용접재료 별 주강 피스톤 크라운 용접부위의 부식 특성에 대한 평가

Abstract

Wear and corrosion of the engine parts surrounded with combustion chamber is more serious compared to the other parts of theengine because temperature of the exhaust gas in a combustion chamber is getting higher and higher with increasing of using the heavy oil of lowquality. Therefore, an optimum repair weldment as well as an available choice of the base metal for these parts are very important to prolong theirlifetime in a economical point of view. It reported that there was an experimental result for repair weldment on the forged steel which would begenerally used with piston crown material, however, it is considered that there is no study for the repair weldment on the cast steel of pistoncrown material. In this study, four types of electrodes such as 1.25Cr-0.5Mo, 0.5Mo Inconel 625 and 718 were welded with SMAW and GTAWmethods on the cast steel which would be generally used with piston crown material. And the corrosion properties of weld metal, heat affected zoneand base metal were investigated using electrochemical methods such as measurement of corrosion potential, anodic polarization curves, cyclicvoltammogram and impedance etc. in 35% H2SO4 solution. In the cases of Inconel 625, 718, the weld metals and base metals exhibited the best andworst corrosion resistance respectively, however, 1.25Cr-0.5Mo and 0.5Mo indicated that corrosion resistance of the base metal was better than theweld metal. And the weld metal welded with electrodes of Inconel 625 revealed the best corrosion resistance among the electrodes, and Inconel 718followed the Inconel 625. Hardness relatively also indicated higher value in the weld metal compared to heat affected zone and base metal. Inparticular, Inconel 718 indicated the highest value of hardness compared to other electrodes in the heat affected zone.