Effect of grain refinement on the corrosion resistance of Nickel 200

Grain refinement is effective method of strengthening of metals. Reduction of grain size increases strength and reactivity. Publications on the corrosion resistance of fine grained metals differ in conclusions - sometimes corrosion proceeds faster, sometimes slower. This paper presents the results of research carried out on Nickel 200 after hydrostatic extrusion. The microstructure, microhardness and corrosion resistance were examined of the samples subjected to this process. It was found that the hydrostatic extrusion results in ultrafine grained nickel structure and is accompanied by a significant increase in microhardness. The study also shows that the grain refinement has a negative influence on the corrosion resistance of nickel.