METHOD OF FABRICATING SEAMLESS STEEL TUBE Russian patent published in 2009 - IPC B21B17/02 

FIELD: metallurgy.

SUBSTANCE: seamless steel pipe is fabricated out of high alloyed steel containing at least 5% of Cr by means of extended rolling using continuous mill of tube hot rolling on retained mandrel. Rate of transfer of the core of the mandrel in axial direction is maintained constant, while rate (Vb) of the mandrel core, rate (Vi) of rolled material at inlet side of the mill with the retained mandrel and rate (Ve) of rolled material at the exit end of the mill with the retained mandrel are maintained in correspondence with ratio 0.15 ≤ Vb/{(Vi + Ve)/2} ≤ 0.70 due to control over rate (Vb) of mandrel core transfer.

EFFECT: preventing problems of mandrel core extraction from rolled tube after extending rolling.

2 cl, 2 ex, 2 tbl, 2 dwg