Experimental studies of laser borided low alloy steel and optimization of parameters using response surface methodology

Laser boriding technique was used to form boride layers on EN25 steel. The main aim of this current study is to form the hard laser borided layer on the low alloy steel surface and analyze the effect of process parameters on borided layer hardness, depth, and width. The properties and microstructure (micro-hardness, boride layer width, and depth) are analyzed after laser boriding process with different laser process parameters (power and speed). The micro-hardness of the boride layer was measured using the Vickers micro-hardness tester. The boride depth and width was measured and captured using a machine vision inspection system. The existence of borides formed in the laser treated layer was confirmed via X-ray diffraction technique. The corrosion rates of the laser borided and as received samples are observed in 3% NaCl solution using Potentiodynamic polarization test. The response surface methodology was used to analyze the effects of power, travel speed on the hardness and the boron layer width and depth. The two-factor three-level full factorial design available in response surface methodology was used to develop the regression model for laser boriding process. A multiobjective optimization technique was used to optimize the laser process parameters to maximize the boron layer width and to minimize the boride layer depth. The validation trail assures that the expected value has good conformant with the actual experimental value.