Processing map for controlling microstructure in hot working of hot isostatically pressed powder metallurgy NIMONIC AP-1 superalloy

Somani, MC and Rao, Bhagiradha ES and Birla, NC and Bhatia, ML and Singh, Vakil and Prasad, YVRK (1992) Processing map for controlling microstructure in hot working of hot isostatically pressed powder metallurgy NIMONIC AP-1 superalloy. In: Metallurgical Transactions. Physical Metallurgy and Material, 23 (10). pp. 2849-2857.

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Abstract

The hot deformation behavior of hot isostatically pressed (HIP) NIMONIC AP-1 superalloy is characterized using processing maps in the temperature range 950-degrees-C to 1200-degrees-C and strain rate range 0.001 to 100 s-1. The dynamic materials model has been used for developing the processing maps which show the variation of the efficiency of power dissipation given by [2m/(m +1)] with temperature and strain rate, with m being the strain rate sensitivity of flow stress. The processing map revealed a domain of dynamic recrystallization with a peak efficiency of 40 pct at 1125-degrees-C and 0.3 s-1, and these are the optimum parameters for hot working. The microstructure developed under these conditions is free from prior particle boundary (PPB) defects, cracks, or localized shear bands. At 100 s-1 and 1200-degrees-C, the material exhibits inter-crystalline cracking, while at 0.001 s-1, the material shows wedge cracks at 1200-degrees-C and PPB cracking at 1000-degrees-C. Also at strain rates higher than 10 s-1, adiabatic shear bands occur; the limiting conditions for this flow instability are accurately predicted by a continuum criterion based on the principles of irreversible thermodynamics of large plastic flow.

Item Type:	Journal Article
Publication:	Metallurgical Transactions. Physical Metallurgy and Material
Publisher:	Minerals Metals Materials Soc
Additional Information:	Copyright of this article belongs to Minerals Metals Materials Soc.
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	30 May 2011 10:02
Last Modified:	30 May 2011 10:02
URI:	http://eprints.iisc.ac.in/id/eprint/37441

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