High-pressure torsion extrusion die

Abstract

The invention discloses a high-pressure torsion extrusion die which comprises an upper anvil block, a lower anvil block, a laminated suite and a rotation control mechanism, an annular cavity is formed in the lower anvil block, the laminated suite comprises a mandrel and a cylindrical part set connected to the mandrel in a sleeving mode, and the cylindrical part set is formed by stacking and sleeving a plurality of cylindrical parts one by one in the radial direction, the top of the mandrel and the top of the lamination suite form a circular plane, the circular plane is matched with the bottom of the annular cavity, the upper anvil block is arranged at the top of the annular cavity in a matched mode and moves up and down in the axial direction, and a sample is placed between the upper anvil block and the lamination suite; the bottom of the lamination suite is connected with a rotation control mechanism, and the rotation control mechanism controls the lamination suite to rotate and controls the angular velocity of the mandrel and the angular velocity of each cylindrical piece to be gradually decreased from inside to outside. The mechanical property of a sample prepared by traditional high-pressure torsion processing is reduced, and 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 invention belongs to the technical field of metal plastic processing strengthening, and in particular relates to a high-pressure torsion extrusion die. Background technique [0002] High-pressure torsion (HPT) is a processing strengthening method, which is mainly composed of upper anvil 1' and lower anvil 2', such as figure 1 As shown, the upper anvil 1' is nested on the upper part of the lower anvil 2'. First, the sample 3' is placed between the two anvils, and then the upper anvil applies pressure P, and the lower anvil rotates to provide shear force. Under the action of pressure P, the upper anvil descends and compresses the sample. Usually, the pressure P is about several GPa. At this time, the shear strain is applied to the sample by the rotation of the lower anvil until the required strain is obtained. . [0003] From this traditional HPT process, it can be seen that HPT obtains ultra-fine-grained materials through the joint action of hydro...

AI Technical Summary

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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