Tribological properties evaluation of AISI 1095 steel chromized at different temperatures

Pack chromization process provides a surface modified coating on steel surface with high hardness, corrosion and temperature resistance. AISI 1095 carbon steels were chromized to form chromium–iron nitride and carbides on surface by pack cementation process at 850 and 900 °C for 1–9 h, respectively. Chromized layer with an outer (Cr,Fe)2N1-x and inner (Cr,Fe)23C6 and (Cr,Fe)7C3 phases were observed. The wear resistance of chromized steels was evaluated by pin-on-disk wear tests. Daimler–Benz Rockwell-C adhesion and scratch tests were further conducted to evaluate the adhesion properties of chromized layers. Surface morphologies of chromized layers and matrix after wear and adhesion tests were studied with an electron probe microanalyzer. Chipping and microradial cracking failures were revealed on the chromized layers after the Daimler–Benz Rockwell-C adhesion tests. The adhesion strength quality of chromized layers was related to HF1–HF4. The critical loads increased with the chromizing temperature and time. It is concluded that the adhesion properties and tribological properties of chromized layers were improved as chromizing temperature and time increased. A chromizing process held at 850/900 °C for 4 h is then proposed for the AISI 1095 steel to achieve the optimal tribological performance.