Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New magnetic techniques for microstructural characterisation of steels

24.06.2005


There is no doubt that steel is one of the materials that has largely contributed to the technological and economical development of the twentieth century. Its mechanical and magnetic properties are determined by its chemical composition and the microstructure obtained in its manufacturing process. Traditionally, it has been necessary to mechanically destroy the material in order to analyze its microstructure by means of a microscope, i.e. to get a small sample, to polish it and to attack it with chemical compounds. Nowadays, significant progress is being made to magnetically obtain information about steel’s microstructure. Besides, due to their non-destructive nature, magnetic techniques allow us to skip destructive mechanical techniques.

In this context, the aim of the doctoral thesis was to design an electronic system capable of determining microstructure variations in steels by means of magnetic non-destructive techniques. In the research a thorough analysis of the signals obtained by means of these techniques was made, which led to the definition of several useful parameters for the characterisation of the microstructure and mechanical properties of steels. These new techniques are based on the following principle: The steel is formed by microscopic regions called magnetic domains. When a magnetic field is applied to the material, these domains tend to grow and their walls find microstructural obstacles in their movement, such as dislocations, grain boundaries, or precipitates, which hinder their growth.

The thesis proposes a measurement system that provides several representative parameters of the movement of the magnetic domain walls. By means of this system the magnetic domains of the material themselves are used as internal sensors that record the characteristics of the microstructure. With this method it is possible to determine whether the material has a high or low dislocation density, the way in which dislocations arrange themselves, whether the material has grain boundaries or precipitates etc.



In order to evaluate the system’s sensitivity, measurements were made on low carbon steel samples with various microstructures. Its sensitivity to plastic deformation was analysed and parameters with enough resolution were obtained to quantitatively investigate the evolution of the microstructure during the thermal treatment applied to the cold rolled steels. Specifically, during the metallurgical processes of recovery and recrystallization. It is remarkable that by means of these techniques recovery processes, which are not detectable by means of traditional techniques such as hardness measurements or optical metallography, can be monitored.

This doctoral thesis opens up new technological possibilities in the field of magnetic non-destructive testing techniques applied to microstructural characterization of steels. Some significant results have been published in international journals, such as Acta Materialia and Materials Science Forum.

Garazi Andonegi | alfa
Further information:
http://www.basqueresearch.com/tesi_sarrera.asp?hizk=I&Gelaxka=12
http://www.elhuyar.com

More articles from Materials Sciences:

nachricht New design improves performance of flexible wearable electronics
23.06.2017 | North Carolina State University

nachricht Plant inspiration could lead to flexible electronics
22.06.2017 | American Chemical Society

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Equipping form with function

23.06.2017 | Information Technology

New design improves performance of flexible wearable electronics

23.06.2017 | Materials Sciences

Individualized fiber components for the world market

23.06.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>