Characterisation of 20 NC6 Treated Thermally by Barkhausen Noise
M. Zergoug, N. Boucherou, G. Kamel, A. Benchaala, CSC, Algeria
ABSTRACT
Controlling of some industrial components require the development of new and particular non-destructive testing techniques. To characterise a steel, it would be necessary to know its chemical composition, physico-chemical constitution, metallurgical state (annealed, hammered) and other parameters (superficial and chemical processing, ...). The microstructure of metallic alloy depends on the chemical composition, elaboration processing and thermal processing. The testing method using Barkhausen noise (B.N.) is a particular method, which can be applied on ferromagnetic materials. It is a magnetic non-destructive evaluation (NDE) method and can provide very important information about the material structure. The aim of our work is to study the material structure using these techniques to characterise the region submitted to thermal processing. Samples of steel have been heated at the temperature of 1100°C with variable maintain time. These methods permit to see the influence of the degree of cold deformation on grain size, microstructure types, microstructural changes, hardness changes after thermal treatment. The welding causes enormous problems to physicists, by the creation of assigned affected thermally zone (ZAT). This zone is fragile, characterised by a new structuring, that depends on operative conditions to the preliminary, following the gradient of temperature assigned. The evaluation of the welds is extremely important for the performance of materials hence the quality and integrity of these joints must be controlled, to ensure that no problems exist in the weld. The spectral density gotten from the Barkhausen noise and the hardness follows the same evolution, it would also permit to determine the mechanical characteristic without resorting to the destructive means.
Publication Source: 3nd International Conference on NDE in Relation to Structural Integrity for Nuclear and Pressurized Components, November 14-16, 2001, Seville Spain. Publisher: Tecnatom s.a. - [Homepage]
