TPT January 2014

Technology News

New casting material for low-temperature applications The gradual unwinding of coils THE UNC Uncoiler from Guild is a machine that is used to hold the coils to allow the gradual unwinding of the coils during press operations. Uncoilers are available in a number of variations, but the most frequently used samples are the single- and double-ended arm units. The machines are designed for use in different types of processing lines including roll form lines to high speed tube and pipe mills. The uncoilers that are used in steel making are available in the sizes of 15,000lb single and 25,000lb double. However, there are a variety of uncoilers available in sizes ranging from 3,000lb to 40,000lb. uncoilers are 12" traversing base, outboard coil retainers, speed funnels, shearwelders and accumulators, hold down arms and snubbers, feed-up and rewinders, powered hydraulic rotation system, hydraulic expansion, manual/ hydraulic expansion of mandrel, wedge/ link type expansion, AC variable speed drives, hydraulic threading drives, quick release narrow coil keepers, loop controls alloy steel main shaft, 4-segment drum, coil joining – tube mill entry systems, 0.5" thick steel back plate, large air brakes, hydraulic cylinders for drum expansion, and two slots per back plate for “C” hook loading. Complete entry systems from Guild International are also available and can be customised to accommodate any application. Commonly included in entry systems are double arm uncoiler, outboard coil retainer, speed funnel, shearwelder and accumulator. The SL Superloop™ Accumulator is suitable for small and medium size mills. The patented overspeed feature produces large amounts of usable storage. Flexible entry and exit points allow for installation in new or existing lines. This accumulator can handle material from about 0.03" thick up to 0.312" thick and line speeds from approximately 50 FPM up to 900FPM. Guild International – USA Fax: +1 440 232 5878 Email: sales@guildint.com Website: www.guildint.com Uncoilers are available with a variety of customised features, however, the standard features available with

without cracks appearing in the casting volume,” explained Dr Petra Becker, head of research and development at Schmolz + Bickenbach Guss. The starting point for the research project was the low-temperature material X8Ni9, which is used as a standard sheet and forging material for applications down to -196°C. However, due to the high cracking sensitivity of the coarse-grained primary structure, no casting alternative to the material previously existed. The aim was to present the material as a casting modification by combining findings from analytics, metallurgy and heat treatment. In addition to extensive materials testing and comprehensive literature research, this also involved cooperation with external experts. The latest technologies were used, including a casting technology simulation, thermodynamic calculations of the material and heat treatment, and the latest methods of analysis for the investigation results. Schmolz + Bickenbach Guss – Germany Website: www.guss.schmolz-bickenbach.com

constructed with thinner walls, which saves not only weight but also costs. Instead of austenitic steel, Schmolz + Bickenbach Guss has started using martensitic steels for jobs in the low- temperature range; this is the result of an extensive research project funded by the German federal ministry of economics and technology. These materials are excellent for tempering and therefore also display significantly higher yield strength (Rp0.2³ 490N/ mm²) than the alternative of austenitic steels – a property that is particularly advantageous in such extreme temperatures.

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 casting can be

However, particular de- mands are placed not only on the strength but also on the toughness (KV (-196°C)³ 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 –

Dr Petra Becker, head of research and development at Schmolz + Bickenbach Guss

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J anuary 2014