Application of the Box-Behnken Design for Modeling of Laser Transformation Hardening Parameters of Unalloyed Titanium

Abstract

This research paper represents the application of Response Surface Methodology (RSM) and Box-Behnken design (BBD) for modeling and an analysis of the influences of dominant Laser transformation hardening parameters: laser power (LP), scanning speed (SS) and focused position (FP) on hardened bead geometries such as hardened bead width (HBW) and hardened depth (HD) of laser hardened surface quality of unalloyed titanium sheet of 1.6 mm thickness, nearer to ASTM Grade 3 of chemical composition using CW 2kW Nd:YAG laser. The effects of laser power, scanning speed and focal point position on the hardened-bead geometry (i.e. hardened bead width (HBW) and hardened depth (HD) were investigated using response surface methodology (RSM). Linear and quadratic polynomial equations for predicting the hardened bead geometry were developed. The results indicate that the developed mathematical models predict the responses adequately within the limits of hardening parameters being used. It is proposed that regression equations can be used to find optimum hardening conditions for desired criteria.