Byung-Chul Ko

Prediction of dynamic recrystallization condition by deformation efficiency for Al 2024 composite reinforced with SiC particle

Hot torsion test has been carried out for Al 2024 composite reinforced with 8 μm SiCp (15 vol.%) to suggest optimum hot working condition for dynamic recrystallization (DRX) at the temperature range of 320 to 520 °C and strain rate range of 0.1 to 3.0/sec. Flow curve and deformed microstructure have been analyzed to identify the hot restoration mechanism of DRX. Processing map showing the variation of the deformation efficiency expressed by [2m/(m + 1)], where m is the strain rate sensitivity, with temperature and strain rate has been described for the composite. The characteristics of domain of DRX and peak efficiency of the composite have been analyzed by observing deformed microstructure. The composite showed 40–50% efficiency at the DRX domain (370–460 °C, 0.1–0.5/sec). Also, the variation of deformation efficiency with Zener-Hollomon parameter (Z = έ exp(Q/RT)) were discussed to find out optimum hot working condition for DRX of the composite. It is found that the optimum temperature and strain rate condition for DRX of the composite is 430–450 °C and 0.5/sec.

Hot-deformation behaviour of AA2124 composites reinforced with both particles and whiskers of SiC

Abstract The hot-deformation behaviour of AA2124 composites reinforced with both whiskers and particles of silicon carbide (15 vol% SiC w + SiC p ) was investigated by means of hot torsion tests in the temperature range 300 to 500 °C over a strain rate range of 1.32 × 10 −3 to 2.38 s −1 . The composites with various SiC w : SiC p ratios of 1:1, 1:2 and 1:3 were fabricated by the powder-metallurgy route. From the flow curves and hot-deformed microstructures, the hot recovery mechanism of composites deformed at 300–400 °C at 1.32 × 10 −3 s −1 strain rate was found to be dynamic recrystallization, while at temperatures higher than 450 °C dynamic recovery was responsible for the hot recovery mechanism of the composites. It was found that the composite with SiC w :SiC p = 1:1 showed the highest flow stress (52 MPa) and failure strain (375%) at 450 °C and 7.94 × 10 −2 s −1 .

Evaluation of hot workability of particle reinforced aluminum matrix composites by using deformation efficiency

The high temperature deformation behavior of Al 6061 composites reinforced with SiC and Al2O3 particles has been studied in the temperature range of 300–550°C and the strain rate range of 0.1–3.0/sec by hot torsion test. The deformation efficiency η, given by (2m/m + 1), where m is the strain rate sensitivity, is calculated as a function of temperature and strain rate to obtain iso-efficiency contour map. The composite reinforced with SiC particle exhibited a domain of dynamic recrystallization (DRX) with a peak efficiency of ∼40% at the temperature range of 450–500°C and strain rate range of 0.2–0.5/sec. On the other hand, the composite reinforced with Al2O3 particle showed the DRX domain at the temperature range of 450–480°C and strain rate range of 0.1–0.2/sec. The characteristics of these domain have been investigated with the help of microstructural observation and hot ductility measurements.

Dynamic softening behavior of Al−18Si alloy produced by spray forming

AbstractThe high-temperature deformation behavior and dynamic softening transition from dynamic recrystallization (DRX) to dynamic recovery (DRV) of Al-18 wt.%Si alloy was studied by torsion tests in a temperature range of 573∼773 K and a strain rate range of 0.001∼1/sec. The alloy was produced by spray-forming followed by hot extrusion. The dependence of flow stress (σ) on strain rate

A Study on the Process Design of Cold-Forged Automobile Parts

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A Numerical and Experimental Analysis on the Forming Limit of AA 3105 Aluminum Alloy in Radial Extrusion Process

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A Design of Manufacturing Processes for Valve-Spring Retainer Component

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