Effects of Sea Water Immersion and Temperature on the Strength of Spot-Welded Steel Plates

Abstract

The spot welded structure operates in diverse climatic situations because of temperature, humidity and precipitation. In addition, factors of environmental pollution such as acid rain, that causes corrosion, have the tendency to increase. But spot welded structure strength is affected by dampness and environment temperature. Therefore, it is important to evaluate the effect of temperature of the spot welded part. In this study, the strength distribution of spot welded plates is evaluated for the environmental temperature of zinc coated steel plates and the test is conducted with the welded part immersed in distilled and synthetic sea water. Specimens are immersed into water for 10, 100, 500 and 1000hours to evaluate the effects of water immersion time on tensile-shear strength under the conditions of -40, 0, 20 and 50°C. Strength is evaluated by using the tensile-shear test. The conditions of spot welding are 240kgf electrode force, 10kA welding current with 0 and 5mm clearance. In this study, spot welded specimens with clearance have lower tensile-shear strength in the distilled water or synthetic sea water compared with spot welded specimens without clearance. And they have lower tensile-shear strength under -40°C and over 50°C.