Solder on Cast Iron Block

[Murdul]

We are trying to repair rust pits at water jackets on a cast iron block with Solder and so far are unsuccessful. We've tried rod, silver solder with flux, tried arc welding with low melting point nickel rod none of which worked. Is there a way to solder cast iron at low temperature, keep cast iron below 400F?

 

[metengr]

The above repair options should work, and I suspect you are not able to clean the pits for acceptance of braze metal or even Ni-base weld metal. The corroded surfaces need to be absolutely clean for welding or brazing, even local grinding to remove the corrosion pit may be necessary.

 

[tomwalz]

Maybe grinding and a degreaser like Easy Off.

Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[arunmrao]

As told by others a clean surface preparation is a must,before attempting to repair.

 

[Murdul]

We clean the surface, wire brush and then degreaser, the problem is the solder doesn't adhere. After soldering the solder can be readily picked off. The solder will only stick if we heat the cast iron over 500F and this causes discoloration, which we want to avoid.

Thank you for the replies. If you have any other ideas, such as a special solder, our rep is out of ideas.

 

[metengr]

What is the maximum temperature of the cast iron in service? If it is less than 300 deg F you might want to look at metal impregnated expoxy to fill in the corroded areas?

 

[Murdul]

Thats a good idea. We have to be able to machine the surface smooth once cured. Is there anything that will hold up to that?

 

[metengr]

http://www.belzona.com/prod1k.aspx

 

[tomwalz]

You said "degrease".

Often a degreasing solvent will leave a film especially with a porous surface such as yours.

Easy Off or a similar caustic product will saponify oils and greases. A commercial product will also have rinsing agents in it.

If the discoloration is an oxidation issue you might wish to flux the area being discolored.

Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[4JawChuck]

Why not pin it, if done properly it is as good as welding as long as there is enough material around the crack to take the procedure.

http://www.enginebuildermag.com/Article/1968/pinning_down_the_cold_repair_process.aspx

 

[unclesyd]

Variations of on the following alloys,Crontron 211 or Certanium 889. are used for repairing dirty Cast Iron. I would contact Lawson Products about you problem.

When welding CI you really don't want to weld in the strict sense of the word. You really need an artist that paints the metal on to the part, I say this as too many welders want to "dig in" and get a good bond.

If possible clean your part either in molten salt bath or a Pyrolysis Furnace. This can be accomplished at many auto repair shops. Ask if they remove the smut that some times forms

Even though they are not allowed in all cases, Cadmium base products do work.

Another one sold by the heating and air supply companies is the Sil-Fos line of brazing materials. Talk someone in the business as there are several different fluxes.

In the repair of CI either by weld, soldering or brazing the flux or rod coating plays a big role in the sucess or failure.

If all of the above don.t pan out contact arumrao's and ask for his secret formula for "Foundryman's Putty"