Sample quality effects of laser cutting : An empirical study on the heat affected zone and the surface quality in laser cut samples

Sammanfattning: This study has been conducted with the aim to examine the extent of the heat affected zone in order to use laser cutting when making samples for tensile testing. When cutting with a laser the material absorbs heat energy from the laser beams which causes changes in the microstructure. The heat affected zone affects the properties of the materials, lowering the accuracy of the tensile test. Therefore, it is desired to know the extent of the heat affected zone in order to remove it before tensile testing. In this study two materials were used, the high strength steel Docol 1000DP and the duplex stainless steel LDX 2101. The materials were cut in the shape of dog bones for tensile testing using two different laser powers, 2500 W and 3500 W. The samples were cut with different cutting speeds, starting at lower cutting speed, increasing until the laser was unable to cut through. Thereafter, the heat affected zone, and the surface quality was examined. The results from this study showed that the heat affected zone decreases with increased cutting speed. When cutting with high cutting speeds in Docol 1000DP it is enough to turn away 0.30 mm in order to remove the heat affected zone with margin. Negligible difference in heat affected zone was observed between the samples cut with 2500 W and 3500 W. The heat affected zone in LDX 2101 was very small, in order of 50 μm, making it hard to measure. This resulted in no exact measurements being made. However, the heat affected zone was in the order of 50 μm for all samples, concluding that turning away 0.15 mm is sufficient to remove the heat affected zone with margin. No difference could be observed between the samples cut with a laser power of 2500 W or 3500 W. Common to both materials is that the amount of dross decreases with increased cutting speed.