Can you MIG weld chromoly?!?!

By - Date 11-03-2000 13:29

I own a gas mig welder and have been told that you can not MIG weld chromoly. Is this true? What kind of wire and gas would you use? Is it because the strength or penatration of the welds? I know that NHRA specifically states that for a chromoly chassis it must be TIG welded. They allow MIG welding for mild steel and prohibit ARC welding whatsoever.

By - Date 11-05-2000 15:30

My shop routinely welds chrome-moly pipe using a GMAW short arc root, and GMAW pulse spray fill and cap. The filler wire needs to be matched to the base metal. For example, for 2-1/4 Cr - 1 Mo, the wire is ER90S-B3. The gas for the short arc is 75% Argon/25% CO2. For the pulse spray portion, the gas is 92% Ar/8% CO2. I'm not familiar with the NHRA specs that you are refering to, but you can get excellent results using GMAW on chrome-moly.

By Neal

Date 11-05-2000 19:00

I believe AWS D10 committee has a spec for the racing community. If it is not out it should be shortly. Call AWS HQ for specifics or ordering info.