34Mn5钢管外折叠缺陷的原因分析

针对34Mn5管坯轧制成钢管后表面上出现的外折叠缺陷,用理化检测手段对钢管化学成分、缺陷形态、金相组织进行分析,对铸坯进行热酸浸蚀试验。分析结果表明圆管坯表面渣沟缺陷在热轧过程中各种复杂应力的作用下扩展,最终形成了34Mn5钢管表面外折叠缺陷。通过对结晶器保护渣理化指标进行调整,基本消除了铸坯表面渣沟缺陷,降低了钢管外折叠缺陷率。

Analysis on Cause of 34Mn5 Pipe Outer Fold Defect

In order to address the outer fold defect presenting on the surface of finish pipe rolled by34Mn5 billet,physical and chemical inspection were conducted to analyze the chemical composition,defect morphology and metallographic structure of steel pipe and hot acid etching test was conducted on billet.Analysis results indicated slag channel on round billet surface extended under the act of complex forces during hot rolling process and eventually formed outer fold defect on the surface of 34Mn5 steel pipe.Adjustment on the physical and chemical indices of mould powder was carried out to basically eliminate slag channel defect on billet surface and reduce outer fold defect rate.