Origin of the porosity in Steel casting 1

[stanislasdz]

We have a problem on part casting, in CF38M. All the part have gaz defects.

Any solutions ?

I know that there is a lot of origins of this porosity, but how to find wich is the source of this defect.

This is a good paper from American Foundry Society. But how can i use these informations to avoid the porosity ?

http://www.moderncasting.com/archive/WebOnly/0905/WebOnly0905.pdf

Stan

 

[arunmrao]

The picture shows that you have a gassy metal. Use clean scrap and pour at 1525-30C. Also add possible deoxidizers and pour fast.Before you pour the casting pour a small quantity into a test cup. Look at the surface of the metal,if it sinks ,you are fine else you need to remove the gases before pouring.

I hope your mold and cores are ok and there is no entrapment or excess release of gases

 

[stanislasdz]

Thanks arunmrao !

wonderfull informations !!!

What can you say about our chemical composition

C : 0.07
Mn : 0.83
Si: 1.20
S: 0.005
P: 0.024
Ni : 10.2
Cr : 19.71
Mo : 2.39
Nb : 0.01
AL : 0.015

 

[arunmrao]

It is CF 8M chemistry. Nothing wrong about it.Though your carbon is dangerously close to 0.08% max level. What is the casting that you are pouring?

 

[stanislasdz]

If i understand your question :

The casting is PUMP the weight is about 500 Kg. Chemical sand(ALPHASET)

I hope i answer your question.

 

[arunmrao]

Pump casing should not be a problem with the molding material used. Please check the melt quality and if possible purge argon gas into the melt.

Do you make thin walled pump impellers. What is the core material?