Newsgroups
You may benefit considerably in your research by reading, and likely posting to, an internet newsgroup.
sci.engr.metallurgy is recommended for a starter. Download an appropriate newsgroup reader application (I have Internews from Penn State CAC), install and open, and enjoy. Alternatively, your web browser may be able to access these newsgroups; try
http://news-reader.org/sci.engr.metallurgy/
Below are some recent postings to sci.engr.metallurgy. Note that 3 and 4 have responses.
1. Can
anyone advise on the electrochemical behaviour of a large area of
Duplex Stainless steel coupled to a small area of alpha titanium alloy
(unalloyed, grade 2).
The environment will be predominantly oxidising with aqueous H2S.
2. I
am looking for high temperature (around 1100F) stress to rupture and
creep strengths for Inconel 718 in the state it comes from the Mill
(solution annealed at 1800F for 18 minutes).
The strength after aging is well above what I need and I don't want to
bother with aging if I don't have too.
3. I'm
seeing an unusual phenomenom with forged Ti64 (recrystallized annealed
about 50 degrees below the transus). The mechanical properties are
normal for Ti 64 (tensile strength, yield strength, elongation, and FTT);
however, the reduction of area is low. It should typically be around 30,
but I am seeing RA values of 15 - 20 (these results have been repeated).
The microstructure is ideal: about 30%- 40% equiaxed alpha, the balance
lenticular alpha in beta matrix. The chemistry appears to be normal.
Has anyone experienced anything like this?
_____________________________________
Any chance of alpha case developed during annealing? Any chance of hydrogen
pickup?
_____________________________________
No, but a good question none-the-less. Alpha case, which does form
during both the forging and annealing process, is removed by chemical
milling ("pickling" in a weak hyrdoflouric acid bath); removal
is verified
by optical microscopy. The hydrogen content is also measured after the
chem mill process, in which it is most susceptible to hydrogen pickup, to
ensure that it is below 150 ppm (well below a level that would be expected
to embrittlement).
4. David Wang wrote in message <01be3a84$5667f460$b601b1c0@David.wika.com>...
>Does any know why stainless steel 302 magnetic (attract to a magnet)
while
>stainless steel 304 & 316 are nonmagnetic? Your help would be greatly
>appreciated.......David (dwang@wika.com)
>
Most 300 series (austenitic) stainless steels are not ferromagnetic.
There
are exceptions. When some stainless steels like 302 are drawn to spring
wire they partly transform to martensite and become magnetic. 304 also can
do this given enough deformation. Look under martensite transformations
in
Chapter 4 of the Handbook of Stainless Steels, McGraw-Hill, 1977 if you
can
find it in your local college engineering library.
_____________________________________
Elaborating on the correct answer given above (as best I can), the tendency
to
transform to austenite is dependent on the relative amounts of ferrite and
austenite stabilizing elements, such as carbon, nickel, molybdenum, and
chromium. So, higher carbon and nickel contents tend to stabilize the
austenite, and higher chromium and molybdenum contents tend to promote the
transformation to martensite. With this in mind, if you look at the
compositions of the 300 series grades, you'll see why 304 and 316 are more
stable than 301 or 302.
_____________________________________
And to further elaborate, in welded 300 series stainless steels you may
also
see some ferrite, and this is measured magnetically and expressed as a
ferrite number (FN). Estimating what microstructure you get based on
composition is done with the Schaeffler diagram which is a pseudoternary
based on chromium and nickel equivalents.
The current state of the art is in Volume 4 of the Eight Edition of the
Welding Handbook, starting on page 264.