Cast Iron Roll Surface Properties Of Laser Strengthening

In recent years, the technology of laser surface hardening is very broad application inrepairing the failure parts of industrial areas. As a clean energy, laser become more and morepopular because of its energy density, high efficiency and good quality repair. Repairing andstrengthening the surface of failure parts by laser can greatly extend the life of the parts, savethe costs for enterprises and conserve resources.In this study, fiber laser and CO2laser were alloyed on the roll surface, contrast andanalyse the performance of the alloyed layer made by two lasers. The material of alloyinglayer is WC-6Co, the mainly action of Co element is to bond the WC strengthening phases. Inthe laser irradiation with high energy density, a part of WC hard phase particles decomposedand form complex carbides with matrix material for the WC is nanoscale ceramic material.Undecomposed WC strengthening phase totally mixed in the bath and dispersed in the alloyedlayer, therefore, improve the hardness and wear resistance property of the alloyed layer. Firstly,determin the optimum parameters of the laser alloying through a large number of experiments.The optical microscopy, scanning electron microscopy and X-ray diffraction analyticalmethods were used to study and analyze the microstructure and phase composition of laseralloyed layer and the heat affected zone. Analyse the wear resistance property of the alloylayer by abrasion test; Use the microhardness tester to detect the distribution of microhardnessin alloyed layer and the transition zone; analyze the performance of thermal fatigue by thermalfatigue testing.The results show that the wear resistance of fiber laser alloyed layer increased3timesthan the base material at room and high temperature, the CO2laser alloyed layer increasedabout2-fold. The hardness of alloyed layer can reach HV900. The vickers hardness increasesby2~3times than the base material, the depth of fiber laser layer is0.4mm, the depth of theheat affected zone is0.6mm, the total depth of strengthening is about1.0mm. With the sameconditions, the total depth of strengthening is about0.7mm by CO2laser. Thermal fatigueexperiments show that the two laser alloyed layer cracking susceptibility slightly above thebase material. The structure of the two laser alloyed layer is similar, both of them werecomposed of hypoeutectic, the composition of hypoeutectic were martensite and complex carbides. The HAZ was constituted by acicular bainite, retained austenite, lath martensite,primitive existence graphite ball and primitive existence Fe3C.