Influence of Programmed Welding Temperature Cycles on the Structure and Corrosion Behavior of Austenitic Steel.

Two steels were investigated, ccommerical X 5 CrNiMo 17 13, used in chemical equipment, and a laboratory steel of the same composition without any Nb and Ti. Experimental data show that exposure to simulated welding temperature cycles rapidly decreases corrosion resistance. This fact is correlted with carbide precipitation at 700 to 900 C and with grain growth and twinning at 900 to 1000 C. Above 1280 C, delta ferrite forms within 15 sec. The presence of small amounts of Nb and Ti aaffected only the delta ferrite formation. Corrosion resistance in H//2 SO//4 solutions was determined by plotting potentiokinetic current density/potential curves.