稀土含量变化对低合金高强度钢性能影响

Effects of Change of Rare Earth Content on Properties of Low Alloy High Strength Steel

钢中加入稀土能够起到净化钢液、夹杂物变性和微合金化作用,能减小夹杂物对钢质的有害影响,从而提高钢材的塑性、韧性、耐低温冲击性。为了研究钢中不同稀土含量对钢材性能影响,利用25 kg真空中频感应炉,使用真空加入方法,进行不同稀土加入量及未加入稀土的锰系低合金高强度钢冶炼,并模拟现场生产工艺进行轧制。通过对轧材化学成分、力学性能、断口、金相组织分析,结果表明,钢中加入稀土时,稀土元素可细化钢材组织晶粒度;随着钢中稀土含量增加,细化的组织晶粒度增加了晶界之间抵抗裂纹形成与扩展的能力,从而提高了钢的塑性和冲击韧性,提高钢材力学性能。

The liquid steel could be purified, inclusions could be modified and steel could be microalloyed by adding rare earth into steel, which could reduce the harmful effects of inclusions on steel so that the plasticity, toughness and resistance to low temperature impact of steel could be improved. In order to study the effects of different rare earth contents on properties of steel, the smelting of low alloy high strength steel with manganese and different quantities of rare earth added and without rare earth are carried out using the 25 kg vacuum medium frequency induction furnace as well as the rolling with production process on site is simulated. Moreover, the chemical composition, mechanical properties, fracture and metallographic structure of rolled products are analyzed. The results showed that the grain size of microstructure for steel could be refined by adding rare earth into steel;with the increase of rare earth content in steel, refined grain size of microstructure makes the resistance to crack formation and propagation between grain boundaries increased so that the plasticity, impact toughness and mechanical properties of steel are improved.