Duplex stainless steel is a type of stainless steel that has a dual microstructure made up of both austenite and ferrite phases. This combination provides the material with higher strength, greater corrosion resistance, and improved weldability compared to other forms of stainless steel. In this blog post, we will discuss the physical properties, mechanical properties, composition, and common uses of duplex stainless steel.
Physical Properties
Duplex stainless steel has excellent strength and fatigue properties due to its two-phase microstructure. This gives it twice the yield strength of austenitic steels as well as higher impact toughness. It also has better stress corrosion cracking resistance than austenitic grades due to its higher chromium content. Additionally, it has lower thermal expansion properties than austenitic grades, which makes it ideal for applications where thermal expansion needs to be minimized, such as cryogenic vessels or high-temperature steam lines.
|
Property |
2205 |
UR52N+ |
|
Density (g.cm3) |
7.805 |
7.810 |
|
Modulus of Elasticity (GPa) |
200 |
205 |
|
Electrical Resistivity (Ω.m) |
0.85 x 10-6 |
0.85 x 10-6 |
|
Thermal Conductivity (W/m.K) |
19 at 100 °C |
17 at 100 °C |
|
Thermal Expansion (m/m.K) |
13.7 x 10-6 to 100 °C |
13.5 x 10-6 to 200 °C |
Mechanical Properties
Duplex stainless steel has excellent mechanical properties thanks to its dual microstructure. The combination of ferrite and austenite gives the material increased tensile strength and yield strength compared to other types of stainless steel. It also increases the material’s fatigue limit, which allows it to withstand cyclic loading without experiencing permanent deformation or failure. Additionally, duplex stainless steel has improved welding characteristics compared to austenitic steels, which makes it an ideal choice for welding applications where higher strength is needed.
|
Grade |
2205 |
UR52N+ |
|
Tensile Strength (MPa) |
620 |
770 |
|
Proof Stress 0.2% (MPa) |
450 |
550 |
|
Elongation A5 (%) |
25 |
25 |
Composition
Duplex stainless steel is composed primarily of iron (Fe), chromium (Cr), molybdenum (Mo), nickel (Ni), manganese (Mn), nitrogen (N), silicon (Si), carbon (C), sulfur (S) and phosphorus (P). The exact composition can vary depending on the specific grade, but generally speaking, these are the main components that makeup duplex stainless steel alloys.
|
% |
2205 |
UR52N+ |
|
C |
0-0.03 |
0.03 max |
|
Mn |
2.0 |
1.5 |
|
Si |
1.0 |
0.8 |
|
P |
0-0.03 |
0.035 |
|
S |
0-0.02 |
0.02 |
|
Cr |
21-23 |
24-26 |
|
Mo |
2.5-3.5 |
3.0-5.0 |
|
Ni |
4.5-6.5 |
5.5-8.0 |
|
N |
0.08-0.2 |
0.2-0.35 |
|
Cu |
– |
0.5-3.0 |
Uses
Duplex stainless steels have become increasingly popular in recent years due to their superior performance over traditional austenitic grades in certain applications. They are widely used in oil and gas industry components such as pipes and valves due to their ability to withstand severely corrosive environments as well as their high-temperature capabilities. Other common uses include chemical processing equipment, desalination plants, food processing equipment, heat exchangers and marine construction components such as propellers and shafts due to their excellent corrosion resistance in seawater environments.
Conclusion
In conclusion, duplex stainless steel is a unique type of alloy that offers superior performance over traditional austenite grades in certain applications due to its two-phase microstructure consisting mainly of ferrite and austenite phases along with other metals like chromium, molybdenum, nickel and more. Its combination provides increased tensile strength and yield strength fatigue limit while simultaneously offering excellent corrosion resistance, making it an ideal choice for many industries such as oil & gas production pipelines & valves, chemical processing equipment desalination plants, food processing equipment heat exchangers, marine construction components such as propellers & shafts etc. If you’re looking for a durable alloy with superior mechanical properties, then consider using duplex stainless steel!
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