904L（00Cr20Ni25Mo4.5Cu、N08904、1.4539）
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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19.0-23.0
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23.0-28.0
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4.0-5.0
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≤1.0
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≤2.0
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≤0.045
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≤0.035
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1.0-2.0
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≤1.0
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2.Physical Properties
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Density
（g/cm3）
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Melting point
(℃)
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Elastic modulus
(GPa)
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Thermal expansion coefficient
(10-6℃-1)
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Thermal conductivity
(W/m℃)
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Electric resistivity
(μΩm)
|
|
8.0
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1300-1390
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195
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15.8
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12
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1.0
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3.Properties
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Temperature
（℃）
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бb
（N/mm2）
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б0.2
（N/mm2）
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δ5
（%）
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HRB
|
|
Room temperature
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≤490
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≤220
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≥35
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≤90
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4.Characteristics
(1).Good resistance to pitting corrosion and crevice corrosion, high resistance to stress corrosion cracking, intergranular
corrosion resistance, good machinability and weldability
(2).Since the low carbon content (≤0.020%), no carbide precipitation under the condition of hot treatment and welding,
to eliminate the general risk of intergranular corrosion after heat treatment and welding.
(3).Since high content of Ci, Ni, Mo, adding with copper, the alloy can be inactivation even in a reducing environment, such
as sulfuric acid and formic acid. Lower corrosion rate even in active condition for the high content of nickel.
(4).Within the scope of 0 ~ 98% of concentration of pure sulfuric acid, the operating temperature up to 40℃.
Within the scope of 0 ~ 85% of concentration of pureorthophosphoric acid, its corrosion resistance is very good.
(5).In all the various kinds of phosphates904L alloy corrosion resistance is superior to the ordinary stainless steel.
In strong oxidizing nitric acid, compared to high alloy without molybdenum steel grade , 904Lshows lower corrosion resistance.
In the environment of hydrochloric acid, hydrochloric acid concentration 1-2%, 904L alloy can be used.
In this concentration range, it has better corrosion resistance than the conventional stainless steel .
(6)904L steel has high corrosion resistance. The crevice corrosion resistance in chloride solution is also very good.
(7)Reduce the corrosion rate of the pit and gaps for the high content of nickel, and have good resistance to stress corrosion
cracking, in the environment of chloride solution, concentration of hydroxide solution and rich hydrogen sulphide.
(8).All kinds of environmental corrosion resistance are as follows:
1）Corrosion rate under the condition of HNO3, 20%+HF, 4% 25℃
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Mark
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Corrosion rate
mm/a
|
|
904L
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0.51
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2) Fatty acid distillation tower at 260℃
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Mark
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Corrosion rate
mm/a
|
|
904L
|
0.06
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5.Structure
Fully austenitic organization, and compared to the general high molybdenum content austenitic stainless steel ,
904 l is not sensitive to precipitation of ferrite and α phase.
6.Applications
(1).Petroleum and petrochemical equipment，such as reactor of petrochemical equipment, etc.
(2).Sulfuric acid storage and transportation equipment, such as heat exchangers, etc.
(3).Power plant flue gas desulfurization device，Main parts of use：the absorber tower body, flue, door plank,
internal parts, spray system, etc
(4).Organic acid scrubber and the fan in the processing system.
(5).Water treatment plant, water heat exchanger, papermaking equipment,sulfuric acid, nitric acid equipment, acid,
pharmaceutical industry and other chemical equipment, pressure vessel, food equipment.
(6).Pharmaceutical: centrifuge, reactor, etc.
(7).Plant foods: soy sauce pot, cooking wine, salt, equipment and dressings.
(8).To dilute sulphuric acid strong corrosive medium steel 904 l is matching.
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