Problems with gas in P91

[FoundryB]

We are currently having problwms with large amounts of gas forming in our casting's poured in material P91 (ASTM A217 c12A)

We have increased the aluminum content however this has had little effect.
All our sand moulds chemically bonded.

1. Are there any other practical ways to de-gas this material.
2. Are there any otheres who have had this problem and did you solve it.

Many Thanks

 

[gieter]

Have you contacted Castings Technology International?

http://www.castingsdev.com/