Super duplex stainless steel: 2507 (UNS S32750/F53/DIN W.Nr. 1.4410)
What is a 2507?
Table of Contents
UNS S32750 or DIN W.Nr. 1.4410, Super duplex 2507 is a super duplex stainless steel with 25% chromium, 4% molybdenum, and 7% nickel designed for demanding applications which require exceptional strength and corrosion resistance, such as chemical process, petrochemical, and seawater equipment. The steel has excellent resistance to chloride stress corrosion cracking, high thermal conductivity, and a low coefficient of thermal expansion. The high chromium, molybdenum, and nickel levels provide excellent resistance to pitting, crevice, and general corrosion.
1. Chemical Composition of Duplex 2507
|The Chemical Composition of SS2507, %|
2. Mechanical Properties of Duplex 2507
|Tensile Strength||Yield Strength||Elongation||Hardness||Impact Test|
* All values shall be minimum unless otherwise specified.
3. Manufacture, Heat Treatment & Weldability
Duplex 2507 piping materials can be manufactured by hot forming or cold forming methods. The hot forming temperature shall be between 1875°F and 2250°F. This should be followed by solution annealing at 1925°F minimum and a rapid air or water quench. The cold forming includes bending, deep drawing, extruding and pressing. After the cold forming process, the heat treatment of solution annealing and quenching is required. Besides, 2507 duplex stainless steels have good weldability.
- Pitting and crevice corrosion: S32750 super duplex stainless steels have better resistance to pitting and crevice corrosion than other duplex stainless steels after 24 hours test in different chloride solutions.
- Stress corrosion in the chloride solution containing 8% ppm oxygen in autoclave, the yield strength of 32750 dual phase steel and other dual phase steel does not change under the external stress equivalent to 232 °.
- Intergranular corrosion: the carbon content of S32750 dual phase steel is usually less than 0.02%, generally controlled at 0.015%. No carbide precipitation is found in the structure. Therefore, the low carbon content and the existence of ferrite phase make the sensitization of steel negligible.
- Uniform corrosion: S32750 steel has good uniform corrosion resistance in some organic and inorganic acids, for example, it can be compared with high alloy austenitic stainless steel in formic acid and acetic acid.
- Wear corrosion: due to the high hardness and wear resistance of S32750 dual phase steel, the steel has good wear resistance in the flow medium with abrasive particles or in the medium with high flow rate, such as used to transport sea water containing sand or to manufacture pumps and other mechanical components used in the corrosion medium.
Welding performance: S32750 super duplex stainless steel can be welded by GTAW, GMAW, SMAW, saw and other welding methods. See the table below for the welding materials used. 25.104l is used for GTAW welding, 25.104lr and 25.10.4lb are used for manual welding, and 25.10.4lb basic electrode is mostly used when weldment has high toughness requirements.
Note: sanicro 60 welding wire is cr22mo9nb3.5ni alloy
The recommended linear energy is 0.2-1.5kj/mm. For rapid cooling, the upper line value is generally adopted for thick plate welding, the lower limit value is adopted for thin plate welding, and the interlayer temperature shall not exceed 150C °.
During GTAW welding, pure argon or Ar + 2% N2 is used for protection.
Cold and hot working performance: the hot forming temperature range is limited, when the temperature is too low, the ferrite with poor plasticity will be seriously cracked in the deformation area, so the temperature is very important in the control. The hot forming temperature range of S32750 dual phase steel is 1200-1025 C °, and the workpieces after hot processing need solution water quenching. Duplex stainless steel is very soft at solution temperature. If the workpiece does not have enough support, it will twist and deform. This is very important for large-diameter thin-walled pipe, so we must pay attention to it. Twisted products are more difficult to form or straighten than austenitic stainless steels.
After cold forming, such as cold bending, S32750 dual phase steel is heated at 1050-1120 ° C and then air cooled or water treated.
Source: China 2507 Pipe Fittings Manufacturer – Yaang Pipe Industry (www.epowermetals.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
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