Study On The Structure Characteristics And Wear Performance Of The High Chromium Hardfacing Composite Wear-Resistant Steel Plate In Mine

Hardfacing technology has developed to the additive manufacturing technology from the application of initial surface repairing field.While the original metal failure components can be completely repaired,the additive manufacturing gives the hardfacing alloy with some special functions,such as the wear resistance,corrosion resistance,heat resistance and oxidation resistance.In the situation that the design and manufacture of traditional wear-resistant steel has not made a breakthrough,the additive manufacturing of hardfacing plate provides an effective way to improve the service life of wear-resistant components.In order to adapt to the complex working conditions of coal mine machinery and equipment,the iron-based hardfacing alloy plate with excellent wear-resistance and economy has been developed and applied to the design and manufacture of the components bearing abrasive or impact wear in coal mine machinery and equipment.In this paper,the microstructure characteristics of CM550 high chromium hardfacing wear-resistant plate were studied.The morphology,size and distribution of M₇C₃ carbide strengthening phase were analyzed.Based on the wear movement forms of the middle trough for scraper conveyor in coal mine et al,the sliding,erosion and free abrasive wear properties of CM550 high chromium hardfacing wear-resistant plate were studied,and the wear failure mechanisms were discussed.The width of hardfacing fusion region for CM550 high chromium hardfacing plate is about 250-350?m.The amount of ferrite in the matrix side of fusion zone decreases and the grain size of ferrite grain decreases.Meanwhile,the proportion and grain size of pearlite increase.There is about 10?m chromium rich ferrite band on the hardfacing side of fusion zone.The microstructure of hardfacing layer consists of primary carbide,eutectic and ledeburite structure.The main phases are(Cr Fe)₇C₃carbide and?-Fe ferrite,followed by a small amount of?-Fe and?-martensite.(Cr Fe)₇C₃ carbides are the hexagonal M₇C₃ type carbides.The primary(Cr Fe)₃C₇carbides are coarse in size and mainly in hexagonal rod shape.The eutectic(Cr Fe)₇C₃ carbides are mostly in flake or fine rod shape,and eutectoid carbides are in fine granular shape.There are a few austenite and martensite transformation zones in the hardfacing layer.The dislocation entanglements and stacking faults are found in austenite zone and the parallel twinning stripes are found in the martensite.The relative wear resistance of high chromium hardfacing wear-resistant plate under dry sliding friction quartz sand wear is about 8.0 and 3.0 times higher than that of Q235 matrix steel,and 1-2 times higher than that of HD450 wear-resistant steel.The average friction coefficient and wear rate of steel ring of CM550 and HD450 wear-resistant plate are at the same level under light or heavy applied loads.High hardness(Cr Fe)₇C₃ carbides played an excellent design role in resisting sliding wear damage,which makes the high chromium hardfacing plate show excellent sliding wear-resistance.The wear mechanism of dry friction is mainly ploughing wear,accompanied by the fatigue peeling wear in local ferrite matrix region.The wear mechanism of quartz sand abrasive is the ploughing wear of hard abrasive and flaking wear of matrix.High chromium hardfacing plate and HD450 wear-resistant steel show the better erosion wear-resistance under the condition of acid,neutral and alkaline slurry erosion wear.The relative wear resistance is about 2.4 and 2.1 times higher than that of Q235matrix steel,respectively.The erosion wear of these three slurries belongs to the friction-corrosion system dominated by the friction.The mechanical wear is the main damage form,which changes regularly with the change of erosion angles.The wear mechanism at low erosion angles is mainly characterized by the micro-cutting wear caused by the harder particles,accompanied by a small amount of fatigue spalling wear.With the increase of erosion angles,the proportion of micro-cutting wear gradually decreases,and the proportion of impact chiseling and fatigue peeling caused by the slurry harder particles increases evidently.The main wear damage at 90°erosion angle is dominated by the chiseling and fatigue peeling wear.The relative wear resistance of high chromium hardfacing wear-resistant plate is about 5.9 times than that of Q235 steel and 1.8 times than that of HD450 wear-resistant steel,showing the better abrasive wear-resistance.The wear mechanism of high chromium hardfacing wear-resistant plate is mainly controlled by the impact gouging wear and fatigue spalling wear.The paper has 52 pictures,7 tables,and 83 references.