QUALITY ANALYSIS OF ALUMINIZED SURFACE LAYERS OBTAINED BY ELECTROSPARK ALLOYING

Abstract

The features of structurization during aluminizing steel 20 and steel 40 samples using electrospark alloying are considered. It is established that with increasing discharge energy, the thickness and microhardness of the “white” and transition layers, and the surface roughness increase, while the chemical and phase compositions change. At low discharge energies, a layer mostly consisting of α-Fe and aluminum oxides is formed. With increasing discharge energy, the layer consists of iron and aluminum intermetallics and free aluminum, which is evidenced by X-ray spectrum analysis. During electrospark alloying of steel 40, compared to steel 20, the increased hardness zone and its microhardness increase. The surface roughness virtually remains the same. To reduce the roughness and increase the continuity of the coatings, it is recommended to carry out the electrospark alloying using the same electrode (aluminum), however, at low discharge energies (W_p = 0.52 J).