On the Laser Quenching of the Groove of the Piston Head in Large Diesel Engines

Abstract

The service life of piston heads and the stability of large diesel engines are remarkably affected by the wear resistance of the groove of the piston head. Unfortunately, conventional high-frequency quenching methods result in several deleterious effects that may impair the antifriction and wear properties of the groove of the piston head. Excellent wear resistance characteristics may be achieved provided the groove surface is properly surface treated. Laser surface quenching is a new candidate technique. A 2 kW CW CO2 laser was employed for the laser quenching of the groove of the piston head in large diesel engines. The hardness and depth of the laser quenched layer reached 750 HV and 0.59 mm, respectively. The microstructure of the quenched layer is composed of martensite and retained austenite. Wear tests were performed using laser quenching and high-frequency quenching samples, and wear resistance was compared by using a method of mass loss. The results show that the wear resistances of laser quenched samples are 1.3x higher than that resulting from the high-frequency quenching method. Practical application of laser quenched piston heads in diesel power plants indicate that it is an effective way to prolong the service life of the piston head in large diesel engines.