非调质钢38MnS6L表面缺陷分析及工艺改进

Surface Defect Analysis and Process Improvement of Non-quenched and Tempered Steel 38MnS6L

本文采用金相显微镜、扫描电镜、能谱分析仪(EDS)和电子探针对非调钢38MnS6L表面缺陷进行了分析和研究。结果表明:由于加热温度过高,在加热炉加热过程中,钢坯表面氧化铁皮和钢基体界面上发生Si元素的富集,经高温氧化后,形成Si、Fe的复合氧化物,嵌入到钢基体中,黏附力强,导致除鳞不干净。在后续的轧制过程中,未除干净的氧化铁皮随金属流动压入基体内,导致成品圆钢表面存在连续裂纹缺陷。通过将加热炉出钢温度由1150～1200℃调整为1100～1150℃,出钢节奏由6 min/支调整为4.5 min/支,圆钢表面除鳞效果得到明显改善,圆钢表面漏磁探伤合格率由44%提升到97%以上,钢材表面质量得到大幅改善。

In this paper,the non-quenched and tempered steel 38 MnS6 L with the surface cracks was analyzed and studied by means of metallographic microscope,scanning electron microscopy(SEM),EDS and EPMA.The results show that because the heating temperature of the steel is too high,the oxide scale on the surface of steel billet and Si elements enriched on the interface of steel matrix formed the composite oxides of Si and Fe after oxidation at high temperature to embed into the steel matrix with strong adhesive force,resulting in descaling not clean.In the subsequent rolling process,the uncleaned oxide sclae was pressed into the matrix with flowing metal to cause the continuous crack defects on the surface of round steel.Through ajusting the tapping temperature from 1150~1200℃to 1100~1150℃and the tapping rhythm from 6 min/branch to 4.5 min/branch,the descaling effect on round steel surface was obviously improved.The qualified rate of magnetic flux leakage inspection on the surface of round steel was increased from 44%to over 97%,and the surface quality of steel was greatly improved.