Langley Alloys for duplex stainless steel

Duplex stainless steel (22% Cr / 2205 / 1.4462 / F51, F60) is a commonly used alloy in the manufacture of valves, providing the next step up in performance over Alloy 316L. Smaller valve bodies can be machined from solid bars rather than being produced from forgings and castings, along with a wide selection of trim and componentry.

Langley Alloys are the preferred partner of Sandvik for the distribution of their duplex and super duplex stainless steels. As such, we carry an extensive stock of this alloy, from ¾″ (19.05mm) to 18″ (450mm) diameter, plus selected sizes of hollow bar in the same alloy too.

Duplex stainless steels were originally developed in the 1930’s for application in paper and pulp manufacture, based around a 22% Cr composition and the mixed austenitic:ferritic (duplex) microstructure that gives them their name. Compared with more generic 304/316 austenitic stainless steels, duplex stainless steel will typically have twice the strength and provide a significant uplift in corrosion resistance.

Rather confusingly, there are two different designations for duplex stainless steel. When originally developed, the grade was identified as UNS S31803 (F51).

However, in order to enhance the resistance to pitting corrosion, steel manufacturers started to produce this grade with the composition of the key alloy additions at or near the maximum levels.

In order to differentiate this enhanced product from the standard product it was re-designated as UNS S32205 (F60). As such S32205 meets the requirements of S31803 but not vice-versa. All of our stock is in the higher-specification S32205.

Langley Alloys duplex stainless steel stock is predominantly in the easier-to-machine Sandvik grade Sanmac™ 2205. This new generation of Sanmac product achieves ‘enhanced machinability as standard’ with reduced tool wear and a significant increase in cutting speeds.

During the steelmaking process the non-metallic inclusions such as sulphides are carefully controlled to encourage easier machining, whilst oxide inclusions improve chip breaking.

This gives machine shops important improvements in productivity and significant cost reductions per produced item.

The same range of additional services provided by Langley Alloys are available in this grade too.

Uniquely for a stockist, we provide an in-house inspection service, with our operators trained in ultrasonic and liquid dye penetrant testing.

Our first stage machining offer continues to grow, now including turning and milling as well as a powerful deep hole borer. Plus, we include a number of metallurgists amongst our team, able to offer technical support and guidance.

Tel: 01782 610250

Published in Valve User Magazine Issue 51

Winter 2019 // Issue 51
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