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High-strength 9% Ni steel for ultra-low temperature engineering fasteners and its preparation method

An engineering fastener, high-strength technology, applied in the field of low-temperature metal materials, can solve problems such as unsatisfactory, and achieve excellent room/low temperature mechanical properties

Active Publication Date: 2021-10-15
SHANGHAI ELECTRIC SHMP CASTING & FORGING CO LTD +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the preparation method disclosed in the prior art cannot obtain the 9% Ni steel that meets this performance requirement

Method used

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  • High-strength 9% Ni steel for ultra-low temperature engineering fasteners and its preparation method

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preparation example Construction

[0024] The invention provides a preparation method of high-strength 9% Ni steel for ultra-low temperature engineering fasteners, comprising the following steps:

[0025] The raw materials are smelted according to the vacuum induction-electroslag remelting process, and the resulting smelting liquid is cast to obtain steel ingots; in terms of element content, the raw materials are weighed according to the following weight percentages: C 0.02-0.06%, Si≤0.15%, Mn 0.30~0.80%, S≤0.005%, P≤0.008%, Cr≤0.10%, V 0.03~0.08%, Ni 9.50~10.0%, Mo0.12~0.16%, H≤1.0ppm, O≤0.01%, N ≤0.01%, the balance is high-purity Fe;

[0026] Forging the steel ingot to obtain a forging;

[0027] The forgings are sequentially quenched and tempered to obtain the high-strength 9% Ni steel for ultra-low temperature engineering fasteners.

[0028] The raw material of the present invention is smelted according to the vacuum induction-electroslag remelting process, and the resulting smelting solution is cast to ob...

Embodiment 1

[0059] According to: C: 0.029%, Si: 0.038%, Mn: 0.61%, Cr: 0.020%, Ni: 9.61%, V: 0.037%, Mo: 0.15%, S: 0.004%, P: 0.0068%, H: 0.8 ppm, O: 0.0086%, N: 0.0064%, and the balance is high-purity Fe.

[0060] Smelting through the process of "vacuum melting + electroslag remelting" and casting the obtained molten liquid to obtain steel ingots required for forging; the process parameters of the "vacuum melting + electroslag remelting" are: the parameters of vacuum induction melting include: chemical power The refining temperature is 1560℃, and the vacuum degree is 2 o 3 25%, CaO 15%; the melting rate is 11 kg / min; the atmosphere is dry air.

[0061] The steel ingot was forged at an initial forging temperature of 1200°C and a final forging temperature of 900°C, with a forging ratio of 7, and the forged piece obtained after forging was buried in sand and cooled to room temperature to obtain a forged piece with an effective thickness of 80mm;

[0062] Raise the temperature at 80°C / h t...

Embodiment 2

[0065] According to: C: 0.043%, Si: 0.12%, Mn: 0.71%, Cr: 0.015%, Ni: 9.97%, V: 0.044%, Mo: 0.15%, S: 0.003%, P: 0.003%, H: 0.5 ppm, O: 0.009%, N: 0.0053%, and the balance is high-purity Fe.

[0066] Through the process of "vacuum melting + electroslag remelting" melting, the resulting molten liquid is cast to obtain the steel ingots required for forging; the process parameters of the "vacuum melting + electroslag remelting" are:

[0067] The parameters of vacuum induction melting include: chemical power of 750kW, power-up rate of 200kw / h; refining temperature of 1570°C, vacuum degree 2 o 3 25%, CaO 15%; the melting speed is 12 kg / min; the atmosphere is dry air, and the content of H element is controlled during the remelting process.

[0068] The steel ingot was forged at an initial forging temperature of 1160°C and a final forging temperature of 850°C, with a forging ratio of 6, and the forged piece obtained after forging was buried in sand and cooled to room temperature to...

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Abstract

The invention provides high-strength 9% Ni steel for ultra-low temperature engineering fasteners and a preparation method thereof, and relates to the technical field of low-temperature metal materials. The present invention adopts the vacuum induction + electroslag remelting smelting process, so that the high-strength 9% Ni steel for ultra-low temperature engineering fasteners of the present invention has higher purity and lower gas content; forging and supporting high-stable The heat treatment process of the microstructure, that is, quenching and tempering, makes the high-strength 9% Ni steel for ultra-low temperature engineering fasteners possess extremely excellent room / low temperature mechanical properties. The data of the embodiment shows that: the yield strength of the high-strength 9% Ni steel for ultra-low temperature engineering fasteners at room temperature is greater than 800 MPa, the elongation after fracture is greater than 20%, the reduction of area is greater than 65%, and the impact absorption energy of -196°C AKv is greater than 85J.

Description

technical field [0001] The invention relates to the technical field of low-temperature metal materials, in particular to high-strength 9% Ni steel for ultra-low temperature engineering fasteners and a preparation method thereof. Background technique [0002] 9% Ni steel is currently the only martensitic steel that can be used at a low temperature of -196°C. 9% Ni steel not only has high yield strength and yield strength, but also has excellent low temperature toughness and welding performance. In the prior art, in order to improve the low-temperature toughness of 9% Ni steel forgings, QLT is generally used during heat treatment, that is, the method of "complete quenching + sub-temperature quenching + tempering" to improve its toughness. V-type impact energy can reach more than 80J, but due to the use of sub-temperature quenching, its yield strength is generally between 500 and 650MPa. [0003] When 9% Ni steel is used as a fastener in large-scale low-temperature equipment a...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/44C22C38/46B21J5/00C21D1/18C21D6/00C22B9/04C22B9/18C22C33/04
CPCB21J5/002C21D1/18C21D6/004C21D6/005C21D6/008C22B9/04C22B9/18C22C33/04C22C38/02C22C38/04C22C38/44C22C38/46Y02P10/25
Inventor 雷雪王长军董凯梁剑雄洪兴福程莉刘振宝周恩民祝长江张智峰杨志勇李向王晓辉
Owner SHANGHAI ELECTRIC SHMP CASTING & FORGING CO LTD
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