Wear Resistance Of Laser Melting Bionic Coupling Gray Cast Iron Rails

As a key part of the machine tool, guideway exerts a direct influence on themanufacturing accuracy and working life of the machine tool.Guideway failuremainly manifests as wear failure.Since machine tool machining tends to developin a way with high speed and high efficiency, highprecisionand high reliabilityhigher requirements for the durability of accuracy and wear resistance of themachine tool are raised. Grey cast iron is widely used in various kindsof machine tool uideways due to its good castability and excellentmachinability, strong wear resistance and its low price as well.The traditional thermal processes processing cannot meet the requirements ofthe further development of machine tools. Therefore, it is absolutelynecessaryto modify the guideway surface by using new techniques to improvethe wear resistance and work life of guideway.After the emergence of laser surface treatment techonology, much researchon laser treatment application to the surface of metal parts has been done byscholars home and abroad and the surface quality of many products has beenimproved. In recent years, bionical technology is widely used in variousfields.And bionic effects have been successfully used in the surface treatment ofsome frictional parts to improve the their wear resistance.In this paper, different bioniccoupling modelsare designedthrough imitatingthe morphological characteristics and structures of ant’s head, pangolin scalesand shells.Then the newly designed binoiccoupling models are worked out onthe surface of the grey cast iron guideway sample through laser melting. Themicrostructure and mechanical properties of the manufactured binoiccouplingmodelsare observed and tested while the laser melting processing parameters areoptimized throughorthogonalexperiment. And finally, a contrast test ofwearresistance between the laser-treated and normally treated samples isconducted in oil-lubricated conditions. The results indicate that the optimizedlaser processing parameters are as follows:0.25mm/s for scanning speed,150Afor current,10ms for pulse width, and7Hz for frequency. The laser-treatedcross sections can be divided into melted zone，phase transformation zone, heat affected zone and matrix zone. The spheroidal graphite is observed in the meltedregion of the lasertreated sample. The grain size in the phase transformationregion is much smaller than that of the melted region and the grain is moreevenly distributed. In the laser-treated zone, the surface hardness is significantlyincreased compared with that of the normally treated one, with no variationgradient in distribution. Compared with the normally treated sample,bioniccoupling samplehas a dramatic improvement in wear resistance, which isresulted from the comprehensive function of the super-refined and morehardened grains, bionic effects and the spherical graphite in the laser-treatedzone.