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研究了扩散退火对碳钢热浸镀铝镀层微观组织的影响,特别是在1000℃扩散退火后镀铝钢的磨损性能,并探讨了磨损机理。结果表明,在低于900℃的温度下扩散退火后的镀层均含脆性相Fe2Al5,在1000℃退火后的镀层其物相全部转化为韧性相FeAl和Fe3Al,且与基体具有良好的冶金结合。随着温度从室温升高到200和400℃,磨损率显著下降,达到一个极低的水平。在室温下镀铝钢的磨损率随着载荷的增加快速升高;在200℃磨损率几乎不随载荷变化,平均磨损率为4.2×10-6mg/mm;在400℃、载荷50-200 N条件下磨损率略低于200℃对应载荷下的磨损率,但在250N时磨损率快速升高。这表明,镀铝钢在200-400℃具有优异的耐磨性。其高耐磨性源于在磨面形成了厚度为1-2μm、含大量Al2O3和Fe2O3及少量W、Mo的氧化物的摩擦氧化层,主要磨损机制为氧化轻微磨损。但是当载荷达250 N时摩擦层因不稳定而剥落,导致镀层剥落,使基体发生塑性挤出。
The effect of diffusion annealing on the microstructure of hot-dip aluminized coatings on carbon steel was studied, especially the wear behavior of the aluminized steel after diffusion annealing at 1000 ℃. The wear mechanism was also discussed. The results show that the brittle phase Fe2Al5 is formed at all temperatures below 900 ℃. All the phases annealed at 1000 ℃ are transformed into ductile phase FeAl and Fe3Al and have good metallurgical bonding with the matrix. As the temperature increases from room temperature to 200 and 400 ° C, the wear rate drops significantly to an extremely low level. At room temperature, the wear rate of aluminized steel increases rapidly with the increase of load. The wear rate hardly changes with the load at 200 ℃, the average wear rate is 4.2 × 10-6mg / mm. At 400 ℃, the load of 50-200N Under the wear rate slightly lower than the 200 ℃ under the corresponding load wear rate, but at 250N wear rate increased rapidly. This shows that the aluminized steel has excellent wear resistance at 200-400 ° C. Its high wear resistance originates from the formation of a friction oxide layer with a thickness of 1-2 μm, a large amount of Al2O3 and Fe2O3 and a small amount of W, Mo oxides on the grinding surface, with the main wear mechanism being slight oxidation wear. However, when the load reaches 250 N, the friction layer peels off due to the instability, causing the coating to peel off, resulting in the plastic extrusion of the substrate.