Problems with pitting corrosion testing of 904L electrode manual surfacing
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For 904L welding rods imported from the USA, when used for manual surfacing, pitting tests are conducted according to Method A of G448 (it seems that the design specifications always require this). These tests keep failing. I wonder if any welding experts have encountered this issue; what welding parameters (voltage, current, welding speed, etc.) should be used for 904L manual surfacing in order to pass the pitting test per Method A of G448?
The welding method should be adjusted here; stick welding is difficult to use for this material, due to the properties of 904L. Since 4% molybdenum is added to enhance its corrosion resistance, the amount of nickel necessary to maintain a stable austenitic structure is not increased. As a result, this material has unstable microstructure. Using electric welding for surfacing in this case causes local overheating, which further destabilizes the structure. Solutions can be sought by considering the following approaches: 1. Use TIG welding, which generates less heat and allows for rapid cooling, thus resulting in a more stable microstructure; 2. If welding on stainless steel, solution treatment can be applied to improve the material’s properties; 3. Choose better materials by using higher-quality surfacing materials.
What type of welding electrode should be used for 904L welding to ensure resistance to pitting?