# US 10,500,817 B2 · Electron-beam welded joint, steel for electron-beam welding, and method of manufacturing the same

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- Number: US 10,500,817 B2
- Document ID: US10500817B2
- Status: Granted
- Kind: B2
- Application number: 13/877,470
- Filed: 2011-10-27
- Published: 2013-07-25
- Granted: 2019-12-10
- Earliest claimed: 2010-11-22
- Assignees: Nippon Steel Corporation
- Applicants: Ryuichi Honma; Ryuji Uemori; Tadashi Ishikawa; Akihiko Kojima; Manabu Hoshino
- Inventors: Ryuichi Honma; Ryuji Uemori; Tadashi Ishikawa; Akihiko Kojima; Manabu Hoshino
- Web page: https://patentgrep.com/patent/US10500817B2

## CPC

- B32B 15/011: {all layers being formed of iron alloys or steels}
- B23K 35/0222: {for use in soldering or brazing (B23K35/0205 takes precedence)}
- B23K 35/3053: {Fe as the principal constituent}
- B23K 35/3073: {with Mn as next major constituent}
- B32B 15/015: {the said other metal being copper or nickel or an alloy thereof}
- C22C 38/001: {containing N}
- C22C 38/002: {containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60}
- C22C 38/02: containing silicon
- C22C 38/04: containing manganese
- C22C 38/08: containing nickel {(C22C38/105 takes precedence)}
- C22C 38/12: containing tungsten, tantalum, molybdenum, vanadium, or niobium
- C22C 38/14: containing titanium or zirconium
- C22C 38/16: containing copper
- Y10T 428/12222: Shaped configuration for melting [e.g., package, etc.]
- Y10T 428/12965: Both containing 0.01-1.7% carbon [i.e., steel]
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A steel for electron-beam welding according to the present invention includes at least C: 0.02% to 0.10%, Si: 0.03% to 0.30%, Mn: 1.5% to 2.5%, Ti: 0.005% to 0.015%, N: 0.0020% to 0.0060%, and O: 0.0010% to 0.0035%, further includes S: limited to 0.010% or less, P: limited to 0.015% or less, and Al: limited to 0.004% or less, with a balance including iron and inevitable impurities. An index value CeEBB obtained by substituting composition of the steel into following Formula 1 falls in the range of 0.42 to 0.65%, the number of oxide having an equivalent circle diameter of 1.0 μm or more is 20 pieces/mm2 or less at a thickness center portion in cross section along the thickness direction of the steel, and the number of oxide containing Ti of 10% or more and having an equivalent circle diameter of not less than 0.05 μm or more and less than 0.5 μm falls in the range of 1×103 to 1×105 pieces/mm2 at the thickness center portion. CeEBB=C+¼Mn+ 1/15Cu+ 1/15Ni+⅕Cr+⅕Mo+⅕V (Formula 1)

## Claims

### Claim 1

An electron-beam welded joint having a welded metal and obtained by applying an electron beam to a steel, the steel having a composition including, by mass %:
C: 0.049% to 0.10%;
Si: 0.08% to 0.30%;
Mn: 1.5% to 2.5%;
Ti: 0.005% to 0.015%;
N: 0.0020% to 0.0060%;
O: 0.0010% to 0.0035%;
Nb: 0% to 0.020%;
V: 0% to 0.030%;
Cr: 0% to 0.50%;
Mo: 0% to 0.50%;
Cu: 0% to 0.25%;
Ni: 0% to 0.50%;
B: 0% to 0.0030%;
S: limited to not more than 0.010%;
P: limited to not more than 0.015%; and
Al: limited to not more than 0.004%,
with a balance including iron and inevitable impurities, wherein
an index value CeEBB obtained by substituting the composition of the steel into following Formula 1 falls in the range of 0.42% to 0.65%,
a number of oxides having an equivalent circle diameter of not less than 1.0 μm is not more than 20 pieces/mm2 at a thickness center portion in cross section along a thickness direction of the steel,
a number of oxides containing Ti of not less than 10% and having an equivalent circle diameter of not less than 0.05 μm and less than 0.5 μm falls in the range of 3.9×103 to 1×105 pieces/mm2 in the thickness center portion,
the welded metal has a composition including, by mass %:
C: 0.049% to 0.10%;
Si: 0.08% to 0.30%;
Mn: 1.2% to 2.4%;
Ni: 1.0% to 2.3%;
Ti: 0.005% to 0.015%;
N: 0.0020% to 0.0060%;
O: 0.0004% to 0.0020%;
Nb: 0% to 0.020%;
V: 0% to 0.030%;
Cr: 0% to 0.50%;
Mo: 0% to 0.50%;
Cu: 0% to 0.25%;
B: 0% to 0.0030%;
S: limited to not more than 0.010%;
P: limited to not more than 0.015%; and
Al: limited to not more than 0.004%,
with a balance including iron and inevitable impurities,
an index value CeEBW obtained by substituting the composition of the welded metal into following Formula 2 falls in the range of 0.56 to 0.73%,
CeEBB=C+¼Mn+ 1/15Cu+ 1/15Ni+⅕Cr+⅕Mo+⅕V (Formula 1)
where C, Mn, Cu, Ni, Cr, Mo, and V represent mass % of elements contained in the composition of the steel,
CeEBW=C+¼Mn+ 1/15Cu+ 1/15Ni+⅕Cr+⅕Mo+⅕V (Formula 2)
where C, Mn, Cu, Ni, Cr, Mo, and V represent mass % of elements contained in the composition of the welded metal, and
a yield point of the steel is 315 MPa to 380 MPa.

### Claim 2 (depends on 1)

The electron-beam welded joint according to claim 1, wherein
a C/CeEBB, which is a ratio of the amount of C by mass % in the steel relative to the index value CeEBB, falls in the range of 0.02 to 0.15.

### Claim 3 (depends on 1)

The electron-beam welded joint according to claim 1, wherein
the steel has a thickness in the range of 45 to 150 mm.

### Claim 4 (depends on 1)

The electron-beam welded joint according to claim 1, satisfying
0.8≤δBM/δWM≤1.25, and
0.5≤δHAZ/δWM≤1.1, where
δWM is a CTOD value of the welded metal,
δHAZ is a CTOD value of a weld heat-affected zone, and
δBM is a CTOD value of the steel.

### Claim 5 (depends on 1)

The electron-beam welded joint according to claim 1, wherein
the amount of O is 0.0010% to 0.0025% in the steel.

### Claim 6 (depends on 1)

The electron-beam welded joint according to claim 1, wherein
the amount of Nb is 0% to 0.003% in the steel.

### Claim 7 (depends on 1)

The electron-beam welded joint according to claim 1, wherein
the amount of O is 0.0004% to 0.0018% in the welded metal.

### Claim 8

A steel for electron-beam welding having a composition including by mass %:
C: 0.049% to 0.10%;
Si: 0.08% to 0.30%;
Mn: 1.5% to 2.5%;
Ti: 0.005% to 0.015%;
N: 0.0020% to 0.0060%;
O: 0.0010% to 0.0035%;
Nb: 0% to 0.020%;
V: 0% to 0.030%;
Cr: 0% to 0.50%;
Mo: 0% to 0.50%;
Cu: 0% to 0.25%;
Ni: 0% to 0.50%;
B: 0% to 0.0030%;
S: limited to not more than 0.010% or less;
P: limited to not more than 0.015% or less; and
Al: limited to not more than 0.004%or less;
with a balance including iron and inevitable impurities, wherein
an index value CeEBB obtained by substituting the composition of the steel into following Formula 1 falls in the range of 0.42 to 0.65%,
a number of oxides having an equivalent circle diameter of not less than 1.0 μm is not more than 20 pieces/mm2 at a thickness center portion in cross section along a thickness direction of the steel,
a number of oxides containing Ti of not less than 10% and having an equivalent circle diameter of not less than 0.05 μm and less than 0.5 μm falls in the range of 3.9×103 to 1×105 pieces/mm2 at the thickness center portion,
CeEBB=C+¼Mn+ 1/15Cu+ 1/15Ni+⅕Cr+⅕Mo+⅕V (Formula 1)
where C, Mn, Cu, Ni, Cr, Mo, and V represent mass % of elements in the composition of the steel, and
a yield point of the steel is 315 MPa to 380 MPa.

### Claim 9 (depends on 8)

The steel for electron-beam welding according to claim 8, wherein
a C/CeEBB, which is a ratio of the amount of C by mass % in the steel relative to the CeEBB, falls in the range of 0.02 to 0.15.

### Claim 10 (depends on 8)

The steel for electron-beam welding according to claim 8, wherein
the thickness of the steel falls in the range of 45 to 150 mm.

### Claim 11 (depends on 8)

The steel for electron-beam welding according to claim 8, wherein
the amount of O is 0.0010% to 0.0025%.

### Claim 12 (depends on 8)

The steel for electron-beam welding according to claim 8, wherein
the amount of Nb is 0% to 0.003%.

### Claim 13

An electron-beam welded joint having a welded metal and obtained by applying an electron beam to a steel, the steel having a composition including, by mass %:
C: 0.049% to 0.10%;
Si: 0.03% to 0.30%;
Mn: 1.5% to 2.5%;
Ti: 0.005% to 0.015%;
N: 0.0020% to 0.0060%;
O: 0.0010% to 0.0035%;
Nb: 0% to 0.003%;
V: 0% to 0.030%;
Cr: 0% to 0.50%;
Mo: 0% to 0.50%;
Cu: 0% to 0.25%;
Ni: 0% to 0.50%;
B: 0% to 0.0030%;
S: limited to not more than 0.010%;
P: limited to not more than 0.015%; and
Al: limited to not more than 0.004%,
with a balance including iron and inevitable impurities, wherein
an index value CeEBB obtained by substituting the composition of the steel into following Formula 1 falls in the range of 0.42% to 0.65%,
a number of oxides having an equivalent circle diameter of not less than 1.0 μm is not more than 20 pieces/mm2 at a thickness center portion in cross section along a thickness direction of the steel,
a number of oxides containing Ti of not less than 10% and having an equivalent circle diameter of not less than 0.05 μm and less than 0.5 μm falls in the range of 3.9×103 to 1×105 pieces/mm2 in the thickness center portion,
the welded metal has a composition including, by mass %:
C: 0.049% to 0.10%;
Si: 0.03% to 0.30%;
Mn: 1.2% to 2.4%;
Ni: 1.0% to 2.3%;
Ti: 0.005% to 0.015%
N: 0.0020% to 0.0060%;
O: 0.0004% to 0.0020%;
Nb: 0% to 0.003%;
V: 0% to 0.030%;
Cr: 0% to 0.50%;
Mo: 0% to 0.50%;
Cu: 0% to 0.25%;
B: 0% to 0.0030%;
S: limited to not more than 0.010%;
P: limited to not more than 0.015%; and
Al: limited to not more than 0.004%,
with a balance including iron and inevitable impurities,
an index value CeEBW obtained by substituting the composition of the welded metal into following Formula 2 falls in the range of 0.56 to 0.73%,
CeEBB=C+¼Mn+ 1/15Cu+ 1/15Ni+⅕Cr+⅕Mo+⅕V (Formula 1)
where C, Mn, Cu, Ni, Cr, Mo, and V represent mass % of elements contained in the composition of the steel,
CeEBW=C+¼Mn+ 1/15Cu+ 1/15Ni+⅕Cr+⅕Mo+⅕V (Formula 2)
where C, Mn, Cu, Ni, Cr, Mo, and V represent mass % of elements contained in the composition of the welded metal, and
a yield point of the steel is 315 MPa to 380 MPa.

### Claim 14 (depends on 13)

The electron-beam welded joint according to claim 13, wherein
a C/CeEBB, which is a ratio of the amount of C by mass % in the steel relative to the index value CeEBB, falls in the range of 0.02 to 0.15.

### Claim 15 (depends on 13)

The electron-beam welded joint according to claim 13, wherein
the steel has a thickness in the range of 45 to 150 mm.

### Claim 16 (depends on 13)

The electron-beam welded joint according to claim 13, satisfying
0.8≤δBM/δWM≤1.25, and
0.5≤δHAZ/δWM≤1.1, where
δWM is a CTOD value of the welded metal,
δHAZ is a CTOD value of a weld heat-affected zone, and
δBM is a CTOD value of the steel.

### Claim 17 (depends on 13)

The electron-beam welded joint according to claim 13, wherein
the amount of O is 0.0010% to 0.0025% in the steel.

### Claim 18 (depends on 13)

The electron-beam welded joint according to claim 13, wherein
the amount of Si is 0.08% to 0.30% in the steel.

### Claim 19 (depends on 13)

The electron-beam welded joint according to claim 13, wherein
the amount of O is 0.0004% to 0.0018% in the welded metal.

### Claim 20

A steel for electron-beam welding having a composition including by mass %:
C: 0.049% to 0.10%;
Si: 0.03% to 0.30%;
Mn: 1.5% to 2.5%;
Ti: 0.005% to 0.015%;
N: 0.0020% to 0.0060%;
O: 0.0010% to 0.0035%;
Nb: 0% to 0.003%;
V: 0% to 0.030%;
Cr: 0% to 0.50%;
Mo: 0% to 0.50%;
Cu: 0% to 0.25%;
Ni: 0% to 0.50%;
B: 0% to 0.0030%;
S: limited to not more than 0.010% or less;
P: limited to not more than 0.015% or less; and
Al: limited to not more than 0.004% or less;
with a balance including iron and inevitable impurities, wherein
an index value CeEBB obtained by substituting the composition of the steel into following Formula 1 falls in the range of 0.42 to 0.65%,
a number of oxides having an equivalent circle diameter of not less than 1.0 μm is not more than 20 pieces/mm2 at a thickness center portion in cross section along a thickness direction of the steel,
a number of oxides containing Ti of not less than 10% and having an equivalent circle diameter of not less than 0.05 μm and less than 0.5 μm falls in the range of 3.9×103 to 1×105 pieces/mm2 at the thickness center portion,
CeEBB=C+¼Mn+ 1/15Cu+ 1/15Ni+⅕Cr+⅕Mo+⅕V (Formula 1),
where C, Mn, Cu, Ni, Cr, Mo, and V represent mass % of elements in the composition of the steel, and
a yield point of the steel is 315 MPa to 380 MPa.

### Claim 21 (depends on 20)

The steel for electron-beam welding according to claim 20, wherein
a C/CeEBB, which is a ratio of the amount of C by mass % in the steel relative to the CeEBB, falls in the range of 0.02 to 0.15.

### Claim 22 (depends on 20)

The steel for electron-beam welding according to claim 20, wherein the thickness of the steel falls in the range of 45 to 150 mm.

### Claim 23 (depends on 20)

The steel for electron-beam welding according to claim 20, wherein the amount of O is 0.0010% to 0.0025%.

### Claim 24 (depends on 20)

The steel for electron-beam welding according to claim 20, wherein
the amount of Si is 0.08% to 0.30%.

### Claim 25

A method of manufacturing a steel for electron-beam welding having a composition including by mass %:
C: 0.02% to 0.10%;
Si: 0.03% to 0.30%;
Mn: 1.5% to 2.5%;
Ti: 0.005% to 0.015%;
N: 0.0020% to 0.0060%;
O: 0.0010% to 0.0035%;
Nb: 0% to 0.020%;
V: 0% to 0.030%;
Cr: 0% to 0.50%;
Mo: 0% to 0.50%;
Cu: 0% to 0.25%;
Ni: 0% to 0.50%;
B: 0% to 0.0030%;
S: limited to not more than 0.010%;
P: limited to not more than 0.015%; and
Al: limited to not more than 0.004%,
with a balance including iron and inevitable impurities, wherein
an index value CeEBB obtained by substituting the composition of the steel into following Formula 1 falls in the range of 0.42 to 0.65%,
a number of oxides having an equivalent circle diameter of not less than 1.0 μm is not more than 20 pieces/mm2 at a thickness center portion in cross section along a thickness direction of the steel, and
a number of oxides containing Ti of not less than 10% and having an equivalent circle diameter of not less than 0.05 μm and less than 0.5 μm falls in the range of 3.9×103 to 1×105 pieces/mm2 at the thickness center portion,
CeEBB=C+¼Mn+ 1/15Cu+ 1/15Ni+⅕Cr+⅕Mo+⅕V (Formula 1),
where C, Mn, Cu, Ni, Cr, Mo, and V represent mass % of elements in the composition of the steel, the method including:
after a steel is subjected to casting, cooling the steel in a manner such that a cooling rate in a temperature range of 1300 to 1100° C. is not less than 9° C./min; and
after casting, heating the steel to a temperature range of 950 to 1150° C., and then, applying a thermo-mechanical treatment.

### Claim 26 (depends on 25)

The method according to claim 25, wherein a C/CeEBB, which is a ratio of the amount of C by mass % in the steel relative to the CeEBB, falls in the range of 0.02 to 0.15.