Numerical study and experimental comparison of laser cutting of 1.2 mm thick austenitic stainless-steel sheet using CW Nd: YAG laser

Abstract

Stainless steel 304 is the most common steel used for corrosion resistance applications, but higher melting point is a limitation in industries from a manufacturing point of view. The non-conventional and subtractive manufacturing technique of laser cutting (a beam directed method), is suitable for this material. The gaussian laser beam is directed at the material that melts, burns, vaporizes, or blows away by a jet of gas leaving a fine edge with good surface finish. In this work, numerical study was performed to study the multi-physical process of laser cutting. Towards this, 1.2 mm thick austenitic stainless-steel was cut using a continuous width neodymium-doped yttrium aluminum garnet (CW Nd: YAG) laser and the process was verified with published experimental results. The simulation was carried out with TruVOF™, FLOW-3D® as it has the capabilities for simulating advanced algorithm for free-surface fluid tracking. To evaluate the optimum condition for kerf width, smooth surface cut, roughness, and heat affected zones within limited time, an assist gas is used with the input parameters: laser power (660 - 1980 Watts), cutting speed (2 - 8 m/min), oxygen gas pressure (9 - 11 bars) and focal position (negative 1 mm to positive 1.0 mm) were varied and analyzed using a full 3D model. The simulation results showed smoother surface cut, little dross formation, lower temperature rise on heat affected zones, and less finished time at cutting speed 8m/min, higher laser power above 1000 Watts, gas pressure of 11 bars, and focus distance of -1.0 mm. It was noticed that increase in laser power at a faster cutting speed led to an increase in kerf width, reduction in dross formation, lower temperature rises on heat affected zones and a reduced finish time. The simulation led to a good agreement with experimental results within a 15 % percentage error margin.