S32750 (UNS S32750, DIN 1.4410, ASTM F53) and S32760 (UNS S32760, DIN 1.4501, ASTM F55) are both super duplex stainless steels (SDSS). S32750 was originally developed as SAF2507 in the 1980s by Sandvik. On the other hand, S32760 was originally developed as Zeron 100 by the UK company, Mather & Platt in the 1970s.
As such, their microstructure is a combination of austenitic and ferritic grains, which imparts the most favourable properties of each microstructure. Both grades achieve a PREN (Pitting Resistance Equivalent Number) of more than 40 and a minimum yield strength of 80 KSI.
They may appear identical to each other, having similar physical and mechanical properties within the limits of measurement. However, there are some slight differences.
S32750 has a composition of approximately 25% chromium, 7% nickel and 4% molybdenum. S32760 has a very similar composition to S32750, but with additions of tungsten and copper.
Both S32750 and S32760 have excellent corrosion resistance. The difference in composition between the two alloys reflects slightly different metallurgical approaches to achieve optimum mechanical properties and corrosion resistance. The main discernible difference in composition is that S32760 contains deliberate additions of copper and tungsten. Copper is widely recognised as having a beneficial effect on resistance to acids, and is utilised more significantly in Ferralium 255, Alloy 825 and Alloy 20. The addition of tungsten is also thought to aid resistance to pitting corrosion, and it is sometimes included in the formula that calculates the Pitting Resistance Equivalent Number (PREN), a comparative measure of an alloy’s corrosion resistance.
S32750 and S32760 are used in similar applications such as oil & gas industry components, pulp & paper industry components, agrochemicals production and the marine industry and seawater environments. In some applications, for instance pipe and fittings, they are often used interchangeably due ease of the supply. There is no difference between the alloys’ galvanic potential, meaning that they can be used side-by-side without a risk of bimetallic corrosion occurring due to any mismatch in their physical properties.
At Langley Alloys, we carry an extensive stock of both S32750 and S32760, alongside Ferralium 255 (UNS S32550, DIN 1.4507, ASTM F61) with bars up to 16″ (406.4mm) diameter, plates up to 3″ (76.2mm) thickness, and a variety of pipes and fittings available ex-stock from our warehouses in the UK and USA.
For more information about S32750 and S32760, please contact us today and we will be happy to answer your questions.