Screw tap for cold extrusion of alloy steel internal thread

The invention relates to a screw tap for cold extrusion of an alloy steel internal thread. The screw tap comprises a screw tap main body and a clamping fixing head. The upper portion of the screw tap main body is a smooth rod part, and the lower portion of the screw tap main body is a tapping part; the outer surface of the tapping part is of a scrub structure, and the tapping part is divided into an upper tapping part body and a lower tapping part body; the upper tapping part body is of a cylinder structure, and the lower tapping part body is of a truncated-cone-shaped structure; a plurality of first screw tap teeth are arranged on the upper tapping part body in the longitudinal direction, and a plurality of second screw tap teeth are arranged on the lower tapping part body in the longitudinal direction; and the outer surfaces of the first screw tap teeth and the second screw tap teeth are each coated with a player of lubricating oil. The processing precision and the surface quality are improved, assembly is