Steel for forging having excellent hydrogen embrittlement resistance and crankshaft

A hydrogen embrittlement-resistant technology for forging, which is applied in the field of forging steel, can solve the problems that hydrogen embrittlement cannot be completely prevented, it is difficult to expect high purification degree fatigue strength, the degree of purification of finished steel and mechanical properties, fatigue strength deterioration, etc. Achieve high fatigue strength, lightweight fatigue strength, and excellent hydrogen embrittlement resistance

Inactive Publication Date: 2006-12-06
KOBE STEEL LTD
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Problems solved by technology

[0006] As in the above-mentioned dehydrogenation treatment, there is a limit to the reduction of the amount of hydrogen in terms of time and processing costs, and generally, production management is performed at the level of 1 to several ppm, but because hydrogen embrittlement occurs due to a trace amount of hydrogen, this level management cannot complet

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  • Steel for forging having excellent hydrogen embrittlement resistance and crankshaft
  • Steel for forging having excellent hydrogen embrittlement resistance and crankshaft

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Embodiment Construction

[0026] The steel for forging excellent in hydrogen embrittlement resistance of the present invention is characterized in that the component composition of the steel is limited, and the characteristic values ​​such as the shape, size, and number of inclusions in the steel are relatively adjusted.

[0027] First, the component composition of steel will be described.

[0028] By containing C: 0.2 to 0.6%, the hardenability and strength of the steel can be improved, and 0.2% or more is necessary for this, but if it is more than 0.6%, the toughness of the steel deteriorates and V segregation is promoted on the contrary. It may be more preferably in the range of 0.3 to 0.5%.

[0029] Containing Si: 0.1 to 0.4% is to expect the strength improvement effect of the steel. In order to ensure sufficient strength, 0.1% or more is required. If it is too much, V segregation will become prominent instead, hindering the purification of steel, so it is 0.4% or less , more preferably 0.3% or le...

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Abstract

The invention provides a hammered steel with good resistant property for hydrogen brittleness and crank made of said hammered steel, said steel comprises following components: C 0.2-0.6% (by weight percent, the same with following ones); Si 0.1-0.4%; Mn 0.7-1.5%; Ni less than 1.0%; Cr 1.2-3.5%; Mo 0.1-0.6%, Al 0.01-0.05%, and mixture containing at least one of Ti, Zr, Hf larger than 0.005%; the average circular degree of foreign material with maximum chord length being larger than 1 um is larger than 0.5; the number of foreign material with maximum chord length being larger than 20 um (100mm2) is less than 100, and the average circular degree is larger than 0.25, and the number of foreign material with maximum chord length being 1-10 um (100mm2) is larger than 100.

Description

technical field [0001] The present invention relates to forging steel used for large crankshafts for power transmission of ships, generators, etc., particularly high-purification steel excellent in high fatigue strength and hydrogen embrittlement resistance. Background technique [0002] So-called Cr-Mo steel represented by ISO standard 36CrNiMo6, DIN standard 32CrMO12, and ISO standard 42CrMo4 has been used as forging steel for large crankshafts for power transmission used in ships and generators, etc. . [0003] Since crankshafts are exposed to severe repetitive stress during use, even if they are manufactured using these Cr-Mo steels, high-purity steels with very little inclusions such as MnS that become the starting point of fatigue fracture are required. On the other hand, the crankshaft naturally has increasing requirements for products with high performance and high fatigue strength that will become lighter in weight in the future. [0004] However, in the case of C...

Claims

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Application Information

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IPC IPC(8): C22C38/44C22C38/50B21B5/00F16C3/06
CPCC22C38/001C22C38/002C22C38/02C22C38/04C22C38/06C22C38/44C22C38/46C22C38/50C22C2202/00F16C3/06
Inventor 漆原亘佐藤俊树深谷庄吾藤纲宣之
Owner KOBE STEEL LTD
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