Cold toughness

The term cold toughness describes the toughness of construction materials that can be achieved at low temperatures . In essence, it is a matter of avoiding their failure, particularly when materials are used in low-temperature applications. For this, such materials must be "cold-tough".

Observation of the cold toughness phenomenon

In order to be able to determine the cold toughness experimentally, special notched bar impact tests are required . With almost all ferritic - pearlitic steels , i.e. materials with a body-centered cubic lattice type , a transition from sliding fracture to brittle fracture occurs when the temperature drops in the notched impact test, i.e. there is a transition from tough to brittle fracture behavior . Such materials that have a transition described in this way are therefore brittle-breaking at low temperatures. They do not meet the criterion of being “cold-tough”. The transition mentioned, if it exists, must be determined on representative material samples and defines a certain notched impact energy (for example 27 J) or a certain notched impact strength at a transition temperature [in ° C] for a material with a certain chemical composition and a corresponding known heat treatment. Usually, Charpy-U or Charpy-V standard specimens according to DIN 50115 are prepared from the test material. Before the test is carried out, the samples of the test material are preheated (e.g. precooled to a certain temperature in a temperature-adjustable freezer).

Access to cold toughness data in relevant reference works and databases

In order to access cold toughness data for a desired material, one should first try to consult relevant reference works and databases . If you cannot find anything in reference works or databases and you are still dependent on certain low-temperature toughness properties for a desired material, then you have to carry out the appropriate notched bar impact tests yourself.

example

In the steel-iron material sheet SEW 685 from March 2000, for example, the materials for low- temperature cast steel are listed, which have the property of quantified low-temperature toughness at ambient temperatures below −10 ° C. In order to maintain the same experimental prerequisites as for the data obtained from the aforementioned steel-iron material sheet, an impact energy of 27 joules on defined, cast samples must not be exceeded.

Remarks

↑ Cf. Eckard Macherauch, Hans-Werner Zoch: Practical course in materials science: 91 detailed experiments from important areas of materials technology. , 11th edition, Vieweg + Teubner, Wiesbaden 2011, ISBN 978-3-8348-0343-6 , pp. 281–287, in particular on p. 283 ff. Macherauch and Zoch mention the term “cold-tough” on p 286.

Individual evidence

↑ C. Berger et al .: Materials Technology. In: KH Grote, J. Feldhusen (Hrsg.): Dubbel - pocket book for mechanical engineering. 21st edition, Springer, Berlin 2005, ISBN 3-540-22142-5 , pp. E1 – E145, in particular on pp. E30 ff.

literature

Wolfgang Weißbach: Materials science and material testing. 15th edition, Vieweg & Sohn Fachverlage GmbH, Wiesbaden 2004, ISBN 978-3-528-11119-9 .
Wolfgang Bergmann: Material engineering 1. Structural structure of materials, 7th edition, Carl Hanser Verlag, Munich 2013, ISBN 978-3-446-43536-0 .
C. Berger et al .: Materials Technology. In: KH Grote, J. Feldhusen (Hrsg.): Dubbel - pocket book for mechanical engineering. 21st edition, Springer, Berlin 2005, ISBN 3-540-22142-5 , pp. E1-E145.

Web links

Contact study materials technology (accessed on March 31, 2016)
Rust, acid and heat-resistant steels (accessed on March 31, 2016)

[2] Cf. Eckard Macherauch, Hans-Werner Zoch: Practical course in materials science: 91 detailed experiments from important areas of materials technology. , 11th edition, Vieweg + Teubner, Wiesbaden 2011, ISBN 978-3-8348-0343-6 , pp. 281–287, in particular on p. 283 ff. Macherauch and Zoch mention the term “cold-tough” on p 286.

[1] C. Berger et al .: Materials Technology. In: KH Grote, J. Feldhusen (Hrsg.): Dubbel - pocket book for mechanical engineering. 21st edition, Springer, Berlin 2005, ISBN 3-540-22142-5 , pp. E1 – E145, in particular on pp. E30 ff.