There are a lot of good FCAW wires out there, but some things to look for in my opinion:
1. There aren't many FCAW wires classified with an H4 anymore since the latest revision of the diffusible hydrogen testing specification, but use a wire with at least a H8 or lower. H4 would be better.
2. If you can, use a FCAW wire with a E7XT-12 classification. This will limit the maximum tensile strength, and result in less residual stress in the base metal (and less cracking potential).
3. Look for a wire with a J on the end for better weld metal toughness and less tendency to crack.
4. If you have very critical applications with high restraint and flat/horizontal only, the best wires to use are E70T-5, but they have a lot of smoke and spatter, so you welders will not like using them. Going to this step is not usually required though.
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