Equal-channel shear extrusion mold and molding method

Abstract

The invention discloses an equal-channel shear extrusion mold and a molding method, and belongs to the technical field of metal material extrusion and molding. The mold is externally of a cuboid structure and is internally provided with a mold cavity, wherein the mold cavity is divided into an entrance section, a shear deformation section I, a shear deformation recovery section I, a shear deformation section II, a shear deformation recovery section II and an exit section. A blank is subjected to dramatic shear strain under the effect of shear strain, so that crystals are shorn and crushed, and the effect of refining the crystals is realized; meanwhile, the blank is limited by the extrusion mold cavity, and is in an intense pressure stress state, and the deformation degrees among the blank crystals in the pressure stress state are difficult, and the development of various original microdefects of a deformation body can be inhibited; the multi-pass shear extrusion can be carried out, and the final superfine crystal blanks with the uniform deformation can be molded; the shapes and the sizes before and after the deformation are not changed, the repeated multi-pass extrusion deformation can be realized, and the plastic deformation of the blank can be improved obviously.

Description

technical field [0001] The invention relates to an equal-channel shear extrusion die and a forming method, belonging to the technical field of extrusion forming of metal materials. Background technique [0002] Extrusion torsion (TE) is a new method of severe plastic deformation (SPD) that has only appeared in recent years (J Mater Process Tech, 2009, 209(7): 3650), because the two ends of the TE mold cavity are square straight channels , with a square spiral channel in the middle. The material thus undergoes severe shear deformation during the TE process. Compared with other SPD methods, the TE deformation material has a large cross-sectional strain gradient, which is beneficial to grain refinement; TE can be realized on existing general-purpose extrusion equipment as a unidirectional extrusion deformation. Although the application scope and industrialization prospect of TE are very broad, the part of TE spiral channel has obvious edges and corners, which is difficult to ...

AI Technical Summary

Problems solved by technology

Although the application range and industrialization prospect of TE are very broad, the edges and corners of the TE spiral channel are obvious, the processing is difficult, and the cost is high. In addition, the TE mold is prone to cracking, serious wear, and short service life.

[0003] In the Chinese patents with publication numbers CN201371172Y, CN201711480U and CN201862645U respectively, the mold channel adopts a circular cross-section into an elliptical cross-section, and then twists the elliptical cross-section into a circle Although the cross-section method extends the application range of TE to circular cross-section blanks, it also has the disadvantages of large load and high cost

The forming methods of Axi-symmetric forward spiral extrusion (Mech Mater, 2011, 43(11): 684) and Vortex extrusion (Mater Sci Eng A, 2011, 530: 469) have also been proposed abroad, but compared with TE, the forming methods are finer. Poor crystallization effect

[0004] It can be seen that the existing methods still have deficiencies in the forming effect and process conditions

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