Global Patent Index - EP 0884399 A1

EP 0884399 A1 19981216 - Process for the manufacturing of a steel spring, the obtained product and the steel used for manufacturing said spring

Title (en)

Process for the manufacturing of a steel spring, the obtained product and the steel used for manufacturing said spring

Title (de)

Verfahren zur Herstellung einer Stahlfeder, Stahlfeder und Stahl zur Herstellung der Stahlfeder

Title (fr)

Procédé de fabrication d'un ressort en acier, ressort obtenu et acier pour la fabrication d'un tel ressort

Publication

EP 0884399 A1 19981216 (FR)

Application

EP 98401309 A 19980602

Priority

FR 9706848 A 19970604

Abstract (en)

Steel for making nitride-coated springs comprises by weight 0.57-0.6% carbon, 1.5-1.6% silicon, 0.65-0.7% manganese, 0.7-0.8% chromium, 0.05-0.08% molybdenum and 0.15-0.2% vanadium, plus iron and impurities. Also claimed is a spring made from wire drawn from that steel which has a nitride surface layer over 150 mu m thick. At least the outer 20 mu m contains over 0.4% nitrogen, the layer having a superficial hardness of over 64 HRC while the hardness of the spring interior is over 50 HRC and the layer is free of white epsilon nitrides. Also claimed is the manufacture of a spring from steel wire containing 0.4-0.7% C, 1-1.7% Si, 0.4-1% Mn, 0.3-1% Cr, 0-0.2% Mo and 0-0.2% V, plus Fe and impurities. The wire is tempered at temperature (T) up to 500 degrees C and exhibits a tensile strength of at least 1990 MPa. The spring is given a nitride surface layer by heating below temperature T, and the layer contains over 0.4% N in at least its outer surface 20 mu m and is free of white epsilon nitrides.

IPC 1-7

C22C 38/22; C22C 38/24; C23C 8/26; C23C 8/50

IPC 8 full level

C22C 38/22 (2006.01); C22C 38/24 (2006.01); C23C 8/02 (2006.01); C23C 8/26 (2006.01)

CPC (source: EP)

C22C 38/22 (2013.01); C22C 38/24 (2013.01); C23C 8/02 (2013.01); C23C 8/26 (2013.01)

Citation (search report)

  • [A] US 5310521 A 19940510 - ASSEIRO ANTHONY M [CA], et al
  • [A] US 5183634 A 19930202 - ABE TSUYOSHI [JP], et al
  • [A] EP 0694621 A1 19960131 - TOGO SEISAKUSHO KK [JP], et al
  • [A] GB 2210299 A 19890607 - NISSAN MOTOR [JP], et al
  • [A] DE 3130914 A1 19820616 - AICHI STEEL WORKS LTD [JP], et al
  • [Y] PATENT ABSTRACTS OF JAPAN vol. 095, no. 010 30 November 1995 (1995-11-30)
  • [Y] PATENT ABSTRACTS OF JAPAN vol. 18, no. 604 (C - 1275) 17 November 1994 (1994-11-17)
  • [Y] PATENT ABSTRACTS OF JAPAN vol. 95, no. 4 31 May 1995 (1995-05-31)
  • [Y] PATENT ABSTRACTS OF JAPAN vol. 95, no. 10 30 November 1995 (1995-11-30)

Designated contracting state (EPC)

AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE

DOCDB simple family (publication)

EP 0884399 A1 19981216; EP 0884399 B1 20020814; AT E222299 T1 20020815; DE 69807155 D1 20020919; DE 69807155 T2 20030508; DK 0884399 T3 20021209; ES 2182243 T3 20030301; FR 2764219 A1 19981211; FR 2764219 B1 19990716; PT 884399 E 20021129

DOCDB simple family (application)

EP 98401309 A 19980602; AT 98401309 T 19980602; DE 69807155 T 19980602; DK 98401309 T 19980602; ES 98401309 T 19980602; FR 9706848 A 19970604; PT 98401309 T 19980602