254SMo

Time:2019-08-14

Similar grade:

GB/T

UNS

AISI/ASTM

ID

W.Nr

015Cr20Ni18Mo6CuN

S31254

254SMo

F44

1.4547

 

chemical composition:

alloy

%

Ni

Cr

Mo

Cu

C

Mn

Si

P

S

254SMO

min

17.5

19.5

6

0.5

0.18






max

18.5

20.5

6.5

1

0.22

0.02

1

0.8

0.03

0.01


Physical properties:

density

8.0 g/cm3

Melting point

1320-1390 


The minimum mechanical properties of the alloy at room temperature:

Status

Tensile Strength 
Rm N/mm2

Yield Strength 
RP0.2N/mm2

Elongation 
A5 %

Solid solution treatment

650

300

35

254SMO alloy properties:

The high molybdenum content and high chromium and nitrogen content make 254SMO extremely resistant to pitting and crevice corrosion. The addition of copper improves the corrosion resistance in certain acids. In addition, due to its high nickel content and high chromium and molybdenum content, 254SMO has excellent resistance to stress corrosion cracking.


A large number of field experiments and extensive experience have shown that even at slightly higher temperatures, 254SMO has high crevice corrosion resistance in seawater, and only a few types of stainless steel have this property.


The corrosion resistance of 254SMO in acidic solutions and oxidizing halide solutions such as paper bleaching can be compared to nickel-based alloys and titanium alloys with the strongest corrosion resistance.


Since 254SMO has a high nitrogen content, its mechanical strength is higher than other types of austenitic stainless steel. In addition, 254SMO has high ductility and impact strength as well as good weldability.


The high molybdenum content of 254SMO allows it to have a higher oxidation rate during annealing, resulting in a rougher surface than normal stainless steel after pickling. However, this has no adverse effect on the corrosion resistance of the steel.


Metallographic structure of 254SMO:

254SMO is a face-centered cubic lattice structure. In order to obtain an austenitic structure, 254SMO is generally annealed at a temperature of 1150 to 1200 degrees Celsius. In some cases, the center of the material may have traces of the metallic mesophase (χ phase and alpha phase). However, under normal circumstances, they have no adverse effect on impact strength and corrosion resistance. When placed in the range of 600-1000 degrees Celsius, these phases may precipitate on grain boundaries.


Corrosion resistance of 254SMO:

The carbon content of 254SMO is very low, which means that the risk of carbide precipitation due to heating is very small. The steel can pass the Strauss Intergranular Corrosion Test (Strauss Test ASTMA 262 Procedure E) even after sensitization for one hour at 600-1000 °C. However, due to the high alloy content of the steel. It is possible for the metal intermediate phase to precipitate on the grain boundaries within the above temperature range. These deposits do not pose a risk of intergranular corrosion when the steel is used in corrosive media. Therefore, soldering can be performed without intergranular corrosion. However, in hot concentrated nitric acid, these deposits may cause intergranular corrosion in the heat affected zone. Ordinary stainless steels containing solutions such as chloride, bromide or iodide are immediately attacked by localized corrosion in the form of pitting, crevice or stress corrosion cracking. However, in some cases, the presence of a halide accelerates uniform corrosion. This is especially the case in the presence of halides in non-oxidizing acids. In pure sulfuric acid, 254SMO has much greater corrosion resistance than 316 ordinary stainless steel. However, the 254SMO has a slightly weaker corrosion resistance than the 904L (NO8904) type stainless steel at high concentrations. Among the sulfuric acid containing chloride ions, 254SMO has the greatest corrosion resistance. 316 normal stainless steel cannot be used in hydrochloric acid due to local corrosion and uniform corrosion, but 254 SMO can be used in diluted hydrochloric acid at normal temperature. There is no need to worry about pitting corrosion in the following areas of the boundary line. But you must try to avoid the existence of gaps. In fluorosilicic acid (H2SiF4) and hydrofluoric acid (HF), the corrosion resistance of ordinary stainless steel is very limited, while 254SMO can be applied in a wide range of concentrations and temperatures.


254SMO application areas:

254SMO alloy is a versatile material that can be used in many industries:


Petroleum, petrochemical equipment, such as bellows in petrochemical equipment.


Pulp and paper bleaching equipment, such as pulp digester, bleaching equipment, barrels and pressure rollers for filter scrubbers, etc.


The flue gas desulfurization device of the power plant mainly uses the tower body of the absorption tower, the flue, the door panel, the internal parts and the sprinkler system.


Offshore systems or seawater treatments, such as thin-walled condensing pipes that are cooled by seawater in power plants, desalination plants, can be used even in equipment where seawater may not flow.


Desalination industry, such as salt or desalination equipment.


Heat exchangers, especially those with a chloride ion working environment.


Prev :329

Next :17-7PH

CONTACT US

Address:

No. 17, West Zone, Xiangyun Road, Jixi County, Xuancheng, Anhui, China

Anhui Baitai Steel Industry Co., Ltd. International Sales Department

Contact: MR TOM

CELL: 15868588652

Tel: 0577-86887759

Fax :0577-86887759

Email: tom123631@163.com

SKYPE: tongwenguan813

Contact: Linda Lu

Cell: +86 15167897803

Tel: +86 0577-86699079

Fax:+86 0577-86859555

Email: linda_lfy@163.com

Skype: lfyulrica51

Copyright© Anhui Baitai Steel Industry Co. ,Ltd.