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Ultra-low-carbon cryogenic steel and heat treatment technique thereof

A low-temperature steel and ultra-low carbon technology, applied in the field of low-temperature steel, can solve the problems of low strength, poor plasticity, low strength and toughness, etc., and achieve the effects of improving low-temperature toughness, improving weldability, and improving toughness.

Active Publication Date: 2018-02-16
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide an ultra-low-carbon low-temperature steel and its heat treatment process. By rationally designing the composition of the ultra-low-carbon low-nickel low-temperature steel, the Mn element is used in two Intra-phase temperature partitioning, and the introduction of nano-precipitated phases such as NiAl during low-temperature tempering 3 etc., prepared a high-strength plastic-product ultra-low carbon nickel nano-precipitation strengthened low-temperature steel, so as to solve the problems of low-strength ultra-low-carbon low-nickel series low-temperature steel, poor plasticity, and overall low strength and toughness

Method used

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  • Ultra-low-carbon cryogenic steel and heat treatment technique thereof
  • Ultra-low-carbon cryogenic steel and heat treatment technique thereof
  • Ultra-low-carbon cryogenic steel and heat treatment technique thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0049] According to the ratio, the raw materials containing various element components are mixed and cast into steel ingots. Each component is composed of the following elements in mass percentage: C: 0.008-0.01%; Ni: 1.5-2.5%; Mn: 6.0-8.0%; Al: 1.5-2.0%; Cu: 1.5-2.5%; P: ≤0.005%; S: ≤0.003%; N: 0.005-0.008%; O: 0.0005-0.002%; the balance is Fe. Derust and degrease the steel ingot and clean it to avoid uneven stress during heat treatment.

[0050] The steel ingot is subjected to multi-step hot rolling from the initial rolling temperature of 1200°C to the final rolling temperature of 750°C and then air-cooled. The rate is 25%, 25%, 25% respectively, and the holding time is 120, 70, 25 minutes respectively. Then, the steel ingot is subjected to cold rolling treatment at 25° C., and the reduction rate of the cold rolling treatment is 60-75%.

[0051] The cold-rolled steel ingot is kept at 50-70° C. above the A1 temperature for 1-2 hours, and then water-cooled to room temperatur...

Embodiment 2

[0053] According to the ratio, the raw materials containing various element components are mixed and cast into steel ingots. Each component is composed of the following elements by mass percentage: C: 0.008-0.01%; Ni: 1.5-4.5%; Mn: 6.0-12.0%; Al: 1.0-3.0%; Cu: 1.0-3.0%; P: ≤0.005%; S: ≤0.003%; N: 0.005-0.008%; O: 0.0005-0.002%; the balance is Fe. Derust and degrease the steel ingot and clean it to avoid uneven stress during heat treatment.

[0054] The steel ingot is subjected to multi-step hot rolling from the initial rolling temperature of 1200°C to the final rolling temperature of 750°C and then air-cooled. The amount is respectively 30%, 25%, 25%, and the holding time is respectively 115, 65, 20 minutes. Then, the steel ingot is subjected to cold rolling treatment at 25° C., and the reduction of the cold rolling treatment is 55-80%.

[0055] The cold-rolled steel ingot is kept at 50-100° C. above the A1 temperature for 0.5-2 hours, and then water-cooled to room temperatu...

Embodiment 3

[0057] According to the ratio, the raw materials containing various element components are mixed and cast into steel ingots. Each component is composed of the following elements by mass percentage: C: 0.008-0.01%; Ni: 1.5-4.5%; Mn: 6.0-12.0%; Al: 1.0-3.0%; Cu: 1.0-3.0%; P: ≤0.005%; S: ≤0.003%; N: 0.005-0.008%; O: 0.0005-0.002%; the balance is Fe. Derust and degrease the steel ingot and clean it to avoid uneven stress during heat treatment.

[0058] The steel ingot is subjected to multi-step hot rolling from the initial rolling temperature of 1200°C to the final rolling temperature of 750°C and then air-cooled. The amount is respectively 20%, 25%, 25%, and the holding time is respectively 125, 75, 30 minutes. Then, the steel ingot is subjected to cold rolling treatment at 25° C., and the reduction of the cold rolling treatment is 55-80%.

[0059] The cold-rolled steel ingot is kept at 50-100° C. above the A1 temperature for 0.5-2 hours, and then water-cooled to room temperatu...

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Abstract

The invention provides ultra-low-carbon cryogenic steel and a heat treatment technique thereof. The ultra-low-carbon cryogenic steel comprises the elements of, by mass, 0.005-0.01% of C, 1.0-4.5% of Ni, 6.0-12.0% of Mn, 1.0-3.0% of Al, 0.5-3.0% of Cu, 0.005% or less of P, 0.003% or less of S, 0.005-0.008% of N, 0.0005-0.002% of O and the balance Fe. According to the ultra-low-carbon cryogenic steel and the heat treatment technique thereof, through the TRIP effect of retained austenite and precipitation hardening of a nano-precipitate phase, the high-strength ultra-low-carbon nickel-saving nano-precipitate reinforced cryogenic steel is prepared and obtained, has good strength, excellent plasticity and good weldability and is low in cost, and the heat treatment technique is simple.

Description

technical field [0001] The invention belongs to the technical field of low-temperature steel, and relates to an ultra-low-carbon low-temperature steel and its heat treatment process, in particular to an ultra-low-carbon nickel-saving nano-precipitation-strengthened low-temperature steel and its high-strength toughness partition-retempering heat treatment process . Background technique [0002] In the context of the increasingly active production and trade of energy sources such as liquefied natural gas (LNG), liquefied petroleum gas (LPG) and liquefied ethylene gas (LEG), the nickel-based low-temperature steel used as storage and transportation materials has gradually developed into the most practical low-temperature steel. Structural materials. Although Ni-rich ferritic low-temperature steel has good low-temperature toughness, and 9Ni steel can even be used in cryogenic conditions, due to the high cost of Ni element and scarce resources, the development of low-nickel low-t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/04C22C38/08C22C38/06C22C38/16C21D8/00C21D1/20
CPCC21D1/20C21D8/005C21D2211/001C21D2211/008C22C38/004C22C38/04C22C38/06C22C38/08C22C38/16
Inventor 李伟金学军黎雨
Owner SHANGHAI JIAO TONG UNIV
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