Process Analysis of Deep Desulfurization and Controlling Nitrogen and Inclusions of X70 Pipeline Steel

The relationship between deep desulfurization, controlling nitrogen and controlling inclusions of X70 pipeline steel were analyzed. It was pointed out that the needed qualifications and the controlling methods of strengthen desulfurization influence controlling nitrogen and inclusions, the better slag composition and slag volume control in CaO-SiO2-Al2O3 slag system which was as the desulfurization slag system and the flow rate of bottom blowing in the process refining influence desulfurization, controlling nitrogen and inclusions. And it focused on the flow of the bottom blowing and the desulfurization time at the enhanced desulfurization. From the perspective of clean steel, it was pointed that the source of the inclusions and the controlling methods and the calcium handling purposes, requirements and the effects of the low-sulfur pipeline steel. In addition, it was pointed the necessity of using the technology of hot iron pretreatment and double refining while smelting low-sulfur pipeline steel.