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Nickel-saving ultralow-temperature high-strength steel and heat treatment process thereof

A low-temperature steel and process technology, which is applied in the field of nickel-saving ultra-low temperature steel and its tempering-double partition heat treatment process, can solve the problems of increasing the heat-affected zone, low mechanical stability, and reducing the welding performance of materials, etc., to achieve The effect of strong economic applicability, low application cost and simple heat treatment process

Pending Publication Date: 2021-10-15
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] 1. The mechanical stability of austenite stabilized by C element is often low at low temperature, and the increase in hardenability caused by excessive C element will further increase the heat-affected zone during welding and reduce the welding performance of the material
[0007] 2. The strengthening method of refining grains and introducing dislocations through cold deformation is not suitable for thicker materials, thus greatly limiting the large-scale industrial application of materials

Method used

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  • Nickel-saving ultralow-temperature high-strength steel and heat treatment process thereof
  • Nickel-saving ultralow-temperature high-strength steel and heat treatment process thereof
  • Nickel-saving ultralow-temperature high-strength steel and heat treatment process thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0053] According to the proportions, the components containing each element are mixed and then smelted, and then slab is continuously cast into ingots. Each component is composed of the following elements by mass percentage: C: 0.008-0.012%; Ni: 5.0-6.0%; 4.0%; Cu: 1.5-2.0%; Mo: 0.4-0.6%; S: ≤0.004%; P: ≤0.003%; N: 0.003-0.005%; O: 0.0005-0.001%; ​​Ca: 0.0005-0.005%; The balance is Fe. Remove rust and oil from the ingot, and clean it to avoid uneven stress during the hot rolling process.

[0054] The ingot is subjected to hot rolling treatment, and is subjected to multi-step hot rolling from a preliminary rolling temperature of 1200 °C to a final rolling temperature of 750 °C, followed by air cooling. The steps of the multi-step hot rolling are as follows: successively at temperatures of 1200, 900 and 750° C., the reduction rates are respectively 25%, 25% and 25%, and the holding times are respectively 120, 70 and 30 minutes.

[0055] The hot-rolled ingots are placed in A 1...

Embodiment 2

[0057] According to the proportion, the components containing each element are mixed and then smelted, and then slab is continuously cast into ingots. Each component is composed of the following elements by mass percentage: C: 0.008%; Ni: 5.0%; Mn: 3.0%; Cu: 1.5 %; Mo: 0.4%; S: 0.004%; P: 0.003%; N: 0.003%; O: 0.0005%; Ca: 0.0005%; Remove rust and oil from the ingot, and clean it to avoid uneven stress during the hot rolling process.

[0058] The ingot is subjected to hot rolling treatment, and is subjected to multi-step hot rolling from a preliminary rolling temperature of 1200 °C to a final rolling temperature of 750 °C, followed by air cooling. The steps of the multi-step hot rolling are as follows: continuously at temperatures of 1150, 850, and 770° C., the reduction rates are 30%, 25%, and 25%, respectively, and the holding time is 115, 65, and 25 minutes, respectively.

[0059] The hot-rolled ingots are placed in A 1 The temperature is below 100℃ for 1.0h for tempering...

Embodiment 3

[0061] According to the proportions, the components containing each element are mixed and then smelted, and then slab is continuously cast into ingots. Each component is composed of the following elements by mass percentage: C: 0.008%; Ni: 5.5%; Mn: 3.0%; Cu: 1.5 %; Mo: 0.4%; S: 0.004%; P: 0.003%; N: 0.003%; O: 0.0005%; Ca: 0.0005%; Remove rust and oil from the ingot, and clean it to avoid uneven stress during the hot rolling process.

[0062] The ingot is subjected to hot rolling treatment, and is subjected to multi-step hot rolling from a preliminary rolling temperature of 1200 °C to a final rolling temperature of 750 °C, followed by air cooling. The steps of the multi-step hot rolling are as follows: continuously at temperatures of 1180, 880 and 760° C., the reduction rates are respectively 25%, 25% and 30%, and the holding times are respectively 125, 65 and 30 minutes.

[0063] The hot-rolled ingots are placed in A 1 The temperature is below 150℃ for 1.0h for tempering, ...

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Abstract

The invention provides nickel-saving ultralow-temperature high-strength steel. The nickel-saving ultralow-temperature high-strength steel consists of the following elements including, by mass, 0.005% to 0.015% of C, 3.5% to 6.5% of Ni, 2.0% to 5.0% of Mn, 0.5% to 2.5% of Cu, 0.2% to 0.8% of Mo, less than or equal to 0.004% of S, less than or equal to 0.003% of P, 0.003% to 0.005% of N, 0.0005% to 0.001% of O, 0.0005% to 0.005% of Ca and the balance Fe. The invention further provides a heat treatment process of the nickel-saving ultralow-temperature high-strength steel. According to the nickel-saving ultralow-temperature high-strength steel and the heat treatment process thereof, the nickel-saving low-temperature steel with obdurability at the low temperature of -196 DEG C can be obtained, cold deformation treatment is not needed, the heat treatment process is simple and can be used for manufacturing low-temperature structural steel, the economic applicability is high, and excellent application and development prospects are achieved.

Description

technical field [0001] The invention belongs to the technical field of low-temperature steel, relates to a nickel-saving type high-strength steel for ultra-low temperature and a heat treatment process thereof, and particularly relates to a nickel-saving type ultra-low temperature steel and a tempering-double-partition heat treatment process thereof. Background technique [0002] In recent years, liquefied natural gas (LNG) has become an extremely important strategic reserve resource, and the materials used in closely related LNG carriers and large storage tanks have attracted extensive attention from industry and academia. The LNG carrier is a special ship for transporting liquefied gas at a low temperature of -162°C. Therefore, the materials for storing and transporting liquefied gas are required to have both excellent strength, toughness and crack arrest ability at low temperature. Value-added "three high products". Studies have shown that ferritic steel can effectively r...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/08C22C38/04C22C38/12C22C38/16C21D6/00C21D8/00
CPCC22C38/08C22C38/04C22C38/16C22C38/12C22C38/001C22C38/002C21D6/001C21D6/005C21D8/005
Inventor 李伟金学军李勇
Owner SHANGHAI JIAO TONG UNIV