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The Banded Structure and Its Effects on the Transverse Elongation and Textures of Mo Bars

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  • This work is supported by the China Postdoctoral Science Foundation (2013M542131) and Central South University Postdoctoral Science Foundation funded project.

Abstract

The transverse elongation, microhardness, and microstructure of different pure molybdenum bars reduction were investigated at room temperature. The results show that the transverse elongation of draw-forged pure Mo bars is gradually improved as the reduction of upsetting increases, which approaches a maximum value of 5% after upsetting to 80%. In the draw-forged molybdenum bars, it forms a 〈011〉 fiber texture. After upsetting deformation, 〈100〉 + 〈111〉 fiber textures are formed. Meanwhile, the orientation density of 〈100〉 fiber and 〈111〉 fiber increases gradually with the increasing reduction of upsetting deformation. The plastic deformation is much heavier and non-homogeneous in 〈111〉 orientation than that in 〈100〉 orientation. Many banded microstructures, especially microshear bands, are formed in 〈111〉 orientation. Meanwhile, many equiaxed dislocation cells are formed in 〈100〉 orientation. Two models are proposed to explain the evolution of texture. The formation of a 〈110〉 fiber or a 〈100〉 fiber can be explained by a cross-slip mechanism, and the formation of a 〈111〉 fiber can be explained by a microshear banding mechanism.

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