Papers by Keyword: Chromizing Process

Abstract: A new configuration of chromizing process was developed by separating Cr powder from NH₄Cl. FC220 gray cast iron specimens were chromized in this new experimental setup at 450, 550, 650,750, 850 and 950°C during 13 hours in order to study the possibility of chromizing at “low” temperature. The chromized specimens were examined using Scanning Electron Microscopy (SEM), macro-hardness, micro-hardness, compression test and salt spray test. The results shows that the specimen chromized at 650°C gives the best compromise between the corrosion resistance and the hardness of the FC220 with 1.73 ڌm of thickness of the chromized layer. However, after 13 hours of the process, the hardness of the FC220 specimens decreased considerably from 93 HRB to 64.2 HRB (31%).

Abstract: Cast iron was chromized by solid powder method at 1000°C. Micro-morphology and microstructure of chromized alloy layer and cast iron matrix were analyzed, their hardness, elements distribution and corrosion resistance were studied in depth. The analysis results revealed that the chromized carbide-chromium layer grew well on cast iron surface, which was smooth and free from macroscopic defect. Campared with the hardness of original cast iron matrix, the hardness of the chromized alloy layer has been improved by 3.5 times, which was as high as 918.8 HV. And the corrosion resistance of the chromized alloy layer has been greatly improved. The relative corrosion rate of the original cast iron matrix was 2.2 times that of the chromized alloy layer according to their polarization curves.