Laser bending of friction stir processed and cement-coated sheets

In this work, laser bending of friction stir processed and cement-coated sheets of aluminum alloy and mild steel was carried out using CO₂ laser. For comparison, the laser bending of uncoated raw sheets was also carried out. It was noted that friction stir processing roughened the surface and helped in getting larger bend angle due to increased absorptivity in laser bending. However, the cement-coated sheets provided much larger bend angles. The micro-hardness of friction stir processed sheets was larger compared with unprocessed sheets and it further increased after laser bending. After laser bending, the micro-hardness increased from bottom surface to irradiated top surface. It was always more than the micro-hardness of the raw sheet. A study of microstructures revealed that the grain size reduced after laser bending and increased from top irradiated surface to bottom surface.