DAY 17 STEELS AND STAINLESS STEEL
A36 STEEL
This is the basic structural steel. Widely used in
load bearing structures.
 NOT quenched and tempered.
 Yield strength: 250 Mpa, or 36 Ksi
 UTS: 550 Mpa, 80 Ksi.
 Ductility: 20% in 200 mm.
 About 0.26% C by weight, 0.75% Mn, small
amounts of Cu, S, and P.

A36 APPLICATION
http://www.tms.org/pubs/journals/JOM/0112/Eagar/Eagar0112.html
HSLA STEELS
This is a family of steels. Very low carbon
content. ( say about 0.05% C) 1.5% Mn. Some
other metals: Called microalloyed.
 Yield strength: 345 Mpa, or 50 Ksi
 UTS: 483 Mpa, 70 Ksi.
 Ductility: 18% in 200 mm.
 Cr, Cu, V and Mn are added.
 About 4 times the corrosion resistance of A36.
 This is automobile body stuff. It is precipitation
hardened. Aging during the paint bake.

HSLA
MEDIUM CARBON STEELS
Typical carbon content 0.40%. Can be quenched
and tempered for many applications: ie. Bolts
and shafts of relatively small diameter.
 Yield strength: 469 Mpa, or 68 Ksi
 UTS: 664 Mpa, 96 Ksi.
 Ductility: 26% in 50 mm.
 Not a lot of alloying mats – plain carbon.
 Other applications: railway tracks, wheels,
gears, bushings, etc.

MEDIUM CARBON STEEL APPLICATION
TOOL STEELS
Carbon Content is high. These will be quenched
and tempered. Typical member of the family:
AISI Type W2. Water quenched and tempered.
 Yield strength: 1090 Mpa, or 158 Ksi
 UTS: 1185 Mpa, 172 Ksi.
 Ductility: 11% in 200 mm.
 Composition 1%C, some Cr, Cu, Mn and V <
1.0%. It’s really a plain carbon steel.
 Used for drills and cutting blades.

TOOL STEEL APPLICATION
STAINLESS STEEL
Problem with steel – corrosion protection with a
surface layer. Iron oxide is not “tenacious”
meaning that it easily flakes off, leaving more
bare metal open to attack.
 Solution: Add more than 10.5% Cr, Chrominum.
This Cr forms a very tenacious oxide. If chipped
off, it repairs itself. It is a passivated layer.
 Having over 10.5% Cr is a common factor in all
stainless steel.
 But, inside the stainless steels there are many
different kinds. Most have very low carbon
content.

FAMILIES OF STAINLESS STEEL
1.
2.
3.
4.
Ferritic
Austenitic
Martensitic
Precipitation Hardenable
http://www.estainlesssteel.com/stainlesssteelandnickelcharts.shtml
FERRITIC STAINLESS STEELS
Typical: AISI 409.
 11% Cr. 0.08% C.
 Yields at 205 Mpa, 30 Ksi.
 Ductility is 20% EL in 2 in.
 This is the cheapest of all stainless steels. Uses:
agricultural spray tanks and automotive exhaust
components.

Grade 409 is a titanium-stabilised ferritic
stainless steel. Although regarded as a
general-purpose chromium stainless steel the
almost exclusive application for Grade 409 is
automotive exhaust systems. Its applications
are those where appearance is a secondary
consideration to mechanical properties and
corrosion resistance, particularly at high
temperatures, and where some weldability is
required.
http://www.atlasmetals.com.au/files/ASM%20Grade%20Datasheets/Atlas%20Grade%20datasheet%20409
%20rev%20May%202008.pdf
SSINA Stainless Steel Design Guidelines
AUSTENITIC STAINLESS STEEL
Key here: we add a lot of nickel say around 10%
in addition to the Cr. This stabilizes the
austenite so that it will not become ferrite at low
temperatures.
 Result: we have an FCC steel that is corrosion
resistant. Also non-magnetic.
 Not strong, but very very tough and ductile. (No
DBTT).
 Of course, this is more expensive stuff. World
demand for Ni is very high. Why? (Ni is now at
about $12/lb.)

Grade 304 is the standard "18/8" austenitic
stainless; it is the most versatile and most widely
used stainless steel. It has excellent forming and
welding characteristics. Grade 304 can be severely
deep drawn without intermediate annealing, which
has made this grade dominant in the manufacture of
drawn stainless parts such as sinks, hollow-ware
and saucepans.
Grade 304L, the low carbon version of 304, does not
require post-weld annealing and so is extensively
used in heavy gauge components (over about 6mm).
Grade 304H with its higher carbon content finds
application at elevated temperatures. The austenitic
structure also gives these grades excellent
toughness, even down to cryogenic temperatures.
http://www.atlasmetals.com.au/files/ASM%20Grade%20Datasheets/Atlas%20Grade%20datasheet%20304%20rev%20May%2020
08.pdf
AUSTENITIC STAINLESS
Cryogenic Tanks
Cookware
TYPICAL AUSTENITIC STAINLESS STEEL
304 Stainless Steel.
 Low carbon (<0.08%C). 18-20% Cr. Nickel 810%.
 Microstructure is austenite base.
 Yield: 215 Mpa. 31 Ksi.
 UTS: 505 Mpa, 73 Ksi.
 Ductility: %EL = 70%.
 Uses: beer kegs, cooking equipment, cryogenic
vessels, surgical equipment (not scalpels!)

SSINA Stainless Steel Design Guidelines
MARTENSITIC STAINLESS STEELS
These steels have (close to, less Cr than austenitic)
the corrosion resistance of other stainless, but
they have very high strength.
 How? They are quenched and tempered. The basic
structure is TM. For this we have 0.1 to 1.0 % C.
(Not as much Ni – we want some for hardenability,
but not enough to prevent the martensite
transformation.
 Result: High strength

TYPICAL MARTENSITIC STAINLESS STEEL
410 Stainless Steel.
 Low carbon (<0.15%C). 12.5%
Cr. Little Ni.
 Quenched and Tempered
 Yield: 721 Mpa. 105 Ksi.
 UTS: 834 Mpa, 121 Ksi.
 Ductility: %EL = 21.5%.
 Uses: Scalpels, cutlery.
Nozzles, shears, valves and
pump components.

http://www.matthewsgauge.com/mgi/prod
ucts/medical-pins
Grade 440C is capable of attaining, after
heat treatment, the highest strength,
hardness (Rockwell C 60) and wear resistance
of all the stainless alloys. Its very high carbon
content of 1.0% is responsible for these
characteristics, which make 440C particularly
suited to such applications as ball bearings and
valve parts.
http://www.atlasmetals.com.au/files/ASM%20Grade%20Datash
eets/Atlas%20Grade%20datasheet%20440C%20rev%20May%2
02008.pdf
SSINA Stainless Steel Design Guidelines
PRECIPITATION HARDENED STAINLESS
Very low carbon content. Has about 7% Ni and
about 17% Cr.
 Steel experiences a martensite transformation.
Can be through cold work or rapid cooling. This
produces the supersaturated solid solution.
 Aging produces the fine dispersion of precipitates
that give this steel extremely high strength.

TYPICAL P-H STAINLESS STEEL
17-7 Stainless Steel.
 Low carbon (<0.09%C). 17%
Cr. 7% Ni.
 Quenched and Aged.
Sometimes Cold-worked
aged.
 Yield: 1590 Mpa. 231 Ksi.
 UTS: 1650 Mpa, 239 Ksi.
 Ductility: %EL = 1%.
 Uses: High strength high
temperature applications.
Chemical processing
equipment, heat exchangers,
boiler tubes.

http://www.superior-ny.com/mk41.htm
Grade 630 martensitic precipitation hardening
stainless steel has a combination of high hardness and
strength after suitable heat treatment. It also has
similar corrosion and heat resistance to Grade 304. The
terms "Type 630" and "17-4PH" refer to the same
grade.
The great benefit of this grade (and of other
precipitation hardening grades of stainless steel) is
that they are generally supplied in the solution treated
condition, in which they are just machinable, and then
can be age hardened to achieve quite high strengths.
This aging treatment is so low in temperature that
there is no significant distortion. These grades are
therefore well suited to production of long shafts, which
require no re-straightening after heat treatment.
http://www.atlasmetals.com.au/files/ASM%20Grade%20Datasheets/Atlas%20Grade%20datasheet%20630%20rev%20May%202
008.pdf
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