Investigation of the accumulation of alloying elements (Mn, Ni, Mo) on the surface of high-alloy steel in acid medium

Abstract

The formation of corrosion products in the surface layers of steel 15KH12VNMF brand was investigated in solutions of hydrochloric, sulfuric, phosphoric, and nitric acids. Comparative data were obtained on the accumulation of impurity alloying elements in surface layers of high-alloy steel 15KH12VNMF brand. The content of alloying elements was defined in the surface layer of steel and corrosion products when holding samples in solutions with a certain concentration for 1 hour. The obtained data indicate that the accumulation of manganese, molybdenum and nickel in the surface layer does not occur in the sulfuric acid solution. The surface layers in the solution of phosphoric acid accumulate intensively alloying impurities, whereas in nitric and hydrochloric acids there is a selective accumulation. The surface films on the steel 15KH12VNMF brand in solutions of hydrochloric, sulfuric, phosphoric, nitric acids were Identified at high concentrations and times of incubation. It was established that the rate of manganese accumulation in hydrochloric acid is constant, regardless of the acid concentration. For nickel and molybdenum, the rate of accumulation increases at initial concentrations, and tends to its constant value at high concentrations. In sulfuric acid solutions, the amount of manganese on the surface depends not only on the concentration, but also on the holding time. The accumulation of nickel and molybdenum on the surface of the plate depends as on the concentration and the time. It was determined that in solutions of phosphoric acid the accumulation of manganese occurs only at the primary time, in the future remains constant. The accumulation of nickel and molybdenum on the surface depends as on the concentration and the time and has a similar character. The data are obtained that the accumulation of manganese, nickel, molybdenum on the surface of the sample in solutions of nitric acid with increasing concentration occurs regardless of the holding time of the sample