METHOD OF MANUFACTURING THIN-WALLED CYLINDRICAL SHELL FROM MARTENSITE-AGEING STEEL Russian patent published in 2008 - IPC B21D51/10 C21D6/00 C22C38/10 

FIELD: technological processes.

SUBSTANCE: invention is related to manufacture of high-strength thin-walled cylindrical shells with wall thickness of less than 0.2 mm. Tubular billet is produced by method of hot pressing from martensite-ageing steel with nickel content of 15-20%. Billet is subjected to thermal treatment by heating up to temperature of 900÷940°C with maintenance at this temperature for 0.8÷1.8 hours and further cooling outside. Repeatedly billet is heated up to temperature of 780÷840°C and maintained at this temperature for 0.7÷1.5 hours and cooled outside. Cutting of billet internal and external surfaces is carried out, then shell rotary extrusion takes place in several preliminary operations and final operation. Thermal treatment for stress relieving after every operation of rotary extrusion is performed at temperature of 800-850°C with maintenance at this temperature for 1÷3 hours and further cooling outside. Best results of method implementation are achieved with application of martensite-ageing steel that contains rare-earth metals.

EFFECT: method allows to increase quality of shells and output of proper produce.

3 cl, 4 dwg, 1 tbl