보수용접봉의 종류와 용접후 열처리가 용접금속의 내식성에 미치는 영향에 관한 전기화학적 평가

Abstract

Recently a fuel oil of the diesel engine of the marine ship is being changed with heavy oil of low quality as the oil price is higher more and more. Therefore the wear and corrosion in all parts of the engine such as cylinder liner, piston crown, spindle and seat ring of exhaust valves are predominantly increased with using of heavy oil of low quality. In particular the degree of wear and corrosion of piston crown is more seriously compared to the other parts of the engine due to operating in severe environment such as the high temperature of exhaust gas and repeating impact. Thus the repair weldment of the piston crown is a unique method to prolong the its life in a economical point of view. By the way, their parts on the ships job site is being actually welded with electrodes of mild steel. Therefore in this study, electrodes such as E4301, E4313 and E4316 were welded at SS401 steel as the base metal and corrosion property of their weld metals in the case of annealing treatment or not was investigated with some electrochemical methods such as measurement of corrosion potential, cathodic and anodic polarization curves, cyclic voltammogram and polarization resistance etc. in natural seawater solution. Corrosion resistance of the weld metal of E4301 was superior to the other weld metals in case of no heat treatment, however, its resistance was considerably decreased with heat treatment(annealing:625℃, 1hr) compared to other weld metals. The weld metals of E4313 and E4316 showed a relatively good corrosion resistance by annealing heat treatment.