A Study of Chromo-Boronizing on DIN 1.2714 Steel by Duplex Surface Treatment

In the current study, the microhardness, layer depth, corrosion properties, and kinetics of chromium boride coatings on DIN 1.2714 hot-worked tool steel have been investigated. Thermodiffusion chromium boride coatings have been carried out for the first time by a duplex salt bath immersion coating by chromizing at 1050 degrees C followed by boronizing at 950 degrees C, 1000 degrees C, and 1050 degrees C (chromo-boronizing). The coating layer obtained was hard (2482 HV), compact, and homogeneous. The kinetics of the chromium boride coating followed a parabolic relation (d(2) = Kt) and the activation energy of the formation of the chromo-boronized layer was calculated as 132 kJ/mol. The corrosion resistance of the coating was evaluated by potentiodynamic polarization in 3.5% NaCl solution. The results showed the degradation of the corrosion properties of the coated samples.