Effect of laser quenching on fatigue properties and fracture morphologies of boronized layer on Cr12MoV steel

• The fatigue limit of boronized sample by LQ is increased by 14.7%.
• The fatigue crack source is transferred to the sample subsurface after LQ.
• The refined and strengthened grains are the mechanism of reducing fatigue limit.

A boronized layer of Cr12MoV steel was processed with LQ (laser quenching), and the fatigue limits of original samples before and laser quenched samples were calculated with Locati tension–tension fatigue test, and the fracture morphologies were observed with a SEM (scanning electronic microscope). The results show that the compressive residual stress of −382 MPa is introduced by LQ, the fatigue strength improves from 368 MPa to 422 MPa, increasing by 14.7%, and the fatigue crack is initiated at the subsurface after LQ. The compressive residual stress of the Cr12MoV by LQ is of the main mechanism of the improving of fatigue property.