Dynamic Recrystallization in Cu-Cr-Zr-Ti Alloy Under Large Plane Strain Conditions
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RODUCTION
HOT working processes such as rolling, forging, extrusion, etc., have been used to impart shape and size changes in metallic materials. Further, the mechanical properties of a hot-worked material largely depend on the microstructure evolved during deformation. A vast amount of work has been carried out by various researchers to understand the effect of the process parameters such as temperature and strain rate on the hot deformation behavior of numerous materials. These include efforts to develop constitutive equations for relating the flow stress of a material with the process parameters and to investigate the evolution of microstructure during deformation. The objectives of these studies were to optimize the hot workability of materials and to achieve microstructure control by studying the underlying mechanisms responsible for the microstructural changes during hot deformation.[1–7] ADITYA SARKAR and M.J.N.V. PRASAD are with the Microstructural Engineering and Mechanical Performance Laboratory, Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai, India. Contact e-mail: [email protected] S.V.S. NARAYANA MURTY is with the Materials and Mechanical Entity, Vikram Sarabhai Space Centre, Trivandrum, India. Manucsript submitted March 16, 2020.
METALLURGICAL AND MATERIALS TRANSACTIONS A
Copper alloys possessing a good combination of properties such as high thermal and electrical conductivity, strength, and fatigue resistance are used to manufacture various electrical and electronic components as well as heat transfer elements.[8–13] One such application is the use of Cu-Cr-Zr-Ti alloy to make the inner wall of the thrust chamber of a rocket engine used in satellite launch vehicles. In the Cu-Cr-Zr-Ti alloy, the Cr-rich bcc precipitates are responsible for the high strength, whereas Zr and Ti are added to retain the strength at elevated temperatures and to prevent embrittlement caused due to sulfur (present as an impurity), respectively.[12–17] This alloy is subjected to a number of intermediate hot working processes such as forging and rolling between casting and final room temperature drawing to form convergent and divergent nozzles of a rocket engine. This highlights the need for studies investigating the hot deformation behavior of the alloy. The authors of this paper have made a few attempts in the recent past to do so. These studies investigated the effect of process parameters and the initial microstructure on the flow stress behavior and microstructural evolution under hot working conditions by performing a series of hot uniaxial compression tests.[18,19] These studies revealed DRX as an important microstructural restoration mechanism and established its dependence on the process parameters and the initial microstructure of the alloy. However, a major limitation of these studies
was a low value of the strain imposed (maximum strain of about 0.5) that too under uniaxial conditions. During actual hot rolling of the alloy, the strains imposed
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