How to identify if a piece of metal is malleable iron?

[Laverda]

I have a iron casting I am trying to identify for the purposes of welding. I think it is malleable iron but it could be cast iron or even mild steel. Is there an easy way to identify what it is without destroying the part? It does bend which makes me think it is malleable but, I don't know.

I have been told if it is malleable iron, welding it can be a problem as the welded are will be brittle and could crack.

 

[technocrat]

grinder spark test

 

[memphisjed]

If it bends and doesn’t crack it is not grey iron (if bent enough, which is not very much). Spark test. Of course tool steel can throw results off.
Welding, use ni-rod or braze with bronze and it will not matter if it is cast malleable mild steel or tool steel.

 

[john.k]

Malleable up to around 1960,after that SG/ductile iron has the same properties but is much cheaper to make......Spark test is good......same spark as cast iron ...dull red short with lots of dust.........if possible ,try to chisel a wire out of the casting....spark test plus a wire will mean malleable/ductile .......Never melt weld any ductile......if you melt the iron reverts to a brittle structure......full strength joins by nickle bronze ,or partial strength by ordinary bronze.......Nickle electrode arc is also possible ,but needs a lot of experience to get an acceptable result.

 

[Laverda]

OK, I will try the spark test. The part was made in 1949 so it looks like malleable is the best guess at the moment.

 

[michiganbuck]

Usually, an iron is not mailable if it is too big to fit in the box.
Welding CA for a crack can be tricky, for some such jobs a drill hole to stop crack growth and then JB weld to fill works better.

 

[sfriedberg]

Usually, an iron is not mailable if it is too big to fit in the box.

 

[memphisjed]

OK, I will try the spark test. The part was made in 1949 so it looks like malleable is the best guess at the moment.

The date of making is not an indicator. Unless old.
Torch Brazing works whatever it is, better question is what are you making, what materials are you trying to weld/attach to what? Is it a tool that gets impact or heat? Is it yard art? Is it a mission critical flight component?

 

[john.k]

Never melt malleable iron....it will harden as brittle cast white iron...........nickle bronze brazing is the most satisfactory......ordinary bronze rod is also OK.......scaling powder is generally needed to wet ,then use ordinary borax...(too much scaling powder will cause bubbles in the braze)

 

[memphisjed]

Gonna need a bigger box