Effects Of Nanometer Metal Additives On The Microstructure And Properties Of Gray Cast Iron

Gray cast iron has been widely used in machinery industry and related manufacturers for its comprehensive characteristics such as great casting properties, competitive price, high hardness, excellent corrosion resistance and wear resistance. Adding alloy elements during the casting process improves gray cast’s properties effectively which make a better application in manufacturing engine block, cylinder head and any other certain field needs special requirements. However, with the increasing demand of society and production, the gray cast we use has been unable to meet the need. Therefore, that how to enhance the properties and make it meet the needs of practical applications in the future has become an important topic to study and explore. Nanometer metal additive is a strong covalent bond compound material that has the advantages of high temperature resistance, wear resistance, corrosion resistance, high hardness, high elastic modulus and low energy consumption. Moreover, nanometer metal additive has a wide development prospects and is focused as a new kind of high-tech material.This paper studies the effect of different species of nanometer metal additive for the impact of microstructure, mechanical property, wear resistance and heat resistance in GB HT250 and alloy HT250 under different experimental conditions. Then make a preliminary discussion on the strengthening and toughening theory of gray cast whose add nanometer metal additive by recording, observing and comparing.The research results show that, nanometer metal additive can improve the comprehensive performance of HT250.For the sample of GB HT250 which adds 7 kinds of nanometer metal additive, its microstructure and properties are improved. For the microstructure, the type of graphite is A distributing uniformly, the size of which is small and the end is blunt flake. The percentage of pearlite increases and structure is dense, but the interlamellar spacing decreases. When it comes to mechanical properties, the hardness of the sample adding nanometer metal additive improves slightly while the tensile strength enhances 21.4% at most and the wear resistance increases 46.7% at most.For the samples of Cr-Cu HT250, adding 4 kinds of nanometer metal additive into the material, these microstructures and properties performs better than the blank one. The graphite is fine and uniform and the pearlite is compact, and the number of eutectic increases. What’s more, the tensile strength and wear resistance of sample containing nanometer metal additive increases 20.8% and 58.3% at most respectively.The properties of HT250 which contains niobium are more prominent than the GB HT250s’, its comprehensive performance will get further improved after adding nanometer metal additive. The wear resistance of the samples whose powder adds into the foundry ladle and into furnace respectively increases 27.1% and 60.8% at most.Nanometer metal additive has a positive influence on promoting microstructure and properties of GB HT250, however, different kinds of incubation time will cause different effects. According to the experiment’s result, when the incubation time is 6 minutes, the performance of casting sample is the most excellent. Compared with the blank sample, the tensile strength, wear resistance and heat resistance respectively increases 12.5%, 62.5 and 66.7 at most.