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1. The influence of carbides on the properties of high manganese steel
Reduce impact toughness and tensile strength
2. Effect of non-metallic inclusions on the properties of high manganese steel
When molten steel solidifies, a large amount of manganese oxide precipitates on the perimeter of the steel in the form of non-metallic inclusions, which reduces the impact toughness of the steel and increases the tendency of hot cracks in the casting.
3. The choice of chemical composition and its influence on the properties of high manganese steel
(1) Carbon content and manganese content When the carbon content in steel is too low, it is not enough to produce effective work hardening effect; and when the carbon content is too high, a large number of carbides will appear in the cast state, especially Coarse carbides appear, so in order to avoid the precipitation of carbides, the carbon content must be controlled not to be too high.
In order to ensure the performance of high manganese steel, there must be sufficient manganese content. When the manganese content is too low, a single austenite structure cannot be formed; and too high manganese content is unnecessary. It is generally stipulated in production that WMn is controlled at 11.0% to 14.0%, and WC is controlled at 0.9% to 1.3%. It should be pointed out that there should be an appropriate match between the manganese content and the carbon content, that is, there should be an appropriate ratio of manganese to carbon, which is generally controlled at Mn/C=10.
(2) The standard content of Wsi in high-manganese steel with silicon content is 0.3% to 0.8%. Silicon will reduce the solubility of carbon in austenite, promote the precipitation of carbides, and reduce the wear resistance and impact toughness of steel. Therefore, the amount of silicon should be controlled at the lower limit of the specification.
(3) Phosphorus content The standard content of high manganese steel is Wp≤0.7%. When smelting high manganese steel, due to the high phosphorus content of ferromanganese, the phosphorus content in steel is generally high. Because phosphorus reduces the impact toughness of steel and makes castings prone to cracking, the phosphorus content in steel should be kept as low as possible.
(4) The specifications of high manganese steel with sulfur content require Ws≤0.05%. Because of the high manganese content of high manganese steel, most of the sulfur and manganese in the steel combine with each other during the smelting process to form manganese sulfide (MnS) and enter In slag, and thus in steel, the sulfur content is often low (generally no more than 0.03%). Therefore, the harmful effect of sulfur in high manganese steel is higher than that of phosphorus.