High-strength alloy steel for gas-fueled vehicle gas cylinder and preparation method of high-strength alloy steel

Abstract

The invention discloses high-strength alloy steel for a gas-fueled vehicle gas cylinder and a preparation method of the high-strength alloy steel. The preparation method comprises the following steps of: smelting and continuously casing to obtain target steel billet including the following components in percentage by weight: not more than 0.32% of C, 0.15%-0.35% of Si, 0.35%-0.65% of Mn, 0.70%-1.00% of Cr, 0.15%-0.25% of Mo, not more than 0.010% of P, not more than 0.008% of S, not more than 0.0002% of H, and the balance of Fe and inevitable impurities; heating up the steel billet to 1180 DEG C to 1280 DEG C; roughing the heated steel billet, wherein a five-phase rolling way is adopted, the down rate of the single rolling phase is not lower than 20%; rolling the steel billet in precision, wherein the start-rolling temperature and the final-rolling temperature are controlled to be 990 DEG C to 1040 DEG C and 870 DEG C to 900 DEG C, respectively; cooling the precision-rolled piece to 650 DEG with the cooling speed of 10-30 DEG C / s, and rolling the piece after air cooling. The high-strength alloy steel for the gas-fueled vehicle gas cylinder with yield strength not lower than 835 MPa, tensile strength not lower than 980 MPa, elongation not lower than 14% and ballistic work not less than 47J at -40 DEG C can be obtained by the preparation method disclosed by the invention.

Description

technical field [0001] The invention relates to the technical field of alloy steel production, and more specifically relates to a high-strength alloy steel for gas cylinders of natural gas vehicles and a manufacturing method thereof. Background technique [0002] Natural gas (CNG) automobile cylinders are high-pressure containers, and the water explosion pressure of the cylinder is an important indicator of the safety design of the cylinder, which is related to the strength of the material. In order to meet the fracture characteristics and fracture morphology of the water burst test, the material must have a reasonable yield ratio and high ductility and toughness. These properties are not only related to the composition of the material, but also related to the heat treatment process of the material. [0003] Cr-Mo series high-strength alloy steels for automobile cylinders have a wide range of applications in the fields of hydrothermal power and coal chemical industry. Howev...

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Problems solved by technology

However, the production of Cr-Mo series high-strength alloy steel with tensile strength (Rm) ≥ 980MPa and elongation (A) ≥ 14% requires the addition of high hardenability elements in the steel. For a common converter smelting , Bloom continuous casting, ordinary hot-rolling mill rolling production-based enterprises, how to produce high-quality products with performance standards has a certain degree of difficulty

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