SPRING AND METHOD FOR PRODUCING SAME

WIPO Patent Application WO/2012/133885

A1

Provided are: a spring that has a high compressive residual stress layer having increased fatigue resistance and that has increased simplicity of the production process and decreased materials cost; and a method for producing the spring. The following are performed in order: a formation step for forming a spring shape in a steel material having the components by mass% of 0.5-0.7% of C, 1.0-2.0% of Si, 0.1-1.0% of Mn, 0.1-1.0% of Cr, no greater than 0.035% of P, and no greater than 0.035% of S, the remainder comprising iron and unavoidable impurities; a heat treatment step for austenitizing at a temperature of the Ac3 point to (Ac3 point + 250°C), then cooling at a rate of at least 20°C/second, isothermally holding for at least 400 seconds at a temperature of (Ms point - 20°C) to (Ms point + 60°C), and then cooling to room temperature at a cooling rate of at least 20°C/second; a setting step for imparting a permanent strain; and a shot peening step for projecting shot.

KUROKAWA SHIMPEI (JP)
SUZUKI TAKESHI (JP)
ONO YOSHIKI (JP)
TAKAMURA NORITOSHI (JP)
YAMAMOTO FUMIO (JP)

PCT/JP2012/058876

October 04, 2012

April 02, 2012

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NHK SPRING CO LTD (JP)
KUROKAWA SHIMPEI (JP)
SUZUKI TAKESHI (JP)
ONO YOSHIKI (JP)
TAKAMURA NORITOSHI (JP)
YAMAMOTO FUMIO (JP)

C21D9/02; B21F35/00; C21D7/00; C21D7/06; C22C38/00; C22C38/34; F16F1/02

JPS63312917A	1988-12-21
JP2010222671A	2010-10-07
JP2007154240A	2007-06-21
JP2000345238A	2000-12-12
JP2012036429A	2012-02-23

SUENARI, Mikio (JP)
End 成 Mikio (JP)

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