Rolling member and producing method thereof

Abstract

The present invention provides a rotating component with excellent dent resistance, spalling resistance, and dedendum bending strength and a manufacturing method thereof. The rotating component according to the present invention includes: formed on the surface layer with a concentration of 0.35 to 0.8% by weight The martensite phase in which carbon is solid-dissolved is the first quench-hardened layer as the parent phase, and the martensite and shellfish in which 0.07 to 0.3% by weight of carbon is solid-dissolved are formed on a layer deeper than the first quench-hardened layer. A second quench hardened layer in which at least one of the tenite phases serves as a parent phase and 2 to 20% by volume of cementite is dispersed.

Description

technical field [0001] The present invention relates to a rotating member used in gear members, bearing members, camshaft members, etc. that require wear resistance, surface pressure resistance strength, and high fatigue strength in construction machinery and the like, and a manufacturing method thereof. Background technique [0002] In the high-frequency quenching method applied to steel, usually, the current induced by the current of 1-400kHz frequency on the surface layer of the applied part is used to heat and then cool, so that a hard martensite phase is formed on the surface layer. It is a very widely used surface hardening technology. This method is used in the manufacture of gears, shafts, crankshafts, camshafts, etc. that require properties such as sliding properties, wear resistance, and high strength. [0003] exist Figure 25 In , a typical induction hardening method for gears is shown (see Non-Patent Document 1, p258). Among them, the primary quenching of all ...

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Problems solved by technology

In low-alloy steels that further contain alloying elements such as Ni, Cr, and Mo, since the hardenability of high-frequency quenching is high, in order to use steel materials with lower carbon concentrations, compared with gears after carburizing and quenching, Its surface hardness is insufficient, for example, there is a problem that it cannot fully meet the requirements for surface pressure resistance, wear resistance, burn resistance, and high strength (see Non-Patent Document 1, p110, Table 2.38, Table 2 39)

[0007] Furthermore, in the aforementioned Figure 26 In the case of forming a quench-hardened layer along the tooth profile as shown, the deep part of the quench-hardened layer (for example, the heat-affected zone) becomes the structure before quenching, which is a soft (iron) structure suitable for machining Element body + cementite) structure (usually, Vickers hardness (Vickers hardness) is Hv160-260), compared with the hardness (Hv260-500) at the deep part of the carburized steel hardened layer of carburized and quenched gear components, it cannot get enough hardness

Therefore, there are problems of insufficient dent resistance (surface pressure resistance) and spallation resistance

In addition, since the soft base part is exposed on the end surface of the tooth part, there is a problem of insufficient strength.

[0008] In addition, since significant tensile residual stress occurs at the interface between the induction hardened layer and the base portion, there is a problem that the spallation resistance of the tooth surface is insufficient.

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