Pi. Marshall et Tg. Gooch, EFFECT OF COMPOSITION ON CORROSION-RESISTANCE OF HIGH-ALLOY AUSTENITIC STAINLESS-STEEL WELD METALS, Corrosion, 49(6), 1993, pp. 514-526
The corrosion resistance of stainless steel weld metal in the ranges o
f 17 to 28% chromium (Cr), 6 to 60% nickel (Ni), 0 to 9% molybdenum (M
o), and 0.0 to 0.37% nitrogen (N) was examined. Critical pitting tempe
ratures were determined in ferric chloride (FeCl3). Passive film break
down potentials were assessed from potentiodynamic scans in 3% sodium
chloride (NaCl) at 50-degrees-C. Potentiodynamic and potentiostatic te
sts were carried out in 30% sulfuric acid (H2SO4) at 25-degrees-C, whi
ch was representative of chloride-free acid media of low redox potenti
al. Metallographic examination and microanalysis were conducted on the
test welds. Because of segregation of alloying elements, weld metal p
itting resistance always was lower than that of matching composition b
ase steel The difference increased with higher Cr, Mo, and N contents.
Segregation also reduced resistance to general corrosion in H2SO4, bu
t the effect relative to the base steel was less marked than with chlo
ride pitting. Segregation of Cr, Mo, and N in fully austenitic deposit
s decreased as the Ni(eq-)'Cr(eq)' ratio increased. Over the compositi
onal range studied, weld metal pitting resistance was dependent mainly
on Mo content and segregation. N had less effect than in wrought allo
ys. Both Mo and N enhanced weld metal corrosion resistance in H2SO4.