Optimisation of laser welding parameters for incoloy 800HT joints using Grey-fuzzy Taguchi approach

Abstract

The present study attempts to find the optimal level of parameters for multi performance characteristics in laser welding of incoloy 800HT using Grey-Fuzzy algorithm. Incoloy 800HT, which comes under the family of austenitic nickel-chromium-based super alloys exhibits good strength, excellent resistance to carburization and oxidation in high-temperature exposure. This alloy has been considered as a prominent material for fourth generation nuclear power plants. Laser welding has proved to be advantageous due to its characteristics such as narrow fusion zone, low heat input, concentrated heat intensity and the ability to align the beam to a specific position with respect to joint line. Taguchi L9 experiment was used to perform laser welding on incoloy 800HT. The input parameters chosen were the welding speed, focal position and laser power. The output performance characteristics were the hardness, toughness and ultimate tensile strength. To improve the quality of the weld, the optimal combination of laser welding parameters was chosen using grey relational analysis and grey fuzzy logic approach offers improved Grey-Fuzzy reasoning grade and has less uncertainties when compared with grey relational technique. Analysis of variance (ANOVA) was used to find percentage contribution of the laser welding parameters and found that welding speed was the most influential factor in welding of incoloy 800HT.