A Study on Mechanical Properties of Stainless Steel Welded Joints for Marine Applications

Corrosion can be defined as a significant reason for structural failure in marine and offshore applications. Pitting corrosion is a savage and detrimental form of corrosion. It is a locally accelerated precipitation of metal that forms as a result of damage in the protective passive film on the material surface. From so many years it is being researched upon; yet, the actual nature of failure of susceptible materials due to pitting corrosion is still not completely comprehended. It penetrates deeply in the materials and weakens the material. More the carbon content, higher will be the risk of getting corroded. So mainly Stainless steel, that contains minimum amount of carbon, will display maximum resistance to this type of corrosion. In this paper, mechanical properties of stainless steel 304 are studied. Shielded metal arc welding is used to weld two SS304 plates and then tensile and impact specimens are prepared using AWS B4 standards. The test specimens are then subjected to accelerated corrosion as per ASTM G48 standards for 0, 48, 96, 144 and 192 h. Later, tensile test and impact test is carried out. The results obtained from testing shows that there is decrease in tensile strength of welded joints as the exposure time increases. The variation in the impact strength is not very prominent. However as compared to non-corroded SS304 material, the ones which are exposed to accelerated corrosion show slightly less impact strength. Microscopic study reveals that there is a change in phase to martensite at heat affected zone with higher carbon content compared to base metal, making the joint brittle compared to base metal.