Any metallurgists out there?

[dickm]

Son-in-law recently bought a secondhand woodburning stove, and the front firebars were very distorted and broken in the middle. Offered to weld it up as a temporary repair, but as soon as the arc was struck, the joint area in the metal turned into a small firework; lots of sparks and hissing, which carried on after the arc stopped.
Anyone know why this happened? Since the firebars were sitting in a front of a red hot fire, anything combustible would presumably have burnt off long since?

So the only way to do a very temporary repair was to rivet a bit of steel on to the original. Fortunately, they've now replaced the cr** stove with a proper Morso.

 

[Digit]

In theory Dick the carbon in the CI can be burned, the fireworks sound like the grains of iron burning.
The arc can be pretty hot of course.

Roy.

 

[No skills]

Sounds a bit like when you try to weld steel that has been galvanised and not cleaned back enough to get to bare metal.

 

[Hitch]

I'd gather its a very cheap/poor quality cast iron, which is also very 'dirty', doesn't really weld any sense.....

Quick bit about it here-
http://www.mig-welding.co.uk/welding-cast-iron.htm

 

[dickm]

Interesting page, Hitch. It mentions magnesium as being one of the alloying metals used; from vague memories of school (in the days when we were allowed to do unsafe chemistry things ) the sparks did look very much like those from burning Mg.
Still surprised that it was so combustible after having been exposed to red hot firebed, though. And "rubbish" just about sums it up.

Though I say it myself, I have actually managed a couple of really good welds in "proper" cast iron, repairing a Parkinson and a Record vice. This was a different experience altogether, and both vices are still doing good service!