High-pressure torsion extrusion method for fine-grain sample

Abstract

The invention discloses a high-pressure torsion extrusion method for a fine-grain sample, which comprises the steps of firstly, assembling a high-pressure torsion extrusion die, then after all parts are assembled, putting the sample on a circular plane of an annular cavity, pressing an upper anvil block downwards, maintaining the pressure, and starting a rotation control mechanism; and finally, driving a transmission shaft to rotate by a driving mechanism, and driving a laminated suite to rotate through meshing of a driving gear and a driven gear, wherein the relational expression of the meshing ratio in between the driving gear and the driven gear and the angular velocity [omega]n is shown in the description. The mechanical property of a sample prepared by traditional high-pressure torsion processing is reduced, the structure state is not uniformly distributed along the radial direction of the sample, and the linear speeds of all points on the surface of the sample in the torsion process are consistent, so that the prepared sample has better quality.

Description

Technical field [0001] The present invention belongs to the technical field of metal reinforced plastic processing, particularly to a fine crystalline sample HPT extrusion process. Background technique [0002] HPT (HPT) as a way to work strengthening, the anvil consisting essentially of 1 'and the lower anvil 2' composition, such as figure 1 , The upper anvil 1 'nest lower anvil 2' upper, first a sample 3 'is placed between the anvil and the anvil is applied pressure P, the rotation of the anvil to provide a shearing force, in under the effect of pressure P, and the sample drop on the anvil pressing, the pressure P in size is usually about several GPa, shear strain is applied at this time by rotating the anvil to the sample until a desired amount of strain . [0003] HPT can be seen from this conventional process, HPT ultrafine-grained materials is obtained by the interaction hydrostatic pressure, friction and shear forces. However, according to the conventional Experiments show...

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Problems solved by technology

However, according to a large number of existing experiments, for samples prepared by the high-pressure torsion method of the traditional integral lower anvil, since the linear velocity of each point on the sample surface is unevenly distributed along the radial direction, such as figure 2 As shown, as the distance L from the center of the sample (hereinafter referred to as the center distance) increases, the linear velocity V increases linearly, which causes the shear strain distribution of the sample to be uneven; the surface hardness increases with the center distance L Large and enlarged, and the surface structure of the sample after traditional HPT processing is uneven, forming microgalvanic corrosion, accelerating alloy dissolution, resulting in a decrease in the corrosion resistance of the alloy after HPT

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