Laser surface melting of γ-TiAl alloy: an experimental and numerical modeling study

Abstract

The objective of present work is to study the evolution of thermal stresses during laser surface melting (LSM) of γ-TiAl alloy using experimental and numerical modeling approaches. LSM of γ-TiAl alloy samples were carried out at different processing conditions in a controlled atmosphere. Material characterization of the melted region was investigated using scanning electron microscope. It was found that fully lamellar microstructure was transformed into predominantly γ-TiAl with little amount of α2-Ti3Al. A maximum improvement in hardness of over 72% was noticed in the melted region compared to that of the substrate. Three-dimensional thermomechanical finite element analysis of LSM of γ-TiAl alloy was carried out. Melt pool dimensions, temperature history, and residual stresses were predicted from the finite element models. Measured and predicted values of melt pool depth were in good agreement with a maximum error of 13.6% at P = 400 W and V = 10 mm s−1. Predicted residual stress in the melted region exceeded the yield strength of γ-TiAl alloy and resulted in cracking of the melted region at all process conditions.