METHOD FOR PRODUCING IN TUBE ROLLING PLANTS WITH PILGER MILLS SEAMLESS HOT-DEFORMED LARGE- AND MEAN-DIAMETER TUBES FOR STEAM BOILERS, STEAM PIPES AND COLLECTORS OF PLANTS WITH HIGH AND SUPER-CRITICAL PARAMETERS OF STEAM FROM INGOTS OF ELECTROSLAG REFINING AND CONTINUOUSLY CAST BILLETS

摘要

FIELD: production of rolled tubes, namely seamless hot deformed tubes of large and mean diameters for steam boilers, steam pipes, collectors of plants with high and super-critical parameters of steam from ingots of electroslag refining and continuously cast billets, possibly in tube rolling plants with pilger mills including helical rolling mills.;SUBSTANCE: method comprises steps of melting ingots in electric and Martin furnaces on base of direct reduction and also with use of stage for treating with liquid slag in ladle; forging ingots at forging ratio 2 - 3 depending upon steel kind; turning and drilling central part of tube blanks; continuously casting steel of predetermined kinds (given in specification) treated with synthetic slag; continuously casting steel of given kinds from evacuated or non-evacuated metal treated with synthetic slag for further forging them to blanks with forging ratio no less than 1.5; melting ingots of given kinds of steel by electroslag refining; drilling central part of ingots of electroslag refining and continuously cast billets; heating billets and ingots till their plastic temperature depending upon steel kind; piercing them in skew rolling mills on mandrels whose diameter depend upon geometry size of sleeves; piercing ingots of electroslag refining while deforming metal in piercing mill with diameter fit in range 8 - 16%; rolling blanks in pilger mills with elongation values depending upon diameter and thickness of wall; calibrating and straightening tubes. Ingots of electroslag refining and continuously cast billets of steels of kinds given in specification are heated till plastic temperature without drilling central opening, pierced in piercing mills to sleeves and rolled in pilger mills to tubes. Bottom portion of ingots of electroslag refining is removed by means of anode-arc cutting. Ingots of electroslag refining are guided to piercing mill forward by their bottom ends. Tubes from sleeves pierced from ingots of electroslag refining are rolled in pilger mills at their bottom end turned forward while forming pilger head from shrinkage portion of ingot. Elongation factors for piercing in piercing mill ingots of electroslag refining and continuously cast billets are determined from expressions: μ_esr = 1.1μ_fbd_{c esr}/d_{o esr,}μ_ccb = 1.1μ_fb d_{c ccb}/d_{o ccb} , where μ_fb -elongation value at rolling tubes of given size from forged blank in piercing mill; d_{c esr} -current value of diameter of ingots of electroslag refining, mm; d_{o ccb} - diameter of ingot of electroslag refining equal to 500 mm; d _{c ccb} - current value of diameters of continuously cast billet; d_{o ccb} - diameter of continuously cast billet equal to 400 mm. Invention provides reduced energy consumption due to elimination of operations for heating ingots for forging and forging ingots to forged pieces, for drilling ingots.;EFFECT: reduced factor of metal consumption at mechanical properties of tube metal equal or higher than those of forged blank metal during conversion such as electroslag refining - boiler tube, lowered cost of boiler tubes.;2 cl, 2 tbl