good info on stainless steel
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From: jax, fl, usa
good info on stainless steel
1. SORTING OUT STAINLESS
The science of metallurgy took big steps forward during the 19th and 20th centuries. One of these steps was the discovery that steel containing a certain percentage of chromium became highly resistant to oxidation and corrosion. “Stainless steel” made its first commercial appearance in the early 1900s as table cutlery. Since them the term has come to describe any ferrous alloy that contains at least 10.5 percent chromium.
Though considerably more expensive than carbon steel, the longer life of stainless steel can make it very cost effective. Its ability to resist rust and corrosion is still its most widely recognized advantage, but new discoveries and refinements in production have turned stainless steel into a family of alloys with characteristics that make it applicable across a wide range of industries.
Low carbon content and sufficient chromium are what all grades of stainless steel have in common, but there are now more than 60 different grades and each has unique characteristics. The grades of stainless steel can be divided into the following categories:
AUSTENITIC
Widely known as the “300 Series.” Non-magnetic. These steels cannot be hardened with heat treatment, but can develop high strength by cold work. Chromium content ranges from 17 to 25 percent, and nickel from 8 to 25 percent. Additions of up to 7 percent molybdenum can make austenitic alloys especially resistant to corrosion. This category includes grades 301, 302, 303, 304 (widely used in food, dairy and beverage industries), 305, 308, 309, 310, 314, 316 (use in chemical processing and pulp and paper industries), 317, 321 and 347 (used primarily in the aircraft industry), 348 and 384.
MARTENSITIC
Straight chromium steel (no nickel). Chromium content ranges from 12 to 15 percent. Magnetic and corrosion-resistant, these steels can be hardened with heat treatment. Often used for fasteners and pump shafts. This category includes grades 410 (used for fasteners), 414 (springs and cutlery), 416 (screw machine parts), 420 (surgical instruments), 431 (valves and pumps) and 440.
FERRITIC
Resistant to corrosion (more so than martensitic) and oxidation, but also resistant to stress corrosion cracking. Magnetic. Cannot be heat treated, but can be cold worked and softened by annealing. Carbon content is “low.” Chromium content is from 12 to 18 percent. This category includes grades 405, 409, 430, 434, 436, 442, and 446. Common uses include decorative trim, sinks and exhaust systems.
DUPLEX
The newest of the stainless steel grades combines austenitic and ferritic material. Used for pipelines, pressure vessels and shafting. More resistance to stress corrosion and cracking than austenitic, but tougher than fully ferritic alloys. Contains from 18 to 25 percent chromium, 4 to 7 percent nickel, and up to 4 percent molybdenum. 2205 is a typical grade.
PRECIPITATION HARDENING
Typically used for valves, gears and petrochemical equipment, this class develops strength through a precipitation hardening reaction during heat treatment. It contains from 12 to 28 percent chromium and 3 to 9 percent nickel (martensitic or austenitic). Grades include 17Cr-4Ni (17-4PH) and 15Cr-5Ni (15-5PH).
One of the most commonly used austenitic steels is 304-grade. Its 18 percent chromium and 8 percent nickel composition puts it in the 18/8 class, but it is distinguished by its 0.08 percent carbon content which gives it higher tensile strength. Its resistance to food acids makes it a workhorse in the dairy and beverage industries, while its high tensile strength makes it useful in the manufacture of fasteners and in the dying industry.
Also in the 18/8 class, 316-grade stainless steel works well in severe environments because of the addition of up to 3 percent molybdenum, a material that increases corrosion resistance against pit type attacks. This grade is often used for industrial equipment, surgical implants, and in the paper, textile and chemical processing industries.
For more information on stainless steel types and classes, go to: http://www.ssina.com/stainless/.
For a chemical compatibility list (includes Stainless Steel 304 and 316), go to: http://www.labsafety.com/refin...4.htm.
To view a selection of stainless steel laboratory supplies, go to: http://www.labsafety.com/store...d=554.
To view a selection of stainless steel carts, go to: http://www.labsafety.com/store...10996.
To view a selection of stainless steel waste containers, go to: http://www.labsafety.com/store...=8538.
The science of metallurgy took big steps forward during the 19th and 20th centuries. One of these steps was the discovery that steel containing a certain percentage of chromium became highly resistant to oxidation and corrosion. “Stainless steel” made its first commercial appearance in the early 1900s as table cutlery. Since them the term has come to describe any ferrous alloy that contains at least 10.5 percent chromium.
Though considerably more expensive than carbon steel, the longer life of stainless steel can make it very cost effective. Its ability to resist rust and corrosion is still its most widely recognized advantage, but new discoveries and refinements in production have turned stainless steel into a family of alloys with characteristics that make it applicable across a wide range of industries.
Low carbon content and sufficient chromium are what all grades of stainless steel have in common, but there are now more than 60 different grades and each has unique characteristics. The grades of stainless steel can be divided into the following categories:
AUSTENITIC
Widely known as the “300 Series.” Non-magnetic. These steels cannot be hardened with heat treatment, but can develop high strength by cold work. Chromium content ranges from 17 to 25 percent, and nickel from 8 to 25 percent. Additions of up to 7 percent molybdenum can make austenitic alloys especially resistant to corrosion. This category includes grades 301, 302, 303, 304 (widely used in food, dairy and beverage industries), 305, 308, 309, 310, 314, 316 (use in chemical processing and pulp and paper industries), 317, 321 and 347 (used primarily in the aircraft industry), 348 and 384.
MARTENSITIC
Straight chromium steel (no nickel). Chromium content ranges from 12 to 15 percent. Magnetic and corrosion-resistant, these steels can be hardened with heat treatment. Often used for fasteners and pump shafts. This category includes grades 410 (used for fasteners), 414 (springs and cutlery), 416 (screw machine parts), 420 (surgical instruments), 431 (valves and pumps) and 440.
FERRITIC
Resistant to corrosion (more so than martensitic) and oxidation, but also resistant to stress corrosion cracking. Magnetic. Cannot be heat treated, but can be cold worked and softened by annealing. Carbon content is “low.” Chromium content is from 12 to 18 percent. This category includes grades 405, 409, 430, 434, 436, 442, and 446. Common uses include decorative trim, sinks and exhaust systems.
DUPLEX
The newest of the stainless steel grades combines austenitic and ferritic material. Used for pipelines, pressure vessels and shafting. More resistance to stress corrosion and cracking than austenitic, but tougher than fully ferritic alloys. Contains from 18 to 25 percent chromium, 4 to 7 percent nickel, and up to 4 percent molybdenum. 2205 is a typical grade.
PRECIPITATION HARDENING
Typically used for valves, gears and petrochemical equipment, this class develops strength through a precipitation hardening reaction during heat treatment. It contains from 12 to 28 percent chromium and 3 to 9 percent nickel (martensitic or austenitic). Grades include 17Cr-4Ni (17-4PH) and 15Cr-5Ni (15-5PH).
One of the most commonly used austenitic steels is 304-grade. Its 18 percent chromium and 8 percent nickel composition puts it in the 18/8 class, but it is distinguished by its 0.08 percent carbon content which gives it higher tensile strength. Its resistance to food acids makes it a workhorse in the dairy and beverage industries, while its high tensile strength makes it useful in the manufacture of fasteners and in the dying industry.
Also in the 18/8 class, 316-grade stainless steel works well in severe environments because of the addition of up to 3 percent molybdenum, a material that increases corrosion resistance against pit type attacks. This grade is often used for industrial equipment, surgical implants, and in the paper, textile and chemical processing industries.
For more information on stainless steel types and classes, go to: http://www.ssina.com/stainless/.
For a chemical compatibility list (includes Stainless Steel 304 and 316), go to: http://www.labsafety.com/refin...4.htm.
To view a selection of stainless steel laboratory supplies, go to: http://www.labsafety.com/store...d=554.
To view a selection of stainless steel carts, go to: http://www.labsafety.com/store...10996.
To view a selection of stainless steel waste containers, go to: http://www.labsafety.com/store...=8538.
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