cast iron material 2

[mauner]

Hi everyone,

Can anyone provide a comparison between cast iron for a motor frame between these two specifications?

ASTM A47/A47M
JIS G5501 FC200

Does FC200 correlate to the strength?

Thanks in advance,

mauner

 

[micalbrch]

"FC200" correlates to the minimum tensile strength.

My data say that JIS G5501 FC200 is equivalent to ASTM A 278, Class 30

 

[mrfailure]

These are indeed two different materials. FC200 is gray iron while A47 is malleable iron. A47/A47M comes in only one grade, 22010 (metric) which has a 340 MPa minimum UTS, 220 MPa minimum yield strength, and 10% minimum elongation. Maximum typical hardness is specified as 156 HB (my references notes hardness for FC200 is 223 HB but it does not state if this is a minimum or maximum).

Aaron Tanzer

http://www.lehightesting.com

 

[mauner]

Thanks for your response, but I have some follow up question.

Is the gray iron per FC200 brittle?

Why doesn't ASTM A 278 spec list a UTS?

Which material is better for handling shock or sudden impulse load? (is it a malleable iron)

Thanks again,

mauner

 

[mrfailure]

All gray iron is brittle, with almost no ductility.

ASTM A278 does specify minimum tensile strength. The equivalent strength class to FC200 is #30 (i.e. 30 ksi minimum tensile strength).


Aaron Tanzer

http://www.lehightesting.com

 

[mauner]

Thanks mrfailure!

However, I meant to ask why ASTM A278 material doesn't list a yield strength. My thought was maybe it doesn't yield before breaking. Hence, only a UTS is listed.

Like you said, ASTM A47 is malleable with a yield of 220 MPa and UTS of 340 MPa. How can I compare an electric motor frame mounted with four bolted feet made of these two different cast materials (the 220 MPa yield of A47 with the 200 MPa UTS of A278)?

Thanks again

mauner

 

[TVP]

mauner,

Essentially, gray iron does not have a defined yield point. Under tensile loading, it will elongate less than 1% (see curves shown in link below).

http://www.nrc-cnrc.gc.ca/eng/projects/irc/gray-cast/gray-cast.html

What exactly are you trying to do with your analysis? Are you performing some hand calculations or finite element analysis using applied forces? Are there forces that will cause tensile stresses in this frame? You mentioned shock/impulse loading before. Gray iron has extremely low fracture toughness, and therefore really isn't suited for shock/impulse loading.

 

[mauner]

Thanks TVP for the link - it is very informative.

I'm not doing an analysis, but comparing materials used in a motor that will pass MIL-S-901 shock to a commercial NEMA motor.

I will be testing the motor in the June and concerned that it might crack, unless its mounted on rubber.

If the material is unacceptable for a shock test, then I will need to select a different motor.