The Raising Wear Resistance Study Of Carbon Steel By Using Surface Alloying

In this paper, the alloyed layer of high carbon ferrochrome particles and WC-high carbon ferrochrome particles had been formed on the surface of ZG 30 by using surface alloying technology. This composite layert was expected to apply to parts of ball mill foils, the partial surface of which requires excellent wear resistance. The microstructures, appearances, diffusion mechanism of the composite layer were studied, and so to the abrasive-wear properties and wear mechanisms of the layer.The ball mill foils requires excellent wear resistance locally. When the variety of key dimension exceeded the wear limits, the foils would be scraped. According to characteristics of such parts, the effect of coating thickness, adhesive, flux, alloy powder particle size and content to the alloy layer thickness and wear resistance was studied in this paper by using an ordinary casting infiltration technique. The best casting infiltration process parameters were optimized through large numbers of experiment: pouring temperature 1600℃, high-carbon ferrochrome powder particles filling 80 to 100 mesh size, enhanced tungsten carbide powder particle size of 100 to 120 mesh, flux is borax for 4 to 6%, binder is phenolic resin for 4%, mold coating thickness is 3mm. The deep-penetrating layer was formed, and it was metallurgical bond with the mother in good quality.The microstructure of the composite layer was studied by means of JSM-5600LV scanning electron microscope, EDAX energy spectrometer, linear distribution of chromium, X-ray analytical instrument. The results indicate that: the interface microstructure of composite layer and matrix was compacted and without any defects; iron and Tungsten distributed uniformly at the longitudinal direction of the layer, and various shapes of chromium tungsten carbide distributed uniformly in cast-penetrated substrate. Chromium carbide mainly exists as (Fe,Cr)7C3 while Tungsten carbide mainly as Fe3W3C with a small amount of WC,Fe3C, Cr23C7. All of the carbide are distributed uniformly in the martensite, which are benefitial to enhance the wear resistance.The effect of content and size of WC particle to wear resistance was determined on ML-100 abrasive wear testing machine, and the abrasion resistanc of the test material and maternal materials ZG30 were compared and analysed. The results show that: the wear resistance of alloying material was greatly improved than the substrate material; the WC particle concentration and granularity affect the wearability of alloying layers greatly.The wear resistance of the composite layer was the best with 15% WC particles, which was 18.8 times than the maternal mate rials. The wear resistance of the composite layer was the highst with 100~120 mesh WC particles which was 14.8 times than the maternal materials. The wear-resisting surface was intact after 48-hours-wearing by application of optimized cast-penetrated craft to ball mill foils actually. Therefore, the material's service life under particle attrition would be improved effectively by making alloyed layer using casting surface alloying technology.