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 Researchers printed graphene-like materials with inkjet
18.08.2017 | Aalto University

nachricht Superconductivity research reveals potential new state of matter
17.08.2017 | DOE/Los Alamos National Laboratory

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>