Case-hardened steel with low heat treatment strain

A kind of steel, the smallest technology, applied in the direction of heat treatment furnace, heat treatment equipment, metal material coating process, etc., can solve the problems that cannot be achieved, and achieve the effect of less vibration, long fatigue life and high dimensional accuracy

Active Publication Date: 2016-01-20
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0014] However, the actual situation is that even if any of the above-mentioned methods and steels are used, it is impossible to achieve low-stress changes that meet the strict requirements of recent consumers.

Method used

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  • Case-hardened steel with low heat treatment strain
  • Case-hardened steel with low heat treatment strain
  • Case-hardened steel with low heat treatment strain

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Embodiment Construction

[0056] In this specification, the present invention will be described mainly for application to gears, but the case-hardened steel material of the present invention is not limited to application to gears, and can be applied to mechanical parts whose surface layers are hardened by the above-mentioned quenching treatment. , especially mechanical parts that are strictly required to reduce the amount of strain after carburizing and nitriding quenching.

[0057] As described above, in order to solve the problems of the present invention and achieve the object of the present invention, the present inventors first carefully investigated the factors affecting heat treatment strain. As a result, it was found that in the macrostructure (solidified structure) of the cross section of the steel material, the following (a), (b), (c), etc. greatly affect the heat treatment strain:

[0058] (a) Decrease in C concentration;

[0059] (b) the area and area ratio of the equiaxed domains where th...

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Abstract

This case hardened steel has a composition including, in mass %: C: 0.05 to 0.45%; Si: 0.01 to 1.0%; Mn: over 0 to 2.0%; Al: 0.001 to 0.06%, N: 0.002 to 0.03%, S: over 0 to 0.1%, P: over 0 to 0.05%; and balance: Fe and inevitable impurities. Equation (1) described below and Equation (2) described below are satisfied in equiaxed zone, or Equation (3) described below is satisfied in columnar zone. Re=(Ae / Ao)×100≰30%  Equation (1) (Cmin,1 / Co)≧0.95  Equation (2) (Cmin,2 / Co)≧0.95  Equation (3)

Description

technical field [0001] The present invention relates to a case-hardened steel material whose surface layer is hardened by carburizing, carbonitriding or carbonitriding (hereinafter sometimes referred to as "carburizing and nitriding") quenching treatment. This case-hardened steel material is particularly useful as a material for mechanical parts such as gears, shafts, and constant velocity joints of automobiles that require high levels of wear resistance and fatigue resistance. [0002] This application claims priority based on Patent Application No. 2012-014474 for which it applied to Japan on January 26, 2012, The content is used for this application. Background technique [0003] In recent years, from reducing CO 2 From the viewpoint of emission reduction and promotion of energy saving, it is required to reduce the body weight of transportation machines including automobiles and motorcycles, and to improve fuel efficiency. As part of measures to reduce the weight of veh...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/06C22C38/60
CPCC22C38/60C21D1/06C21D1/18C21D6/00C21D9/32C22C38/001C22C38/002C22C38/005C22C38/008C22C38/02C22C38/04C22C38/06C22C38/08C22C38/12C22C38/14C22C38/16C22C38/18C22C38/38C23C8/02
Inventor 矶部浩一土江雅彦
Owner NIPPON STEEL CORP
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