Study On Microstructure And Wear Resistance Of High Strength And Toughness Of70CrMo Wear Resistant Steel

The bad service environment of ball mill liner which is used in mine requiresbetter performance to material. the using life of traditional material is short. CrMosteel with high wear resistance could effectively defend the wear of material. Itincreased the duration of the ball mill liner and reduced the consumption, therebyimproved the economic efficiency.By referring to CrMo steel material of relavent domestic and foreign components,a CrMo steel composition range is designed: C0.6-0.7%, Mn0.81.2%, Si0.5-0.8%,Cr1.5-2.0%Ni0.75-1.0%, Mo0.3-0.4%, PS≤0.04%. Impact of the Technology forHeating Processing on the microstructure and properties of materials has been studied.The influence of heat treatment had been studied by the microstructure and propertiesof materials. the hardness was determined by the HR-150A Rockwell hardness tester;the impact and tensile tests was determined by the JB-300B impact test machine andthe SHIMAD (Shimadzu) ZUAG-I250KN electronic tensile testing machine; thefriction and wear performance test was determined by the MMS-1G high-temperaturehigh-speeding plate the friction and wear testing machine. The influence of the heattreatment process on the microstructure of the test material, analysis of the impact andtensile fracture surface, wear resistance and wear morphology had been studied byJSN-5610LV scanning electron microscopy, energy dispersive spectroscopy. The heattreatment is:680℃×2h(preheated)+890℃×3h (oil quenching)＋590℃×3h(tempering).The results shows that the mechanical properties were improved after the process ofheat treatment. the hardness is up to HRC37, σbreached to1180MPa, the impactenergy αkreached to92J, elongation value of δ is7%; reduction of area ψ is12.5%.The electron microscope was used to analyze the organization of the70CrMosteel; the microstructure are tempered sorbite+residual austenite+eutectoidcementite. The mechanism of plasticity and toughness was studied from the process ofalloying, melting, heat treatment, modification. The wear resistance of the new kind of70CrMo steel was studied by the installedwear test. It was compared with manganese steel and high chromium cast iron, theworn surface morphology and wear mechanisms were studied by the SEM. the resultsshowed that: with the increase of speed of friction velocity, the wear rate graduallyincreased, when the load is90N. the wear rate increased significantly at the speed of70m/s. That is all because the surface temperature which was caused by the high speedis too high to induce the plastic deformation of materials. When the speed is50m/s,with the increase of the load, the wear volume increased significantly. The mechanicalproperties and wear resistance were improved after the process of heat treatment. Theheat treatment is680℃×1h (preheated)+890℃×3h (oil quenching)+590℃×3h(tempering). The abrasion is mainly in form of grain-abrasion, plastic deformationabrasion and adhesive abrasion. The wear resistance of the new70CrMo steel isimproved, as1.03times of the high Cr cast iron,2.04times of the high manganesesteel.