Title:
STEEL HAVING SUPERIOR ROLLING FATIGUE LIFE
Document Type and Number:
WIPO Patent Application WO/2015/020169
Kind Code:
A1
Abstract:
Provided is a steel that is for a machine component, has a superior L1 life and rolling fatigue life, and of which in the steel, the oxygen, sulfur, and Al content, and the average compositional ratio and number percentage among all the oxides of MgO-Al2O3 oxides are stipulated. The steel is used in a machine component having a surface hardness of at least 58 HRC, has in the steel an oxygen content by mass ratio of no greater than 8 ppm, a sulfur content of no greater than 0.008 mass%, and an Al content of 0.005-0.030 mass%, and is such that the number of non-metallic inclusions having an inclusion size of at least 20 μm and less than 100 μm detected for every 1000 mm3 of volume of the steel material by means of an ultrasonic inspection method is no greater than 12.0, the number of non-metallic inclusions having an inclusion size of at least 100 μm detected for every 2.5 kg of the weight of the steel material by means of an ultrasonic inspection method is no greater than 2.0, the mass% ratio (MgO)/(Al2O3) in the average composition of the MgO-Al2O3 oxides present in the steel is stipulated to be in the range of 0.25-1.50, the number ratio of MgO-Al2O3 oxides among all the oxide inclusions is at least 70%, and the rolling fatigue life is excellent.
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Inventors:
FUJIMATSU TAKESHI (JP)
TSUNEKAGE NORIMASA (JP)
TAKASU ICHIRO (JP)
TSUNEKAGE NORIMASA (JP)
TAKASU ICHIRO (JP)
Application Number:
PCT/JP2014/070936
Publication Date:
February 12, 2015
Filing Date:
August 07, 2014
Export Citation:
Assignee:
SANYO SPECIAL STEEL CO LTD (JP)
International Classes:
C22C38/00; C21C7/00; C21C7/04; C22C38/38; C22C38/58
Foreign References:
| JP2004323938A | 2004-11-18 | |||
| JP2007224413A | 2007-09-06 | |||
| JP2013185250A | 2013-09-19 | |||
| JP2013253314A | 2013-12-19 |
Attorney, Agent or Firm:
KATSUNUMA Hirohito et al. (JP)
Katsunuma Hirohito (JP)
Katsunuma Hirohito (JP)
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