Influence Of Cryogenic Treatment On Hearer Boots Wear-resisting Layer

Sliding shoes are important load components of the shearer base. Because ofshearer’s poor working conditions, and with the increasing quality of shearer,performance requirements of the sliding shoes become higher and higher. Materials ofsliding shoes should have high strength, less prone to plastic deformation, goodtoughness and high wear resistance. Cryogenic treatment is an extension of thecommon cold treatment, now widely used in the processing of the cutting tools forimproving its wear resistance, strength and toughness, and the effect is very obvious.In this paper, we discuss cryogenic treatment on the effect of wear resistance ofsliding shoes. Make different heat treatment process,such as-80℃cryogenictreatment and-196℃cryogenic treatment, through the determination of hardness,observation of microstructure and the friction and wear experiments and impact test,study the improve the performance of the cryogenic treatment on sliding boots, Theconclusion is as follows:The sample after cryogenic treatment group are tempered martensite+carbideprecipitation+dispersion of ultrafine carbides, black cellular and lamellar martensite,and uniform grain size and distribution, carbide particles increased obviously, theresidual austenite is few, in the organization and the organization more evenmeticulous, extremely low porosity.The cryogenic treatment promote the retained austenite to martensitetransformation, and makes martensite fragmentation, refine the organization, withcarbide precipitation in cryogenic process, uniform distribution of carbide dispersionstrengthening effect, at the same time with high hardness in the process of cryogenicsecondary carbides Cr, Fe）7C3generation, and generate dispersion strengthened, so asto effectively improve the hardness and strength.Under the condition of dry friction and quartz sand friction condition, the frictioncoefficient are presented by the start of volatility to the instability of small upwardtrend will be leveled off in the end. Under the condition of dry friction, heat treatmentbefore sample wear mechanism mainly adhesion wear, abrasive wear,-196℃aftercryogenic treatment sample mainly abrasive wear, and the wear surface level off,smooth, good wear resistance. Quartz sand friction wear under the condition ofsample surface micro cutting and plowing, cutting groove, narrow furrow width isblunt, the former is mainly due to the abrasive effect of quartz sand particles, the latter is due to the pressure into the grinding grain more pliable and pressure into theshallow depth, caused by plastic deformation on the surface.Compare with the samples of non-heat treatment and traditional heat treatment,the impact absorbing energy of the sample are decreased. This kind change of theimpact absorbing energy is caused by the organizational change of quenching. Aftercryogenic treatment, there is a good fiber area in the shape of the sample, meanings itshave good ductility. At the same time, the fracture roughness of samples after thecryogenic processing relative to other sample is lighter, the characterization of theradiation pattern of the tiny fracture characteristics, explain the cleavage andintergranular fracture plays a main role, its fracture crack extension is consumed whenthe work is also small. Illustrates the cryogenic treatment in improving the samplehardness and wear-resisting performance at the same time also has a good toughness.