The modified microstructure of Al-Si-Pb alloys irradiated by high current electron beam (HCPEB) reveals three distinct regions: a molten zone, an overlapped zone of heat-affected and quasistatic thermal stress-affected zone, and a transition zone followed by the substrate. The hardness and wear properties of the alloys were significantly improved. To better understand these changes in microstructure and properties, the physical model for the simulation of temperature and quasistatic stress fields was established. Based on experimental investigation and physical models, the temperature field and stress field were simulated for Al-Si-Pb alloy. The starting melting position, largest crater depth, melting layer thickness, and quasistatic stress distribution were obtained. These results reveal the mechanism of crater formation on the surface and improvement of hardness and wear resistance.