Stainless Steel Grade EN 1.4501 | S32750 | X2CrNiMoCuWN25-7-4

EN 1.4501 | S32750 | X2CrNiMoCuWN25-7-4 - duplex stainless steel with excellent properties: impact toughness, high strength, corrosion resistance to a large number of organic and inorganic acids. It has high resistance to strong alkalis and is resistant to corrosion in a number of non-oxidizing acids.

It can be used in areas where traditional duplex steels are no longer suitable. It has a higher content of chromium and molybdenum in combination with tungsten. It has good impact properties and wear resistance at - 40 °C. This alloy is resistant to sea water, has high resistance to surface corrosion, as well as pitting and crevice corrosion, and is suitable for use in sulfuric acid.

The special feature of this duplex steel is that it can be used in the temperature range from - 45 °C to + 310 °C.

Welding

The steel is suitable for welding by all processes (TIG welding, solid wire MAG, arc welding, flux welding). The exception is gas welding. There is a risk of intermetallic compounds. When welding, welding materials should be used, preferably similar electrodes, as they increase the relative elongation properties at high temperatures. However, a change in the corrosion properties in the weld area (heat-affected zone) should be expected.

Forging

Before forging, the steel must be heated to a temperature of 1150 °C to 1180 °C. The forging process takes place at a temperature of 1200 °C and 1000 °C, followed by air cooling. The surface treatment measures required for all corrosion-resistant and acid-resistant steels also apply to EN 1.4501 steel. Homogenisation during deformation creates local weak points in the alloying elements, which is an advantage over cast materials.

Mechanical processing

Machining should be carried out in the annealed condition, with low cutting speeds. Due to the low thermal conductivity (due to the high content of alloying elements), care must be taken to ensure sufficient cooling and, as a result, tool life.

Sawing is a mechanical treatment of the material, which leads to a significant reduction in unintended deformation and an increase in the hardness of the existing structure, for example, in thermal cutting. Thus, the processed workpiece has a uniform structure even at the edge, which does not change as the material continues. This circumstance allows immediate finishing of the workpiece by milling or drilling. Therefore, there is no need to pre-anneal the material or perform a similar operation.

Corrosion resistance

This stainless steel has very good corrosion resistance. Use in environments that cause pitting or stress cracking is possible because tungsten increases resistance to pitting.

Polishing

Due to the two-phase ferrite-austenite structure, the polishing pattern characteristic of this material changes.

Heat treatment

Heat treatment of EN 1.4501 | S32750 | X2CrNiMoCuWN25-7-4 steel is carried out by solution annealing at 1040 °C - 1120 °C with rapid cooling in sufficient water, which is also recommended after welding large sections.

Physical properties

Applications

The main areas of application for this stainless steel are, among others, the chemical and petrochemical industry. Further applications include desalination of seawater or brackish water (H₂S), food technology and shipbuilding (construction of chemical tankers).