The “Research on Quality Control Technology of Carbon Steel End/Edge” Project was recently completed by Beijing Shougang Co., Ltd. and the Academy of Science and Technology, successfully solving three quality problems occurring at Shougang Co., Ltd.: cold hard burrs at the end of IF steel, filaments at the edges of hot rolled low-alloy steel, and longitudinal cracks in the edges of high-carbon steel. A unique end/edge quality control technology system has been formed to provide good references and guidance for the Shougang Group and other steel mills in the industry to solve similar defects. With achievements rated at the international advanced level, this project won first prize at the Shougang Science and Technology Awards in 2020, embodying the Shougang Group’s technical capacity in the quality control of the edges and ends of hot rolled carbon steel.

In the process of improving low-temperature heating, the workers of Shougang Co., Ltd. encountered quality problems at the edges of IF steel. The occurrence rate of burrs in downstream cold rolling reached 75%, severely restricting production efficiency and product quality. Meanwhile, different forms of defects on low-carbon steel and medium to high-carbon steel such as filaments and longitudinal cracks in the edges also existed in hot rolling production. To tackle such an age-old difficulty and ensure the efficiency and stability of the production line, the research team focused on the reason behind the defects and launched a formidable battle against them, fighting tooth and nail. In order to figure out the different manifestations and occurrence regularity of the defects, the team members often delved into slab libraries and hot and acid rolling lines, confirming and troubleshooting detailed defects in actual situations, and monitoring slabs in the libraries and the quality of steel ends and edges. They successively carried out hundreds of technical adjustment experiments, examined tens of thousands of hot/cold steel strips and took nearly a thousand defect images as sample data.

Adhering to its status as a listed supervisor, the Qianshun Technology Center of Shougang Co., Ltd. concentrated on the “edge quality” issue. They analyzed the composition, structure, nature and processing of the material, comprehensively considered the influence of phase transformation, heat transfer and metal flow, systematically studied the manifestation pattern, formation mechanism and control technology of end/edge defects occurring in different types of steel, and finally gained an understanding of the causes of end/edge defects in hot rolled carbon steel. Closely integrating field process optimization and equipment improvement, a distinct quality control technology system was formed, presenting the perfect solution for the challenges of edge quality control in the industry.

With the application of this project’s results, the incidence of burrs at the edges of IF steel with low-temperature tapping has been greatly reduced, lifting the burden of manual grinding in the subsequent process and improving production efficiency. At the same time, the degradation rate of product defects caused by longitudinal cracks and filaments at the edges has also been decreased significantly. What’s more, the annual direct economic benefits have reached RMB 11.15 million, and we have realized the further reduction in tapping temperature for all kinds of steel, greatly contributing to the Group’s energy conservation and emission reduction. Rich intellectual property achievements were gathered during the implementation of this project, with applications filed for seven invention patents and two papers published.