Welding 4140 to 4130 tube

[Fatoldman7]

I want to make some tube ends for some aero tube. I can't seem to find any 7/8 thick rectangular bar stock in 4130. There is lots of 4140 stock available, so is this safe to do? Is the extra carbon going to make things to brittle?. would it be better to go the other way, and use 1020? I've welded 1020, and SS to 4130 with good results but never 4140. I'd like to hear from some folks that have experience welding these two alloys together.

Thanks

[ghickman]

I'd opt to use 1018 mild steel for a weldment like this. I've built 100's of a-arms for everthing from Atlantics to Off Road cars using 1018 weldments....works just fine.

GH
Edge Engineering Inc.
FB #76

[R. Pare]

E70 0r E80 rod. Pre-heat. Post draw.

[Fatoldman7]

Mr Hickman, what welding rod do you use for welding 1018 to 4130? Depending on what a costumer spec'd, I've used mild steel, 4130, and 309L rod.

Thanks for the replies

[ghickman]

Mr Hickman, what welding rod do you use for welding 1018 to 4130? Depending on what a costumer spec'd, I've used mild steel, 4130, and 309L rod.

Thanks for the replies

I prefer ER70S2 filler rod for this type weldment. I've also used ER70S3 but can't tell any difference in the weld.

GH

[J Leonard]

Check ralt.co.uk, they may have the parts already built for you.

[last]

when tig welding 4130 to 4130 or 4130 to cold rolled 1018-1020, i use ER70S2. I have seen 4130 in large reqtangular sizes to make machined pieces, but it was cost prohibitive to use. Use CR 1018-1020. You will run the risk of cracking in or near the weld zone with 4140. Sometimes i will use ER80S2 for parts that will be heat traeted.
nick fuhs

[brownslane]

when tig welding 4130 to 4130 or 4130 to cold rolled 1018-1020, i use ER70S2. I have seen 4130 in large reqtangular sizes to make machined pieces, but it was cost prohibitive to use. Use CR 1018-1020. You will run the risk of cracking in or near the weld zone with 4140. Sometimes i will use ER80S2 for parts that will be heat traeted.
nick fuhs

4140 is specifically designed for machining and hardening after. Heat application will/may harden the welded area, so stay away.

Tom

[carl correll]

4130 comes in tubing and sheet in the normalized condition. It does not deep heat treat. 4140 comes in bigger sections and is indeed intended for machining and deep heat treat. Serious folks fabricate from 4130 tube and sheet welded to machined sections od 4140 using a heat treatable filler. This is followed by stress relieving and heat treat to around 32C. That's how we did it building parts for our Indycars at Truesports.

I weld 4130 tube and sheet to machined 1020 because I'm not going to heat treat it and the 1020 is free machining. I preheat thicker 4130 sections and draw out the weldment, letting it air cool slowly. On the rare occasions that I choose to machine from 4140, I pre and post heat it always. Cold material in thick sections, no matter what the ferrous alloy, acts to chill the weld and causes underbead cracking.

[Fatoldman7]

One more question....

First, thanks for all of your replies, you've all been very helpful. I just received my welding rod and I have a few more questions. My welding supplier sells ESAB rod, and I assumed I would get ESAB rod but, I got an off shore brand instead, it's ER70S-2 rod. What concerns me is that it is copper coated. It's been a few years since I've welded CrMo, but I do seem to remember that copper coated rod, was not the best rod for welding CrMo or mild steel. I wish I could connect a few more grey cells together, and remember why, but it's been a few decades,and I can't recall the particulars. So, is this the right rod, and is copper coated rod OK?

[last]

yes , copper coated is ok to use for 4130 and or 1018. As long as its ER70 S2 , and you can trust the source. Best yet also is when its stamped on the rod.
nick fuhs

[Pop Chevy]

Yup ! You got the right rod. Been buying it for years and it has always been coated. I work on antique and custom Harley frames including moly drag bike frames and swingarms, thats the best rod I found. I called S+W Race cars once(they build rails, funny cars, etc) thats what they use.