Fabrication Of The Cemented Carbide And Steel Bimetal Composites And Investigation On The Structure And Performance

Base on the conventional preparation technology of steel matrix bimetal composites,this article proposes two new methods to prepare the steel matrix wear resistance composites reinforced by cemented carbide.The first method is called electromagnetic induction melting-infiltration method.According to the particularity of electromagnetic induction heat, this method made the steel melting in the cast form and infiltrating the space of cemented carbide bars on the bottom of the cast form.By this way,the metallurgical compound between the cemented carbide and steel was successfully gained.By adjusting the spacing interval of the cemented carbide bars,the test studied this preparation technology.The second method is called overlay weld composite technology.Taking advance of the particularity of overlay weld technology,this method welded homogeneous alignment cemented carbide bars layer upon layer into low-carbon steel and obtained metallurgy compound connection between the cemented carbide and steel.The microscope,interface structure and phase composition were analyzed by optics microscope binocular,SEM, FE-SEM,EDX and XRD methods.Then the interface bonding mechanism was investigated. The hardness measure was performed on the composites prepared by different method and technology.At last,the three-body abrasive wear test was performed on a group of choose composites and normalized 45 steel.After the abrasive wear test,the wear surface and wear mechanism of every sample was analyzed.The results show that the cemented carbide and steel bimetal composites could be prepared successfully by both of the methods proposed in this article.To the electromagnetic induction melting-infiltration method,when the spacing interval of the cemented carbide bars was decreased,the time of melting-infiltration need prolong.As the melting-infiltration time prolongs,the heat-affected zone on the surface layer of cemented carbide bars enlarge.To the overlay welding compounding technology,there is an obvious weld pad between the cemented carbide and the steel matrix.XRD results show that there is a new phase(Co3W3C) formed in both of methods.The hardness measure results indicate that there is a hardness transition zone between the cemented carbide and the steel matrix,and that the center zone of cemented carbide bars still remains its initial hardness.Under the working condition of quartz sand grinding abrasion,when the load is 3.65kg, the maximal wear-resisting property of the induction melting-infiltration composites is 3.33 times of the 45 steel(it is 2.7 times for the overlay welding composites).As the load increase, the relative wear resistance of all composites rose.Under the load of 5.25kg,the maximal wear-resisting property of the induction melting-infiltration composites reaches 4.88 times of the 45 steel(it is 3.7 times for the overlay welding composites).The worn pattern analysis shows that the main wear mechanism on the steel matrix are micro-cutting and micro-ploughing,while the main wear mechanism on the cemented carbide zones is fatigue wear.