Structural features and properties of nickel coating-steel substrate composition after laser irradiation

This study presents the metallophysical analysis of the structural features and properties of chemical nickel coatings on steels subjected to extreme thermal effects of laser radiation. It is shown that thermostrictive stresses, estimated at 320 MPa, drive the structure formation processes in nickel coating-metal substrate compositions during irradiation. The iron-nickel phase diagram and temperature field model suggest that contact melting occurs in the transition zone between the coating and the steel substrate. Laser processing at a power density of 120 MW/m(2) increases the adhesion strength of the nickel coating to the substrate due to contact melting in the transition zone. Laser processing promotes the formation of a thin transition layer (1.6 mu m) consisting of solid iron and nickel solutions. An analysis of the properties of irradiated nickel coating-steel substrate compositions leads to the conclusion that laser processing guarantees the serviceability of irradiated steel products with nickel coatings.