Steel for processing movement limiting core stick of continuous tube grimper and its producing process

Abstract

The present invention belongs to the field of steel-smelting technology. The steel consists of C 0.30-0.43 wt%, Mn less than 0.60 wt%, Si 0.70-1.00 wt%, P less than 0.010 wt%, S less than 0.007 wt%, Cr 4.50-5.50 wt%, Mo 1.00-1.50 wt%, V 0.7-1.00 wt%, Nb 0-0.25 wt%, Al less than 0.015 wt%, Ni 0.10-0.75 wt%, Cu less than 0.10 wt%, O less than 30 ppm and H less than 2 ppm, except Fe. It may contain one or several of RE, W, B, Ca, Mg, Zr and Ti. The steel of the present invention has reasonable production process, high performance and long service life of the core rod therewith.

Description

technical field [0001] The invention belongs to the technical field of steelmaking, and in particular relates to a steel which can be used for processing a stop mandrel of a continuous rolling pipe mill and a production process thereof. Background technique [0002] The stop mandrel of the continuous rolling mill is an indispensable and important tool for the production of large-diameter seamless steel pipes. When rolling steel pipe, a mandrel is inserted into a billet that is heated through a hole and pushed together into a rolling mill. At the end of the rolling process, the mandrel is pulled out from the billet and cooled rapidly by spraying. The mandrel is subjected to a large contact stress during rolling, and its surface temperature can reach 700°C within 10 seconds, followed by quenching. Such cyclic stress often leads to the formation of thermal fatigue cracks on the mandrel surface. [0003] At present, 4Cr5MoSiV (H11) and 4Cr5MoSiV1 (H13) steels are commonly used...

AI Technical Summary

Problems solved by technology

The high content of residual aluminum in the steel will reduce the creep strength and fracture toughness of the steel, and the mandrel made of this steel has a low service life, and it will be less than 1000 times from one installation to offline repair.