22% chromium 3% molybdenum stainless steel super duplex stainless steel 2205 (UNS S32205 / S31803)
Has 34 times read 2010-01-09 01:38 Tags: 2205 UNS S32205 duplex stainless steel
22% chromium 3% molybdenum stainless steel super duplex stainless steel 2205 (UNS S32205 / S31803)
General Properties
2205 by 22% chromium, molybdenum and duplex 3% nitrogen constitutes 5-6% nickel stainless steel. It has high strength, good toughness and good overall and partial resistance to stress corrosion. Compared with austenitic stainless steel 316L and 317L, 2205 in resistance to pitting and crevice corrosion resistance superior, it has high corrosion resistance, compared with austenitic lower its coefficient of thermal expansion, thermal conductivity higher.
2205 is twice the yield strength of austenitic stainless steel, this feature allows designers to reduce the weight in the design of products, so this alloy is more than 316,317L price advantage. This alloy is particularly applicable to -50 ° F / + 600 ° F temperature range. Beyond this temperature range of applications, this alloy can be considered, but there are some limitations, especially when used in welded structures.
Applications
• Pressure vessels, high pressure storage tanks, pressure piping, heat exchangers (chemical processing industry).
• Oil and gas pipelines, heat exchanger tube.
• sewage treatment system.
• Pulp and paper industry classification, bleaching equipment, storage and processing systems.
• High-strength corrosion resistant rotary environment, press rolls, blades, impellers and so on.
• ship or cargo tank truck
• Food processing equipment
Standard
ASTM / ASME ........... A240 UNS S32205 / S31803
EURONORM ........... 1.4462 X2CrNiMoN 22.5.3
AFNOR ................... Z3 CrNi 22.05 AZ
DIN ......................... W. Nr 1.4462
Corrosion resistance
Uniform corrosion
Since the chromium content (22%), molybdenum (3%) and nitrogen content (0.18%), anti-corrosion properties of 2205 is better than in most environments 316L and 317L.
Localized corrosion
Chromium, molybdenum and nitrogen content of the 2205 and so in an acidic oxidizing solution, pitting and crevice corrosion of a strong resistance.
Resistance to stress corrosion
Duplex stainless steel microstructure help to improve resistance to stress corrosion cracking of stainless steel capacity. At a certain temperature, the tension should be, in the case of oxygen and the presence of chlorides, austenitic stainless steel to chloride stress corrosion occurs. Since these conditions are difficult to control, so 304L, 316L and 317L of limited use in this regard.
Corrosion fatigue
High strength and corrosion resistance alloys 2205 it has a high resistance to corrosion fatigue strength. Processing equipment susceptible to corrosive environments and loading cycle, 2205 is very suitable for the characteristics of such applications.
Structure
The chemical composition in 2205 after 1900 ° / 1922 ° F (1040 ° / 1080 ° C) solution annealing treatment, obtain the ideal microstructure 50 α / 50 γ. If the heat treatment temperature is higher than 2000 ° F, may cause an increase of ferrite components. Like other duplex stainless steels, alloy susceptible 2205 precipitation of intermetallic phases. Intermetallic phases between 1300 ° F and 1800 ° F to precipitate at 1600 ° F temperature, the precipitation of the fastest. Therefore, we need to test for 2205, to ensure that no metal phase,, test between reference ASTM A 923.
Processing
Thermoforming
We recommend forming should be at a temperature below 600 ° F conduct. When hot forming, the workpiece should be the overall heat, should be 1750 ° F to 2250 ° F within a temperature range of 2205 alloy is very soft at this temperature. If the temperature is too high, the 2205 alloy to hot tearing. If less than this temperature, the austenite will fracture. Below 1700 ° F, due to the effects of temperature and deformation of intermetallic phases quickly formed. Hot forming is done, should immediately be solution annealed at 1900 ° F minimum temperature, and quenched to restore the phase balance, toughness and corrosion resistance. We do not recommend stress relief, but if you must do so, the material should be solution annealed at the lowest temperature of 1900 ° F, then rapidly cooled by water quenching.
Cold forming
2205 alloy can be cut and cold forming. However, since 2205 its high strength and hardness, it is more needed than the austenitic steel cold forming, but also because of its high strength, should give full consideration to the factors rebound.
Heat Treatment
2205 should be annealed at a minimum temperature of 1900 ° F and then rapidly cooled by water quenching. This treatment applies to solution annealing and stress relief. Stress relief treatments at temperatures below 1900 ° F were easily lead to harmful metal or non-metallic phase precipitation.
Mechanical cutting of
On the high-speed machine, feed rate and cutting speed and 2205 alloy 316L is the same. If charring knife, cutting speed and 316L reduced by about 20% compared to the performance of machinery and equipment and its components plays a key role in this.
Welding
2205 good weldability. 2205 performance to be achieved for the weld metal and heat deterioration and base metal section remains the same corrosion resistance, strength and toughness. Welding 2205 is not difficult, but necessary to design welding procedures for welding, you can maintain a good state of equilibrium phase, phase to avoid precipitation of harmful metals or non-metallic phase. 2205 may be carried out in the following devices Welding: GTAW (TIG); GMAW (MIG); SMAW ("stick" electrode); SAW; FCW; and PAW.