Design And Research On Microstructure And Property Of Wet Ball Mill Liner Material

In the process of mining, as the main consumption part, the ball mill liner not only bearsimpact wear of medium and material, but also corrosion wear of the slurry, the servicecondition is hard. Now, the high manganese steel cannot completely meet the needs of the ballmill liner. Based on the high alloy wear resistant steel of Cr-Ni-Mo system, two wearresistant steels with different carbon content were designed by means of Thermo-Calc and thealloying mechanism, melted and casted. A series of quenching and tempering processes weredesigned. By the mechanical properties test, metallographic observing and X-ray diffraction,SEM and TEM, the influence on structure and properties of different heat treatment processeswere researched; the morphology characteristics, types, distribution of the wear resistant steelprecipitates were analyzed; At the same time, the corrosion resistance of two differentmaterials was analyzed comparatively.The result shows that the matrix is lath-shaped martensite with a small amount ofcarbides after the heat treatment. In the1000-1100℃quenching, if the quenchingtemperature is low, ferrite exists because of austenitizing incompletely. If the quenchingtemperature is higher, the structure of lath martensite is bulky, the hardness and toughness ofthe experiment material decline. The microstructure and the mechanical properties are the bestafter the heat treatment of that the quenching temperature is1050℃, with holding time of1hour, and the tempering temperature is250℃, with holding time of2hours. After the sameheat treatment process, the strength and hardness of the sample raise as the carbon contentincreases, but the toughness and the corrosion resistance decline.We finally choose C0.265%, Cr8.98%, Mn0.525%, Si0.423%, Ni1.776%, Mo0.668%,Cu0.445%, B0.004%, Re0.156%as the composition of the wet ball mill liner, after the heattreatment, the hardness reaches to HRC48, tensile strength and yield strength reach to1640MPa and940MPa, impact u-shaped notch toughness is45J·cm-2. The dimple of the fractureof the impact specimen is deep, most of them are gliding fracture after SEM scanning. Thepassivation performance is good in the weak acid medium, the surface of the material couldgenerate dense passivation membrane, and the corrosion resistance raises as the immersiontime raises. The precipitates of the material basically are M7C3types, the carbides precipitatedin the lath boundary and within lath, which morphology is different. These hard and fragile carbides increase the hardness and wear resistance of the martensitic matrix, but they reduceimpact toughness as brittle materials. RE is able to make the inclusion of the steel becomesmall, improve the comprehensive mechanical properties of the material.This paper designs a good wear resistant steel, it not only has general performance, butalso good corrosion resistance, in order to meet the needs of the ball mill liner in the wet weakacidic medium under the hard condition.