Rare earth containing, high strength and high toughness seamless steel pipe used for gas cylinder and production method thereof

Abstract

The invention provides a rare earth containing, high strength and high toughness seamless steel pipe used for a gas cylinder and a production method thereof, belonging to the technical field of metallurgy and molding. Raw materials comprises, by weight percent, 90 % of blast furnace molten iron and 10 % of high-quality scrap steel. A pipe blank comprises the following chemical components by weight percent: 0.10-0.15 of C, 0.10-0.30 of Si, 0.90-1.20 of Mn, less than or equal to 0.020 of P, less than or equal to 0.010 of S, 0.90-1.20 of Cr, 0.10-0.30 of Mo, 0.40-0.70 of Ni, 0.06-0.20 of V, 0.01-0.03 of Ti, 0.005-0.030 of Al, 0.0005-0.0100 of rare earth element RE, and the balance being Fe and undetectable trace elements. A technology proves comprises steps of pretreatment of molten iron, combined blown converter smelting, LF furnace refine, VD vacuum treatment, round ingot continuous casting, cutting, pipe blank heating, perforation, pipe rolling, sizing, cooling, sawing, heat treatment, straightening, hydrostatic test and flaw detection. Mechanical properties comprises a yield strength of 860-930 MPa, a tensile strength of 1000-1100 MPa, a yield ratio of less than or equal to 0.90, an elongation percentage of more than or equal to 19 %, a transverse impact value aKV of more than or equal to 150 J / cm<2>(-40 DEG C), a grain size of more than 8.0 grade, and a residual stress of less than or equal to 30 MPa. The product provided by the invention has characteristics of low impurity element content, small residual stress, high intensity, good toughness and excellent technology performance.

Description

1. Technical field: [0001] The invention belongs to the field of ferrous metal smelting and metal pressure processing, and relates to a rare earth-containing seamless steel pipe for high-strength and high-toughness gas cylinders and a production method thereof. 2. Background technology: [0002] A high-pressure gas cylinder is a refillable mobile steel cylinder with a nominal pressure of 10-30MPa or even higher, used to hold high-pressure gas or liquefied natural gas. There are two methods for manufacturing seamless gas cylinders, one is to use a steel billet to stretch and seal by hot stamping; Manufacturing high-pressure gas cylinders with seamless steel pipes has the advantages of low cost and good quality. [0003] In recent years, high-pressure gas cylinders are developing towards high pressure and light weight. The materials are required to have the characteristics of high strength, good toughness, and excellent process forming performance to ensure the safety and rel...

AI Technical Summary

Problems solved by technology

[0004] There is no record of this type of seamless steel pipe and its manufacturing method in the invention patent literature of China, and there is no report in books and periodicals at home and abroad.