Chromo

[Oakesmobile]

Hey guys, been a while since I've been on, lots o stuff has been going on lately (lost the girlfriend, gained a dog, started playing lap steel, etc.). Anyways, I'm curious about welding some chromoly alloys, (I haven't looked that far into it yet, but I'm guessing 4130 or something similar) and I'm not sure what process I need to use to weld these types of steel alloys. I imagine I could mig it with the correct wire (and gas mixture?), but I'm not sure. Would an alloy like this need to be tig'd? Could you weld 4130 together with a regular mild steel wire? If so, would the strength of the weld be adequate? Of course I'm still learning (always will) and I'd appreciate some advice. Thanks a lot!

Oakes

[Aerometalworker]

Hey guys, been a while since I've been on, lots o stuff has been going on lately (lost the girlfriend, gained a dog, started playing lap steel, etc.). Anyways, I'm curious about welding some chromoly alloys, (I haven't looked that far into it yet, but I'm guessing 4130 or something similar) and I'm not sure what process I need to use to weld these types of steel alloys. I imagine I could mig it with the correct wire (and gas mixture?), but I'm not sure. Would an alloy like this need to be tig'd? Could you weld 4130 together with a regular mild steel wire? If so, would the strength of the weld be adequate? Of course I'm still learning (always will) and I'd appreciate some advice. Thanks a lot!

Oakes

Oakes,
Just keep in mind that 4130 is an air hardening steel, so where most of the trouble with the material comes in is the cooling phase of the weld. Electic welding by nature will have a much more rapid cooling rate then an OA weld. Mig is of course worse then Tig for this as well. Pre-heating is commonly used, but its effectiveness can really only be determined by sample parts and DT. Post weld tempering ( often called stress relieving ) either locally with a heat source or in an oven is the best cure for the metals condition after electric welding. Common fillers in aerospace use on 4130 are ER70S-2 for electric welding and RG-45 for OA welding.