MANUFACTURING METHOD OF PLATES FROM LOW-ALLOY PIPE STEEL WITH STRENGTH CLASS K56 Russian patent published in 2012 - IPC C21D8/02 C22C38/20 C22C38/48 B21B1/26 

FIELD: metallurgy.

SUBSTANCE: workpiece obtained from steel with the specified chemical composition is heated to 970÷1080°C, and subject at that temperature to roughing-down at single relative swagings of not less than 12%. The obtained rolled metal is cooled down, subject to finish rolling with rolling end temperature equal to 830°C; after that, hot-rolled plate having the temperature of not less than 770°C is quickly cooled at cooling rate of 14÷25°C/sec. In order to obtain the plate with final thickness of 14.0÷15.0 mm, finish rolling beginning temperature is equal to 850±20°C, and cooled cooling of the plate is performed to 530±20°C. In order to obtain the plate with thickness of 15.1÷17.0 mm, finish rolling beginning temperature is equal to 840±20°C, and quick cooling is performed to 520±20°C.

EFFECT: providing improved mechanical properties in hot-rolled plate with thickness of 14-17 mm, which are equal across the section and correspond to strength class K56.

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