PRODUCTION OF COLD ROLLED HIGH-CARBON STEEL STRIP

Japanese Patent JP3266902

B2

PROBLEM TO BE SOLVED: To stably and inexpensively obtain a cold rolled high-carbon steel strip excellent in workability and homogeneity of crystalline structure by preventing the occurrence of seizure defect while attaining the shortening of annealing time.
SOLUTION: A high carbon steel slab, having a composition consisting of 0.3-0.8% C, 0.03-0.35 Si, 0.20-1.50% Mn, and the balance essentially Fe with inevitable impurities, is hot-rolled, pickled, descaled, and cold-rolled at 25-80% draft. Subsequently, by using a bell-type batch type annealing furnace of a gaseous atmosphere having a composition consisting of ≥75vol.% hydrogen and the balance essentially nitrogen with inevitable impurities, the resultant cold rolled steel strip is subjected to annealing treatment consisting of heating up to a temp. between 680°C and a temp. right under the Ac1 point at (20 to 100)°C/Hr heating rate, soaking and holding for ≥6Hr, heating up to a temp. between the Ac1 point and (Ac1 point + 50°C) at ≤100°C/Hr heating rate, soaking and holding for ≤8Hr, and cooling down to a temp. not higher than the Ar1 point at ≤50°C/Hr cooling rate. By this method, the occurrence of seizure defect at the time of annealing can be prevented, and the softened cold rolled high-carbon steel strip excellent in workability can be produced inexpensively.

Hideaki Miyazaki
Kiyoshi Fukui

JP1737797A

March 18, 2002

January 14, 1997

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SUMITOMO METAL INDUSTRIES,LTD.

C21D8/02; C21D9/46; C21D9/52; C22C38/00; C22C38/04; (IPC1-7): C21D9/46; C21D8/02; C21D9/52; C22C38/00; C22C38/04

JP5287390A
JP5171288A
JP428823A
JP987736A
JP987805A

Shigenobu Ikejou (1 person outside)

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