TWI Industrial Member Report Summary 1042/2013
By Vinod Kumar, Qing Lu, and Mike Gittos
Nickel alloy weld overlay claddings are used on carbon and low alloy steel components to provide corrosion resistance to their operating environment. Currently, there is no clear guidance on the allowable maximum preheat/interpass temperatures for their manufacture, without compromising productivity and quality. This work investigates the influence of preheat/interpass temperatures on alloy 625 welding overlay on a carbon steel substrate.
Material and consumable suppliers give very little guidance on allowable interpass temperature for nickel alloy weld overlay cladding. An excessive interpass temperature might, potentially, result in excessive dilution and microstructural changes within the weld metal, reducing the corrosion resistance. On the other hand, if the interpass temperature is set unnecessarily low, the productivity could be affected. Hence it is necessary to have a clear understanding on the effect of interpass temperature on alloy 625 weld overlay cladding.
- For the same welding parameters, a change in preheat/interpass temperature could affect the corrosion rate.
- The change in corrosion rate appeared to be related to the increased dilution of the overlay.
- Experimental results did not show a direct relationship between the corrosion rate and any metallurgical changes such as degree of second phase precipitation associated with an increased preheat/interpass temperature.