Langley Alloys at Stainless Steel World

4th December 2019

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Technical Paper presented at Stainless Steel World 2019

Stainless Steel World is the leading exhibition and conference specifically for the stainless steel industry. With nearly 300 exhibitors, and three days of technical presentations running alongside, it showcases the latest products and knowledge of the industry. As the originator of super duplex stainless steels, and a leading distributor of high-performance austenitic, duplex and super duplex stainless steels, it was only right that Langley Alloys should maintain a prominent position within the event.

Rodney Rice (rodney.rice@langleyalloys.com), Business Development Director, commented “I was pleased to be able to share our latest work during the Duplex/Super Duplex session, alongside fellow speakers from Butting, Nippon Steel, Kobelco Steel Tube and Outokumpu. It’s an incredibly knowledgeable audience, drawn from the largest producers and end-users of stainless steel across the world. It was therefore good to receive a positive level of interest and questions about our comparison of Ferralium 255 and other super duplex stainless steels.”

Ferralium 255 was the very first super duplex stainless steel, invented by Langley Alloys in 1967. A number of competing alloys have been subsequently brought to market, based upon subtle changes to composition in order to avoid our original patent. Langley Alloys is working with the University of Swansea to shed new light on the corrosion performance of these alloys.

Ferralium 255 ( S32550, 1.4507, F61) contains approximately 2% copper, which is understood to significantly improve the resistance to corrosion in a range of acids such as sulphuric acid, phosphoric acid and nitric acid.

Alloy 32760 (S32760, 1.4501, F55, Zeron 100) contains up to 1% copper and 1% tungsten. Tungsten is claimed to improve the immunity of this alloy to crevice corrosion.

Alloy 32750 (S32750, 1.4410, F53, SAF2507) may contain no more than 0.5% copper and no deliberate additions of tungsten.

The technical paper presented explores the history of these super duplex stainless steels; the differences between their composition; a review of the prior art and literature of the influence of copper and tungsten, and shares the results of some recent investigations undertaken with the University of Swansea and their leading analytical techniques.

Ferralium 255 has been shown to provide superior performance in acids, as demonstrated by commercially available data from several sources.

Potentiodynamic polarisation experiments indicate differences in performance between the three alloys considered, as well as a number of performance features worthy of further investigation. Ferralium 255 and S32750 were observed to re-passivate more quickly than S32760 at lower temperatures.