The Effect of Bainite Volume Fraction on Wear Behavior of AISI 4340 Ferrite-Bainite Dual-Phase Steel

The tribological behaviors of an AISI 4340 ferritic-bainitic dual-phase steel with different bainite (V-B) content were investigated. The effects of V-B on wear resistance and the corresponding wear mechanisms were investigated using a pin-on-disk wear testing machine, at normal loads of 10 and 50 N, at a constant sliding velocity. The tensile and hardness tests showed that the yield strength, ultimate tensile strength, and hardness increased with increasing the V-B. The wear test results at the 10 N normal load showed a direct correlation between the tensile and tribological behavior of the samples. Nevertheless, at the normal load of 50 N, unexpected behavior was observed due to the carbon content of the hard sub-structure and the occurrence of a transition in wear mechanisms. Indeed, for the normal load of 10 N, there is a correlation between the work hardening exponent and strength coefficient versus wear rate. In contrast, no direct correlation was observed at the normal load of 50 N. Moreover, scanning electron microscopy studies showed that the plowing and delamination wear mechanisms were predominant at the normal load of 10 N. Contrariwise, the adhesive wear mechanism increased dramatically by increasing the normal load to 50 N.