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US 7,169,243 B2Granted
Aluminum-killed medium-carbon steel sheet for containers and process for its preparation
AssigneeSollac
InventorMohamed Bouzekri
Life of this patent
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Abstract
A process is provided for preparation of an aluminum-killed medium-carbon steel sheet containing by weight from 0.040 to 0.080% of carbon, from 0.35 to 0.50% of manganese, from 0.040 to 0.070% of aluminum, from 0.004 to 0.006% of nitrogen, the remainder being iron and the inevitable trace impurities, wherein the steel contains carbon in free state, a grain count per mm2 greater than 20000 and, in the aged condition, has a percentage elongation A % satisfying the relationship: (640-Rm)/10≦A %≦(700-Rm)/l1 where Rm is the maximum rupture strength.
Claims13
A process comprising
- a first cold-rolling of a hot-rolled steel strip to form a first cold-rolled steel strip;
- annealing the first cold-rolled steel strip;
- and
- a second cold-rolling of the annealed first cold-rolled steel strip,
- wherein the hot-rolled steel strip comprises from 0.040 to 0.080% of carbon, from 0.35 to 0.50% of manganese, from 0.040 to 0.070% of aluminum, from 0.0035 to 0.0060% of nitrogen, and the remainder being iron and trace impurities, where % is % by weight based on the total weight of the hot-rolled steel strip;
- wherein the annealing is a continuous annealing comprising:
- raising the temperature of the first cold-rolled steel strip to a first temperature in a range of from 740° C. to 780° C.,
- then holding the first cold-rolled steel strip above the first temperature for longer than 10 seconds, and
- then rapidly cooling the first cold-rolled steel strip to a second temperature of below 350° C. at a cooling rate of from 100° C./s to 300° C./s;
- and
- wherein the second cold-rolling is at a percentage elongation of from 2 to 16% and results in an aluminum-killed medium carbon steel strip having a maximum rupture strength Rm in a range of from 500 to 650 MPa.
8 more elements
Dependencies are inferred from the claim text.