Study On The Preparation And Properties Of Heterogeneous TiC-high Manganese Steel Bonded Carbides

TiC-high manganese steel bonded carbides as a kind of excellent wear-resistant materials,are widely used in the mining,cement and other industries.However,the high manganese steel bonded carbides which is being used has its drawback,such as scant toughness,low intensity,as a result,which make it more and more difficult to meet the requirements of complex conditions.Based on this kind of present situation,in this paper,the particle size of TiC was taked as a starting point,the alloy with heterogeneous structure was prepared by the combination of coarse and fine TiC particles to improve the comprehensive mechanical properties of the alloy.Based on the existing research,the influence of the different matching ratio of coarse and fine TiC grain on the microstructure and properties of TiC-high manganese steel bonded carbides TM60 was studied in depth,and compared with the coarse grain and fine grain alloys.The results show that:1)The heterogeneous structure distribution that the fine grain was filled into the coarse particles can effectively reduce the stacking porosity of the alloy,reduce the number of pores in the alloy.Coarse grained alloy is easy to form large-sized pores,while fine-grained alloy is easy to form more small-sized pores,and the effect of large-sized pores on the densification of the alloy is greater than the large number of small-sized pores on the damping of the fine-grained alloy.The nonuniform distribution of the coarse and fine grain TiC particles has improved the uniformity of the hard phase,the comprehensive properties of the alloy are best when the thickness ratio is 5:5,the rockwell hardness is 59HRC,which is higher than coarse grain and fine grain;The flexural strength is 1624MPa,which is about 15%higher than coarse grain alloy,which is about 8%higher than fine grain alloy;The impact toughness is about 35%higher than fine grain alloy,reaching 2.86J/cm2.Selecting the thickness ratio of 5:5,comprehensive performance is best.2)heterogeneous structure TiC-high manganese steel bonded carbides' fracture have no obvious yield phenomenon,it is a kind of brittle fracture;From micro-analysis,TiC phase have a typical brittle cleavage fracture characteristics,large size particles with cleavage fracture,there is clear river shape pattern;small size particles with the intergranular fracture,the matrix fracture surface showed tearing edge.Pore,inclusions,the hard phase zone and the interface combination are prone to cause crack.3)After 1050? water toughening treatment,the supersaturation of matrix increased,there are a phenomenon which is dwarfing and widening of the austenite diffraction,water toughening promotes the element diffusion at interface where between hard phase TiC and matrix,improved the interface bonding strength and performance.The wear resistance of heterogeneous structure TM60 was carried out by MLD-10 abrasive wear testing machine,and compared with coarse and fine grained alloy in the same cpmposition,then sub-surface wear morphology were analyzed after high impact energy.The results show that:1)Compared with the different alloy and different impact energy,it can be seen that the heterogeneous structural alloy showed excellent wear resistance.Under low impact energy,the heterogeneous structural alloy's wear resistance improved by 19%compared with coarse grained alloy,so was the wear resistance improved by 13.41%compared with fine grained alloy;Under high impact energy,the heterogeneous structural alloy's wear resistance improved by 55%compared with coarse grained alloy,so was the wear resistance improved by 93%compared with fine grained alloy.The heterogeneous structural alloy's wear resistance had more obvious advantages under the high impact energy than low impact energy.During the impact wear process,the matrix of the high manganese steel will undergo work hardening,under the high impact energy,the time to achieve the best hardening effect is shorter than under the low impact energy.2)Contrasting the wear morphology of the heterogeneous structure TM60 and coarse grain,fine grain TM60 can be seen,the wear surface of the heterogeneous structural alloy is more smooth,furrow scratches is less and shallower,it is mainly due to higher bulk density,which can indirectly promote the body evenly distributed,enhance the strength and wear resistance of the alloy.The wear mechanism of the heterogeneous structure TM60 is mainly manifested as micro-cutting wear,fatigue peeling wear and crushing wear.In the low impact energy state,the micro-cutting wear is dominant;In the high impact energy state,fatigue Peeling wear and grinding wear is dominant,it has a certain degree of micro-cutting wear.3)the analysis of the heterogeneous structural alloy's sub-surface crack propagation found that,the nonuniform distribution of the coarse and fine grain TiC particles will cause that:when the migration of the crack meet the coarse grains,it is easy to turn back and turn that can increase the crack stroke and the energy required for crack propagation,thereby enhancing the toughness,strength,wear resistance of the heterogeneous structural alloy.