Modeling of precipitation and Cr depletion profiles of Inconel 600 during heat treatments and LSM procedure

A model based on the thermodynamic and kinetic was conducted to simulate the Cr depletion profiles near the grain boundary in Inconel 600 during the heat treatments and laser surface melting (LSM) process using Thermo-Calc and Dictra code. Based on the good agreement of Cr concentration distribution during heat treatments measured by experiments, the microsegregation of Cr induced by cellular microstructure formed during the LSM process was also modeled. The Cr depletion profile was evaluated using the Cr depletion area below the critical Cr concentration for intergranular cracking/intergranular stress corrosion cracking (IGC/IGSCC) susceptibility (8 mass%). Comparing with the result of Streicher test, the Cr depletion area calculated showed good coherence with the IGC/IGSCC susceptibility. The sample after SR + LTS treatment with the largest Cr depletion area showed the worst IGC/IGSCC resistance, while, the sample after LSM process with the smaller Cr depletion area showed the excellent IGC/IGSCC resistance.