Surface Quality and Marking of Ribbed Steel Bar from Hot Rolling
Surface quality and marking of ribbed steel bar produced through hot rolling are regulated by a series of national standards. This paper will focus on the specific requirements of GB 1499-1998 and explain the requirements of the Chinese national standard in detail.
Surface Quality and Defects
GB 1499-1998 outlines the surface quality requirements of ribbed steel bars and rolled products. For ribbed steel bars produced through hot rolling, surface quality should be classified according to the degree of surface defects present. Surface defects should be measured according to the requirement of Table 1.
Table 1. Surface Defects Classification Requirements
Surface Quality Classification Degree of Surface Defects A Minor Defects B, C, D General Defects E, F Severe Defects
The standard provides the details of defects for each surface quality class. For the A-level surface quality, the A-level defects include indentations, slag particles, pitting and other defects that do not exceed 0.5 mm in length; there are also some minor lapping defects. For B-level surface quality, the B-level defects include indentations and other defects that do not exceed 1.0 mm in length; there are also more obvious lapping defects. For C-level surface quality, the C-level defects include indentations, rolling lines and other defects that do not exceed 2.0 mm in length; there are also large lapping defects. For D-level surface quality, the D-level defects include indentations, rolling lines and other defects that exceed 2.0 mm in length; there are also medium-size scraping and lapping defects. For E-level surface quality, the E-level defects include indentations and other defects that exceed 5.0 mm in length; there are also large scraping and lapping defects. For F-level surface quality, the F-level defects include indentations and other defects that exceed 10.0 mm in length; there are also very large scraping and lapping defects.
Marking
GB 1499-1998 also regulates the marking requirements for ribbed steel bars from hot rolling. It requires that each bar is marked with the following information: name of the mill, product type, surface quality level, steel grade, date of production, production number and thermal treatment. The marking should be printed on the surface of the bar, and it should be clear. In addition, the bar should also be stampted within 10 centimeters of one end.
Conclusion
Surface quality and marking of ribbed steel bars produced through hot rolling are strictly regulated by the Chinese national standard GB 1499-1998. This standard outlines the surface quality classification requirements and defect details for each level. It also specifies the marking requirements for each bar, which should include the mill name, product type, surface quality level, steel grade, date of production, production number and thermal treatment. All the mentioned information should be clearly marked on the bar for easy identification.
