Steel for nitriding and nitrided steel components

Abstract

Provided is a steel for nitriding, which has a reduced strength before nitriding and therefore exhibits improved machinability. In the steel for nitriding, addionally, a nitrided layer with a large effective case depth can be formed for the purpose of improving the fatigue strength. A steel for nitriding, characterized by containing by mass 0.05 to 0.30% of C, 0.003 to 0.50% of Si, 0.4 to 3.0% of Mn, 0.2 to 0.9% of Cr, 0.19 to 0.70% of Al, 0.05 to 1.0% of V, and 0.05 to 0.50% of Mo, the contents of Al and Cr satisfying the relationship: 0.5% <= 1.9Al + Cr <= 1.8%, and the balance being Fe and unavoidable impurities.

Description

technical field [0001] The present invention relates to a steel for nitriding which secures workability and strength and has a hard nitrided layer obtained by nitriding treatment such as gas nitriding, plasma nitriding, gas nitrocarburizing, and salt bath nitrocarburizing, and A nitriding-treated part having a hard nitrided layer on the surface layer of the nitriding-treated steel. Background technique [0002] In automobiles and various industrial machines, surface hardened parts are widely used for the purpose of improving fatigue strength. Typical surface hardening methods include carburizing, nitriding, induction hardening, and the like. Nitriding treatments such as gas nitriding, plasma nitriding, gas nitrocarburizing, and salt bath nitrocarburizing are performed at a low temperature below the transformation point unlike other methods, and thus have the advantage of being able to reduce heat treatment strain. [0003] Gas nitriding in an ammonia atmosphere in the nitr...

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Problems solved by technology

[0003] Gas nitriding in an ammonia atmosphere in the nitriding treatment can obtain high surface hardness, but the diffusion of nitrogen is slow, and usually requires more than 20 hours of treatment time

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