Study of high-temperature ageing and creep on bainitic 5Cr–0.5Mo steel by magnetic NDE techniques

Mohapatra, J N and Bandopadhyay, N R and Gunjan, M K and Mitra, A (2010) Study of high-temperature ageing and creep on bainitic 5Cr–0.5Mo steel by magnetic NDE techniques. Journal of Magnetism and Magnetic Materials, 322 (6). pp. 589-595.

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5Cr–0.5Mo steel having initial bainitic microstructure has been aged at 600 °C for 5000 h and subjected to creep at 600 °C/60 MPa. At different lengths of time the tests were interrupted for magnetic measurement using magnetic Barkhausen emissions (MBE) and magnetic hysteresis loop (MHL) techniques. Composition, morphology and distribution of carbides were studied using scanning electron microscopy (SEM). Magnetic softness was observed in the material up to 1600 h of ageing due to the decrease in pinning density for the coarsening of carbides by accumulation of large number of finer carbides. At higher ageing periods the demagnetizing field offered by the large massive carbides causes magnetic hardening. During creep test since the material has been normalized at 50 h of creep test also the structural change in creep test is accelerated, the magnetic softening for the interstitial carbon migration to the grain boundary and stress relaxation has removed in such early periods of ageing. When the carbides started coarsening the number density of the carbides decreased and inter-carbide distance increased which enhances the magnetic softening in the material in the secondary stage of creep. Formation of massive carbides and micro voids at the late tertiary stage of creep offers demagnetizing field causes magnetic hardening before failure of the material.

Item Type:Article
Official URL/DOI:
Uncontrolled Keywords:Ageing; Creep; Magnetic Barkhausen emissions; Magnetic hysteresis loop and Microstructure
Divisions:Material Science and Technology
ID Code:477
Deposited By:Sahu A K
Deposited On:13 May 2010 10:18
Last Modified:25 Jan 2012 11:00
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