Which filler metal families are commonly used in GMAW for carbon steel, stainless steel, and aluminum, and what are their typical applications?

• A. Carbon steel ER70S-6 for general structural welds; Stainless ER308L for 304/304L welds; Aluminum ER4043 or ER5356 for 6xxx/5xxx alloys.
• B. Carbon steel ER4043 for structural welds; Stainless ER310 for 316L welds; Aluminum ER70S-6 for 6xxx alloys.
• C. Carbon steel ER308L for structural welds; Stainless ER70S-6 for 304/304L; Aluminum ER5356 for 6xxx alloys.
• D. Carbon steel ER5356 for structural welds; Stainless ER4043 for 304/304L; Aluminum ER308L for 6xxx alloys.

Answer: (A)

In GMAW, choosing filler metal is about matching the base metal and the weld’s service needs so the joint has good strength, ductility, and corrosion resistance. For carbon steel, ER70S-6 is a widely used general-purpose filler because it provides reliable elongation and toughness in structural welds and works well with common shielding gases, giving a dependable, easy-welding filler for typical steel joints. For stainless steel, ER308L is the standard filler for welding 304/304L because its composition yields a compatible austenitic weld that resists corrosion, and the lower carbon helps prevent carbide precipitation in the heat-affected zone. For aluminum, ER4043 and ER5356 are the common options: ER4043 (Al-Si) flows well and is well-suited to 6xxx-series alloys, while ER5356 (Al-Mg) is a good match for 5xxx-series alloys and offers strong, corrosion-resistant welds. These fillers are among the most commonly used in their respective families, aligning with typical structural steel, stainless, and aluminum applications.