The Microstructure And Mechanical Properties Of WC_p/40CrNi₂Mo Composites

Cutter is a wear resistant part which widely used in mining machinery, it is alwaysreceive bigger impacts and abrasions for the direct contact with sand, so, the composites werealways to prepare for it. The purpose of this experiment is improve the wear resistance of thecomposite. The steel with high strength and toughness, beside, the steel substrate has thecharacterisTics of heat treatment, this paper designs a composite reinforced by particles, bycombining the advantages of them could greatly improve the wear resistance of the compositematerial.In this experiment,40CrNi2Mo steel which has high strength and wear resistance wasselected as the matrix of the composites, and the WC particles was select as the strengtheningphase which mean well the good wettability with steel substrate. By stirring casting methodand adding WC particles to the high strength matrix to fabricate the composite. After casting itcould eliminate the internal stress, improve the organization and mechanical properties by heattreatment. In the process of preparation, in order to investigate the influence of different WCmass fraction （2%、5%、10%） on its cast microstructure and hardness; The composites incast condition with10%(wt%) WC particles has been heat treatment, whose process isannealing at900℃for6.5hrs and air cooling plus oil quenching at880℃for2hrs plustempering with different temperature （180℃,220℃,400℃,500℃）, the OM, SEM andFESEM are employed to study the microstructure, the Brinell hardness meter, Wear testingmachine and Electronic universal testing machine are adopt to test mechanical properties.The results showed that, the microstructure of the composites is reticular ferrite+partiteflake+WC+Fe3W3C+W2C, with the increase of WC particles, the microstructure of thecomposite gradually thinner and the hardness increase gradually; The microstructure of thecomposites is different after different tempering temperature; With the increase of thetempering temperature, the hardness reduces, the hardness value of the composite is highestfor446HB after tempering at180℃, after tempering at500℃is lowest for404HB; With thetempering temperature increase, the wear resistance reduce, the wear weight loss of thecomposite is0.7352g after tempering at180℃, after tempering at500℃is1.3820g; The cutteris0.8214g which is bigger than the composite after tempering at180℃; With the increase of the tempering temperature, the tensile strength and yield strength are decrease, the elongationincreases; The high strength of the composite act on the particles as the “support effect” toprevent the shedding, the WC particles act on the matrix as the “shadow effect” to reduce thewear loss, the “support effect” and “shadow effect” work together to improve the wearresistance of the composite.