A Survey of the Effects of Delta Ferrite in Austenitic Steel Weldments

Delta ferrite in the austenitic stainless steel weld plays a dual role. On the one hand it affects the corrosion resistance and on the other helps in reducing the susceptibility of the weld to hot cracking. So controlling delta ferrite in austenitic stainless steel weldments has become one of the tricky problems faced both by the consumable manufacturers as well as fabricators. This is more so in the case of equipments subjected to severe corrosive service conditions like urea service where the presence of ferrite in excess of 2% leads to corrosive attack- In such cases special techniques and consumables are required to produce sound joints for satisfactory service performance.