高强度汽车大梁钢700L的夹杂物控制研究

Study on Inclusions Control of High Strength Steel 700L for Automobile Beam

在高强度700L开发过程中,针对钛元素易氧化及与氮元素结合能力强的特点,在转炉冶炼、LF精炼处理以及连铸三个环节严格控制氮含量,钢水经LF还原后精炼末期加入钛铁,有效防止了钛的氧化物夹杂的生成,钢中的TO≤0.0028%,[N]≤0.0060%。钢中的非金属夹杂控制,D类细1.5级以下。对钢中存在的呈规则形状的淡黄色夹杂采用扫描电镜分析,显示为TiN和Ti、Nb(C、N)的复合夹杂,通过工艺优化,含量大幅度减少,生产的钢材各项性能满足标准和用户要求。

In that development process of the high-strength 700L,in view of the characteristics that the titanium element is easy to oxidize and has strong combine ability with the nitrogen element,the nitrogen content is strictly controlled in three links of converter smelt,LF refining treatment and continuous casting,and ferrotitanium is added at the end of refining after the molten steel is reduced by LF,so that the generation of titanium oxide inclusions is effectively prevented,TOin steel is less than or equal to 0.0028%,[N]is less than or equal to 0.0060%.The non-metallic inclusions in the steel are controlled to be below 1.5 grade of D-type fine.The light yellow inclusions with regular shape in steel were analyzed by scanning electron microscope.The results showed that the inclusions were complex inclusions of TiN,Ti and Nb(C,N).Through process optimization,the content of inclusions was greatly reduced,and the properties of the produced steel met the standards and user requirements.