Investigation On WC Particles Reinforced High Manganese Steel Matrix Surface Composites

The high manganese steel casting can not be hardened fully and good wear resistance in the slow-stress conditions, in order to improve its resistance, a method was made in this thesis. At first the alloy castings were compounded, they contained WC particles, high-carbon ferrochromium powder, borax and appropriate binder. Then the alloy castings were pressed into powder blocks and porous alloy powder blocks. These powder blocks were then attached to EPS appearances after drying, and the EPS appearances were coated with plug-fire and anti-sticking coating of sand. Finally the WC particulate reinforced high manganese steel surface composite was obtained by V-EPC. This thesis studied the effects on the surface of composites of the addition of WC casting, WC particles size, high-carbon ferrochrome powder particle size changes, relative thickness of the composite layer and pre-way. The microstructures were observed and analyzed by using optical microscope, X—ray diffraction and SEM. Microhardness of the composite layer were measured using miscro-hardness tester. Finally, the mechanism of the surface composite was discussed.The results show that: The typical microstructures of the composite are consisted of composite layer and the matrix (austenite). The compound layer mainly is composed of alloy- austenite, WC, branches rod-shaped carbide and other alloy carbides. WC particles are more evenly distributed in the composite layer. It forms a good metallurgical bonding between the matrix and composite layers. In the composite layer of a typical composite material that was prepared, the hardness of WC is about 2005HV, the hardness of branch rod-shaped carbide is about 1750HV, but the hardness of herringbone carbide is about 1450HV. The interface bonding quality of the composite is well using precast porous alloy powder block than pressing block.With the increasing in the volume fraction of WC particles, the interface bonding quality declines between composite layer and the matrix. The addition of WC particles is less, WC particles dissolve more serious. The addition of WC particles should control in 55vol. % or so better reasonably. Choosing these two different WC particles between 0.613mm to 0.90mm and 0.15μm to 0.282μm, the WC particles dissolve serious. With increase of the size of WC particles, the size of carbide particles in composite layer is bigger. Relative thickness of the composite layer is bigger, their coalescent is better between the alloy layer and the matrix, the quality of composite layer is better.