Creep Behaviors Evaluation of IN738 Superalloy Welded by Pulsed Nd:YAG Laser Through the Small Punch Creep Test

In this study, the creep behavior of base metal, weld metal, and heat-affected zone of IN738 superalloy welded by pulsed Nd:YAG laser was investigated by the newly developed small punch creep testing method in the temperature 700 °C and under the punch forces 350 N and 45N. The results of time–displacement creep behavior showed that the aging heat treatment causes a significant increase in rupture time compared to the casting specimen. This was due to an increase in the volume fraction and a decrease in the size of the γ´ particles, which create a more substantial barrier to the movement of the dislocations. On the other hand, by performing solution heat treatment before welding, phases such as γ´, γ–γ´ eutectic, Cr-Mo boride, Ni-Zr intermetallic, and MC carbide, which reduced the rupture time in the cast specimen by forming a partial liquation in the HAZ, were removed.