Welding EN8M

[DaveoC]

Does anybody have experience of welding EN8M, we have had produced a large machined block from this material & it is under-size in a tenon key-way, the supplier is suggesting it can be TIG welded and then machined back to achieve size. this is a large piece of EN8M approx 400mm x 200mm with lots of machined features on it. My concerns are that the welded area will be visible after machining back and the penetration/robustness of the weld may not last or crack in the future.

Any guidance appreciated

 

[Rocketman]

I wouldn't have thought tig would be the best but most other methods would require pre heating. If it's only a small amount it needs increasing you could look at laser welding as that wouldn't require pre heating. There are places that specialise in welding tools of various metallurgy and have all the heat treatments in house too.

 

[Richard.]

http://www.google.co.uk/url?sa=t&so...iFgegF&usg=AFQjCNHePDtV61y6p8NEv1a9DNcjUuW2ZQ

 

[Rocketman]

The trouble is being that it sounds like it's a precision product that would appear to be in a finished state can it take heat treatments of any sort without deforming. I'm guessing that is why they were looking at tig for minimal deformation.

 

[hotrodder]

EN8M is the free machining version, higher sulphur which lowers weldability, http://www.twi-global.com/technical...aqs/faq-can-i-arc-weld-free-machining-steels/. There are various techniques used in tool and die welding to avoid undercutting at the border of the repair, generally known as 'sink runs' but it's not my area so dunno about the other potential issues

 

[TechnicAl]

I dont think you will produce a weld that isnt noticeable. It WILL contain porosity and could crack. The most successful way is by using a 7016 or a 7018. The Lime and Fluorspar in the flux have a desulpurising effect but there is too much to control completely. If you are determined enough you may get something reasonable by welding, grinding, welding, grinding etc etc until you are welding to weld metal thats not high sulphur.

Good luck

 

[Richard.]

I dont think you will produce a weld that isnt noticeable. It WILL contain porosity and could crack. The most successful way is by using a 7016 or a 7018. The Lime and Fluorspar in the flux have a desulpurising effect but there is too much to control completely. If you are determined enough you may get something reasonable by welding, grinding, welding, grinding etc etc until you are welding to weld metal thats not high sulphur.

Good luck

That's a blinding explanation,
I've not had much experience with this material either so in depth understandable info like that is wicked. (I'd "like" it twice if I could)

 

[TechnicAl]

Its called being old...........

 

[Richard.]

And there's the 2nd like . Cheers Al

 

[Rocketman]

I'd say still the maximum success if not much is need to be put on is laser welding assuming there is that much machining invested in the part already. I doubt you would get any distortion what so ever. It costs more to weld but you save a load by not having to re-machine loads and doesn't effect the natural structure of the base steel.

Here is one place that does it.

http://www.impressionmoulds.co.uk/html/laser_welding.html

There is quite a few places that do it though.

 

[Kent]

Does anybody have experience of welding EN8M, we have had produced a large machined block from this material & it is under-size in a tenon key-way, the supplier is suggesting it can be TIG welded and then machined back to achieve size. this is a large piece of EN8M approx 400mm x 200mm with lots of machined features on it. My concerns are that the welded area will be visible after machining back and the penetration/robustness of the weld may not last or crack in the future.

Any guidance appreciated

Did they mis make it or was the drawing wrong?. In the latter case fair enough do whatever can be done in the former just give it back and tell them "do it again" , if they think it could be tigged they should have done it in advance of even telling you