254Smo(S31254、F44、W.-Nr.1.4547、1.4547、SA-240)
1.Composition(wt%)
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C
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Cr
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Ni
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Mo
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Si
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Mn
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P
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S
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Cu
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N
|
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≤0.02
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19.5-20.5
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17.5-18.5
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6.0-6.5
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≤0.8
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≤1.0
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≤0.03
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≤0.01
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0.5-1.0
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0.18-0.22
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2.Physical Properties
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Density
(g/cm3)
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Melting point
（℃）
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8.0
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1320-1390
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3.Properties
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Condition
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бb/N/mm2
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б0.2/N/mm2
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δ5/%
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HB
|
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Sheet, steel strip
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≥690
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≥310
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≥35
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≤223
|
|
Plates
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≥655
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≥310
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≥35
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≤223
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4.Characteristics
Corrosion resistance：
(1). Lower the danger of precipitation of carbide from heat largely, for the low content of carbon. (2)Even though sensitized treatment for an hour at600℃-1000℃, it can still pass Strauss intergranular corrosion
test（Strauss Test ASTMA262 procedures E）.
Welding can be performed without crystal between corrosion.
(3).In hot concentrated nitric acid, the grain boundary precipitated phase may cause intergranular corrosion in the heat affected zone. (4)254 SMO in pure sulfuric acid has strong corrosion resistance. But under the high concentration, corrosion resistance weaken.
In sulfuric acid with the chloride ion, 254 SMO has the greatest corrosion resistance. (5)Under the general temperature 254 SMO can be used in dilute hydrochloric acid. But must try to avoid the existence of the gap.
(6)In fluorosilicic (H2SiF4) acid and hydrofluoric acid (HF)，254SMO can applied in considerable wide ranges of concentration and temperature.
(7)At a slightly higher temperature，254SMO in sea water also has the very high crevice corrosion resistance.Good corrosion
resistance to acidic solution and oxidizing halide solution needed in such as paper bleaching production.
(8).Since 254SMO has high nitrogen content, so its mechanical strength is higher than other types of austenitic stainless steel. In addition,
254SMO also has high malleability and impact strength and weldability.
5.Structure
Face-centered cubic lattice structure.
6.Applications
254SMO alloy is a versatile material, which can be applied in many fields of industry：
(1)Petroleum、petrochemical equipment，Such as corrugated pipe of petrochemical equipment.
(2)Pulp and paper bleaching equipment，Such as pulp digester, bleaching equipment,Filter washing for bucket cylinder and press roll
(3)Power plant flue gas desulfurization device，Main parts of use：The absorber tower body、flue, door plank, internal parts, spray system, etc.
(4)The sea or water processing system，such as the thin wall condensation pipe of power plants using water cooling ,desalination
processing equipment, even in the sea may not flow can also be applied in the system.
(5)Desalination industry, such as salt or desalination equipment.
(6)Heat exchanger, especially in heat exchanger with chloride ion work environment.
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