Turning Welded steel

Hi Guys,

I've just arc welded a piece of 1/8th plate to the end of a short length of scaffold pole, to seal the end.

The plate and the pole (I think in each case is mild steel) both turn beautifully

using HSS lathe tooling.

However as soon as I get to the weld the HSS is abraded away.

It's not slag as I ground that off. The metal is also very resistant to being filed.

Any ideas why the weld metal is so hard?

regards

Bernard

PS The welding rods are by ESAB and are labelled :-

OK 46.00

2.0 x 300mm

5-70A

ABS Grade 3

BV Grade 3

DRiV Grade 3

GL Grade 3

LR Grade 3

TUV eignungagepruft

AWS A5.1 E 6013

SFA 5.1 E 6013

ISO E 43 3 R 12

DIN 1913 E 43 32 R (C) 3

DS 317 E 42 D

SS Norm 14 32 01

The welding supplies shop who sold them to me advised they were a good general purpose rod.

And to be fair I've had no trouble using them, so far.

PPS I also tried 'annealing' the job by heating it to just below red hot (my gas torch hasn't got the humpf) and letting it cool slowly in a tin of ashes. Result - it's just the same.

Edited By Bernard Greatrix on 01/12/2018 14:48:06

It probably cooled too fast.

See if you can heat it to red with a torch for a hew minutes, then let it cool slowly - or this is where a brazed carbide tool can be useful.

Neil

Slow speed on backgear with an M35 cobalt hss tool

Carbide can do it but is prone to chipping if the wrong type

What welding rod or wire did you use? Any chance some hardfacing electrode got mixed in with the regular mild steel rod / wire supply?

Hardfacing electrodes are used to put beads of very hard metal on things like steel digger buckets , bulldozer blades, and earth augers to reduce wear. The resulting beads are just barely machineable.

If annealing as Neil mentioned does not soften it, carbide tools may be the only answer. If you need to turn the part, might be wise to start over with known mild steel welding wire. We have no project details - excuse me if it's not possible - but can you cut off the last half inch of the pole and make a new end plate?

Thanks guys,

I think you were too quick for me to post the additional information.

I was using about 100 RPM (I use a Warco WM180 so can't get much slower)

I don't know what grade of HSS tooling I have - I didn't realise that there were different types. I shall have to investigate for next time around.

I have some small carbide tools (triangular inserts on a 8mm body) but I've chipped them all when previously machining 'knobbly' work.

regards

Bernard

Scaffold poles are usually galvanised. I hope you didn't breath the fumes. I also do not know what effect the zinc will have on the weld filler metal.

Martin C

Hi Guys,

I don't have any more pole to make a second item - The project is simply to provide a shield for the exposed capacitor on the back of my woodworking band saw.

I really just wanted to tidy up the welding prior to painting.

I eventually solved the problem using an angle grinder and my slowest lathe speed- A bit messy, but no more so than it throwing cutting oil all over the back.

So thanks for you taking the time to give advise, it is most appreciated and I will bear in mind your comments when the next project come up. As I would like to crack it.

regards

Bernard

I ground off the galvanising prior to welding

Edited By Bernard Greatrix on 01/12/2018 15:15:58

Just to add more information I've looked at the ESAB website

https://www.esab.co.uk/gb/en/products/index.cfm?fuseaction=home.product&productCode=410003

and it advises :-

OK 46.00 is the best, all-round, rutile electrode and it is relatively insensitive to rust or other surface impurities. It deposits smooth weld beads in all positions, including vertical down, and the slag is easy to remove. OK 46.00 is very easy to strike and restrike, making it ideal for short welds, root runs and tacking.

Another tab gives the weld analysis as :-

I did note the word 'rutile' and discovered that this means titanium

So maybe I need to buy some more rods

regards

Bernard

over the years got better at welding and using a small grinder....I now know the settings on the oil cooled welder and size of rod to use for a smooth and lump free weld.....buzz box's don't help much......normally turning the material whilst welding helps a lot......

never really found any rods that turn nicely........

have a 20 x 20mm turning tool with a beat up industrial carbide bit I use just for that job.......because it wrecks everything else I've tried inc Cobalt HSS......clogs

Forgive me for throwing in my tuppence worth,but I found long ago that trying to turn welded steel parts is a very good way of ruining good turning tools,to say nothing of the lathe itself. Welding seems to harden the steel to such a point that it just laughs at the toolbit,before breaking it.

I dont do it any more. Angle grinder is a lot cheaper,and just as fast.

As I say,,For what it,s worth !

Rutile is just the flux on the rods.

Neil

JS never seemed to struggle building up worn motor spindles with weld and turning them.

Take a look here:

www.model-engineer.co.uk/forums/postings.asp?th=96032

Neil

To be fair, JS was mig welding with a known quality of filler wire ... I assume he was choosing a filler wire which would turn, given the face he did this more than occasionally.

I'm no welder but I've found that welds made with stick electrodes seem to show up as hard spots, even in mild steel, though usually machinable in my experience. AFAIK, rutile fluxes use cellulose binders. My "home-brewed" theory is that this could introduce some carbon into the weld metal, hence making it tougher and harder than the parent metal.

I can't recall ever trying to machine a mig weld, so can't comment on this.

Clive

The key clue is 6013 towards the bottom of your list. 6013's should be ideal for what you were doing, as stated they are tolerant of surface contaminants like rust or scale and are considered a reasonable all round rod for general work. One characteristic though is they leave a heavy flux deposit over the weld. You mention you "ground the slag off" - if it was a good weld the flux should just chip off easilly with a tap from an old file or if you are really good, slowly peel itself off as the job cools. If you had to grind it off then I would guess your weld was done moving the rod too fast and possibly at too low an amperage leading to a lack of penetration and slag inclusion in the weld metal itself, it's the latter that will be giving you the issues with machining.

I have recently fabricated the drawbars for my 6" scale traction engine from 8mm plate using 2.5mm 6013 rods at about 85 amps and milled the back faces off after welding to a flat surface, machined fine and you can't see the join!

Paul.

"Mostly just common or garden MiG wire although I do keep one welder with some better quality wire on for things like the Bridgy rotors that are a wear item."

One of his posts shows a brazed carbide tool he was using for roughing out and how he resharpened it with an angle grinder in a chopsaw holder.

Neil

Bernard quotes the composition of his rods as containing Manganese.

This is possibly the cause of the problem?

I have also found that steel deposited by arc welding rods was harder than the parent metal.

MIG welding wire probably does not contain Manganese, so the problem would then not arise.

I thought that Manganese steel work hardens and becomes virtually unmachinable. Only a grinding wheel will touch it.

Because of this it was the favourite material for liners on the horn guides on locomotives, to minimise wear.

Howard.

The 6013/E 43 32 weld deposit should machine fairly easily. It is possible that the scaffold pole was a reasonably high carbon & manganese alloy and has a hard layer in the heat affected zone.

To soften it to the point that an M2 HSS tool or similar is happy cutting it, you really need to get it to a low red heat ~800°C or so.

Any zinc plating on the pole will not have any effect on the weld, it would have boiled off before the steel melted.

Likewise, if there had been enough zinc oxide in the air to give you metal fume fever, you would already know about it!

A 6013 rod should be machineable straight off the arc, hot or cold. Having said that I hate ESAB 6013 rods and won't use them, simply because whatever the blurb says for position welds with this rod I can't help but get slag inclusions in the weldment. I've been using Oerlikon 6013 rods for years and never had this problem but (other than incompetence on my part) I don't know why the difference is so pronounced. Fincord M is a lovely docile rod, try it and marvel.

The "rutile" descriptor refers to the composition of the flux, which - as we all know - never ends up in the weld metal (ho ho!). If you google rutile you will see an explanation of what it is, and how it does what it does. Rutile is simply a mineral, with a complex composition which happens to make a nice flux coating for MMA. The presence of some manganese (for example) in the rutile doesn't affect the metallurgy of the weld metal, as the flux isn't incorporated into the weld pool. The composition of the weld pool is governed by the parent metal and the composition of the added weld metal from the rod core.

I doubt that the scaffold tube is anything other than mild steel, certainly it shouldn't have enough carbon (or anything else for that matter) in it to upset its machineability after welding. For this reason the idea of annealing post weld is irrelevant. If the weld is hardened by cycling through the weld zone there is something wrong with the metallurgy of the base metal. It's vastly more likely that the hard spots are slag inclusions.  A good guide to this with 6013 or similar is that the slag should fall off the weld as it cools of its own accord, if you have to do more than scrape it to get it to let go then the slag is contaminating the weld.

Please steer well clear of welding galvanised stuff, even grinding the coating off isn't guaranteed. I've had Zinc fever (no it'll be OK!!!). Never again. Oh, and zinc contamination will cause slag inclusions, it doesn't burn off completely, some of it gets trapped in the weld pool.

Damp rods (for damp read "not absolutely bone dry" can also cause slag trapping, but rutile is pretty tolerant of moderate damp and the act of passing a current through the rod to use the first inch or so will heat the rest of the rod up so much that any residual moisture is vapourised. Still, it's good practice to put the rods in the oven for an hour at 150 C or so immediately prior to use. It's also good practice not to let them get damp in the first place.

After that, you need to think about welding AC or DC, and polarity can also make a difference., But for my money all of these tweaks are missing the point, this is ESAB syndrome. They may be very good in expert hands, but I'm not that person and I like the results of following the gospel according to Oerlikon.

And, as ever and for the avoidance of doubt, I have no connection with Oerlikon, I'm just a satisfied user.

One last thought, if the rods were at all oily you're on a hiding to nowhere.

Good luck, HTH

Simon

Edited for yellow face eviction

Edited By Simon Williams 3 on 01/12/2018 22:47:35

Edited By Simon Williams 3 on 01/12/2018 22:49:38

Hi Guys,

I should explain that I did in fact easily chip away the slag, but as the plate was originally square I ground off the corners etc so that the surface of the weld metal was exposed.

This was the material I found impossible to turn down. The base metal (pipe and plate) both turned easily, but when encroaching onto the weld metal the lathe tool just wore away.

I then tried annealing but my gas torch (which runs off butane gas) could only get the steel up to a dull red, even when positioned in a corner of fire bricks.

I'll call in at the local welding supplier when next in town and see what else he has to offer then try again - I have a 1" piece of tube left over. The required length for another shield would be 3-1/4".

As I said above I got around the problem by grinding off the excess and the shield is now painted black to match the motor on the back of the saw.

Once again may thanks to all who've offered support.

regards

Bernard

Nearly forgot -my welder is a simple arc welder, a  SIP Weldmate 140 bought back in 1983 and I found 60A to be about optimum for 2mm rods.

Edited By Bernard Greatrix on 02/12/2018 00:10:53