The hot deformation behavior of a newly developed AA6099 alloy was investigated after homogenization. To this end, Gleeble® isothermal hot compression tests were performed at temperatures of 350, 400, 450, and 500 °C, and strain rates of 0.01, 0.1, and 1 s−1 up to a true strain of 0.8. The dependency of the flow stress on the deformation temperature, strain, and strain rate was analyzed. In addition, the constitutive equations relating the flow stress to the deformation temperature and strain rate were derived using a power-law empirical model. Also, the microstructures and dynamic softening mechanisms of the alloy under various deformation conditions were examined using light optical microscopy (LOM) and electron back scattered diffraction (EBSD) techniques. The correlation between the flow behavior, different microstructures, and dynamic softening mechanisms at various hot compression conditions was determined. The kinetic analysis and microstructural evolution indicated that the main flow softening mechanism for homogenized AA6099 was dynamic recovery (DRV). Partial dynamic recrystallization (DRX) enhanced the flow softening especially at low deformation temperatures and high strain rates, i.e., at high Zener-Hollomon parameter (Z) values.

Analysis of flow stress and microstructure during hot compression of 6099 aluminum alloy (AA6099)

Fracture toughness, crack-growth-rate and creep studies of alloy 276

High temperature deformation of haynes alloy no. 188

High temperature deformation of Hastelloy alloy C-276 was studied. Hot compression tests were carried out at 1900, 2000, 2050 and 2100°F and at strain rates ranging from 10s3 to 1 set-I. The relationship between flow stress, strain, strain rate and temperature was examined and the mechanical equation of state was developed. Stress, strain and strain rate behavior at 2100°F was found to be markedly different from that at 1900 and 2000°F. The material showed a high degree of strain hardening at 2100°F. The activation energy for the deformation of Hastelloy alloy C-276 was found to be 109 Kcal/mole which is much higher than the activation energy for self-diffusion of nickel. It is suggested that dynamic recrystallization could be the rate-controlling mechanism. Microstructure examination revealed that recrystallization was promoted by higher temperature and higher deformation speed.

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Pankaj Agarwal

Papers

High temperature deformation of hastelloy alloy c-276