Microstructural characterization of hypoeutectoid steels quenched from the Ae1 - Ae3 intercritical temperature range by magnetic barkhausen noise technique

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2006

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Boyacıoğlu, Beril

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This thesis aims to examine the possibility of using Magnetic Barkhausen Noise technique in characterizing the ferritic-martensitic microstructure of hypoeutectoid steels quenched from the intercritical temperature range. For this purpose, rectangular specimens were prepared from SAE 1020, 1040 and 1060 steels. The specimens were heated at different temperatures within the intercritical temperature range and then quenched into water. Microstructures of the specimens were characterized by metallographic examinations and hardness measurements. The measurements of the Magnetic Barkhausen Noise (MBN) were performed by using both Rollscan and æSCAN sensor connectors. It was seen that, for specimens having identical carbon content, Barkhausen emission decreased as the heating temperature increased. Moreover, in specimens heated at the same temperature, Barkhausen emission decreased as the carbon content of the specimen increased. In both cases, the decrease in Barkhausen emission is associated with the increase in martensite content. The results indicate that MBN is inversely proportional to hardness and that MBN is very sensitive to the microstructural condition of the material. It has been shown that using MBN is a powerful tool for evaluating the microstructure of hypoeutectoid steels quenched from the intercritical temperature range and that the use of this technique could be extended to characterize industrial dual phase steels.

Subject Keywords

Metallurgy.

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http://etd.lib.metu.edu.tr/upload/12606921/index.pdf
https://hdl.handle.net/11511/15683

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

B. Boyacıoğlu, “Microstructural characterization of hypoeutectoid steels quenched from the Ae1 - Ae3 intercritical temperature range by magnetic barkhausen noise technique,” M.S. - Master of Science, Middle East Technical University, 2006.