EP 3831970 B1 20230510 - SPRING STEEL HAVING SUPERIOR FATIGUE LIFE, AND MANUFACTURING METHOD FOR SAME
Title (en)
SPRING STEEL HAVING SUPERIOR FATIGUE LIFE, AND MANUFACTURING METHOD FOR SAME
Title (de)
FEDERSTAHL MIT VERBESSERTER ERMÜDUNGSLEBENSDAUER UND VERFAHREN ZU SEINER HERSTELLUNG
Title (fr)
ACIER À RESSORT PRÉSENTANT UNE DURÉE DE VIE EN FATIGUE SUPÉRIEURE, ET SON PROCÉDÉ DE FABRICATION
Publication
Application
Priority
- CN 201810842312 A 20180727
- CN 2019096726 W 20190719
Abstract (en)
[origin: EP3831970A1] A spring steel having a superior fatigue life, and a manufacturing method for the same. The chemical components thereof are as follows in weight percentage: C: 0.52-0.62%, Si: 1.20-1.45%, Mn: 0.25-0.75%, Cr: 0.30-0.80%, V: 0.01-0.15%, Nb: 0.001-0.05%, N: 0.001-0.009%, O: 0.0005-0.0040%, P: ≤ 0.015%, S: ≤ 0.015%, and Al: ≤ 0.0045%, with the remainder being Fe and incidental impurities, wherein the following condition is also met 0.02 ≤ (2Nb+V)/(20N+C) ≤ 0.40. The spring steel of the present invention has a microstructure of tempered troostite + tempered sorbite, a prior austenite grain size less than 80 um, a size of alloy nitride and carbide precipitates being 5-60 nm, and a maximum width of single-grain inclusions being less than 30 µm. The spring steel has a handling strength greater than 2020 MPa, superior ductility and toughness (the reduction of area ≥ 40%), and a fatigue life ≥ 800,000 times, thereby meeting application requirements of high-stress springs in industries, such as automobiles, machinery, and the like.
IPC 8 full level
B21C 1/00 (2006.01); B22D 11/12 (2006.01); B22D 11/20 (2006.01); C21C 7/072 (2006.01); C21C 7/10 (2006.01); C21D 1/25 (2006.01); C21D 1/58 (2006.01); C21D 1/60 (2006.01); C21D 8/06 (2006.01); C21D 9/02 (2006.01); C21D 9/52 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/24 (2006.01); C22C 38/26 (2006.01)
CPC (source: CN EP KR US)
B21C 1/003 (2013.01 - EP); B22D 11/1206 (2013.01 - EP); B22D 11/20 (2013.01 - EP); C21C 7/072 (2013.01 - EP); C21C 7/10 (2013.01 - CN EP KR); C21D 1/25 (2013.01 - EP); C21D 1/58 (2013.01 - EP); C21D 1/60 (2013.01 - EP); C21D 7/06 (2013.01 - KR); C21D 8/06 (2013.01 - EP); C21D 8/065 (2013.01 - CN KR US); C21D 9/02 (2013.01 - EP KR US); C21D 9/525 (2013.01 - EP); C21D 9/5737 (2013.01 - US); C22C 38/001 (2013.01 - EP KR); C22C 38/002 (2013.01 - EP US); C22C 38/02 (2013.01 - CN EP US); C22C 38/04 (2013.01 - CN EP); C22C 38/06 (2013.01 - US); C22C 38/24 (2013.01 - CN EP KR US); C22C 38/26 (2013.01 - CN EP KR US); C22C 38/60 (2013.01 - KR); C21D 9/562 (2013.01 - US); C21D 2211/001 (2013.01 - US); C22C 38/04 (2013.01 - US)
Designated contracting state (EPC)
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
DOCDB simple family (publication)
EP 3831970 A1 20210609; EP 3831970 A4 20210609; EP 3831970 B1 20230510; CN 110760748 A 20200207; CN 110760748 B 20210514; JP 2021530623 A 20211111; JP 7110480 B2 20220801; KR 20210036916 A 20210405; US 2021164078 A1 20210603; WO 2020020066 A1 20200130
DOCDB simple family (application)
EP 19841872 A 20190719; CN 201810842312 A 20180727; CN 2019096726 W 20190719; JP 2021503062 A 20190719; KR 20217001643 A 20190719; US 201917261457 A 20190719