Dvelopment And Research On Hot-Continuous-Rolling Production Technics Of Big Size Steel Stick Under Small Reduction Ratio

Experiment and research on trying to decrease reduction ratio and at the same time insuring product macrostructure and mechanical properties of Hot-Continuous-Rolling stick are summarized in this paper. In order to use the existing production conditions sufficiently, by the quality control of the continuous-casting billet and hot (red) sending process and the cooling process after rolling, especially the process controlling of Hot-Continuous-Rolling, realizing the small reduction ratio Hot-Continuous-Rolling production technics to produce big size steel stick upwards Φ 120mm using rectangular continuous-casting billet of 235 X 265mm, the lowest limit of 6.00 used in China currently is broken. The experiment and the research indicate that:(1) Through the Hot-Continuous-Rolling production technics under small reduction ratio of 4.04 and 5.08, the rectangular continuous-casting billet of 235×265mm can be used to produce big size steel stick of Φ140mm and Φ 125mm whose macrostructure and mechanical properties meet the standards, this technics is viable; (2) This rolling technics can make the deformation penetrate to the center of the billet by low temperture and low velocity and big roller diameter and large reduction quantity at every pass and optimum design and arrangement of rollers, which is the key of Hot-Continuous-Rolling technics under small reduction ratio; (3) The sending technics used in Xining Special Steel Co.,Ltd can not use waste-heat of billet adequately, but the sensitive temperature section of A1N or sulphides or inclusions separating out is avoided, creating a favorablecondition for insuring good surface quality of final rolled steel; (4) The Hot-Continuous-Rolling technics under small reduction ratio has a close relationship with the billet quality control and the hot(red) sending process control and the cooling control after rolling.