GX40CrNiSi20.14 surface problem

[berkrefik]

Hello everyone,

I have a problem on my casting surface, which I never experienced before.
Cast material specification is GX25CrNiSi20.14.
In the as cast condition; after machining, a surface appeared like in the picture below.








The order is cast in 4 melt charges.
All charges have the same problem.
Melt is prepared in 500kg induction furnace, cast in a cold setting resin mould.

Any comments will be appreciated.

Thanks

 

[arunmrao]

Can you tell more about the resin sand system and the coating used. What is the solvent used in the coating?


"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

 

[berkrefik]

It is a phenolic resin system, silica sand is used in the mould. Zr coating is applied, solvent is isopropyl alcohol (IPA).

 

[berkrefik]

Also i tried heat treating today, water quench from 1050C. Nothing changed.

 

[arunmrao]

The defect you see, is due to metal mould reaction. Possibly your resin or IPA needs to be checked.

Did you try pouring the same casting in a CO2/Sodium silicate system.


"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

 

[berkrefik]

Thanks arunmrao.

I didn't try with sodium silicate system, it doesn't look possible with my current moulding system.

I have some concerns from IPA, now looking for a place with gas chromatography to test IPA.