High Strength Weld Metal for Demanding Structural Applications

• US 20150129559A1
• Filed: 06/24/2013
• Published: 05/14/2015
• Est. Priority Date: 07/27/2012
• Status: Abandoned Application

• Current Assignee: Adnan Ozekcin, Douglas P. Fairchild, Hyun-Woo Jin, Mario L. Macia, Nathan E. Nissley, Raghavan Ayer
• Original Assignee: Adnan Ozekcin, Douglas P. Fairchild, Hyun-Woo Jin, Mario L. Macia, Nathan E. Nissley, Raghavan Ayer
• Inventors: Fairchild, Douglas P., Macia, Mario L., Jin, Hyun-Woo, Ozekcin, Adnan, Nissley, Nathan E., Ayer, Raghavan
• Application Number:
  US14/408,239
• Publication Number:
  US 20150129559A1
• Time in Patent Office: Days
• US Class Current: 219/73
• CPC Class Codes: B23K 35/3066 with Ni as next major constituent
• CPC Class Codes: B23K 35/308 with Cr as next major constituent
• CPC Class Codes: B23K 35/3086 containing Ni or Mn
• CPC Class Codes: B23K 35/383 mainly containing noble gases or nitrogen
• CPC Class Codes: B23K 9/173 and of a consumable electrode
• CPC Class Codes: B23K 9/186 making use of a consumable electrodes
• CPC Class Codes: C22C 38/00 Ferrous alloys, e.g. steel alloys cast-iron alloys C22C37/00
• CPC Class Codes: C22C 38/002 containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
• CPC Class Codes: C22C 38/02 containing silicon
• CPC Class Codes: C22C 38/04 containing manganese
• CPC Class Codes: C22C 38/08 containing nickel C22C38/105 takes precedence
• CPC Class Codes: C22C 38/12 containing tungsten, tantalum, molybdenum, vanadium, or niobium
• CPC Class Codes: C22C 38/14 containing titanium or zirconium
• CPC Class Codes: C22C 38/16 containing copper
• CPC Class Codes: C22C 38/42 with copper
• CPC Class Codes: C22C 38/44 with molybdenum or tungsten
• CPC Class Codes: C22C 38/50 with titanium or zirconium
• CPC Class Codes: C22C 38/58 with more than 1.5% by weight of manganese

Abstract

Weld metals and methods for welding ferritic steels are provided. The weld metals have high strength and high ductile tearing resistance and are suitable for use in strain based pipelines. The weld metals are comprised of between 0.03 and 0.08 wt % carbon, between 2.0 and 3.5 wt % nickel, not greater than about 2.0 wt % manganese, not greater than about 0.80 wt % molybdenum, not greater than about 0.70 wt % silicon, not greater than about 0.03 wt % aluminum, not greater than 0.02 wt % titanium, not greater than 0.04 wt % zirconium, between 100 and 225 ppm oxygen, not greater than about 100 ppm nitrogen, not greater than about 100 ppm sulfur, not greater than about 100 ppm phosphorus, and the balance essentially iron. The weld metals are applied using a power source with pulsed current waveform control with <5% CO₂ and <2% oxygen in the shielding gas.

Claims

1. A weld metal for ferritic steel base metals, comprising:

between 0.03 and 0.08 wt % carbon;

between 2.0 and 3.5 wt % nickel;

not greater than about 2.0 wt % manganese;

not greater than about 0.80 wt % molybdenum;

not greater than about 0.70 wt % silicon;

not greater than about 0.03 wt % aluminum;

not greater than 0.02 wt % titanium;

not greater than 0.04 wt % zirconium;

between 100 and 225 ppm oxygen;

not greater than about 100 ppm nitrogen;

not greater than about 100 ppm sulfur;

not greater than about 100 ppm phosphorus; and

the balance iron,

wherein the weld metal comprises an SBD-AFIM microstructure, the weld metal is applied using a pulsed gas metal arc welding process with an advanced pulsed waveform power supply and utilizes a shielding gas comprised of less than 5% CO₂ and less than 2% O₂, the applied weld metal has a tensile strength of greater than 90 ksi and a SENT R-curve delta value of greater than 0.75.

2. The weld metal of claim 1, wherein the weld metal contains an oxide inclusion population smaller than 4×

10¹⁰ m<sup>−

2</sup>.

3. The weld metal of claim 2, wherein the applied weld metal exhibits common lack of fusion defects in a pipeline construction project smaller than 3 mm in height and a weld reject rate on a daily basis less than 5%.

4. The weld metal of claim 1 further comprising at least one of the following:

not greater than about 0.30 wt % copper,

not greater than about 0.04 wt % vanadium,

not greater than about 0.30 wt % chromium,

not greater than about 0.40 wt % molybdenum,

not greater than about 0.04 wt % niobium,

not greater than about 0.02 wt % titanium,

not greater than about 0.02 wt % zirconium, and

not greater than about 20 ppm boron.

5. The weld metal of claim 1, wherein the applied weld metal has a tensile strength of greater than 100 ksi.

6. The weld metal of claim 1, wherein the applied weld metal has a tensile strength of greater than 110 ksi.

7. The weld metal of claim 1, wherein the applied weld metal has a tensile strength of greater than 120 ksi.

8. The weld metal of claim 1, wherein the applied weld metal has an SENT R-curve delta value of greater than 1.0.

9. The weld metal of claim 1, wherein the applied weld metal has an SENT R-curve delta value of greater than 1.25.

10. The weld metal of claim 1, wherein the applied weld metal has an SENT R-curve delta value of greater than 1.5.

11. The weld metal of claim 1, wherein the applied weld metal has an SENT R-curve delta value of greater than 2.0.

12. The weld metal of claim 1, wherein the applied weld metal has a Charpy V-notch energy of greater than 100 J at a temperature of −

5°

C. or colder.

13. The weld metal of claim 1, wherein the applied weld metal has a Charpy V-notch energy of greater than 125 J at a temperature of −

5°

C. or colder.

14. The weld metal of claim 1, wherein the applied weld metal has a Charpy V-notch energy of greater than 150 J at a temperature of −

5°

C. or colder.

15. The weld metal of claim 1, wherein the applied weld metal has a Charpy V-notch ductile-to-brittle transition temperature of −

5°

C. or colder.

16. The weld metal of claim 1, wherein the applied weld metal has a Charpy V-notch ductile-to-brittle transition temperature of −

20°

C. or colder.

17. The weld metal of claim 1, wherein the applied weld metal has a Charpy V-notch ductile-to-brittle transition temperature of −

40°

C. or colder.

18. The weld metal of claim 1, wherein the applied weld metal has a CTOD at −

5°

C. of at least 0.10 mm.

19. The weld metal of claim 1, wherein the applied weld metal has a CTOD at −

20°

C. of at least 0.10 mm.

20. The weld metal of claim 1, wherein a girth welded pipe containing the applied weld metal has a global strain capacity of at least 0.5% as measured in a pressurized pipe strain test containing a girth weld defect at least as large as 2 mm deep and 25 mm long.

21. The weld metal of claim 1, wherein a girth welded pipe containing the applied weld metal has a global strain capacity of at least 0.75% as measured in a pressurized pipe strain test containing a girth weld defect at least as large as 2 mm deep and 25 mm long.

22. The weld metal of claim 1, wherein a girth welded pipe containing the applied weld metal has a global strain capacity of at least 1.0% as measured in a pressurized pipe strain test containing a girth weld defect at least as large as 2 mm deep and 25 mm long.

23. A method of welding ferritic steel pipelines comprising:

determining a desired HSW weld metal chemistry comprising between 0.03 and 0.08 wt % carbon, between 2.0 and 3.5 wt % nickel, not greater than about 2.0 wt % manganese, not greater than about 0.80 wt % molybdenum, not greater than about 0.70 wt % silicon, not greater than about 0.03 wt % aluminum, not greater than 0.02 wt % titanium, not greater than 0.04 wt % zirconium, between 100 and 225 ppm oxygen, not greater than about 100 ppm nitrogen, not greater than about 100 ppm sulfur, not greater than about 100 ppm phosphorus, and the balance iron;

determining and providing a welding consumable wire chemistry from a calculation using as inputs dilution percent, a pipeline base metal chemistry, and the desired HSW weld metal chemistry; and

girth welding the pipeline base metal using the welding consumable wire to produce a weld metal, the girth welding process comprising;

applying the girth welding using a gas metal arc welding process using a shielding gas with less than 5% CO₂ and less than 2% O₂, and

using an advanced pulsed waveform power supply constructed and controlled to mitigate the negative weldability aspects of using a shielding gas with less than 5% CO₂,

wherein the weld metal achieves a target weld metal oxygen content that is not greater than about 225 ppm oxygen and a weld metal inclusion population not greater than 4×

10¹⁰ m<sup>−

2</sup>, the weld has an SBD-AFIM microstructure, a tensile strength of greater than 90 ksi and a SENT R-curve delta value of greater than 0.75.

24. The method of claim 23, wherein the shielding gas comprises a mixture of less than 5% CO₂, helium, and argon in the amount of at least 50 volume percent.

25. The method of claim 23, wherein the shielding gas comprises a mixture of less than 5% CO₂, at least 10% helium, and argon in the amount of at least 50 volume percent.

26. The welding method of claim 23, wherein the shielding gas comprises a mixture of less than 5% CO₂ and the balance being argon.

27. The method of claim 23, wherein the step of girth welding further comprises using a hybrid laser arc welding process.

28. The method of claim 23, wherein the step of girth welding further comprises using a submerged arc welding process.