maraging steel

A maraging steel, Vickers hardness technology, applied in the direction of V-belt, coating, belt/chain/gear, etc., can solve the problem of insufficient strength, and achieve excellent mechanical properties, high strength and fatigue strength properties , the effect of long fatigue life

CN103827334BActive Publication Date: 2016-08-17HITACHI METALS LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2016-08-17

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Abstract

The present invention provides a maraging steel which has excellent fatigue strength after nitriding and can obtain stable high strength. A maraging steel containing C: 0.008% or less, Si: 0.5% or less, Mn: 0.5% or less, Cr: 0.5%-1.5%, Ni: 16.0%-22.0%, Co: 3.0% to 7.0%, Mo: 3.0% to 7.0%, the thickness is less than 0.5mm, and has been subjected to nitriding treatment. The maraging steel also contains Al: 0.6% to 1.3% by mass percentage, and the rest Composed of Fe and impurities, as the above-mentioned impurities, Ti: 0.01% or less, Nb: 0.01% or less, Ta: 0.01% or less, W: 0.01% or less, and the ratio of Al to Ti satisfies Al / Ti≥250, According to Vickers hardness, the surface hardness of maraging steel is 800HV-1050HV, and the internal hardness is 570HV or less.
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Description

technical field

[0001] The present invention relates to a nitriding-treated maraging steel suitable for, for example, a metal endless belt for a CVT (Continuously Variable Transmission). Background technique

[0002] Maraging steel has a very high tensile strength of about 2000 MPa. Therefore, for example, maraging steel can be processed into a steel strip of 0.5 mm or less, and used for metal endless belts requiring high strength in CVTs.

[0003] In a typical composition of a maraging steel, 18% by mass % of Ni, 8% of Co, 5% of Mo, 0.45% of Ti, 0.1% of Al, and the balance is Fe.

[0004] However, although the above-mentioned maraging steel can obtain very high tensile strength, its fatigue strength is not necessarily high. TiN inclusions are cited as the biggest cause of the decrease in the fatigue strength of maraging steel. The size of the TiN inclusions tends to be large, and the shape is also cubic, so fatigue fracture originating from the inclusions tends to occur. ...

Examples

Embodiment

[0086] The present invention will be described in more detail using the following examples.

[0087] Seven kinds of steel ingots weighing 10 kg were produced using a vacuum induction melting furnace. In order to more reliably prevent contamination of Ti, Nb, Ta, and W, elements that should be restricted, high-purity alloy raw materials are used as the alloy raw materials to be added.

[0088] Homogenizing annealing was performed on the produced steel ingot, and then hot forging was performed. Then, it is made into maraging steel with a thickness of about 0.2mm by hot rolling and cold rolling, which is used as the maraging steel for the metal endless belt of CVT.

[0089] Table 1 shows the chemical composition and Al / Ti ratio of the obtained maraging steel. The content of C in all the maraging steels was adjusted to a range of 0.008% or less, thereby preventing a decrease in weldability. In addition, the Al content of the maraging steels No. 1, No. 2, and No. 7 exceeded the ...