| High chromium cast iron of Fe-Cr-C has been proven to be an important kind of wear-resistant overlaying welding materials. As the main hard and wear-resistant phase, high hardness of primary carbide M7C3is observed in surfacing welding alloy microstructure.And the high wear resistance of the material is attributed to the combination of primary carbide M7C3and a good performance of hypereutectic matrix. However the abrasion mechanism still needs further research.There are four kinds of Fe-Cr-C high chromium cast iron flux-cored wire with different components in this article. Two of these are homemade, and the other two are saled in the market. Ingot samples with wear-resistant overlaying welding deposited metal layer were prepared using arc welding. The microstructures, hardness and wear resistance of samples were examined by Optical microscope (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), hardness tester and wear tester. The test results are compared, and the effects of chemical compositions, microstructure mechanism, hardness on the material abrasion resistance are discussed. Then the wear mechanism was analyzed. In addition, the appropriate welding parameters and process is chosed and so as the best welding flux cored wire to abtain the best wear resistance of deposited metal. Such a result could have a positive effect on the development of the flux cored wire. After the experiments, we draw several conclusion listed in follows.After compare the two kinds of homemade flux-cored wire, it is found that the wear resistance of the surfacing alloy added TiB2increases than not but the degree is limited. However the abrasion resistance of the flux-cored wire imported respectively from UK and Germany is high, the former is the highest.The single element C or Cr content in the alloy layer and the wear resistance change no significant linear relationship, the wear resistance of the hardfacing layer is increased with the increase of Cr/C ratio. The addition of TiB2,make wear resistance of surfacing alloy higher than that of without TiB2,but the improvement of the wear resistance is not so obvious;The high chromium cast iron welding alloy deposited metal layer composition mainly consists of alpha-Fe, Fe3C, M7C3. The matrix structure is martensite (M) and a small amount of residual austenite. This is a clear indication that a large number of primary carbide and eutectic carbide distributes on the matrix. To improve the wear resistance of the material, TiC-TiB2composite compound is formed by adding TiB2, which disperses on the primary carbides, the matrix and the grain boundaries. This also increases the crystalline nucleation dot, inhibit the growth of the grain size, so that the final size of the carbides becomes smaller, which increase the number and the carbides content of M7C3. As a result, the hardness and wear resistance of surfacing layer are improved.Wear resistance of the hardfacing layer is increased with increasing the ratio of carbide microhardness and matrix microhardness. The Rockwell hardness of the surfacing on the hardfacing alloy was high, which does not represent the wear resistance of the alloy layer was high also. The wear resistance of the sample D-1-D-4was sequentially increase, but the Rockwell hardness of D-4is not the highest, which was lower11.13than the Rockwell hardness of D-2. |
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