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US 12,655,505 B2Granted
Mechanical structure steel for cold-working and manufacturing method therefor
AssigneeKobe Steel, Ltd.
InventorsKoji Yamashita, Shogo Murakami, Masayuki Sakata, Masamichi Chiba
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Abstract
Disclosed is a mechanical structure steel for cold-working, including: C: 0.32 to 0.44% by mass, Si: 0.15 to 0.35% by mass, Mn: 0.55 to 0.95% by mass, P: 0.030% by mass or less, S: 0.030% by mass or less, Cr: 0.85 to 1.25% by mass, Mo: 0.15 to 0.35% by mass, and Al: 0.01 to 0.1% by mass, with the balance consisting of iron and inevitable impurities, wherein an area ratio of proeutectoid ferrite is 30% or more and 70% or less, and an average grain size of ferrite crystal grains is 5 to 15 μm.
Claims9
A mechanical structure steel, comprising:
- C:
- 0.32 to 0.44% by mass,
- Si:
- 0.15 to 0.35% by mass,
- Mn:
- 0.55 to 0.95% by mass,
- P:
- 0.030% by mass or less,
- S:
- 0.030% by mass or less,
- Cr:
- 0.85 to 1.25% by mass,
- Mo:
- 0.15 to 0.35% by mass, and
- Al:
- 0.01 to 0.1% by mass,
- with a balance being iron and inevitable impurities, wherein
- a microstructure of the mechanical structure steel includes proeutectoid ferrite and bainite,
- an area ratio of proeutectoid ferrite is greater than 35% and 70% or less, and
- an average grain size of ferrite crystal grains is 5 to 13.2 μm.
17 more elements
Dependencies are inferred from the claim text.