METHOD OF MAKING MANDREL FOR PIERCING-ROLLING Russian patent published in 2016 - IPC B21B25/00 B21B19/04 C23C4/02 C23C4/10 

FIELD: metallurgy.

SUBSTANCE: invention relates to manufacture of mandrel for piercing tube mill for making seamless steel pipe. Proposed method comprises arc deposition of melted iron wire and sputtering its molten material upon surface of base metal of mandrel using arc sprayer in order to form a film containing iron oxide and iron on surface of base metal of mandrel. At stage of arc spraying, surface of main mandrel metal is divided into multiple sections in axial direction of mandrel and arc sputtering is performed separately in each one of multiple sections. Angle of crossing between axial line of sprayed flow from arc sprayer and surface of main metal of mandrel is maintained within range from 35° to 90°. Mandrel has bullet-like shape and includes body part and end part, and multiple sections contain region of body part and region of end part. Film is formed on end part after its formation on body part.

EFFECT: strong adhesion of film formed on surface of mandrel applied by arc sputtering, and reliable extension of service life of mandrel are provided.

3 cl, 13 dwg, 1 tbl, 2 ex