Yield strength of ASTM A7-55T ???
Ken Meltsner
as it is.
I'm following up for a good reason: this is a fairly common question.
How does one find xx for material xx?
In the case of the ASTM, one finds a copy of the standards books (or CD-ROM)
and uses the index to find which volume the spec is in. A7 is obsolete, and
listed as such, so, given our extensive knowledge of the material's
application, we check all of the standards which have replaced it.
I don't recall them all, but A36 (a standard structural steel spec) isn't
right -- there's no "55-T" grade. We keep looking and come to A663 and A675,
which have slightly different application areas. Both have Grade 55s.
We find the Grade 55 refers to the ultimate strength, and then look in the
text for a table with the yield strength. Both lists yield strengths, one
of 27.5 and one of 30.0. Both are defined as "yield point" which doesn't
give us the real "proof stress" (typically at 0.2% offset), but should
be adequate.
Now, which one is the T version? Neither. Which number is appropriate for
use for design? Neither. For a really good answer to the question, you
need to dig up the A7 spec. I find it hard to imagine the ASTM can't
sell you the spec, even though it's obsolete, but I could be wrong. And
even though you can't buy an A7-55T material any more, it's useful to know
how it was originally defined.
As a note, the Document Center in California has a nice Web page, and sells
copies (cleared with the appropriate organizations) of most useful standards.
Here's the URL: http://www.service.com/doccenter/
In case you wonder about the rationale for this long answer, I'm currently
running a project to support materials substitution for obsolete materials.
As a result, I'm trying to provoke discussion in this area. Feel free to
contact me for more details if you're at an American manufacturer or
defense site.
By the way: does the use of the Internet by consultants to find answers come
under the same disfavor as the use of the Net by students to answer homework
problems?
Ken Meltsner
Concurrent Technologies Corporation
Wayne H. Langley 1-4047
In article <35s9se$d...@server1.ctc.com>, melt...@CTC.COM (Ken Meltsner) writes:
|>(deleted)
|> I don't recall them all, but A36 (a standard structural steel spec) isn't
|> right -- there's no "55-T" grade. We keep looking and come to A663 and A675,
|> which have slightly different application areas. Both have Grade 55s.
|>
|> We find the Grade 55 refers to the ultimate strength, and then look in the
|> text for a table with the yield strength. Both lists yield strengths, one
|> of 27.5 and one of 30.0. Both are defined as "yield point" which doesn't
|> give us the real "proof stress" (typically at 0.2% offset), but should
|> be adequate.
|>(deleted)
Sorry, but I disagree. As far as I have ever seen, the -xx in an ASTM spec refers
to the year of adoption or revision, and the "T" means that the standard is a
Tentative Specification.
I don't have A7-55T, but I was able to find the following:
A7-46 Fy=33 ksi Fu=60-72 ksi ref. AISC manual 5th Ed.
A7-61T Fy=33 ksi Fu=60-75 ksi ref. AISC manual 6th Ed.
(It is pretty much a sure bet that A7-55T is also Fy=33 ksi)
I sent most of this info to the original poster, but I probably should have posted it
publicly.
|>(deleted)
|> By the way: does the use of the Internet by consultants to find answers come
|> under the same disfavor as the use of the Net by students to answer homework
|> problems?
|>(deleted)
As far as I'm concerned, anyone with an interest in engineering is welcome.
That's how we'll have the most talent possible here.
(These are my opinions only, etc,)
Wayne Langley