Each family of stainless steels has its strengths and weaknesses. Ferritic stainless steels have useful properties – a lower rate of thermal expansion, higher thermal conductivity, strong ferromagnetism and very high resistance to chloride stress corrosion cracking (SCC). When looking at selecting any alloys, it is important to consider all the factors for successful usage.
The duplex alloys are “problem-solving alloys” for good reason, they have been successfully used in many places where carbon steels and standard austenitic alloys have failed. Just like with the austenitic family, there are many different duplex alloys to choose from, with corrosion resistance varying from moderate with the lean duplex alloys to very high with the superduplex alloys.
The selection of an alloy should be guided by careful examination of the needs of the application. Before making a switch, it’s important to fully investigate an alloy’s strengths, weaknesses and applicability to your structure.
Think of the largest cruise ship. Then imagine how much it weighs – just over 100,000 tonnes, in fact. Now think about 500 of those ships, and what they weigh. That is the staggering amount of new electronic waste that we generate every year.
Even small quantities of nickel in an application can make a big difference to successful deployment.
The upstream and midstream oil and gas industries rely on nickel-containing corrosion resistant alloys for flowlines and risers. Rodrigo Signorelli, Outokumpu’s lead technical manager for marine and energy, explains how alloys reach the market.
Ever-tightening sulphur oxide (SOx) emission regulations are increasing the use of marine scrubbers globally. Scrubbers operate in a highly corrosive environment and require the resilience of nickel-containing alloys to prevent failure.
Most nickel production is destined for stainless steel. But a significant 8% is used in the production of alloy steels which are needed to deliver specific characteristics for specialised and often critical applications.