Influence of Multiple Gleeble®-Simulated Weld Thermal Cycles on Maraging 17-4 and 13-8+Mo A preliminary investigation to determine whether controlled weld metal deposition procedures are feasible for Maraging Stainless Steels 17-4 and 13-8+Mo

Multipass welding provides an opportunity to restore the strengthening precipitates that dissolve during primary welding thermal cycles by using the heat from subsequent weld passes. In the current investigation, a Gleeble (R) thermo-mechanical simulator was used to subject samples of 17-4 and 13-8+Mo to primary and secondary thermal cycles representative of 1000 and 2000 J/mm heat input multipass welds. Both the unaffected age-hardened base metal and as-deposited weld metal were considered to investigate the precipitation response of each. Hardness measurements were recorded after each thermal cycle to estimate the extent of precipitate dissolution or growth. The secondary welding thermal cycles were sufficient to promote hardening in both the base metal and weld metal for each heat input, indicating precipitate growth was occurring. Alloy 17-4 demonstrated a higher precipitation response when compared to 13-8+Mo that was attributed to an increased level of supersaturation and larger temperature range in which precipitation could occur. Additionally, the weld metal and base metal possessed similar precipitation responses for each material. Microchemical measurements and solidification simulations showed that backdiffusion relieves the concentration gradients in the weld that can form during solidification. These results explain the similarities in precipitation response between the base metal and weld metal. The results of this work demonstrate that controlled weld metal deposition may be used to eliminate the need for a postweld heat treatment (PWHT) in these alloys.