Questionable 80-55-06 Ductile Iron Certifications
Questionable 80-55-06 Ductile Iron Certifications
(OP)
Dwg spec is 80-55-06. Received cert with castings as follows:
Tensile: 119,400 psi
Yield: 84,900 psi
Elongation: 6%
Chemicals: 3.63 C, 2.56 Si, .64 Mn, .01 P, .02 S, .02 Cr, .06 Ni, .11 Mo, .55 Cu, .04 Mg.
Hardness: 207 Brinell
Is it believable that tensile and yield are that high, and that elongation is still 6%? Are tensile and yield too high as typical ranges?
This is the same foundry that sent bogus 65-45-12 certs about one month ago on another casting about which I posted.
Thanks,
Tensile: 119,400 psi
Yield: 84,900 psi
Elongation: 6%
Chemicals: 3.63 C, 2.56 Si, .64 Mn, .01 P, .02 S, .02 Cr, .06 Ni, .11 Mo, .55 Cu, .04 Mg.
Hardness: 207 Brinell
Is it believable that tensile and yield are that high, and that elongation is still 6%? Are tensile and yield too high as typical ranges?
This is the same foundry that sent bogus 65-45-12 certs about one month ago on another casting about which I posted.
Thanks,





RE: Questionable 80-55-06 Ductile Iron Certifications
This appears to be yet another case of false certification. There are no alloying elements like Ni, Mo, Cu in sufficient quantities to achieve such high mechanical properties. Also 6% elongation is a dream figure at those strength levels.
My suggestion would be to destroy a casting and prepare a tensile specimen for testing. This will enable you to know the deviations before you decide to scrap the castings.
" All that is necessary for triumph of evil is that good men do nothing".
Edmund Burke
RE: Questionable 80-55-06 Ductile Iron Certifications
RE: Questionable 80-55-06 Ductile Iron Certifications
Of course, if we test these and they pass load tests, then production shows up closer to the minimums, there could be a strength problem, yet the foundry could say they met our minimums. They are going to send us an extra test bar from this heat for test by our local test lab. Would it be better to cut a sample out of one of the castings, as you suggested, arunmrao?
RE: Questionable 80-55-06 Ductile Iron Certifications
RE: Questionable 80-55-06 Ductile Iron Certifications
Also check the chemistry of the new test bar offered and the casting sample,this will let the cat out of the bag.(if it is there!!).
" All that is necessary for triumph of evil is that good men do nothing".
Edmund Burke
RE: Questionable 80-55-06 Ductile Iron Certifications
Tensile: 74,500 psi v. 119,420 (cert)
Yield: 58,000 psi v. 84,927
Elongation: 2.9% v. 6.0
Hardness: 222 BHN v. 2.7
The chemicals also showed some large differences:
P .016 v. .01 (cert)
S .058 v. .02
Ni .08 v. .06
Mg .05 v .04
C 3.71 v 3.62
Si 2.25 v 2.56
Mn .64 Same
Cr .03 v .02
Mo .12 v .11
Cu .55 v .53
They offered a duplicate test bar, which was not sent, but I see no need to test one if sent.
The tensile and yield are not far off the spec for 80-55-06 but the elongation is way off. Does anyone see a reason for this? How close would you expect the test results from a test bar and a specimen from the casting to agree? The test specimen was .354" dia. Elongation was in 1.4".
Thanks,
RE: Questionable 80-55-06 Ductile Iron Certifications
Hardness: 222 BHN v. 207 (not 2.7)
I am thinking we should not use these castings or this foundry. Any differing opinions?
RE: Questionable 80-55-06 Ductile Iron Certifications
The issue of false certs is a big problem, but that aside, would these castings be acceptable? The tensile strength tested 7% below minimum but that alone would not be a problem.