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SWRCH22A盘条表面结疤原因及改进措施

Scarring causes on SWRCH22A wire rod surface and improvement measures

  • 摘要: 研究SWRCH22A 盘条表面结疤的原因,对提升紧固件用钢质量稳定性、降低下游加工废品率具有重要意义。本文旨在明确 SWRCH22A 盘条表面结疤的成因并制定全流程改进措施,实现结疤缺陷的有效控制。通过采集表面结疤的SWRCH22A盘条试样,观察结疤的分布特征与宏观形貌;对结疤部位进行金相分析,观察夹杂物分布及基体组织;采用扫描电子显微镜(SEM)与能谱分析(EDS)确定结疤区域的夹杂物类型及元素组成,并对钢中夹杂物进行评级。结果表明氧化铝类(B类)夹杂物是导致 SWRCH22A 盘条表面结疤的主要原因,源于钢水脱氧产物上浮不充分而形成的大颗粒富集。通过转炉出钢挡渣控制、优化脱氧制度、研发专用精炼渣系(w(CaO)/w(Al2O3)在1.3~1.8范围内,w(Al2O3)在25%~35%范围内)、控制钢中w(Ca)/w(Al)大于0.1、加强连铸保护浇注及优化保护渣等措施,钢中夹杂物显著减少,盘条结疤率从0.63%降至0,连铸过程无絮流,有效提升了产品质量稳定性。

     

    Abstract: It is of great significance to investigate the scarring causes on SWRCH22A wire rod surface for improving the quality stability of steel for fastening piece and reducing the scrap rate in downstream processing. This paper aimed to clarify the scarring causes on SWRCH22A wire rod surface and formulate overall process improvement measures to effectively control the scarring defects. By collecting SWRCH22A wire rod samples with surface scarring, the distribution characteristics and macroscopic morphology of scarring were observed. The inclusions distribution and the matrix structure in the scarring areas were observed by metallographic analysis. The types and elemental composition of inclusions in the scarring areas were determined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), and the inclusions in the steel were rated. It indicated that aluminum oxide type (Class B) inclusions were the main scarring cause on SWRCH22A wire rods surface, resulting from insufficient flotation of deoxidation products in the molten steel and the formation of large particle accumulations. Through measures such as converter steel pouring slag control, optimization of deoxidation system, development of dedicated refining slag system (with w(CaO)/w(Al2O3) ranging from 1.3 to 1.8 and w(Al2O3) ranging from 25% to 35%), control of w(Ca)/w(Al) more than 0.1 in the steel, strengthening continuous casting protection pouring and optimizing protective slag, the inclusions in the steel were significantly reduced, the wire rod scarring rate decreased from 0.63% to 0, and there was no flocculation during the continuous casting process, effectively improving the product quality stability.

     

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