Effect of laser shock peening on microstructure and mechanical properties of TiC strengthened inconel 625 alloy processed by selective laser melting

A bulk nano-TiC particle reinforced Inconel 625 alloy (TiC/IN625) was manufactured using selective laser melting. The effect of post treatment on the microstructural evolution and mechanical properties of the TiC/IN625 alloy was investigated by using optical microscope, scanning electron microscope, transmission electron microscope, X-ray diffraction, microhardness tests, and uniaxial tension tests. The results demonstrated that heat treatment brought uniformly dispersed gamma' and gamma '' phases, coarse MC carbides, and fine secondary carbides to the TiC/IN625 samples. After heat treatment followed by laser shock peening, high-density dislocations and some nanoscale grains were generated in the subsurface of the TiC/IN625 sample. The tensile residual stresses were transformed into compressive residual stresses by laser shock peening. In the laser shock peened TiC/IN625 sample, relatively higher surface microhardness, ultimate tensile strength, and elongation were observed compared to the as-built and heat-treated samples. Furthermore, a synergistic strengthening mechanism, involving precipitation strengthening, grain refinement, and dislocation strengthening, was clearly revealed.

Automated summary

In this study, a bulk nano-TiC particle reinforced Inconel 625 alloy was manufactured using selective laser melting, and the effect of post treatment on the microstructural evolution and mechanical properties of the alloy was investigated. The results showed that heat treatment and laser shock peening improved the performance of the alloy, generating high-density dislocations and nanoscale grains.