The new alloy, an upgrade to traditional super-duplex stainless steels, adds to the company’s growing duplex portfolio. The main application is heat exchangers in the chemical and petrochemicals industries.
“We’re thrilled to welcome this new super duplex to our expanding duplex family. It provides that ‘missing duplex tool’ for customers battling acids in heat exchangers, giving them that extra edge. With the addition of SAF 3006 (UNS S83071), we strengthen our presence in duplex materials tailored for acidic corrosion, where we see strong growth potential. Applications may include caustic evaporators, acid coolers and evaporators,” said Eduardo Perea, market & product manager EMEA at Alleima tube division.
Alleima was part of the ‘duplex revolution’ of the 1960s and 1970s, introducing a cost-efficient stainless-steel alternative to more expensive nickel alloy grades. Duplex grades, with a 50-50 austenitic-ferritic structure, are said to offer more than twice the strength of standard stainless steels and superior corrosion resistance.
The company introduced the SAF 2507 (UNS S32750) in 1985 to combat wet corrosion in a range of industrial applications. SAF 2507 offers resistance to stress corrosion cracking (SCC) in chloride-bearing environments, as well as to pitting and crevice corrosion.
“SAF 3006 will complement SAF 2507 in dealing with corrosive conditions in heat exchanger tubing exposed to hydrochloric, sulphuric, formic or other acids. This is our super duplex tailored to resist acids,” Perea added.
“From an R&D perspective, this new super duplex reflects a sharper focus on optimising the material for acid corrosion resistance. Previously, most of our duplexes were developed with chloride resistance as the main focus, with high PRE levels to resist pitting and crevice corrosion. Resistance to acidic conditions was less prioritised. Now, we have fine-tuned the chemical composition to resist acidic environments better. This involves a high chromium content of 30 % and a molybdenum level of 3.2 % to maintain good structural stability and balancing of the alloying elements,” said Daniel Gullberg, manager of product development CRA.
