Some
Types of Stainless
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200 Series—austenitic
chromium-nickel-manganese alloys
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Type 201—austenitic that is
hardenable through cold working
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Type 202—austenitic general
purpose stainless steel
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300 Series—austenitic
chromium-nickel alloys
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Type 301—highly ductile, for
formed products. Also hardens rapidly during mechanical working. Good
weldability. Better wear resistance and fatigue strength than 304.
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Type 302—same corrosion
resistance as 304, with slightly higher strength due to additional
carbon.
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Type 303—easier machining
version of 304 via addition of sulfur and phosphorus. Also referred to
as "A1" in accordance with ISO 3506.
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Type 304—the most common
grade; the classic 18/8 stainless steel. Also referred to as "A2" in
accordance with ISO 3506.
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Type 304L—the Low Carbon
grade but specially modified for welding.
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Type 309—better temperature
resistance than 304
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Type
316—the second most common grade (after 304); for food and
surgical stainless steel uses; alloy addition of molybdenum prevents
specific forms of corrosion. 316 steel is used in the manufacture and
handling of food and pharmaceutical products where it is often required
in order to minimize metallic contamination. It is also known as marine
grade stainless steel due to its increased resistance to chloride
corrosion compared to type 304. SS316 is often used for building nuclear
reprocessing plants. Most watches that are made of stainless steel are
made of Type 316L; Rolex is an exception in that they use Type 904L.
Also referred to as "A4" in accordance with
ISO 3506. 316Ti (which includes titanium for heat resistance) is
used in flexible chimney liners, and is able to withstand temperatures
up to 2000 degrees Fahrenheit, the hottest possible temperature of a
chimney fire.
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Type 317 ---
Alloy 317LMN and 317L are
molybdenum-bearing austenitic stainless steels with greatly increased
resistance to chemical attack as compared to the conventional
chromium-nickel austenitic stainless steels such as Alloy 304. In
addition, 317LMN and 317L alloys offer higher creep, stress-to-rupture,
and tensile strengths at elevated temperatures than conventional
stainless steels. All are low carbon or "L" grades to provide resistance
to sensitization during welding and other thermal processes. The "M" and
"N" designations indicate that the compositions contain increased levels
of molybdenum and nitrogen respectively. The combination of molybdenum
and nitrogen is particularly effective in enhancing resistance to
pitting and crevice corrosion, especially in process streams containing
acids, chlorides, and sulfur compounds at elevated temperatures.
Nitrogen also serves to increase the strength of these alloys. Both
alloys are intended for severe service conditions such as flue gas
desulfurization (FGD) systems.
more
information
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Type 321—similar to 304 but
lower risk of weld decay due to addition of titanium. See also 347 with
addition of niobium for desensitization during welding.
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400 Series—ferritic and
martensitic chromium alloys
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Type 405—a ferritic
especially made for welding applications
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Type 408—heat-resistant;
poor corrosion resistance; 11% chromium, 8% nickel.
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Type 409—cheapest type; used
for automobile exhausts; ferritic (iron/chromium only).
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Type 410—martensitic
(high-strength iron/chromium). Wear-resistant, but less
corrosion-resistant.
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Type 416—easy to machine due
to additional sulfur
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Type 420—Cutlery Grade
martensitic; similar to the Brearley's original rustless steel.
Excellent polishability.
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Type 430—decorative, e.g.,
for automotive trim; ferritic. Good formability, but with reduced
temperature and corrosion resistance.
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Type 440—a higher grade of
cutlery steel, with more carbon in it, which allows for much better edge
retention when the steel is heat-treated properly. It can be hardened to
around Rockwell 58 hardness, making it one of the hardest stainless
steels. Due to its toughness and relatively low cost, most display-only
and replica swords or knives are made of 440 stainless. Also known as
razor blade steel. Available in four grades: 440A, 440B, 440C, and the
uncommon 440F (free machinable). 440A, having the least amount of carbon
in it, is the most stain-resistant; 440C, having the most, is the
strongest and is usually considered a more desirable choice in
knifemaking than 440A except for diving or other salt-water
applications.
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Type 446—For elevated
temperature service
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500 Series—heat-resisting
chromium alloys
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600 Series—martensitic
precipitation hardening alloys
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601 through 604: Martensitic
low-alloy steels.
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610 through 613: Martensitic
secondary hardening steels.
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614 through 619: Martensitic
chromium steels.
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630 through 635:
Semiaustenitic and martensitic precipitation-hardening stainless steels.
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Type 630 is most common PH
stainless, better known as 17-4; 17% chromium, 4% nickel.
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650 through 653: Austenitic
steels strengthened by hot/cold work.
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660 through 665: Austenitic
superalloys; all grades except alloy 661 are strengthened by
second-phase precipitation.
15-5 Stainless Steel
Also known as a PH, or precipitation-hardening, grade of stainless, this
alloy is used a great deal in the aircraft industry in part due to its
strength, and also because there are a wide range of heat treatments to
choose from to reach a specified hardness or other properties.
17-4 Stainless Steel
Also known as a PH, or precipitation-hardening, grade of stainless, this
alloy is used a great deal in the aircraft industry in part due to its
strength, and also because there are a wide range of heat treatments to
choose from to reach a specified hardness or other properties. This alloy is
very similar to 15-5 except that 17-4 tends to have more ferrite, and is
slightly more magnetic.
17-7 Stainless Steel
Also known as a PH, or precipitation-hardening, grade of stainless, this
alloy is used a great deal in the aircraft industry in part due to its
strength, and also because there are a wide range of heat treatments to
choose from to reach a specified hardness or other properties. 17-7 has
exceptionally high strength and hardness, as well as the corrosion
resistance normally associated with stainless. It is one of the more
formable of the PH grades.
Nitronic 50 Stainless
This specialized alloy has better corrosion resistance than alloy 316, but
twice the strength of that alloy. It can be hardened by cold working, but
unlike most 300 series alloys, it does not become magnetic when cold-worked.
Nitronic 60 Stainless
There are a lot of stainless steel alloys. We're still trying to
think of something interesting to write about this one. Nitronic 60 has a
corrosion resistance somewhere between T-304 and T-316, but with roughly
twice the strength of those materials.
18/8 and 18/10 designations are older terms, and refer to the
amount of chromium and nickel alloyed with the iron, to comprise the
stainless steel. The 18/8 name has been pretty much replaced, in the States
at least, by several other designations. 301 stainless steel has 16-18% Cr,
and 6-8% Ni 302 stainless steel has 17-19% Cr, and 8-10% Ni 304 stainless
steel has 18-20% Cr, and 8-10.5% Ni. That may explain your difficulty in
finding information on these alloys. Similarly, 18/10 is usually referred to
as 316 stainless steel, with 16-18% Cr, 10-14% Ni, and also 2-3% molybdenum,
which greatly increases the resistance to pitting corrosion in seawater. ] |