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Steel for high strength fastener for marine environment

A marine environment, high-strength technology, applied in the field of steel, can solve problems such as the effect is questionable, and achieve the effect of reducing probability and risk

Pending Publication Date: 2019-11-12
LUOYANG SUNRUI SPECIAL EQUIP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The focus of the above patents is to prevent and control the problem of hydrogen embrittlement by means of adding alloy elements and controlling the structure, but does not explain the core mechanism of controlling hydrogen-induced delayed fracture from the essential properties of the material. Discuss

Method used

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  • Steel for high strength fastener for marine environment
  • Steel for high strength fastener for marine environment
  • Steel for high strength fastener for marine environment

Examples

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specific Embodiment approach

[0047] The steel grades A1-A3 of the present invention and the comparative steel grade A4 were poured into steel ingots through a 50kg vacuum melting furnace, the chemical composition was as shown above, forged and cut to Φ45mm, and peeled to Φ40mm polished rods for subsequent test samples.

[0048] All steel types in this example are quenched + tempered to obtain the tempered martensite matrix, and the specific heat treatment process is:

[0049] A1: 870°C, water cooling; 550°C, air cooling;

[0050] A2: 900°C, water cooling, 590°C, water cooling;

[0051] A3: 900°C, water cooling, 620°C, water cooling;

[0052] A4: 860°C, water cooling, 500°C, air cooling.

[0053] In addition, the difference in the microstructure obtained in this example is that there is a small amount of reversed austenite structure in steels A1, A2, and A3. It can be seen from the results of mechanical properties that A1 steel has better strength-plastic compatibility, which is due to the increase of s...

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Abstract

The invention relates to steel for a high strength fastener for a marine environment. The steel is prepared from the following raw materials in percent by weight: 0.08-0.20% of C, 0.10-1.0% of Si, 0.3-1.0% of Mn, less than or equal to 0.005% of S, less than or equal to 0.005% of P, 0.2-1.2% of Cr, 4.5-9.5% of Ni, 0.3-1.0% of Mo, less than or equal to 0.15% of V and the balance Fe and other inevitable impurities. The hydrogen diffusion coefficient D of the steel is smaller than or equal to 10<-8>mm<2> / s. A hydrogen trap type of the steel is a reversible hydrogen trap, and the hydrogen escape activation energy Ea is smaller than 30 kJ / mol. Starting from an essential attribute design of a material, the average hydrogen content in the steel is reduced, and process and influence of hydrogen atoms taking part in hydrogen induced delayed fracture in an irreversible hydrogen trap are eliminated, so that the hydrogen induced delayed fracture problem of the high strength fastener for the marineenvironment is controlled effectively.

Description

technical field [0001] The invention relates to the technical field of steel materials, in particular to a steel for high-strength fasteners used in marine environments. Background technique [0002] Fasteners, as connecting parts, are widely used in marine engineering equipment, and usually face complex and harsh environmental media such as marine atmosphere and seawater media. However, with the fastener strength grade (tensile strength R m >1000MPa), under the action of stress, the hydrogen-induced delayed fracture susceptibility of high-strength fasteners increases, resulting in the loss of plasticity of the material and unexpected fracture, which endangers the safe operation of the equipment. Therefore, the hydrogen-induced delayed fracture control technology of high-strength fasteners has been widely concerned and valued. [0003] At present, domestic and foreign researches on steels for anti-hydrogen-induced delayed fracture fasteners mainly focus on the chemical ...

Claims

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Application Information

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IPC IPC(8): C22C38/02C22C38/04C22C38/44C22C38/46
CPCC22C38/002C22C38/02C22C38/04C22C38/44C22C38/46
Inventor 孙永伟陈继志王灵水范芳雄
Owner LUOYANG SUNRUI SPECIAL EQUIP
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