Stahlwerke Peine-salzgitter Ag

Salzgitter Ag

Klaus Freier

Volker Flaxa

Constantin M Vlad

Birgit Reichert

Klaus Hulka

Walter Zimnik

The production of a cold-rolled strip or sheet of steel with good deforming properties, which is subjected to recrystallizing annealing and, if appropriate, a dressing operation after hot rolling, coiling and cold rolling and has a bake-hardening potential after a subsequent deformation and for a subsequent temperature treatment, succeeds because the recrystallizing annealing is carried out in a bell-type furnace while coiled and because the strip or sheet is subjected to cooling at a cooling rate of &gE;1&deg; C./s after the recrystallizing annealing from a temperature T of 200&deg; C.&lE;T&lE;A . It is consequently possible to obtain properties of bell-annealed steels and nevertheless attain a bake-hardening effect, in particular for C contents of &gE;0.02%.

Process for producing a cold-rolled strip or sheet of steel and strip or sheet which can be produced by the process

In order to produce sheet possessing good forming properties, in particular for rotationally symmetrical deep-drawings, a low-carbon steel containing not more that 0.009% N is alloyed with 0.01 to 0.94% Ti and in certain cases with 0.01 to 0.06% Nb and continuously cast. The plate slabs are heated to a temperature above 1120 degrees Celsius, rolled to obtain a hot strip above the Ar.sub.3 point, and would at 520.+-.100 degrees Celsius. After cold rolling to the desired fine sheet thickness, the steel strip is annealed by recrystallizaiton, skin-passes and made into sheets.

Cold rolled sheet or strip steel and a process for production thereof

An improved method for the manufacture of hot strips or heavy plates from a denitrated steel composed of 0.04 to 0.16% carbon, 1.25 to 1.90% manganese, 0.2 to 0.55% silicon, 0.004 to 0.020% phosphorus, 0.002 to 0.015% sulfur, 0.02 to 0.08% aluminum, 0.02 to 0.08% niobium, the remainder iron and possibly contaminants, including the steps of having the hot strips or plates leaving the last finishing stand of rolls at a temperature of 750.degree. C. to 820.degree. C., cooling the hot strips or plates to an intermediates temperature of 450.degree. C. to 500.degree. C. at a cooling rate of 2.degree. to 10.degree. C./s and then slowly cooling the hot strips or plates in air to room temperature in a coil or in a pile.

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Wolfenbuttel, Germany

Klaus Freier