Metal treatment – Process of modifying or maintaining internal physical... – Heating or cooling of solid metal
Patent
1991-09-12
1993-02-23
Yee, Deborah
Metal treatment
Process of modifying or maintaining internal physical...
Heating or cooling of solid metal
148606, 148641, 148546, 148506, C21D 802
Patent
active
051886812
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a process for manufacturing a thin strip or sheet of a Cr-Ni-base stainless steel, which comprises casting a cast strip having a thickness close to that of a product, by the synchronous continuous casting process wherein a casting mold is moved synchronously with a cast strip, and cold-rolling the strip.
2. Background Art
A thin sheet of a stainless steel is currently manufactured by a continuous casting process, which comprises casting a cast slab having a thickness up to about 100 mm while oscillating a casting mold in the direction of casting, surface-treating the slab, heating the treated slab to a temperature of 1000.degree. C. or above in a heating furnace, hot-rolling the heated slab by using a hot-strip mill comprising rough-rolling stands and finish-rolling stands to form a hot-strip having a thickness of several millimeters, cold-rolling the hot-strip, and subjecting the cold-rolled strip to necessary treatments, such as annealing, pickling and skin-pass rolling, to form a cold-rolled product.
Before the cold-rolling, the hot-strip obtained by the hot-rolling is annealed to soften the hot-strip, which is in a work-hardened state due to heavy hot working, thereby ensuring the shape (flatness), material quality (grain size and mechanical properties), and surface quality (prevention of roping) required of a final product, and further, is pickled and ground to remove oxide scale present on the surface thereof.
The above-described conventional process requires lengthy facilities for hot-rolling and a vast amount of energy is consumed for heating and working the material, and thus the conventional process is not considered an optimum manufacturing process, from the viewpoint of productivity.
Further, since a texture developed during the hot working firmly remains in the final sheet product, the press working of the product sheet in the user is subjected to many limitations, such as the need to take into consideration the anisotropy attributable to the texture.
Accordingly, a process wherein the continuous casting step is directly connected to the cold-rolling step without the hot-rolling step is now under development, to thereby avoid the need to provide lengthy facilities and use a vast amount of energy for manufacturing a hot-strip through the hot-rolling of a cast strip having a thickness of 100 mm or more, and at the same time, eliminate the limitations on the use of the product derived from the hot worked texture. Specifically, in this process, a cast strip (a thin strip) having a thickness equivalent or close to that of the hot-strip obtained by the conventional hot-rolling is continuously cast, and the thin cast strip is cold-rolled. Such a process is described in, for example, special reports in "Tetsu-to-Hagane", vol. 85, 1985, pages A197 to A256.
The thin sheet product manufactured by the above-described continuous casting/cold-rolling process (hereinafter referred to as "strip continuous casting"), however, has a finer grain structure than that of the thin sheet product manufactured by the conventional continuous casting/hot-rolling/cold-rolling process (hereinafter referred to as "conventional process"), which causes the elongation to be lowered, whereby the workability during a press working or the like by the user is unfavorably lowered. This phenomenon is reported in, for example, "CAMP ISIJ, vol. 1, 1988, 1670-1705. In this report, the annealing of the cast strip to cause .delta.-ferrite remaining in the cast strip to disappear is described as a countermeasure.
Detailed studies conducted by the present inventors on the Cr-Ni-base stainless steel manufacturing process by strip continuous casting have revealed that the presence of .delta.-ferrite and fine MnS remaining in the cast strip inhibits the growth of recrystallized grains during the cold-rolling and annealing and is a cause of the formation of the fine structure and the lowering in the elongation of the final product. Therefore, to eliminate the lowering in the elon
REFERENCES:
patent: 5045124 (1991-09-01), Suehiro et al.
Patent Abstracts of Japan, vol. 12, No. 128 (C-489) Apr. 20, 1988.
Patent Abstracts of Japan, vol. 14, No. 571, (C-0790) Dec. 19, 1990.
Patent Abstracts of Japan, vol. 12, No. 18 (M-660), Jan. 20, 1988.
European Search Report EP 91 90 2761.
"Tetsu-to-Hagane", 1985, A197-A256 (English Version Attached).
Suehiro Toshiyuki
Teraoka Shin-ichi
Ueda Masanori
Nippon Steel Corporation
Yee Deborah
LandOfFree
Process for manufacturing thin strip or sheet of Cr-Ni-base stai does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for manufacturing thin strip or sheet of Cr-Ni-base stai, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for manufacturing thin strip or sheet of Cr-Ni-base stai will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2202033