Does Mild Steel Absorb ?

[W.olly]

I got a load of 40mm x3mm angle iron recently and just started to use it to make a table frame.

Now its old stuff used and rusty. It cleans back ok to fresh steel. BUT, when welding it gives off a type of crackle/hiss as if its galv`d. It has done it on say 50% of the welds i have done. And welds bad.

I was wondering if mild steel could absorb maybe a chemical or something to cause this. Not knowing what it was used for.

 

[morph]

It’s probably some type of cast if it welds that badly, I’ve had the same trouble with recycled metal out of a Dutch barn. Looks like good metal but nearly impossible to do a decent job with (possible to bodge but it won’t be pretty or strong!)

 

[anto44]

Is it from old bed frames by any chance, I've read on here that the angle from old bed frames is a pita to weld

 

[Screwdriver]

Yup that was my first thought too. Quite common to find cast angle say 50 years ago.

And no, mild steel doesn't absorb anything at STP so far as I am aware.

 

[W.olly]

The chap i got it off said it was from old factory frame work. he just gets them as scarp frames and cuts out half decent lengths and sells on. I would thunk its old but not sure how old but its metric if that means much for age. Not a clue when steel went to metric sizes. if it has changed at all actually. never thought of that.

 

[Richard Stowe]

if it's bed frame stuff i've found 90argon/10co sort's it

 

[Screwdriver]

I worked on some brackets for a truss frame roof in an old factory building, probably mid century, definitely cast angle trusses. One good indicator is to see it they were previously bolted or riveted, if so they are quite likely cast (cast angle typically won't have been welded, for obvious reasons...)

 

[nickk]

Bed angle is springy,just try and twist it along its length,it goes farther than mild steel in my experience,yet returning to normal,I’ve been told it was recycled tram rails.

 

[W.olly]

I worked on some brackets for a truss frame roof in an old factory building, probably mid century, definitely cast angle trusses. One good indicator is to see it they were previously bolted or riveted, if so they are quite likely cast (cast angle typically won't have been welded, for obvious reasons...)

they were welded frames.

 

[Screwdriver]

The plot thickens...

 

[Munkul]

you say the rust cleans off, but are you really cleaning it back properly? Often can look clean enough to weld, but be smeared with paints/coatings that will not weld. Smeared galv does the same thing too.

 

[W.olly]

you say the rust cleans off, but are you really cleaning it back properly? Often can look clean enough to weld, but be smeared with paints/coatings that will not weld. Smeared galv does the same thing too.

cleaned it back to clean steel, i have worked with lots of scabby and galv`d steel and this is first time welding it has been like this.

 

[Turbo]

Could it be wrought iron? The impurities in it mean its not nice to arc weld.

 

[awemawson]

A lot of bed frames, particularly Vono ones, were Re-rolled tram lines that were high manganese for wear resistance..it work hardens as well as horrible to weld.

 

[Screwdriver]

Could it be wrought iron? The impurities in it mean its not nice to arc weld.

W.olly says it was welded and you wouldn’t weld wrought iron, forge weld yes, electric arc, no. Not for structural use.

Am I wrong about that??

 

[Popcorn]

Old bed frames are made of 'Pig Iron' it's a mixture of all sorts of metal, thats why it's so difficult to weld. Arc welding with high Nickel rods works better than anything else.

 

[awemawson]

There is absolutely no way bed frames are pig iron. Zero tensile strength and cannot be rolled into angle. Pig iron is very brittle so I think that you are thinking of some other material.

 

[Munkul]

Easy way to tell if it's high carbon iron/steel:

zap it with a welder, and try to file it away. If its high carbon (and therefore probably cheap material with high impurities) it will have a very hard spot. The welds may be brittle as well.

It does sound like cheap olden-days material. Not the high grade olden-days stuff, but the cheapest stuff which had poor carbon control.

EDIT: Apart from the fact that it's metric and was arc welded to start with, which means its not olden-days stuff.

I'm coming back to thinking there's a coating on it...! Or maybe something else... what are you welding it with?

 

[Popcorn]

If you look at a bed frame there not rolled, they look to be cast cheaply.

 

[awemawson]

Vono beds had cast end fittings and rolled frame bars.