Influence of nickel on the susceptibility to corrosion fatigue of duplex stainless steel welds

The object of this work is to analyse the mechanisms of corrosion fatigue a nd to study the influence of Nickel on the susceptibility to corrosion fati gue in welded Duplex stainless steels. A 'Ferralium 255' type cast Duplex s tainless steel was used as base material. Four types of experimental electr odes of chemical composition similar to base material were used, with varyi ng compositions of Ni (2.8, 4.7, 6.8 and 9.8 wt%). Experimental three point bending fatigue tests were carried out in air at 10 Hz, and in normalised seawater at 3 Hz, with anodic polarisation to 800 mV ECS. The strain gauge technique was used to monitor subcritical propagation of cracks. The effect of the corrosive environment on crack growth rates and on the coefficients of the Paris equation were assessed for each type of electrode. Comparing the experimental results, it was determined that the best electrode is the one that contains 4.7% Ni. (C) 2001 Elsevier Science Ltd. All rights reserv ed.