Systems and methods for welding zinc-coated workpieces
A welding system includes a welding power source configured to provide pulsed electropositive direct current (DCEP), a gas supply system configured to provide a shielding gas flow that is at least 90% argon (Ar), a welding wire feeder configured to provide tubular welding wire. The DCEP, the tubular welding wire, and the shielding gas flow are combined to form a weld deposit on a zinc-coated workpiece, wherein less than approximately 10 wt % of the tubular welding wire is converted to spatter while forming the weld deposit on the zinc-coated workpiece.
1. A method of forming a weld deposit on a zinc-coated workpiece, comprising:
feeding a tubular welding wire toward a surface of a galvanized workpiece;
directing a flow of shielding gas toward the surface of the galvanized workpiece near the tubular welding wire, wherein the flow of shielding gas consists essentially of argon (Ar) or a mixture of Ar and carbon dioxide (CO 2 ) that is at least 90% Ar; and
forming the weld deposit on the zinc-coated workpiece using the tubular welding wire while providing the flow of shielding gas near the weld deposit,
wherein the tubular welding wire comprises a granular core disposed inside of a metallic sheath, wherein the granular core comprises:
an organic stabilizer component comprising one or more organic molecules or organic polymers bound to one or more Group I or Group II metals;
a carbon component comprising graphite, graphene, carbon black, lamp black, carbon nanotubes, diamond, or a combination thereof, and
an agglomerate comprising Group I or Group II metal oxides, titanium oxide, and manganese oxides; and
wherein less than approximately 10 wt % of the tubular welding wire is converted to spatter while forming the weld deposit on the zinc-coated workpiece; and
wherein the tubular welding wire is electrified with direct current electrode positive (DCEP).
2. The method of claim 1 , wherein the weld deposit has a length porosity less than approximately 10% and an area porosity less than approximately 4%.
3. The method of claim 2 , wherein the length porosity is less than approximately 8% and the area porosity is less than approximately 3%.
4. The method of claim 3 , wherein the length porosity is less than approximately 6% and the area porosity is less than approximately 2.5%.
5. The method of claim 4 , wherein less than approximately 9 wt % of the tubular welding wire is converted to spatter while forming the weld deposit on the zinc-coated workpiece.
6. The method of claim 5 , wherein less than approximately 8 wt % of the tubular welding wire is converted to spatter while forming the weld deposit on the zinc-coated workpiece.
7. The method of claim 6 , wherein less than approximately 7 wt % of the tubular welding wire is converted to spatter while forming the weld deposit on the zinc-coated workpiece.
8. The method of claim 1 , wherein the flow of shielding gas consists essentially of Ar.
9. The method of claim 1 , wherein the flow of shielding gas consists essentially of at least 90% Ar and 10% or less CO 2 .
10. The method of claim 1 , wherein the flow of shielding gas consists essentially of at least 95% Ar and 5% or less CO 2 .
11. The method of claim 1 , wherein the flow of shielding gas consists essentially of at least 99% Ar and 1% or less CO 2 .
12. The method of claim 1 , wherein the weld deposit has a Charpy-V-Notch toughness greater than approximately 20 ft. lbs. at approximately −20° C. and at approximately −40° C.
13. The method of claim 12 , wherein the Charpy-V-Notch toughness of the weld deposit is at least 30 ft. lbs. at approximately −20° C. and at approximately −40° C.
14. The method of claim 1 , wherein the weld deposit has an ultimate tensile strength (UTS) of at least 70 kilopounds per square inch (kpsi), a yield strength (YS) of at least 70 kpsi, and a percent elongation of at least 18%.
15. The method of claim 1 , wherein the tubular welding wire is a metal-cored carbon steel tubular welding wire in accordance with AWS A5.18 or A5.36.
16. The method of claim 1 , wherein the tubular welding wire is a metal-cored low-alloy steel tubular welding wire in accordance with AWS A5.36.
17. The method of claim 1 , wherein the granular core further comprises:
one or more filler metals;
one or more alloying components;
one or more carbon components; and
one or more alkali metal or alkali earth metal compounds.
18. The method of claim 1 , wherein the one or more organic stabilizer components comprise between approximately 0.5% and 1% by weight of the granular core of the tubular welding wire.