Influence of pre- and post-weld heat treats on microstructures of laser welded GTD-111 with IN-718 as filler metal

The present research work studied and evaluated conditions of pre-weld and post-weld heat treatments for the laser welding process, aiming to avoid weld cracking, which usually occurs after tungsten inert gas and/or laser welding processes in cast nickel-based superalloys with high aluminum and titanium contents. The pre-weld heat treatment conditions used in the experiments were (1) 1473 K for 7.2 ks, (2) 1433 K for 7.2 ks + 1298 K for 56.7 ks, (3) 1413 K for 7.2 ks + 1298 K for 56.7 ks, (4) 1393 K for 7.2 ks + 1298 K for 56.7 ks. A laser welding process on cast nickel-based superalloys, grade GTD-111, with metal filler of Inconel 718, a nickel-iron based alloy was conducted. From all obtained results, it was found that the pre-weld heat treatment conditions significantly influence microstructures before laser welding. After laser welding and post-weld heat treatment at a temperature of 1473 K for 7.2 ks followed by precipitation aging at a temperature of 1118 K for 86.4 ks (standard heat treatment), all welded specimens exhibited similar microstructures and hardness values. Furthermore, no weld cracking was observed in all welded specimens.