Impossible 65-45-12 Material Certs? 3

[farmer2]

Received certifications from a foreign ductile foundry with the following mechanical and chemical properties:

106,500 psi Tensile C 2.75, Si 2.44, Mn .39, P .o1, S.02
77,700 psi Yield Cr .03, Ni .09, Mo .22, Cu .13, g .05
16% elongation
187 HRB

Material ordered was 65-45-12. Now I am no metallurgist, but these values look completely absurd and impossible. They don't even look reasonable for 100-70-03 ductile. Please let me have your thoughts.

 

[TVP]

Perhaps the parts were austempered after casting. Austempered ductile iron (ADI) can have quite favorable strength and elongation numbers. Use the following link for more information:

http://www.ductile.org/didata/section4/4intro.htm

 

[farmer2]

TVP,
We did not specify austempered ductile iron and I do not know why they would furnish it as such. The cert says nothing about post treatment.

What maximum tensile, yield and elongation values should you get on 65-45-12 ductile?

If they did austemper the castings, would that result in decreased machinability? Also, does the BHN of 187 look reasonable for the tensile strength?

 

[Flesh]

The tensile strength and hardness don't really match up. I would expect a hardness starting at 241 BHN, for that tensile strength. The properties do look like an ADI material, as TVP mentioned, but they don't meet any ASTM grade. Plus, the hardness would have to be much higher to be ADI. Is it possible there was a metric to english conversion error in the numbers?

 

[arunmrao]

There is certainly a flaw in the test report. If the TS properties are correct, the elongation cannot be that high.

Also the chemical prroperties do not suggest anything to have high such high values. this must be a coked up certificate. Destroy a casting and check for micro and mechanical properties.

I once had a research student who honestly made such claims of high tensile value and also high elongation. I verified his results ,method of testing etc and I could not find a fault. But I was sure about the error in testing. One day I walked upto the testing machine while the test was being conducted. guess what!! The machine had a Zero error. He was reading a higher breaking load without factoring for the zero error.

" All that is necessary for triumph of evil is that good men do nothing".
Edmund Burke

 

[TVP]

I didn't even notice the hardness: 187 HB is not high enough for ADI. Definitely something is wrong here. FYI, 187 HRB is nonsensical-- the HRB (Rockwell B) scale only goes to 100. HB is Brinell hardness.

 

[arunmrao]

farmer 2 can you please reveal the country of origin of the castings. The test certificate appears to be fraudulent one and no typographical or any such error can be attributed.

" All that is necessary for triumph of evil is that good men do nothing".
Edmund Burke

 

[farmer2]

TVP: Hardness is HB not HRB. My error.

Arunmrao: Mexico

Thanks for you help.