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运用拉伸、冲击、SEM、TEM和EDS等测试方法,对添加稀土镧和未添加稀土镧的Nb-Ti-Mo系管线钢进行研究,分析稀土元素和卷取温度对组织和性能的影响。结果表明:稀土元素镧能有效的改善夹杂物的形貌,在铸坯中形成由Al、Mn、O、S、La组成的复合夹杂物,并最终提高管线钢的低温冲击韧性;两种管线钢的强度均随着卷取温度的降低而升高,且添加稀土镧的Nb-Ti-Mo系管线钢的强度上升趋势更为显著;并且镧能够提高管线钢低温卷取时获得板条贝氏体的能力,精细结构中观察到有200～900 nm的亚板条结构,M/A组元中马氏体为孪晶结构。
The effects of rare earth elements and coiling temperature on the microstructure and properties of the Nb-Ti-Mo based pipeline steel with addition of lanthanum and without addition of lanthanum were investigated by means of tensile test, impact test, SEM, TEM and EDS. The results show that lanthanum can effectively improve the morphology of inclusions and form composite inclusions composed of Al, Mn, O, S, La in the slab and finally improve the low temperature impact toughness of the pipeline steel. Two kinds of pipeline The strength of steel increases with the decrease of coiling temperature, and the strength of Nb-Ti-Mo based pipeline steel with rare earth lanthanum increases more obviously. And lanthanum can increase the strength of strip steel The ability of the martensite, sub-lamellar structure of 200 ~ 900 nm observed in the fine structure, martensite twin structure in the M / A component.