature field distribution of laser processing aluminum was constructed. The mechanism of laser surface marking and physical phenomenon of laser irradiation on metal surface were discussed. The theoretical model of laser irradiation on the metal surface and the heat conduction equation for solving the temperature distribution were constructed. It provided a theoretical basis for the next finite element simulation and experimental research.The finite element simulation model of single-track laser irradiation on aluminum alloy was established in order to analyze the effect of laser power and scanning velocity. The simulating process of COMSOL Multiphysics was discussed, including the selection of physical fields, the definition of geometric model and material parameters, mesh and solving etc. Select the field of heat transfer and establish the simulation model. The laser beam was considered as a heat source and the boundary conditions of heat transfer, radiation and cooling convection wear taken into consideration. The laser power had an effect on laser energy density and scanning speed has an effect on laser interaction time. Through adjusting laser parameters, different simulation results were obtained, such as temperature field, the depth, width and area of melting and vaporization material, the cooling rate and temperature gradient. They were proportional to the laser power, and inversely proportional to the scanning speed, and higher closer to the center of the laser beam.The finite element simulation model of multi-track laser irradiation on aluminum alloy was established in order to analyze the effect of filling space. The filling line spacing was considered. The line spacing had affect on interaction time and overlapping between laser tracks. With smaller the line spacing, the laser track had higher influence on the next laser track. Then the material had higher temperature and greater vaporization ratio.The removing depth of material was obtained through laser processing and they were close to the simulation results. Then we can say the simulation model was correct and provided a guide to the actual laser processing. The experiments of laser surface processing on aluminum alloy were conducted. The pattern consisted of lattice, linear and mesh. The micro-hardness of aluminum alloy was improved after laser surface marking. And lattice-pattern material had higher micro-pattern than the linear-mark material and mesh- pattern material. Laser surface processing can improve the stability of material and reduce the friction coefficient. The friction coefficient of aluminum alloy was smaller with denser marking density.