Steel material

Patent metadata

Field	Value
Publication number	US-12435401-B2
Application number	US-202117995368-A
Country	US
Kind code	B2
Filing date	Apr 15, 2021
Priority date	Apr 15, 2020
Publication date	Oct 7, 2025
Grant date	Oct 7, 2025

Abstract

The steel material according to the present disclosure consists of, in mass %, C: 0.15 to 0.45%, Si: 0.05 to 1.00%, Mn: 0.05 to less than 0.80%, P: 0.030% or less, S: 0.0100% or less, Al: 0.100% or less, Cr: 0.30 to 1.50%, Mo: 0.25 to 2.00%, Ti: 0.001 to 0.015%, N: 0.0100% or less, O: 0.0050% or less, V: 0 to 0.05%, Nb: 0 to 0.010%, B: 0 to less than 0.0005%, Ca: 0 to 0.0100%, Mg: 0 to 0.0100%, and rare earth metal: 0 to 0.0100%, with the balance being Fe and impurities. In the steel material, the grain size number of prior-austenite grains is less than 7.0, Formula (1) to Formula (4) described in the specification are satisfied, the yield strength is 896 MPa or more, and the absorbed energy at −10° C. is 95 J or more.

First claim

The invention claimed is:

1. A steel material consisting of, in mass %,
C: 0.15 to 0.45%,
Si: 0.05 to 1.00%,
Mn: 0.05 to less than 0.80%,
P: 0.030% or less,
S: 0.0100% or less,
Al: 0.100% or less,
Cr: 0.30 to 1.50%,
Mo: 0.25 to 2.00%,
Ti: 0.001 to 0.015%,
N: 0.0100% or less,
O: 0.0050% or less,
V: 0 to 0.05%,
Nb: 0 to 0.010%,
B: 0 to less than 0.0005%,
Ca: 0 to 0.0100%,
Mg: 0 to 0.0100%,
rare earth metal: 0 to 0.0100%,
Ni: 0 to 0.50%, and
Cu: 0 to 0.50%,
with the balance being Fe and impurities,
wherein:
a grain size number of prior-austenite grains is less than 7.0;
on a precondition that a content of each element is within a range described above, Formula (1) to Formula (4) are satisfied;
a yield strength is 896 MPa or more; and
an absorbed energy at −10° C. is 95 J or more:
{C+Mn/5+(Cu+Ni)/15+(Cr+Mo+V)/5+10×B}×(7.0/GN) 0.45 ≥0.678  (1)

{Mn/5.5+10×Ti+1.2×V+15×Nb+200×B}×(7.0/GN) 0.45 ≤0.240  (2)

10×Ti+V+10×Nb≥0.015  (3)

(10×Ti+1.2×V+30×Nb)/Mo≤0.205  (4)

where, a content in mass % of a corresponding element is substituted for each symbol of an element, and the grain size number is substituted for “GN”.

2. The steel material according to claim 1 , wherein:
a number density of Mn sulfides having an equivalent circular diameter of 5.0 μm or more is 10/100 mm 2 or less; and
an absorbed energy at −10° C. is 100 J or more.

3. The steel material according to claim 1 , containing one or more types of element selected from the group consisting of:
V: 0.01 to 0.05%,
Nb: 0.001 to 0.010%,
B: 0.0001 to less than 0.0005%,
Ca: 0.0001 to 0.0100%,
Mg: 0.0001 to 0.0100%,
rare earth metal: 0.0001 to 0.0100%,
Ni: 0.01 to 0.50%, and
Cu: 0.01 to 0.50%.

4. The steel material according to claim 2 , containing one or more types of element selected from the group consisting of:
V: 0.01 to 0.05%,
Nb: 0.001 to 0.010%,
B: 0.0001 to less than 0.0005%,
Ca: 0.0001 to 0.0100%,
Mg: 0.0001 to 0.0100%,
rare earth metal: 0.0001 to 0.0100%,
Ni: 0.01 to 0.50%, and
Cu: 0.01 to 0.50%.

5. The steel material according to claim 1 , wherein:
the steel material is an oil-well steel pipe.

6. The steel material according to claim 2 , wherein:
the steel material is an oil-well steel pipe.

7. The steel material according to claim 3 , wherein:
the steel material is an oil-well steel pipe.

8. The steel material according to claim 4 , wherein:
the steel material is an oil-well steel pipe.

Assignees

• Nippon Steel Corp

Inventors

• Kondo Keiichi
• Arai Yuji
• Nakamura Keiichi
• Oe Taro
• Kuramoto Takenori
• Takeda Yosuke
• Kamitani Hiroki

Classifications

• C21D8/10

  during manufacturing of tubular bodies · CPC title

• C22C38/50

  with titanium or zirconium · CPC title

• C22C38/48

  with niobium or tantalum · CPC title

• C22C38/46

  with vanadium · CPC title

• C22C38/44

  with molybdenum or tungsten · CPC title