Correlation of Grain Size, Stacking Fault Energy, and Texture in Cu-Al Alloys Deformed under Simulated Rolling Conditions

Ehab A El-Danaf,Mahmoud S Soliman,Ayman A Al-Mutlaq

doi:10.1155/2015/953130

Ehab A El-Danaf, Mahmoud S Soliman + Show 1 more

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https://doi.org/10.1155/2015/953130

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Abstract

The effect of grain size and stacking fault energy (SFE) on the strain hardening rate behavior under plane strain compression (PSC) is investigated for pure Cu and binary Cu-Al alloys containing 1, 2, 4.7, and 7 wt. % Al. The alloys studied have a wide range of SFE from a low SFE of 4.5 mJm−2for Cu-7Al to a medium SFE of 78 mJm−2for pure Cu. A series of PSC tests have been conducted on these alloys for three average grain sizes of ~15, 70, and 250 μm. Strain hardening rate curves were obtained and a criterion relating twinning stress to grain size is established. It is concluded that the stress required for twinning initiation decreases with increasing grain size. Low values of SFE have an indirect influence on twinning stress by increasing the strain hardening rate which is reflected in building up the critical dislocation density needed to initiate mechanical twinning. A study on the effect of grain size on the intensity of the brass texture component for the low SFE alloys has revealed the reduction of the orientation density of that component with increasing grain size.

Highlights

The mechanical behavior of pure metals and solid-solution alloys has been observed to be greatly influenced by microstructural parameters such as grain size, stacking fault energy (SFE), and experimental conditions [1,2,3,4,5,6,7,8,9,10,11,12]
[(σ − σ0)/G] ∗ 1000 (c) deformation. Taking this value at the onset of stage B would correspond to the critical dislocation density required for twin initiation
The constant value of/G for each set of grain size when plotted against the normalized SFE shows that there is no direct dependence on the SFE since the normalized stress parameter did not change for the different SFE materials of the same grain size

Summary

Introduction

The mechanical behavior of pure metals and solid-solution alloys has been observed to be greatly influenced by microstructural parameters such as grain size, stacking fault energy (SFE), and experimental conditions [1,2,3,4,5,6,7,8,9,10,11,12]. Where b is the Burgers vector and α is a constant having a value of ∼1 It was demonstrated [1] that the value of (σt − σo)/G (where σt is the flow stress at which twinning was initiated and σo is the initial yield strength) was nearly the same for a number of polycrystalline FCC metals deformed in simple compression with different values of SFE and having almost similar initial grain size. This suggested that there is a critical dislocation density required for twins to be initiated for the FCC alloys tested. The selected state of stress here, PSC, is chosen because it simulates the rolling operation, which is an industrially important operation in metal forming

Experimental Work

Results

Discussion

Conclusion