Effect of Laser In Situ Heat Treatment on the Grain Boundary Characteristics and Microstructure of GH4169 Superalloy

This study investigates the effect of laser in situ heat treatment on the grain boundary characteristics and microstructure of GH4169 superalloy fabricated via point‐type forging–laser deposition. By controlling the laser remelting rate (4 and 6 mm/s), systematic EBSD analysis was conducted to evaluate grain boundary distribution, misorientation angles, crystallographic texture, and kernel average misorientation. The results demonstrate that at a remelting speed of 4 mm/s, the fraction of high‐angle grain boundaries reaches 87.0%, the average grain size is refined to 11.2 μm, and the material achieves optimal mechanical properties with tensile strength of  ~700 MPa and internal hardness of 450–520 HV. This work provides a theoretical basis for optimizing laser additive manufacturing processes through in situ heat treatment.