Experimental study of the laser quenching of 40CrNiMoA steel

The service life of the piston head and the stability of a large diesel eng ine are greatly affected by the wear resistance of the groove of the piston head. Conventional high-frequency quench-and-temper treatment results in s everal deleterious effects that may impair the anti-friction and wear prope rties of the groove of the piston head. Laser surface quenching is a new ca ndidate technique. In this study, based on orthogonal experimental design, the effect of the surface condition, the laser power, the traverse speed. t he incident angle and the gas flow rate on the quenched zone of 40CrNiMoA s teel was investigated systematically. The profile, hardness and microstruct ure of the quenched zone vary with the surface condition, the laser power, the incident angle and the traverse speed. However, they are not significan tly affected by the gas flow rate. The optimum processing parameters are ob tained for the laser quenching of the groove of the piston head. Using the optimum processing parameters, quenched zones with not only sufficient case depth and greater hardness but also of a suitable profile and a finer micr ostructure, are obtainable. The hardness of the laser quenched zone is subs tantially higher than that resulting from conventional high-frequency quenc h-and-temper treatment. (C) 1999 Elsevier Science S.A. All rights reserved.