The effect of borocoppering duration on the composition, microstructure and microhardness of the surface of carbon and alloy steels

Introduction. Borocoppering is one of the methods thermochemical treatment (TCT) aimed at forming diffusion layers with high physical and mechanical properties on surface carbon alloy steels. The thickness layer most important characteristic TCT, which determines depth hardening. Consequently, intensity main characteristics TCT (layer thickness, alloying element concentration profile) depend process conditions (temperature, duration, amount element). purpose this work to determine temperature-time parameters borocoppering, contribute formation a maximum thickness. paper considers results hardening steels (for example, Steel 45 (0.45% C), U10 (1.0% 0.5C-Cr-Ni-Mn steel) by high-temperature soaking in powder mixtures containing boron copper. was carried out sealed containers mixture consisting carbide, copper oxide, sodium fluoride as an activator temperature 950 °C for 3–5 h. resulting specimens were examined using optical microscope scanning electron (SEM); microhardness, elemental phase composition also determined, well roughness obtained surfaces. Results discussions. microstructure studied; diagrams changes layers’ microhardness distribution over are shown. It established that increase time from 3 5 h, increases 120 170 μm C); 110 155 µm C) 130 230 steel. A gradual decrease along 15–16% 2–3% surface, respectively, zero values boundary base metal revealed. borocoppering more thick boride compared pure boriding. Moreover, duration during contributes greatest study microgeometry out, microtopographies profilograms specimens’ surfaces shown before after borocoppering. 2-3 times initial one, does not have significant effect roughness.