Corrosion Behavior of Nickel Alloys NiFe and NiCu Welding on Base Metal in Alkalie Solution

Abstract

Clading metal weld is a composite product developed to provide effective and economic utilization of expensive materials. The welding layer NiCu and NiFe that will be in contact with the corrosive media is made of the corrosion resistant alloys, whilst the less expensive base carbon steel covers the strength and toughness required to maintain the mechanical integrity. In a nuclear power plant clading metal weld joints are necessary for joining the different materials chosen for the various parts of the heat transfer circuit. Also Clading metal welds are utilized in processing pressure vessels, heat exchangers, tanks and storage facilities. Anodic polarization curves for deposited as weld and heat treated Ni alloy weld metal in 3.5% NaCl solution with alkaline pH are studying. Anodic polarization curve for NiFe weld metal on carbon steel heat treated for 50,500 and 1000 hr at 550 oC are recorded. The results indicated that, for example, the anodic polarization curve for NiFe weld metal heat treated for 500 hr at 550 oC in 3.5% NaCl solution, the corrosion current density was 11.23 μ A/cm 2 .The corrosion current density increase at constant rate which indicate a uniform corrosion. The hardness is 205Hv measured at 300 gmload.As for the anodic polarization curve for Ni-Cu weld metal heat treated for 500 hr at 550 °C tested in 3.5% NaCl solution, the corrosion current density was 28.42 µA/cm 2. The corrosion current density increases after that with constant rate till and of the experiment. The hardness is 235Hv measured at 300 gm load.