低碳微合金钢中TiN的析出行为分析

Analysis of precipitation behavior of TiN in low carbon micro-alloyed steel

低碳含钛微合金钢作为一种典型的高强度钢,近年来在工业上得到了广泛的应用。细小的TiN析出物可以细化奥氏体晶粒,提高钢的韧性,增强钢的良好成形性和可焊性,并降低工艺的生产成本。但是大量的或者大尺寸的TiN在铸坯中析出则会影响钢的裂纹敏感性。在整个炼钢过程中对样品进行了氧氮分析。结果表明钢包炉(LF)过程中氮含量异常增加。除了空气和钢水之间的反应外,炼钢的原料和辅助材料也可能是导致钢水中氮含量增加的原因,重点研究了铁钛合金的洁净度对TiN析出行为的影响。根据热力学计算结果,当氮质量分数从0.005%降低到0.002%时,TiN的沉淀温度可以降低到1400℃,而TiN的析出量将大为降低。

As a typical high-strength steel,low-carbon titanium-containing micro-alloy steel has been widely used in industry in recent years.The fine TiN precipitates can refine the austenite grains,improve the toughness of the steel,enhance the good formability and weldability of the steel,and reduce the production cost of the process.However,a large amount or large size of TiN in the slab will affect the crack sensitivity of the steel.Oxygen and nitrogen analysis were carried out on the samples throughout the steelmaking process.It is indicated that the nitrogen content increased abnormally during the ladle furnace(LF)process.In addition to the reaction between air and molten steel,the raw materials and auxiliary materials for steelmaking may also cause the nitrogen content in molten steel to increase.The effect of the cleanliness of the iron-titanium alloy on the precipitation behavior of TiN was studied.According to the thermodynamic calculation results,when the nitrogen content is reduced from 0.005%to0.002%,the precipitation temperature of TiN could be reduced to 1400℃,and the precipitation amount of TiN would be greatly reduced.