Effect Of Hammer Handle Surface Welding On Interfacial Bonding And Wear Resistance Of The Duplex Metal Composition Hammer

At present, the hammer crusher use the duplex metal composition hammer with high-chromium and casting steel extensively. If this kind of hammer composite good, it can not only meet the toughness requirements, and also has a high abrasion resistance. However, because of the high melting point of cast steel hammer-handle, when combined with the hammer-head, it is difficult to achieve metallurgical bonding so that the hammer prone to the loose, fall off, and so on. In addition, the part of the hammer-handle near by the hammer-head is made of the ordinary carbon steel, and have a lower resistance. The actual use prone to serious wear and tear, leading to early failure of the entire hammer, and even fracture caused by damage to the equipment and safety accidents. In order to solve these problems, firstly, welding on the composite parts and the surface of the hammer-handle, then, compositing it with the hammer-head. The surfacing layer has low melting point and the homogeneous high-chromium cast iron materials. This method can improve the surface wear resistance of the hammer-handle, meanwhile it can make the composite part to achieve more sophisticated interface combination, so that the hammer’s service life will be further improved.The paper chooses ZG270-500as the material of the hammer-handle, and high-chromium cast iron as the material of the hammer-head. Experimented with D618, as well as homemade variety of different components of the high-chromium cast iron electrode welding rod. On this basis, the temperature of the hammer-handle were preheated at room temperature,300℃and600℃respectively with the technique of the internal induction preheating, then pouring the hammer-head. Soon afterwards, heated it to960℃and preservation for4h, come the wind quenching, then heated to250℃and preservation for2h, come air-cooling tempering treatment. By XRD, metallurgical microscope, scanning electron microscopy and energy spectrum to analysis the metallurgical structure and the combination of the sample of surfacing layer and composite layer, Chrome’s hardness values and microhardness values measurement, and homemade abrasion tester for wear test. According to the test results, we can choose the appropriate surfacing electrode. Finally, we will do impact toughness test, and the impact toughness of calibration.The research shows that:Using high carbon ferrochrome, graphite, ferrosilicon(Si75), high carbon ferromanganese and iron powder as raw material. It is good performance, and ensures the quality of the surfacing layer. Keeping the chromium content of20%the same, adjust the ratio to reach a different carbon content, then made these into different electrodes, from1#to4#. To analysis the surfacing layer after surfacing, the3#has the lowest melting point in the light of Fe-Cr-C alloy liquid phase plane projection. Welded hardness results:42.3HRC,48.7HRC,55.7HRC,59.4HRC. Metallographic observations show that:with carbon content increasing, the organization changed from hypoeutectic to hypereutectic, and the primary austenite is less and less, the eutectic carbides are more and more. When it comes to the hypereutectic, it is consisted of the bulk of primary carbides and eutectic. After compound casting, and heat treatment, it can get the following metallographic structure:M7C3type carbide+tempered martensite+dispersed secondary carbide+retained austenite. Meanwhile, the hardness of the hammer-handle surfacing layer is improved. The thickness of the surfacing layer is2mm. Using coal gangue for abrasive to do wearing test. Wear test results:The average weight loss for grinding of the ZG270-500is3.5372g. The loss after surfacing of1#to4#which is converted as relative wear resistance respectively is about11,16,26,30times.Finally, we choose the third kind of homemade electrode, because the surfacing layer has the lowest melting point and high hardness. It can achieve abundantly for the requirement of the hammer. Using300℃preheat temperature, the high-chromium and the surfacing layer comes to the miscible state, there is no dividing line between them. It can promote the atomic interdiffusion in the binding interface. The interfacial bonding is indented, and it strengthen the degree of metallurgical bonding. At last, the result of the impact toughness of calibration show that the hammer can fully meet the impact of the working conditions. The hammer is more secure and reliable. Meanwhile the wear resistance of the hammer-handle is greatly enhanced. The hammer of the trial were used in factory. The life is4times than high-chromium hammer. Meanwhile, when the hammer-head failure, the surfacing layer had not been weared entirely so that the matrix of the hammer-handle had been protected from wearing. The hammer have higher life and lower cost. The hammer showed to be good effect in the actual production, and achieved the pre-design requirements.