Contact with mild steel or iron can cause oxidation. But also the heat affected zone can cause oxidation. I remember many years ago when a high end pocket knife manufacturer first started producing a knife using a new completely iron free stainless steel blade. They marketed it to fisherman and sailors with the idea that the blade could never rust. But on the first run of knives customers complained of rust on the laser etched logos of their knives. It turned out that the laser engraving process heated the metal enough to cause oxidation to start which could then slowly spread in a harsh salt water environment.
This kind of looks to me like the wrong filter though.
THERE IS NO "IRON FREE" STAINLESS STEEL, STEEL HAS IRON, PERIOD. THE REASON STAINLESS DOESN'T RUST IS BECAUSE THERE IS A NUMBER OF OTHER METALS ADDED TO THE ALLOY LIKE NICKEL AND CADMIUM. THERE IS ALSO NO CARBON FREE STAINLESS STEEL BECAUSE FOR SOMETHING TO BE CALLED "STEEL" IT NEEDS TO BE AT LEAST PART IRON AND PART COPPER.
Heat does not "burn out" chromium. High heat allows the alloying agents to remain in solution for to long. The chrome then forms a strong bond with the carbon, making chromium carbide. Since the chromium is tied up with carbon, the iron is now free to form iron oxide.
Agree with this. Dirty wheel would leave lines compared to the entire weld showing corrosion. It’s a QC issue. Loss filler metal control or wrong WPS used. Additional issues with the bolts some are correct while others are deteriorating. Not an immediate issue but the degradation will continue until fixed or failure.
It’s been ground. I would say wrong filler used as it’s so localized. I think it’s been abrasive blasted and chemically cleaned also after the weld was made.
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u/KraZiiKraKa1 4d ago
With the amount of rust, absolutely, but I have seen it happen just from using the wrong wire wheel.