Etchant for Ductile iron - Nickel filler Weld 2

[Hercules28]

Dear all, what would be a nice etchant to examine a ductile iron weld.?

I use nital for Ductile iron but I would like to etch the Ni filler.
any ideas on that?

Thanks

 

[Guest102023]

Etching gets tricky when you have a low or non-alloyed ferrous material welded to a corrosion resistant material (there's a reason they are called CRAs!).

Someone out there may know of a compromise etchant, but tThe best advice I can offer is to etch the cast iron first (nital) and then mask the cast iron with scotch tape (yup, the stuff on your desk) before etching with a suitable nickel etchant. Works best if your fusion line has some straightness.

I take it this is for a weld procedure or welder qualification, and the applicable code insists you etch the assembly before visual examination for flaws. This is an instance where the saying 'the law is an a$$' is applicable.

 

[Hercules28]

I agree with you brimstoner. I was actually going to try exactly that. But I was thinking to do the split perpendicular to the weld.
I will try Nital for Ductile and MArbles for Ni and will update on results.

thanks,

 

[CoryPad]

For our ductile iron welds we use nital and we leave the weld metal essentially unetched. High concentration (4 %), long etch time, and high magnification can reveal some dendritic structure in the weld metal.