厚规格高强耐候H型钢缺陷分析

Analysis on Defects of High Strength Weathering Resistant H-shaped Steel with Heavy Gauge

针对Q420NHB耐候H型钢在腹板和翼缘表面产生微裂纹,影响产品质量。通过金相显微镜和扫描电镜观察,分析了裂纹产生的原因。结果表明,翼缘表面缺陷是由于铸坯内弧皮下裂纹及间裂造成的,而腹板表面缺陷是由于在轧制过程中铸坯表面的氧化铁皮压入导致。通过对连铸过程中结晶器冷却工艺以及轧制工艺的优化,有效改善了耐候H型钢表面质量。

The causes of cracks are analyzed through the observation with metalloscope and scanning electron microscopy aiming at the problem that product quality is affected by the microcracks on surfaces of web and flange of Q420NHB weathering resistant H-shaped steel.The results showed that the surface defects of flange were caused by the subcracks and intercrystalline cracks on inner arc of ingot blank,while the surface defects of web were caused by the pressfit of scale on surface of ingot blank during rolling process.The surface quality of weathering resistant H-shaped steel is effectively improved through optimizing the cooling process of crystallizer and rolling technology during continuous casting process.