CWNd:YAG laser cutting of ultra low carbon steel thin sheets using O2 assist gas

There are many non-linear interaction factors responsible for the performance of the laser cutting process. Identification of the dominant factors that significantly affect the cut quality is important. The present research aims to evaluate the CW ND:YAG laser cutting parameters (the gas pressure, laser power, and scanning speed) for 1.2 mm thick ultra-low carbon steel sheets. The effect of the cutting parameters on the cut quality was then investigated, by monitoring the variation in hardness, oxide layer width and microstructural changes within the heat affected zone (HAZ). Results revealed that good quality cuts can be produced in ultra low carbon steel thin sheets, at a window of laser scanning speed of 1100-1500 mm/min and at a minimum heat input of 337 W under an assisting O-2 gas pressure of 5 bar. Higher laser power resulted in either strengthening or softening in the HAZ surrounding the cut kerfs. The oxide layer width is not affected by the energy density input, but is affected by the O-2 gas pressure due to exothermal reaction. (c) 2007 Published by Elsevier B.V.