Steel for carburized parts

Abstract

To provide steel materials for carburized parts that can obtain excellent fatigue strength even when the parts are produced by welding before carburizing. The steel material of the present disclosure has C: 0.09-0.16%, Si: 0.01-0.50%, Mn: 0.40-0.60%, P: 0.030% or less, S: 0.025% or less, Cr: 0.90-2.00%, Mo: 0.10 to 0.40%, Al: 0.005 to 0.030%, Ti: 0.010% to less than 0.050%, Nb: 0.010 to 0.030%, N: 0.0080% or less, O: 0.0030% or less, B: 0.0003 to 0.0030%, Ca: 0.0005% to 0.0050%, and the balance: Fe and impurities, and satisfy the chemical composition of formula (1) to formula (3) described in the specification. In the section parallel to the axial direction of the steel, the Mn sulfide is 70.0 / mm 2 Below, 25.0 oxides / mm 2 the following.

Description

technical field [0001] The present invention relates to steel materials, and more specifically, to steel materials used for carburized parts. Background technique [0002] Steel materials used for machine structural parts generally contain Mn, Cr, Mo, Ni, etc. in combination. Among the machine structural parts, there are carburized parts. Steel materials used for carburized parts have the chemical composition described above and are produced by casting, forging, rolling, or the like. Hereinafter, in this specification, a carburized part will be referred to as a "carburized part". [0003] A carburized part is produced, for example, by the following method. For steel materials, intermediate products are produced by machining such as forging and cutting. Carburizing is performed on intermediate products to manufacture carburized parts including a carburized layer, which is a hardened layer on the surface, and a core, which is a base material that is not affected by carburi...

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Problems solved by technology

In addition, when forming steel materials into complex shapes, there are problems such as cracks in the parts where large processing is applied.

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