The weld metal corrodes much faster than the parent metal if type 316L steel welded with a matching filler is exposed to hot organic acids. Nine commercial filler metals were evaluated by preparing welded coupons and exposing them to different plant environments (with different organic acid mixtures and temperatures) for several months. The filler metals were chosen to yield different solidification modes, and to vary chromium, molybdenum and nickel contents. Only filler metals that are much more highly alloyed than the parent metal gave lower corrosion rates than the parent metal. Partitioning during and after solidification, and the average alloy content, both affect weld bead corrosion.
SchillmollerCM: ‘Selection and use of stainless steels and nickel bearing alloys in organic acids’NiDI Technical series no. 100631–6; 1992Toronto, Ont., Nickel Development Institute.
OrsmondCPM: ‘The effect of filler metal on the corrosion resistance of stainless steel weldments in a hot organic acid environment’MEng dissertationPretoria, South AfricaUniversity of Pretoria2010.
