FABRICATION METHOD OF SEAMLESS HOT-DEFORMED MECHANICALLY TREATED TUBES WITH DIAMETRE OF 530-550 mm FROM CORROSION-RESISTANT DIFFICULT-TO-FORM GRADES OF STEEL AND ALLOYS ON TUBE-FORMING INSTALLATION 8-16" WITH PILGER MILLS Russian patent published in 2010 - IPC B21B21/00 

FIELD: metallurgy.

SUBSTANCE: invention refers to fabrication method of seamless hot-deformed mechanically treated tubes with diametre of 530 - 550 mm from corrosion-resistant difficult-to-form grades of steel and alloys on tube-forming installation 8-16" with pilger mills. Method involves manufacture of ingots of electroslag melting of the size 610×1725±25 mm, mechanical treatment-turning of ingots into workpieces with diametre of 590±5.0 mm, drilling of central hole with diametre of 100±5.0 mm in workpieces, heating of workpieces to ductility temperature depending on steel and alloy grade, conversion of workpieces into shells-workpieces on the mandrel with diametre of 260±10 mm with rise as to diametre of not more than 2.0% and not more than 2000 mm long; repeated heating of shells-workpieces from cold or hot shoving to ductility temperature, conversion-rolling of shells-workpieces into shells on mandrels with diametre of 360±10 mm with rise or fit as to diametre of not more than 5.0%, rolling of hot-deformed tubes with diametre of not more than 450 mm with ratio D/S<10; at that, workpieces with size of 590±5.0×100±5×1725±25mm are bored to 590±5.0×220±5.0×1725±25 mm, heated to ductility temperature and converted in skew rolling mill to shells-workpieces with size of 620×365×1950-2000 mm on mandrel with diametre of 350 mm with rise as to diametre δ=4.0-6.0%; after repeated heating the shells-workpieces are rolled in skew rolling mill into shells with size of 660×505-515×2950-3100 mm on mandrel with diametre of 490-500 mm with rise as to diametre δ=5.5-6.5%, which are rolled on tube-forming installation 8-16" with pilger mills into tubes with diametre of 530-550 mm with ratio D/S=13.5-15.0 with allowance for wall thickness for mechanical treatment-turning and boring. There described are mathematical equations to determine values of thickness of the metal layers removed during turning and boring. Method allows adopting manufacture of quality hot-deformed tubes 550×37×5400 mm on tube-forming installation 8-16" with pilger mills from corrosion-resistant difficult-to-deform steel and alloy grades manufacture: ingot of electroslag melting - hot-rolled tube with further mechanical treatment to the size of 530×20×5400 mm in compliance with TU 14-3R-197-2001 as per mechanical properties, geometrical sizes and quality of surface.

EFFECT: enlarging range of tubes.

2 cl, 1 tbl