ABSTRACT
This research work was carried out to study the effects of seawater, 0.5M hydrochloric acid and wet steam corrosive media on the fatigue strength and microstructure of welded austenitic stainless steel. The immersion time in the corrosive media was 30 days to simulate the effect on stainless steel structures/equipment in offshore and food processing applications. Annealing heat treatment was carried out on the samples. The weight loss method was used for the corrosion tests. From the results of the corrosion test, seawater sample has highest weight loss of 4.0mg for the heat treated samples and 4.5mg for the unheat-treated samples. For the different media used, seawater sample has the highest corrosion rate of 0.64x10-6 mm/yr for the heat treated samples and 0.72x10-6 mm/yr for the unheat-treated samples. The findings from the fatigue tests show that seawater corroded specimen have lower fatigue stress of 0.5x10-5 N/mm2 for the heat treated sample and 0.1x10-5 N/mm2 for the unheat-treated sample compared to the corresponding hydrochloric acid and steam samples. The post welding heat treatment was found to increase the mechanical properties of the austenitic stainless steel especially tensile strength but it reduces the transformation and thermal stresses of the samples. These findings were further corroborated by the microstructural examination of the stainless steel specimen.