大规格50BV30盘条麻面缺陷成因分析及控制措施

为符合当前节约、绿色的生产发展，用户在大规格50BV30盘条的加工中采用轻拉拔工艺，因此对盘条的表面质量提出了较高的要求。针对永钢大规格50BV30盘条表面麻面缺陷问题，分析了该缺陷对拉拔加工的影响，统计得到麻面缺陷深度需要控制在30μm以内才能满足客户的使用要求，而当前生产的盘条麻面缺陷平均深度达70μm。为此，从轧辊表面质量及氧化铁皮压入两个方面分析了对麻面缺陷的影响。结果表明：轧槽过钢量是影响轧辊表面质量的主要因素之一，从而影响盘条表面麻面缺陷。随着轧槽过钢量的增加，大规格50BV30盘条表面麻点缺陷越发严重，因此实际生产中，粗、中轧轧槽过钢量不应超过600 t。轧件表面氧化铁皮压入，尤其是次生氧化铁皮压入轧件基体后，盘条表面麻点缺陷数量和深度明显增加，将轧前高压水除鳞压力由10 MPa提升至19 MPa,并在终轧前增加二次除鳞工艺，大规格50BV30盘条麻面缺陷改善明显。采用上述措施，麻面缺陷平均深度由70μm降至30μm以下，满足了下游客户的加工使用要求。

Cause analysis and control measureas of pitting defects on the surface of large gauge 50BV30 wire rod

In order to meet the current economical and green production development, users adopt the light drawing process in the processing of large gauge 50BV30 wire rods, so higher requirements were put forward for the surface quality of the wire rods. Aiming at the problem of pitting defects on the surface of large gauge 50BV30 wire rods produced by Yongsteel, the influence of the defects on drawing processing was analyzed. According to statistics, the depth of pitting defects needs to be controlled within 30 μm to meet the requirements of customers, while the average depth of pitted defects is 70 μm on the surface of large gauge wire rods. For this reason, the influence on pitting defects was analyzed from the two aspects of roll surface quality and oxide scale pression. The results show that the rolling amount of the groove is one of the main factors affecting the surface quality of the roll, and thus affects the pitting defects on the surface of the wire rod. With the increase of the rolling amount of the groove, the surface pitting defects of large gauge 50BV30 wire rods become more and more serious. Therefore, in actual production, the rolling amount of the rough and medium grooves should not exceed 600 t. After the oxide scale on the surface of the rolled piece is pressed, especially the secondary oxide scale is pressed into the piece matrix, the number and depth of pitting defects on the surface of the wire rod increase significantly. The desaling pressure of high-pressure water before rolling was increased from 10 MPa to 19 MPa,and the secondary descaling process was added before finishing rolling, and the pitting defects on the surface of large gauge 50BV30 wire rods were significantly improved. Using the above measures, the average defect depth was reduced from 70 μm to below 30 μm, which met the processing and use requirements of downstream customers.