Welding 3/4" steel with MIG

[raferguson]

Hello guys,

I have a project coming up in a couple days where I will be MIG welding 1/2" and 1/4" thick square tubing together, and then welding them to a couple 3/4" thick plates. Mostly fillet with some butt welds. I will be working in a shop that has all the proper equipment for the job. I have plenty of experience with sheet metal, and thin stuff up to 1/4", so I'm just looking for a few tips to ensure good penetration. I should be able to move the piece around so I can keep all the welds in the flat or horizontal position so I can use spray transfer.

Any suggestions/ tips would help! Thank you!
-Anthony

The Miller welding calculator says spray arc, 98% argon and 2% oxygen, 315 amps, .045 wire at 390 inches per minute. If the shop normally works in heavy steel they should have a powerful enough welder. My concern would be if they have gas suitable for spray arc. I know that I don't have suitable gas for spray arc in my little shop. I believe that there are other gases which can be used for spray arc; I will let someone with more expertise comment on that.

[gnforge]

Welding 3/4" steel with MIG

045 dual shield if they hv it. Spray arc.
Pre heat the 3/4.

[70Chevelle]

Hello guys,

I have a project coming up in a couple days where I will be MIG welding 1/2" and 1/4" thick square tubing together, and then welding them to a couple 3/4" thick plates. Mostly fillet with some butt welds. I will be working in a shop that has all the proper equipment for the job. I have plenty of experience with sheet metal, and thin stuff up to 1/4", so I'm just looking for a few tips to ensure good penetration. I should be able to move the piece around so I can keep all the welds in the flat or horizontal position so I can use spray transfer.

Any suggestions/ tips would help! Thank you!
-Anthony