Porosity on 347SS investment casting
Porosity on 347SS investment casting
(OP)
Was wondering if any anyone has experienced porosity/microshinkage with SS347 investment castings. These defects are visible in FPI and concentrated
in pockets, cores, holes etc. Any help would be greatly appreciated.
in pockets, cores, holes etc. Any help would be greatly appreciated.





RE: Porosity on 347SS investment casting
RE: Porosity on 347SS investment casting
Performed and casting meets grade. Is there anyway to
Minimize or eliminate these defects
RE: Porosity on 347SS investment casting
RE: Porosity on 347SS investment casting
"Even,if you are a minority of one, truth is the truth."
Mahatma Gandhi.
RE: Porosity on 347SS investment casting
RE: Porosity on 347SS investment casting
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P.E. Metallurgy, Plymouth Tube
RE: Porosity on 347SS investment casting
What specification are Your castings being produced to?
ASMH 1309 for Type 347 [UNS S34700] and Type 348 [UNS S34800] CRES lists the casting version for these two alloys as CF-8C [UNS J92710]???
The only specs that I could find for CF-8C [= CF8C] are as follows
AMS5364 Steel, Corrosion and Heat-Resistant, Investment Castings 19.5Cr - 10.5Ni - 0.65Cb (CF-8C) Solution Heat Treated - UNS J92710
ASTM A351 Standard Specification for Castings, Austenitic, for Pressure-Containing Parts
ASTM A488 Standard Practice for Steel Castings, Welding, Qualifications of Procedures and Personnel
ASTM A703 Standard Specification for Steel Castings, General Requirements, for Pressure-Containing Parts
ASTM A743 Standard Specification for Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application
ASTM A744 Standard Specification for Castings, Iron-Chromium-Nickel, Corrosion Resistant, for Severe Service
ASTM A781 Standard Specification for Castings, Steel and Alloy, Common Requirements, for General Industrial Use
ASTM A985 Standard Specification for Steel Investment Castings General Requirements, for Pressure-Containing Parts
Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]
RE: Porosity on 347SS investment casting
RE: Porosity on 347SS investment casting
AMS2175 Class/Grade ????
Per AMS2175
3.1.1 Determination of Classes and Grades
The cognizant engineering organization shall establish the class and grade(s) for each casting design in accordance with
1.3). If the grade of casting is not specified on the drawing or other contractual document, Grade C shall apply, except for
Class 4 castings, where Grade D shall apply. Sections of a casting may be of varying grades depending on the applied
stresses to that portion of the casting. Particular attention should be given to areas that contain, or will eventually contain,
stress risers after machining (such as sharp internal corners, holes, or notches).
Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]
RE: Porosity on 347SS investment casting
RE: Porosity on 347SS investment casting
You aren't letting out-gassing from the cores to escape.
And poor melt degassing makes you more sensitive to this.
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P.E. Metallurgy, Plymouth Tube
RE: Porosity on 347SS investment casting
RE: Porosity on 347SS investment casting
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P.E. Metallurgy, Plymouth Tube
RE: Porosity on 347SS investment casting
RE: Porosity on 347SS investment casting
I took a hard look at AMS2175 for Class 3C. Based on Your description I am NOT convinced Your castings meet 3C quality requirements. However, IF they do, then You may have 'gotten what You paid for'. IF Your finish-machined part meets drawing requirements and NDI's OK, then 'it is what it is'... even IF the appearance is not 'ideal'. IF your finish-machined parts can't pass final drawing requirements, then a higher quality requirement [more stringent casting quality controls] might be in order.
Is the caster's shop in a high humidity environment? Make sure Your cores and molds are baked dry and [as mentioned] that the melt is thoroughly degassed before pouring.
Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]
RE: Porosity on 347SS investment casting
RE: Porosity on 347SS investment casting
Microshrinkage is often due to local solidification conditions. Changes to the cross section transitions or geometry of the casting, changes to the local shell thickness of the mold, or any other change that will provide a more uniform solidification rate in the local area would be helpful.