Journal Published Online: 25 June 2019
Volume 8, Issue 5

A New Criterion for Construction of Instability Maps in Hot Deformation

CODEN: MPCACD

Abstract

A new instability criterion has been developed to identify safe and unsafe regions in hot deformation of metals. The instability function takes into account both the material variable (m) and process variable (ε˙) as well as the efficiency of power dissipation (η). The proposed instability function is based on Narayana Murty’s efficiency of power dissipation expression and can be used for a wide range of materials, including materials in which the stress-strain curve does not obey the power law. Different criteria as well as the new one were used for construction of the instability maps for the Mg-4Sn alloy, single-phase brass, and aluminum alloy AFNOR 7020. Concerning the Mg-4Sn alloy, compression tests were conducted at the temperature range of 300°C–500°C and strain rates of 0.001–1 s−1. It has been shown that the prediction of Prasad and Narayana Murty instability criteria is more conservative than the new presented criterion.

Author Information

Salari, O.
Faculty of Materials Science and Engineering, K. N. Toosi University of Technology, Tehran, Iran
Abdi, A.
Faculty of Materials Science and Engineering, K. N. Toosi University of Technology, Tehran, Iran
Aghaie-Khafri, M.
Faculty of Materials Science and Engineering, K. N. Toosi University of Technology, Tehran, Iran
Pages: 13
Price: $25.00
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Details
Stock #: MPC20180189
ISSN: 2379-1365
DOI: 10.1520/MPC20180189