Evaluation of tempering behaviour in modified 9Cr–1Mo steel by magnetic non-destructive techniques

Kumar, Harendra and Mohapatra, J N and Roy, Rajat K (2010) Evaluation of tempering behaviour in modified 9Cr–1Mo steel by magnetic non-destructive techniques. Journal of Materials Processing Technology, 210 (4). pp. 669-674.

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Abstract

Modified 9Cr–1Mo steels were normalized at 1050 °C/30 min and tempered over a wide range of temperatures to observe the effect of tempering temperature on the material properties. The material revealed mechanical softening when tempered at temperature less than the lower critical temperature (810 °C: Ac1). Beyond Ac1 temperature the materials strength increased drastically due to the formation of fresh martensite. Magnetic Hysteresis Loop (MHL) and Magnetic Barkhausen Emissions (MBE) techniques were used to evaluate the magnetic properties of the materials with tempering. Magnetic softening was observed by tempering the material below the Ac1 temperature where a decrease in coercivity and an increase in RMS voltage of the MBE were found. Tempering beyond Ac1 magnetic hardening was observed by the increase in coercivity and the decrease in RMS voltage of MBE. Such results revealed that magnetic techniques could be a better tool for the evaluation of tempering of modified 9Cr–1Mo steel.

Item Type:Article
Official URL/DOI:http://dx.doi.org/10.1016/j.jmatprotec.2009.12.003
Uncontrolled Keywords:Modified 9Cr–1Mo steel; Tempering; Hardness; Magnetic Hysteresis Loop; Magnetic Barkhausen Emissions; Scanning electron micrograph
Divisions:Material Science and Technology
ID Code:479
Deposited By:Sahu A K
Deposited On:13 May 2010 10:06
Last Modified:20 Mar 2012 14:25
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