Metal treatment – Process of modifying or maintaining internal physical... – Heating or cooling of solid metal
Patent
1996-04-08
1998-03-10
Yee, Deborah
Metal treatment
Process of modifying or maintaining internal physical...
Heating or cooling of solid metal
148542, 148602, 148625, 72 39, 72 41, C21D 802, C21D 960, C21D 9573
Patent
active
057256969
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for the production of stainless steel strip or plates, in which the cast material is annealed and cooled in batches, and to a process covering casting and cooling in batches.
In the processes already known for production of stainless steel, in particular for stainless steel strip or plate, the stainless steel is melted with all alloying elements and the melting charge cast to a slab, the surface of which is cleaned mechanically to remove any impurities after cooling. After this the cleaned slab is heated again and fed to a hot rolling mill, where it is rolled out to a strip--typically with a thickness of not more than 15 mm, and measuring 2.5 m wide maximum and up to 100 m long or more--or rolled to a plate--typically with a thickness between 10 and 150 mm and measuring approximately 10 m in length and 3 m in width. Hereinafter, the term "strip" will be used in a generic sense to include both thin strip, i.e., up to about 15 mm in thickness, and plate, i.e., with a thickness up to 150 mm or greater. If the hot rolling mill is a Steckel mill, the stainless steel strip can be treated in batches in a suitable pickling line, as described, for example, in AT-PS 394 734, without requiring any further annealing. Here it is possible to treat different grades of steel and strip or plates of different dimensions immediately after one another without requiring any complicated change-over work.
If there is no Steckel mill, the hot stainless steel strip is annealed in continuous operation on annealing and pickling lines in a gas-heated annealing furnace, then cooled and most of the scale removed mechanically, the rest being removed by pickling, preferably using acids, with the possibility of saving acids by pre-treating with electricity in neutral salt solutions. In this type of plant the stainless steel strips are welded to form an endless strip which is separated again at the end of the line. Plates or other shapes of raw casting are conveyed through the plant in different ways. Apart from the high investment costs for the welding machine, conveying equipment and other devices required in connection with this, this means of production also has the disadvantage that the strip has to be taken from a looper during the welding time and the looper then has to be replenished. In addition, if there is a fault at the welding machine or looper, all of the strip that is in the annealing furnace when the fault occurs has to be scrapped because it is annealed for too long.
More recently, more and more raw stainless steel castings have been cast in the form of plates, then de-scaled after cooling and, preferably, pickled. These plates do not always have to be annealed, however in some cases annealing may be required. If so, the plates also have to go through the subsequent or each subsequent treatment plant if they are to be de-scaled and pickled, and possibly also be annealed before reaching these treatment stages.
The invention is intended to avoid the above mentioned disadvantages and to provide a process and a plant in which there is greater flexibility in the sequence of stainless steel grades and dimensions of the stainless steel strip or plates in the entire production process for raw stainless steel castings.
According to the invention, this is achieved in the variant with rolled raw castings by heat treatment of the material in batches, without any intermediate storage, where the material is pushed through a heat treatment system such as an annealing furnace if necessary and through the de-scaling system, preferably a pickling plant, until the leading end of the material comes out of the de-scaling plant, after which the material is pulled exclusively or additionally through the annealing furnace and the de-scaling plant by devices located after the de-scaling plant. Thus, no equipment is required to thread the material in and pull it through, and the batch production and treatment of stainless steel strip and/or plates of different qualities and dimensions are thus greatly simplified.
REFERENCES:
patent: 5003804 (1991-04-01), Kenmochi et al.
patent: 5279141 (1994-01-01), Kenmochi et al.
patent: 5292374 (1994-03-01), Maresch et al.
International Search Report for PCT/EP94/02215, dated Jul. 12, 1994.
Patent Abstracts of Japan, vol. 14, No. 159 (M956), for publication JP A, 02 020 610, dated Jan. 24, 1990.
Braun Edgar
Maresch Gerald
Andritz-Patentverwaltungs-Gesselschaft m.b.H.
Yee Deborah
LandOfFree
Process and plant for production of raw stainless steel castings 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 and plant for production of raw stainless steel castings, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process and plant for production of raw stainless steel castings will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-135984