Study On Micro Structure And Properties Of Tungsten Carbide Particles Based On High Chromium Cast Iron Welding Layers Manufactured By High Frequency Induction Cladding

Surfacing technology is an important branch of surface treatment technology，including induction welding technology developed in recent years， but also has greatapplication potential. Among various kinds of alloy powder Fe base alloy powder iswidely used with high cost performance. In order to further improve the wearresistance of high chromium cast iron surfacing layer by high frequency induction andto prolong its life，in this paper，welding technology on Q235steel surfacepreparation of tungsten carbide reinforced high chromium cast iron matrix ofsurfacing welding layer by using high frequency induction.Firstly，this paper has optimized the high frequency induction welding processparameters and cooling treatment after welding. Then high chromium cast iron basesurfacing layer and contains mass fraction respectively10%，20%，30%，20%and45%tungsten carbide particles of high frequency induction welding highchromium cast iron surfacing layers was obtained，and the macro morphology of thesurfacing layer， organization structure，species，type and hardness，wearresistance was analyzed by means of optical microscope、 scanning electronmicroscope、X-ray diffraction and hardmeter，and the result showed that the integraleffect of40%tungsten carbide surfacing layer was best. Under the optimizedhigh-frequency induction welding process， welding layer surface was smooth，dense， smooth and no obvious crack; It is obviously that the micro structure wasorganization of the rapid solidification. The main phase in high chromium cast ironbase surfacing layer are austenitic and M7C3((Cr，Fe)7(C，B)3).The main phase inhigh chromium cast iron matrix surfacing layer reinforced by tungsten carbide areaustenitic，M7C3((Cr， Fe)7(C，B)3)，WC and W2C， etc. With the increase ofthe tungsten carbide content， the eutectic microstructure of surfacing layer is morewell-distributed， dense and the quantity of carbide (main types of M7C3，M3C andM23C6，etc) was increase. The changes of tungsten carbide particles in morphology and microstructure ofsurfacing layer were researched， and it was concluded that tungsten carbide particlesare smooth， but the volume fraction of tungsten carbide particles changed little， thedissolved metal part and matrix form carbide that the main types are M6C ((W，Fe)6C). With the increase of tungsten carbide content，this kind of carbide producedfrom crystal boundary to transgranular，this is helpful to the improvement of theperformance of the surfacing layer as a whole. At the same time，this paper also hasevaluated on the tungsten carbide particles in high frequency induction welding layerdiffusion loss situation，the dissolution of quantitative formula was semi-quantitative.This formula can evaluate ceramic phase damage degree with different content oftungsten carbide particles and tungsten carbide grain size of the surfacing layer.The rockwell hardness of surfacing layer in the lateral section beyond the edge ofbased high chromium cast iron with no tungsten carbide was about60.8HRC，the40%tungsten carbide particles content reached maximum，63.8HRC. In the longitudinalsection of sample，microhardness decrease after rising first along the parent metal tosurfacing layer surface. The main reason mainly concentrated in the surfacing layer oftungsten carbide particles in the junction of parent metal. The microstructure of the40%tungsten carbide content in the junction of tissue samples was well-distributed，withmaximum microhardness value，1005HV. The main wear form of the surfacing layeris the micro-cutting，furrow. The wear resistance of surfacing layer of40%tungstencarbide content was best，with very shallow furrow.Three high chromium cast iron layers reinforced by tungsten carbide content(40%) particles was prepared by matrix high-frequency induction. The thickness ofthe first layer was about1mm，the second was about2mm，the third layer wasabout3.5mm. Scanning electron microscopy (SEM) image showed that there is noobvious line between three layers. Surfacing layer surface was smooth，uniformcompact structure，no defects such as inclusions. Using XRD phase analysis，thequantity of M7C3carbide，M6C in surfacing layer are higher than that of singlesurfacing layer. In a certain range，the surfacing layer thickness，surface rockwellhardness surfacing layer is higher，the wear resistance is better.