Ultrafine/nanocrystalline metal and short-process and large-deformation preparing method thereof

Abstract

The invention belongs to the technical field of metal machining, and particularly relates to ultrafine / nanocrystalline metal and a short-process and large-deformation preparing method thereof. A metal rod is fed into a continuous flowing deformation extruder, and after the metal rod is subjected to twisting motion shearing deformation, equal-channel corner extruding deformation and expanding extruding deformation in sequence, a single-pass extruding deformation metal rod is obtained; and the single-pass extruding deformation metal rod is fed into the continuous flowing deformation extruder again to be extruded and deform, and the ultrafine / nanocrystalline metal is prepared through many times of repetition of the process. The single-pass metal deformation is large, metal material grains can be obviously refined, and an ultrafine / nanocrystalline metal material with the unlimited length and the changeable section size can be continuously prepared.

Description

technical field [0001] The invention belongs to the technical field of metal processing, and in particular relates to a short-process and large-deformation preparation method of ultrafine / nanocrystalline metal and the ultrafine / nanocrystalline metal prepared by the method. Background technique [0002] Among the strengthening methods of metal materials, fine-grain strengthening is the only method that can simultaneously improve the strength and plasticity of metal materials. The large plastic deformation method (Severe Plastic Deformation, SPD) makes the metal grains significantly refined through strong plastic deformation, so as to obtain ultra-fine-grained / nano-crystalline metal materials, and at the same time improve the strength and plasticity of metal materials, so it has attracted the attention of researchers at home and abroad. . Existing large plastic deformation methods include Equal Channel Angular Pressing (ECAP), Accumulative Roll Bonding (ARB), High Pressure To...

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Problems solved by technology

[0003] ECAP is the most widely studied and most representative SPD method. This method allows metal materials to pass through channels with the same cross-sectional size and shape and a certain angle to each other. Shear deformation occurs at the corner of the channel. The amount of deformation achieves the purpose of refining grains, but this method has problems such as short mold life, complicated process, small deformation in a single pass, and low yield, which limits the wide application of ECAP; The surface-treated metal sheets are stacked together and rolled at a certain temperature to weld the interface, and the metal grains are refined through multiple passes of lamination, rolling, and welding, but this method is difficult to solve Due to the problem of interfacial bonding, the thickness of the product is also limited, which cannot be widely used in the preparation of ultra-fine crystal / nanocrystalline metal materials; Torque is applied to the cross-section of the sample, and the sample undergoes tangential torsional shear deformation under axial pressure, thereby achieving grain refinement. However, it is difficult to prepare large-sized ultrafine-crystalline / nanocrystalline metal materials with this method, and the yield is low. , and the strength and plasticity of ultra-fine-grained / nano-crystalline metal materials obtained by this method are poor; MDF continuously changes the external axial load, the sample is continuously compressed and elongated, and the grain is refined through repeated deformation, but the The process stability of the method is poor, and the structure of the product is uneven

[0004] In summary, the existing methods for preparing ultrafine-crystalline / nanocrystalline metal materials generally have problems such as complex process, long process, high cost, and limited product size. Preparation method of nanocrystalline metal material

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