Investigation of friction and wear resistance of carbonitrided AISI 4130 steels using single and multi-pass scratch technique

The present paper investigates the friction and wear resistance of carbonitrided AISI 4130 steels using single and multi-pass scratch techniques. The influence of carbon concentration in high-temperature gas carbonitriding on friction, wear, and corrosion behavior was studied. The microstructure and morphological properties of carbonitrided layers were investigated employing optical microscope and XRD. The corrosion performance of carbonitrided layers was also evaluated using potentiodynamic polarization in 3.5 wt.% aqueous solution of NaCl. The results of microstructure showed the formation of an arrangement of carbonitrides, chromium nitride, retained austenite, and Fe3C carbides phases in the carbonitrided layers. The carbonitrided layer microhardness increased as a function of increasing carbon concentration to attain a maximum value of about 980 HV0.1 at a carbon content between 1 and 1.2%. The microhardness value was more than 3 times than those of the untreated AISI 4130 steels. Moreover, carbon content has a significant influence on the scratch resistance. For single pass, a critical load (L-C1) of about 3.5 N was found. The use of multi-pass scratching allowed to examine friction coefficient, wear volume, and damage mechanism. Carbonitrided layers revealed a low friction coefficient (0.06) and a low wear volume that does not exceed 0.16*10(6) mu m(3). Moreover, the multi-pass scratch technique can extract valuable information about the wear behavior of the carbonitrided layers. The results of corrosion test showed that the formation of epsilon(Fe2-3CN)S, gamma'(Fe4N) and chromium nitride phases in carbonitrided layers were at the origin of high electrochemical resistance.