Bolt, and steel material for bolts
AssigneeNippon Steel Corporation
InventorsShingo YAMASAKI, Miyuri UMEHARA, Toshiyuki MANABE
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Abstract
Provided are a bolt that exhibits excellent delayed fracture resistance at a high strength level of from 1,200 MPa to less than 1,600 MPa in tensile strength, where the possibility of delayed fracture is generally quite high, and a steel material for a bolt to be used as the material for such a bolt. The bolt has a composition satisfying Formulae (1) and (2), and a tensile strength of from 1,200 MPa to less than 1,600 MPa. In Formula (1) and Formula (2), Mo and V represent the contents (% by mass) of Mo and V contained in the steel for a bolt, respectively. 0.48≤Mo/1.4+V<1.10 (1) 0.8<Mo/V<3.0 (2)
Claims9
A bolt having a composition comprising, in terms of % by mass:
- C:
- from 0.35 to 0.45%,
- Si:
- from 0.02 to 0.10%,
- Mn:
- from 0.20 to 0.84%,
- Cr:
- from 0.60 to 1.15%,
- V:
- from 0.30 to 0.50%,
- Mo:
- from 0.25 to 0.99%,
- Al:
- from 0.010 to 0.100%,
- N:
- from 0.0010 to 0.0150%,
- P:
- 0.015% or less,
- S:
- 0.015% or less, and
- a balance consisting of Fe and impurities,
- wherein the bolt has a tensile strength of from 1,200 MPa to less than 1,600 MPa, and
- wherein the composition satisfies the following Formula (1) and the following Formula (2):
- 0.48≤Mo/1.4+V<1.10 (1)
- 0.80<Mo/V<3.00 (2)
- wherein in Formula (1) and Formula (2), Mo and V represent contents (% by mass) of Mo and V contained in the bolt, respectively.
Dependencies are inferred from the claim text.