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SUS304 stainless steel is typical of austenitic stainless steel,which organization is metastable austenite,easily appears work hardening in cold rolling.According to the common process,the max reduction of cold rolling in one stage is below 80%,we try to rasie the max reduction to 90%in one stage (wecalled that “great reduction” ) from the view of cuting cost.Due to the work hardening,great reduction brings lots of problem(the difficulty of flatness control,strip break..etc)。This article analyzed the great reduction from properity of SUS304 steel,mill types,flatness control,rolling technics etc,supplied the corresponding solutions,and formed a sophisticated great reduction theory. This article focuses on the unusual thermal crown of raw materials(ie,abnormal distribution of horizontal thickness) and the rolling force fluctuations in “great reduction” rolling.First,the “distortion” phenomenon which caused by unusual thermal crown of raw materials is explained,wedge-shaped strip In coiling, because of a big difference in thickness on both sides,leads to different compressive stress on both sides of flatness roll,so that the flatness measurement is distorted;Second,the “strip shifting” phenomenon caused by wedge shape of strip is explained,we analysis the stress on both sides of the strip,concluded that the wedge-shaped strip on the coiler will shift to the thick side of the deviation,the amount of strip shifting is related to the wedge level;Because of the characteristics of SUS304,the strip is difficult to be rolled in the last few passes.so the strip breaking is easily occurred,we found the reasonable parameters(rolling speed, cooling oil,tension,etc) to solute that problem;The deviation of rolling force will cause the shape of the roll gap,thus affecting the shape control,especially in the head and tail part of the strip,It is important to minimize the deviation of rolling force;The “great reduction” process provide the favorable flatness(< 8I-unit) and thickness deviation which less than±3 um,with no significant difference between common process.In mechanical properties,the elongation of the great reduction strip is less than common products by 2%-3%,but that can be adjusted through the annealing process improvement.At present,we have been using this technology for mass production,achieving good economic benefits.
SUS304 stainless steel is typical of austenitic stainless steel, which organization is metastable austenite, easily appears work hardening in cold rolling. According to the common process, the max reduction of cold rolling in one stage is below 80%, we try to rasie the max reduction to 90% in one stage (wecalled that “great reduction ”) from the view of cuting cost. Due to the work hardening, great reduction brings lots of problem (the difficulty of flatness control, strip break..etc). This article analyzed the great reduction from properity of SUS304 steel, mill types, flatness control, rolling technics etc, supplied the corresponding solutions, and formed a sophisticated great reduction theory. This article focuses on the unusual thermal crown of raw materials (ie, abnormal distribution of horizontal thickness) and the rolling force fluctuations in “great reduction ” rolling. First, the “distortion” phenomenon which caused by unusual thermal crown of raw materials is explained, wedge-shaped strip In coiling, because of a big difference in thickness on both sides, leads to different compressive stress on both sides of flatness roll, so that the flatness measurement is distorted; Second, the “strip shifting” phenomenon caused by wedge shape of strip is explained, we analysis the stress on both sides of the strip, concluded that the wedge-shaped strip on the coiler will shift to the thick side of the deviation, the amount of strip shifting is related to the wedge level; Because of the characteristics of SUS304, the strip is difficult to be rolled in the last few passes.so the strip breaking is very easily occurred, we found the reasonable parameters (rolling speed, cooling oil, tension, etc) to solute that problem; The deviation of rolling force will cause the shape of the roll gap, thus affecting the shape control, especially in the head and tail part of the strip, It is important to minimize the deviation of rolling force; The “great reduction ” process provide a favorable flatness (<8I-unit) and thickness deviation which less than ± 3 um, with no significant difference between common process. mechanical properties, the elongation of the great reduction strip is less than common products by 2% -3%, but that can be adjusted through the annealing process improvement .At present, we have been using this technology for mass production, achieving good economic benefits.