Carburized steel part having excellent low cycle bending fatigue strength

Patent metadata

Field	Value
Publication number	US-9469883-B2
Application number	US-201314014983-A
Country	US
Kind code	B2
Filing date	Aug 30, 2013
Priority date	May 13, 2009
Publication date	Oct 18, 2016
Grant date	Oct 18, 2016

Abstract

A carburized steel part having excellent low cycle bending fatigue strength which is comprised of a steel material which contains, by mass %, C: 0.1 to 0.6%, Si: 0.01 to 1.5%, Mn: 0.3 to 2.0, P: 0.02% or less, S: 0.001 to 0.15%, N: 0.001 to 0.03%, Al: 0.001 to 0.06%, and O: 0.005% or less and has a balance of substantially iron and unavoidable impurities and which is carburized and quenched, and then tempered, which steel part has a surface hardness of HV550 to HV800 and a core hardness of HV400 to HV500.

First claim

The invention claimed is:

1. A carburized steel part having excellent low cycle bending fatigue strength which is comprised of a steel material consisting of, by mass %,
C: 0.45 to 0.6%,
Si: 0.06 to 1.5%,
Mn: 0.3 to 2.0%,
P: 0.02% or less,
S: 0.001 to 0.15%,
N: 0.001 to 0.03%,
Al: 0.001 to 0.06%,
Ti: 0.01 to 0.2%,
B: 0.0002 to 0.005%,
Cr: 1.2 to 3.0%,
Ca: 0.0002 to 0.005%,
O: 0.005% or less and
Cu: 0.1 to 2.0, and
one or both of Nb: 0.01 to 0.2% and V: 0.03 to 0.2%, and
a balance of substantially iron and unavoidable impurities,
wherein the steel material which is carburized, quenched, and then tempered,
wherein said carburized steel part has a surface hardness of HV550 to HV800, and a core hardness of HV400 to HV500.

2. The carburized steel part having excellent low cycle bending fatigue strength as set forth in claim 1 , wherein said low cycle bending fatigue strength is 20 kN or more.

3. The carburized steel part having excellent low cycle bending fatigue strength as set forth in claim 1 , wherein said carburized steel part is a differential gear or transmission gear.

4. The carburized steel part having excellent low cycle bending fatigue strength as set forth in claim 2 , wherein said carburized steel part is a differential gear or transmission gear.

Assignees

• Nippon Steel & Sumitomo Metal Corp
• Sanyo Special Steel Co Ltd

Inventors

• Kozawa Shuji
• Kubota Manabu
• Kada Osamu
• Nishikawa Motohiro
• Tanaka Takashi
• Tsunekage Norimasa

Classifications

• C21D9/32

  for gear wheels, worm wheels, or the like · CPC title

• C21D2211/004

  Dispersions; Precipitations · CPC title

• C22C38/002

  containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60 · CPC title

• C23C8/22

  of ferrous surfaces · CPC title

• C21D1/68 Primary

  Temporary coatings or embedding materials applied before or during heat treatment · CPC title