| Four steel samples with different copper addition were prepared with vacuum induction furnace in this paper, and the samples were reheated to 250℃, 550℃, 850℃, 1150℃for 2 hours respectively . The microstructures were observed with microscope and scanning electronic microscope(SEM) and the micro-hardness was tested. The results show that, under the same heat treatment condition, the grain sizes become smaller with the increasing of the content of Cu in the test steel samples, and there are more second phases which are confirmed to be copper rich phase tested by energy spectrum in SEM. For the same sample, the grain sizes do not change obviously after heat treated at the temperature of 250℃and 550℃, but when the temperature increases to 850℃, the grains grow up, while, when the temperature increases to 1150℃, the grain size becomes smaller. The micro-hardness is greater for the higher copper content in the steel samples. For each sample, the micro-hardness shows minimum value after heat treated at 850℃, and the maximum value appear after heat treated at 1150℃. The corrosion-resistance property of all the copper bearing steels is better than that of copper free steel when the test time is long enough, the corrosion speed decrease with the copper content increased in the test steels. With the technology of laser cladding, the copper coating is fabricated on the surface of ferrite steel. The microstructure, the component analysis and the micro-hardness of the coating layer, the bounding surface and the ferrite substrate have been studied respectively. The ferrite grains sizes are rather fine near the interface and the grains are coarsened sharply away from the interface. The micro-hardness increased obviously by cladding copper on the surface of ferrite with laser. The maximal micro-hardness values are at the coating surface, the less micro-hardness values are near the interface,which is also about 3 times that of the ferrite substrate. The interfaces are metallurgical bonds. |
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