Effect of Mo Substitution by W on the Passive Characteristics and Mechanical Properties of AISI 316L Austenitic Stainless Steel

This work studied the influence on pitting corrosion resistance and mechanical behavior of the partial or total substitution of Mo by W in AISI 316L austenitic stainless steel. Alloys that contain 0%, 25%, 50%, 75%, or 100% of Mo substitution by W in atomic content were produced and analyzed. Microstructural analysis showed that W does not cause any difference in the size, distribution, and composition of inclusions. However, the grain sizes are slightly reduced in samples with W. Tensile tests did not show any difference in their mechanical properties. Cyclic polarization results do not show any difference between the samples with and without W in 3.5% NaCl at room temperature. However, the sample with 50% W and 50% Mo showed the highest critical pitting temperature in 1 M NaCl solution after potentiostatic polarization at 180 mV_Ag/AgCl, 40±4°C. This result shows a synergic effect of Mo and W for pitting corrosion resistance of austenitic stainless steel.