摘要
圆坯经过穿孔、轧管加工的无缝钢管内表面存在缺陷,在手掌大小的区域内看到四处形貌不同的缺陷.利用金相显微镜、扫描电子显微镜和能谱分析仪对缺陷部位的表面样品和横、纵截面样品进行观察.在四个缺陷处均观察到高温氧化铁和高温氧化源,可以确定钢管内表面缺陷是在连铸的过程中产生的.通过对表面形貌的观察分析和纵截面缺陷深度的测量,确定形成缺陷的原因为连铸坯中心裂纹、中心缩孔和缩松,是经轧制变形所引起的.四个缺陷处都存在Na、Mg、Al、Si、P、K、Ca等元素,为穿孔过程中使用磷酸钠润滑剂的残留物.
Abstract
There are defects in the inner surface of the seamless steel pipe processed by the round billet through piercing and rolling.Four defects with different appearances can be seen in the palm-sized area.The surface samples and transverse and longitudinal cross-section samples of the defect site were observed by using a metallurgical microscope,a scanning electron microscope and an energy spectrum analyzer.High-temperature iron oxide and high-temperature oxidation origin were observed at the four defects.It can be determined that the internal surface defects of the steel pipe are generated during continuous casting.Through the observation and analysis of the surface morphology and the measurement of the depth of the longitudinal section defects,the causes of defect formation are the central crack,central shrinkage hole and shrinkage porosity,which are caused by rolling deformation.There are Na,Mg,Al,Si,P,K,Ca and other elements in the four defects,which are the residues of the sodium phosphate lubricant used in the perforation process.
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