In the early years, Nisshin Steel company in Japan for the first time to use senjimil 20 high cold rolling machine, which greatly improved the production efficiency of stainless steel sheet. From the system of austenite stainless steel work hardening characteristics, at the beginning of the cold rolling mill using the work roll diameter is small, and can be carried out under the big reduction Jimmy, rolling, rolling mill, but around 1990, the Japanese domestic stainless steel companies have construction shape control of high speed and automation equipment, it is easier to 12 roll body frame type cold rolling mill. Nippon Steel sujin stainless steel uses this kind of high level multi-roll mill, in 1992 Kashima manufacturing mill rolling speed 1000m/min, in 1993 light manufacturing mill rolling speed 1200m/min.
Double AS-U and FSBA (Flexible Shift Backing Assembly) are being developed to improve the shape control function of the original Single AS-U and the Backing Assembly of the Senjimil rolling mill. The senjimil mill with a maximum speed of 1000m/min is also under construction.
After 80’s, in the trend of strengthening automobile environmental protection and high performance of engine, stainless steel is rapidly applied to automobile exhaust system, especially in order to process into a complex shape of exhaust pipe, etc., the processing performance of materials has put forward higher and higher requirements. In order to meet such requirements, a series cold rolling mill (with large diameter work roll) was developed to improve the processability and reduce the cost while developing materials. Through this series process, the application of ferritic stainless steel in automobile is greatly expanded.
In the annealing and pickling process of stainless steel, high temperature annealing is necessary. In order to remove the oxide formed during annealing, a large descaling equipment is required. Therefore, when increasing the production capacity of HAP line, the capacity of annealing furnace should be enlarged to improve the heating efficiency, and the mechanical descaling capacity and the length of pickling tank should be increased by using high grinding brush. In addition, in chemical descaling, it is also hoped not to change the basic composition of sulfuric acid and nitric acid/hydrofluoric acid mixed acid, through the installation of high performance iron ion removal device to stabilize pickling capacity, through the forced convection in the pickling tank to produce turbulent pickling, and the use of jet pickling to improve descaling capacity. The production capacity of the new HAP line can reach 1 million T /a in the setting space is not limited.