Nippon Steel Corporation

Jirou Harase

Mitsuo Ishii

Tadashi Nakayama

Shozaburo Nakashima

Hirofumi Yoshimura

Fumio Matsumoto

Kunihide Takashima

Tadashi Sawatani

Hisanobu Nakayama

Yakichiro Kawamo

Yasukazu Mori

The ferritic stainless steel sheet involves a problem that the ridging is likely to generate at the forming step, such as the deep drawing step. The ridging is believed to be caused by a band structure in the hot rolled band, which structure exerting an influence on the formability of a cold rolled sheet. The ridging is prevented in the present invention by means of the combination of the three technical measures: incorporating aluminum into a ferritic stainless steel; heating a slab to a low temperature of 1200.degree. C. or less; and, carrying out a drastic hot rolling of at least one pass with the draft of 20%/pass or more. As a result of these technical measures, the structure of a hot rolled band is made and uniform and thus both the formability and anti-ridging property are enhanced.

Method for producing ferritic stainless steel sheets or strips

A process for producing an aluminum-bearing grain-oriented silicon steel strip from a silicon steel slab containing up to 0.02% carbon, 0.01 to 0.1% aluminum, 2.7 to 4.0% silicon, and 0.002 to 0.02% nitrogen, the balance being iron and unavoidable impurities, said slab optionally containing at least one of 0.01 to 0.5% antimony and 0.01 to 1.0% copper, said process comprising: recrystallization hot rolling said slab, said rolling being commenced when said slab has a temperature up to 1,250.degree. C., and effected at a total reduction rate of at least 80% with a plurality of passes, including at least one pass having a reduction rate of at least 35%, before said steel has a temperature of 900.degree. C.; strain accumulation finish hot rolling said steel at a total reduction rate of at least 40% and at a steel temperature up to 900.degree. C.; annealing said hot rolled steel continuously at a temperature of 700.degree. C. to 950.degree. C.; cold rolling said steel; annealing said cold rolled steel continuously at a temperature of 700.degree. C. to 900.degree. C. for primary recrystallization; and finish annealing said steel, an atmosphere gas containing at least 30% of nitrogen being introduced during the heating step of said finish annealing when a temperature of 800.degree. C. to 1,000.degree. C. prevails.

Process for producing aluminum-bearing grain-oriented silicon steel strip

Process for producing a ferrite stainless steel having excellent workability, comprising hot rolling a ferrite stainless steel slab with a total reduction of at least 80% in a temperature range of from 1150.degree. C. to 900.degree. C. at the central portion of the slab thickness, and, without annealing the hot rolled sheet, cold rolling the hot rolled sheet by a single step into a final thickness.

Process for producing ferrite stainless steel sheets having excellent

Process for producing a grain-oriented silicon steel sheet from silicon steel slabs, particularly from continuously cast steel slabs, comprising at least one recrystallization rolling at high reduction rate in a temperature range from 1190.degree. C. to 960.degree. C. in the hot rolling step. The process of the present invention is very effective in preventing the streaks of smaller, poorly oriented grains very often seen in the final product produced from silicon steel slabs.

Process for producing a grain-oriented silicon steel sheet

A grain oriented electrical silicon steel sheet containing aluminium and having an extremely high magnetic flux density, for example, a B8 of 1.90 or more, is produced by a secondary recrystallization annealing operation in which, during the period of elevating the temperature of a reducing atmosphere to a level within a range of from 850.degree. to 950.degree. C., the partial pressure of nitrogen in the reducing atmosphere is limited to 20% or less based on the entire pressure of the reducing atmosphere, and during the period of elevating the temperature of the reducing atmosphere in which the secondary recrystallization is in progress, the partial pressure of nitrogen is maintained at a level of at least 3%.

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Munakatamachi, Japan

Jirou Harase