High friction rolling of thin metal strip
AssigneeNucor Corporation
InventorsTao Wang, Kishlay Mishra, Jeffery Edward Keffer
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Abstract
Described herein are thin metal strips having hot rolled exterior side surfaces characterized as being primarily or substantially free of all prior austenite grain boundaries, or at least primarily or substantially free of all prior austenite grain boundaries, and including elongated surface structure. As a result, because the prior austenite grain boundaries are not primarily or substantially present, all such prior austenite grain boundaries are not susceptible to grain boundary etching due to acid etching or pickling. In particular examples, the thin metal strips undergo hot rolling performed with a coefficient of friction equal to or greater than 0.20 with or without use of lubrication.
Claims22
A method of making a carbon steel strip, the method comprising:
- assembling a pair of counter-rotatable casting rolls having casting surfaces laterally positioned to form a gap at a nip between the casting rolls through which a thin metal strip having a thickness of less than 5 mm is cast,
- assembling a metal delivery system adapted to deliver molten metal above the nip to form a casting pool, the casting pool being supported on the casting surfaces of the pair of counter-rotatable casting rolls and confined at the ends of the casting rolls,
- delivering a molten metal to the metal delivery system;
- delivering the molten metal from the metal delivery system above the nip to form the casting pool;
- counter rotating the pair of counter-rotatable casting rolls to form metal shells on the casting surfaces of the casting rolls that are brought together at the nip to deliver the thin metal strip downwardly, the thin metal strip having a thickness less than 5 mm;
- and
- removing prior austenite grain boundaries by hot rolling the thin metal strip with a coefficient of friction equal to or greater than 0.20 using a pair of opposing work rolls, thereby creating opposing hot rolled exterior side surfaces of the thin metal strip primarily free of prior austenite grain boundaries and characterized as having a plurality of elongated surface structure formations formed by shear.
Dependencies are inferred from the claim text.