High-strength spring steel excellent in brittle fracture...

Details High-strength spring steel excellent in brittle fracture... High-strength spring steel excellent in brittle fracture...

2007-01-23

2011-10-18

King, Roy (Department: 1733)

Alloys or metallic compositions

Ferrous

Chromium containing, but less than 9 percent

C420S083000, C420S084000, C420S115000, C420S117000, C148S328000, C148S331000, C148S333000, C148S504000, C148S580000, C148S908000

Reexamination Certificate

active

08038934

ABSTRACT:
A spring steel having a high strength of 1900 MPa or more and superior in the brittle fracture resistance, as well as a method for manufacturing the same, are provided.The high strength spring steel comprises, as basic components in mass %, C: 0.4-0.6%, Si: 1.4-3.0%, Mn: 0.1-1.0%, Cr: 0.2-2.5%, P: 0.025% or less, S: 0.025% or less, N: 0.006% or less, Al: 0.1% or less, and O: 0.003% or less, the amount of solute C being 0.15% or less, the amount of Cr contained as a Cr-containing precipitate being 0.10% or less, and a TS value represented by the following equation being 24.8% or more, and in point of structure, the pre-austenite grain diameter being 10 μm or smaller, wherein TS=28.5*[C]+4.9*[Si]+0.5*[Mn]+2.5*[Cr]+1.7*[V]+3.7*[Mo] where [X] stands for mass % of element X.

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