Abstract
Induction cladding technology is a new surface treatment technology developed in recent years, and it has a very broad application prospects in industrial technology and other fields.On account of wide raw material sources, low price, good performance, at room temperature and below 400℃ it has good abrasion resistance and weak corrosive Fe-based alloy powder is widely used, while the Fe-based high chromium cast iron alloy is a kind of good wear-resistant material, it has more than the general white cast iron with high toughness and strength, but also it has good resistance to high temperature and corrosion, and because of its convenient production, low cost, it is regarded as the one of the most excellent resistance to abrasive wear of materials. Cladding coating wear-resistant materials in low carbon steel surface, not only could retain the good plasticity and toughness of low carbon steel, but also greatly improve the surface hardness and wear-resistance of the material, prolong the service life of the workpiece . In this paper, high chromium cast iron cladding coating was prepared through high-frequency induction cladding technology in low carbon Q235 surface, and then made a preliminary analysis in Microstructure and mechanical properties of the cladding coating.
In this paper, the binder which about induction cladding was selected at first ,the optional adhesive were sodium metasilicate, polyvinyl alcohol, phenolic resin, experimental results showed that sodium metasilicate was the best as binder, after drying, the surface of alloy powder was smooth, and the substrate sample without stripping. Then the induction cladding process parameters and the cladding after the end of the cooling process were optimized selected, when concussion current was 50A, 60A, 70A, 80A, 90A, 100A ,cladding coating prepared by macroscopic observation and microstructure observation, and concluded that the current for 90 A shock when cladding effect was most ideal; through the cladding after the end of cladding coating water cooling and air cooling treatment contrast, obtained that the effect of water cooling is better than air cooling. Then the coating of four groups of different Cr content in the alloy powder were prepared, and the microstructure, phase and mechanical properties of the cladding coating before and after heat treatment were analysed, the cladding on Microstructure and mechanical properties were compared, obtained the content of Cr was 20% when the quality of cladding coating was preferable, and microhardness and macro hardness was the highest, the hardness of cladding coating about content of 20% and 15% for Cr increased slightly, the hardness of cladding coating about content of 25% and 30% for Cr decreased .The cladding coating on the content of 20% for Cr was measured with XRD, a large number of blocks, strips of eutectic distributed in the cladding coating on the surface of radial organization. Organizations are mainly in the martensite C0.14Fe1.86 and γ-( Fe, Cr,Ni, C ) alloy solid solution phase as well as the hard phase (Fe, Cr )7C3 and Fe5Si3 intermetallic compounds.
At last , layers(three) of high chromium cast iron cladding coating was prepared, the thickness of first layer was about 1mm, the second is about 2.5mm,the third was about 3.5mm,the microstructure and properties of cladding coating were uniformly dense ,there were not impurities and defects such as shrinkage hole, the cladding coating and the Q235 matrix were metallurgcally combined. As the detection of XRD, the numbers of carbide Cr7C3 and martensite phase C0.14Fe1.86 on the surface of cladding coating about the thirst layer were higher than the single cladding coating. From the hardness distribution curve it informed that ,within a certain range, with the cladding coating thickness increased, the surface hardness of cladding coating increased, the surface hardness could reached 62.28 HRC in the third layer of cladding coating.
Key words: high frequency induction cladding; high chromium cast iron; Q235 steel;hardness; multilayer cladding coating
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