racookpe1978 - I had a talk with an industrial consultant recently and he has confirmed that this is nothing but mold gas evolving while the metal is yet to freeze completely. I have considered his advice and will take all necessary steps to overcome the defects. I will update here my results...
EdStainless Please find attached pics.
racookpe1978 Sir because the furnace sample was good enough to pour. The cavity was filled smoothly and feeders were in action of feeding creating a cone cavity, but within in a few seconds they sparkled and right from the center of the feeder metal started...
Castings weight 120 Kg, Pouring Temp - 1187o C.
Melting in Induction medium frequency furnace.
Ceramic filter of 10 ppi was used. Marble grit plunging was used to remove gas for 4 min approximately in a melt of 170 Kg and Mg was used in ladle for degassing.
Furnace sample was good but late...
THANKS FOR THE RATIO EdStainless, I WILL TRY PICKLING WITH THE GIVEN RATIO AND CONDITION. ALSO AS SUGESTED BY McGuire THE 'SMUT' IS OFCOURSE Fe PRECIPITATES AS THE SHOTBLASTING IS DONE WITH CARBON STEEL SHOTS. FREQUENTLY CHANGING THE SOLUTION MIGHT HELP. I WILL LET YOU NOW THE RESULTS SOON...
While acid pickling of castings made of grade cf8, cf8m ,cf3m, etc a kind of black deposition on the surface and inside the bore of casting is observed which gives a bad look and is tough to remove. Acid used is HNO3:HCl:H2O - 2:1:1 and dipped for approximately 30 to 40 min. please advice
A M...
