Weld metal having excellent temper embrittlement resistance

Patent metadata

Field	Value
Publication number	US-9505087-B2
Application number	US-201214350985-A
Country	US
Kind code	B2
Filing date	Nov 21, 2012
Priority date	Nov 21, 2011
Publication date	Nov 29, 2016
Grant date	Nov 29, 2016

Abstract

A weld metal according to the present invention has a specific chemical composition, contains carbide particles each having an equivalent circle diameter of greater than 0.5 μm in a number of 0.25 or less per micrometer of grain boundary length, and has an A-value as specified by Formula (1) of 0.12 or more, Formula (1) expressed as follows:

A -value=([V]/51+[Nb]/93)/([Cr]/52+[Mo]/96)   (1)

where [V], [Nb], [Cr], and [Mo] are contents (percent by mass) of V, Nb, Cr, and Mo, respectively, in the weld metal.

First claim

The invention claimed is:

1. A weld metal, comprising: in percent by mass,
C in a content of 0.05% to 0.15%;
Si in a content of 0.1% to 0.50%;
Mn in a content of 0.60% to 1.30%;
Cr in a content of 1.80% to 3.0%;
Mo in a content of 0.80% to 1.20%;
V in a content of 0.25% to 0.50%;
Nb in a content of 0.010% to 0.050%;
N in a content of greater than 0% to 0.025%;
O in a content of 0.020% to 0.060%, and;
wherein
the weld metal comprises carbide particles each having an equivalent circle diameter of greater than 0.5 μm in a number of 0.25 or less per micrometer of grain boundary length; and
the weld metal has an A-value as specified by Formula (1) of 0.12 or more;
A-value=([V]/51+[Nb]/93)/([Cr]/52+[Mo]/96)  (1)

where [V], [Nb], [Cr], and [Mo] are contents, in percent by mass, of V, Nb, Cr, and Mo, respectively, in the weld metal.

2. The weld metal of claim 1 , having a number density of oxide particles each having an equivalent circle diameter of greater than 2 μm of 100 or less per square millimeter.

3. The weld metal of claim 1 , further comprising:
at least one element selected from the group consisting of:
Cu in a content of greater than 0% to 1.0%;
Ni in a content of greater than 0% to 1.0%;
B in a content of greater than 0% to 0.0050%;
W in a content of greater than 0% to 0.50%;
Al in a content of greater than 0% to 0.030%; and
Ti in a content of greater than 0% to 0.020%.

4. A welded structure, comprising the weld metal of claim 1 .

5. A welded structure, comprising the weld metal of claim 2 .

6. A welded structure, comprising the weld metal of claim 3 .

7. The weld metal of claim 1 , wherein the A-value is 0.13 or more.

8. The weld metal of claim 1 , wherein the A-value is 0.20 or less.

9. The weld metal of claim 1 , obtained by a shielded metal arc welding performed with a heat input of from 2.3 kJ/mm to 3.0 kJ/mm and at a preheat-interpass temperature of from 190° C. to 250° C.

10. The weld metal of claim 9 , wherein a core wire comprising Mo in a content of 1.20 mass% or less and Cr in a content of 2.30 mass% or less is used in the shielded metal arc welding.

11. The weld metal of claim 9 , wherein a coating flux comprising Mo in a content of 1.2 mass% or less and having a Si/SiO 2 ratio of 1.0 or more is used in the shielded metal arc welding.

12. The weld metal of claim 11 , wherein the coating flux comprises MgO in a content of 2.0 mass% or more.

Assignees

• Kobe Steel Ltd

Inventors

• Nako Hidenori
• Yamashita Ken
• Otsu Minoru
• Taniguchi Genichi
• Sakata Mikihiro

Classifications

• B23K35/365

  Selection of non-metallic compositions of coating materials either alone or conjoint with selection of soldering or welding materials · CPC title

• C22C38/46

  with vanadium · CPC title

• B23K35/308

  with Cr as next major constituent · CPC title

• C22C38/24

  with vanadium · CPC title

• C22C38/42

  with copper · CPC title