Heat treatment of mandrel steel for pipes’ piercing

Abstract

Abstract Seamless pipes are mainly used in the oil, gas and defense industry, what places special demands on its reliability and safety. It is very important to select the steel grade and heat treat the mandrels for flashing and cross rolling of seamless pipes in order to ensure the required operational characteristics. The work is devoted to the substantiation of the choice of 4Kh5MF1S steel and the development of the technological cycle of manufacturing mandrels of increased strength for sheet and transverse-spiral rolling of seamless pipes. The optimal combination of strength and ductility of this steel during heat treatment was established, which includes quenching at 1070 ° C and tempering in the temperature range of 650-700 ° C. Based on the analysis of the structure and mechanical characteristics, an optimal mode of heat treatment of steel 4Kh5MF1S was proposed: quenching from 1070 °C in oil and tempering for 2 hours at the temperature of 650-700 °C, which makes it possible to recommend it for use as a heat-resistant structural material for highly loaded metal products with the yield stress o0.2 from 750 to 1000 MPa.