Shot peening effect on 904 L welds corrosion resistance

• 904 L (SS) is resistant to 5% NaCl salt spray in the 34.2 ÷ 35.7 °C temperature.
• The shot peening resulted in inhibition of corrosion processes.
• In the laser welded samples branched NaClNi crystals occurred.
• In the GTAW welded joints not peened, corrosion occurred from the face in the HAZ.

Here we investigated the effect of shot peening on the corrosion resistance of 904 L austenitic stainless steel joints made by CO2 laser beam and GTAW welding. Corrosion tests on the fusion zone in welds made by each of these welding methods were performed on shot peened and non-peened specimens. The samples were placed in a salt chamber and inspected after 24, 48, 72, 120, 240, 480, 720 and 1000 h.Pitting corrosion on non-peened welds made by GTAW welding was visible in the heat-affected zone from the face of the weld and reached a depth of 40 μm. Shot peening of welded joints decreased corrosion by 75%. In the case of shot peened welds made by laser beam welding, pitting corrosion had not occurred after 1000 h of salt mist exposure.

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