High tensile steel for deep drawing and manufacturing method thereof

Abstract

There are provided a steel for deep drawing, and a method for manufacturing the steel and a high pressure container. The steel for deep drawing includes, by weight: C: 0.25 to 0.40%, Si: 0.15 to 0.40%, Mn: 0.4 to 1.0%, Al: 0.001 to 0.05%, Cr: 0.8 to 1.2%, Mo: 0.15 to 0.8%, Ni: 1.0% or less, P: 0.015% or less, S: 0.015% or less, Ca: 0.0005 to 0.002%, Ti: 0.005 to 0.025%, B: 0.0005 to 0.0020% and the balance of Fe and inevitable impurities, wherein a microstructure of the steel has a triphase structure of ferrite, bainite and martensite. The steel for deep drawing may be useful to further improve the strength without the deterioration of the toughness by adding a trace of Ti and B, compared to the conventional steels having a strength of approximately 1100 MPa. Also, the a method for manufacturing a steel may be useful to save the manufacturing cost and time by significantly curtailing time used in the spheroidization heat treatment during the deep drawing process, and to manufacture a steel for deep drawing that is used for a low-temperature, high-pressure container having a tensile strength of approximately 1200 Mpa by reducing a depth of the softening layer to prevent the deterioration in strength of the steel.

Description

Technical field [0001] The present invention relates to a steel for deep drawing with a tensile strength of about 1200Mpa and used for low temperature and high pressure vessels and a preparation method thereof, and more specifically, to a high tensile strength steel for low temperature and high pressure vessels and a preparation method thereof The high-strength steel ensures low-temperature toughness during the preparation of steel used in low-temperature and high-pressure containers, CNG storage containers for automobiles, etc., reduces the strength reduction caused by decarburization by shortening the spheroidizing heat treatment required for the steel, and Shows excellent economic efficiency and productivity. Background technique [0002] In order to prepare steel for low temperature and high pressure vessels with high tensile strength (usually about 1100 MPa), a method for preparing cylinders for pressure vessels is used in the prior art, which includes: rotating a seamless t...

AI Technical Summary

Problems solved by technology

Therefore, the problem of this spheroidizing heat treatment is its low steel productivity and high production cost, and the strength of the steel may also be deteriorated due to decarburization caused by the spheroidizing heat treatment for a long time

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