The Effect Of Nanoceramic Particles Added From Outside On Microstructures,Mechanical Properties And Wear Behaviors Of Steel And Iron Wear Resistant Materials

High-chromium cast iron,high-manganese steel and carbidic austempered ductile iron?CADI?are three commonly used steel wear-resistant materials,but in the process of productions of these wear-resistant materials,the carbide coarseness,grain size and low and poor graphite nodularity phenomenon are prone to occur on them respectively,which can seriously affect the wear resistance of the materials.Heterogeneous nucleation can be promoted by adding nanoparticles to steel materials,which can effectively refine microstructure.According to the characteristics of the three wear-resistant materials and the actual production environment,the nano-CeO₂,nano-ZrO₂ and nano-SiC were added to high-chromium cast iron,high-manganese steel and CADI respectively.The effects of additional nanoparticles on the microstructure,mechanical properties,wear resistance and wear behavior of wear resistant materials were investigated.The 0.08 wt.%of nano-CeO₂ particles were fixed in a foaming mold for casting,and then,the nanoparticles were introduced into the high-chromium cast iron samples by a casting process.The test results show that the carbide morphology of the high chromium cast iron sample with nano-CeO₂ is obviously improved compared with the sample without the addition of nanoparticles.The hardness of the quenched and tempered sample is increased by 2.7 HRC,and the impact absorption energy is increased by 31.6%.The anti-three-body abrasive wear performance has also been significantly improved.The triad abrasive wear behavior study found that the refined and distributed homogenized carbide can effectively hinder the intrusion and sliding of the abrasive particles,reduce the abrasion of the abrasive grains on the matrix structure,and at the same time,the carbides can also obtain the protection of the matrix structure,reducing the fracture during wear,so the sample added with nano-CeO₂ shows better wear resistance.The 0.2wt.%nano ZrO₂ particles were added into high manganese steel by means of intermediate alloy method.The test results showed that the high manganese steel with nano ZrO₂was added compared with the sample without nanoparticles,the grain size of the sample was increased from 2.5 to 3.5,the Brinell hardness of the water toughened sample was increased by3.8 HBW,the impact absorption energy was increased by 28.9%,and the impact abrasive wear resistance was also significantly improved.The study of impact abrasive wear behavior found that the deepening of wear hardening can improve the wear resistance of high manganese steel,while the wear hardening degree of high manganese steel is related to the grain size and the impact work of the wear test,and the grain size level is improved.When the impact energy is increased,the degree of work hardening is deepened;when the abrasive grains move on the surface of the material,furrows and plastic extrusion deformation are formed,and the furrow edge and the plastic extrusion deformation region are prone to cracks,causing the material to peel off,when the high manganese steel When the grain size is increased,the degree of hardening is deepened,which can reduce the formation of deep furrows and severe crushing deformation,thereby reducing the amount of wear to a certain extent.The 0.1wt.%nano-SiC particles were also added to CADI by the intermediate alloy method.The test results showed that:the CADI sample balls with nano-SiC were added compared with the samples without nano-SiC,the nodularity was increased by 13.8%,the size of the graphite sphere was refined,the impact absorption energy was increased by 41.3%,and the impact abrasive wear resistance was significantly improved.The impact abrasive wear behavior of CADI found that:during the impact wear process,there existed work hardening in the subsurface of worn surface,and the nanocrystalline were found under the worn surface,which can deepen the degree of plastic deformation and strain misfit of the graphite nodules and the surrounding matrix?ausferrite?.However,the graphite can result in notch effect and their morphology significantly influences the value of stress concentration.The graphite nodules with low nodularity can vastly increase the stress concentration,and result in cracks initiation,coalescence and propagation in ahead of time.