TPT March 2014

Technology News

New casting material for low- temperature applications

cryogens such as dry ice or liquid oxygen and nitrogen are used. This applies to air liquefaction and separation systems, in which air components are separated using thermal separation processes to extract nitrogen, oxygen, argon and other noble gases in high-purity concentration. Another application is the liquefaction of natural gas, where the natural gas is cooled to as low as -164°C in LNG terminals. The demands on the components used are high. Similar demands apply for cold grinding and cryogenic recycling. These processes are used, for example, in the food industry and in the area of composite materials. Schmolz + Bickenbach Guss – Germany Email: v.jansen@schmolz-bickenbach.com Website: www.guss.schmolz-bickenbach.com

excellent for tempering and therefore also display higher yield strength (Rp0.2 ≥ 490N/mm²) than the alternative of austenitic steels – a property that is particularly advantageous in such extreme temperatures. However, particular demands are placed not only on the strength but also on the toughness (KV (-196°C) ≥ 40J). The prerequisite for high strength at low temperatures is primarily a low content of selected trace elements. Otherwise, the segregations caused result in embrittling of the casting. “For us, the challenge lay in achieving reliable manufacture of the castings with a focus on optimised structure and therefore adequate strength,” explained Dr Petra Becker, head of research and development. The newDux Cryomaterial is suitable for all areas in which work is carried out at temperatures between -100°C and -196°C and wherever

PARTICULAR demands are placed on steels that are used in the low temperature range: they have to withstand temperatures down to -196°C. To date, austenitic steels have been used. However, because of their low yield strength, these are subject to the risk of early deformation and must therefore be cast with very thick walls. This was the starting point for the development of the new low-temperature material Dux Cryo ® , which displays higher strength values with good toughness. The advantage for use is that the casting can be constructed with thinner walls, saving both weight and costs. Instead of austenitic steel, Schmolz + Bickenbach Guss has started using martensitic steels for jobs in the low- temperature range, as a result of an extensive research project funded by the German federal ministry of economics and technology. These materials are

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M arch 2014