A method for ultra-fine grain rolling of large-size titanium alloy rods

Abstract

The invention discloses an ultra-fine grain rolling method of a large titanium alloy bar and relates to the field of machining, in particular to the ultra-fine grain rolling method of the large titanium alloy bar. The ultra-fine grain rolling method of the large titanium alloy bar comprises the following steps that rolling tools are designed, roller design and guide plate design are included, eachroller is designed into a double-curved face type circular truncated cone roller, and specifically, a bus of each roller is formed by connecting two curves, and one face of each guide plate is designed into a curved face; a deformation zone is configured, wherein the curved faces of the two guide plates are oppositely arranged, the two rollers are arranged between the guide plates, and a regiondefined by the two guide plates and the two rollers is the deformation zone; an equal ovality deformation zone is configured, wherein ovality in the deformation zone is kept unchangeable; and a rolling feeding manner is selected, wherein a backward advancing rolling manner is adopted. According to the ultra-fine grain rolling method of the large titanium alloy bar, by designing the double-curved face type circular truncated cone rollers and the curved face-shaped guide plates and configuring the equal ovality deformation zone, intensive plastic deformation can be generated on the promise of remarkably restraining a Mannesmann effect of the heart.

Description

technical field [0001] The invention relates to the field of mechanical processing, in particular to an ultrafine-grain rolling method for large-size titanium alloy rods. Background technique [0002] Ultrafine crystal / nanocrystalline materials and their preparation technology are one of the research hotspots in the field of material science. Research in this direction embodies people's efforts to continuously improve the strength and toughness of polycrystalline materials through continuous refinement of grains. Among them, the research results of severe plastic deformation (Severe Plastic Deformation, referred to as SPD) technology are eye-catching. [0003] At present, the mainstream SPD process includes five methods: high pressure torsion (HPT), equal channel angular extrusion (ECAP), cumulative stack rolling (ARB), multidirectional forging (MF) and torsion extrusion (TE), among which: [0004] (1) High-pressure torsional deformation: While loading a pressure of severa...

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Problems solved by technology

[0014] (1) During the ECAP deformation process, the blank is in full contact with the mold, and the friction force is large, so the forming load is large, the finished product size is small, and the material utilization rate is low, the production efficiency is low, and it is difficult to realize the preparation of large-scale ultra-fine-grained materials required by industrialization

[0015] (2) The forming load of HPT is huge. The existing forming equipment generally does not have the loading capacity of more than tens of GPa for industrialized large-scale products, and is only suitable for the forming of ultra-thin products such as films. Usually, the blank before deformation is Φ10~15×1~ 10mm cylinder

[0016] (3) The ARB process is limited by the volume of the deformation zone and the uniformity of deformation, and the thickness of the deformation zone is only mm level

At the same time, since the prepared ultrafine grains are elongated grains in the shape of cakes, their mechanical properties are worse than those of three-dimensional equiaxed grains.

Therefore, limited by the loading capacity and uneven deformation, ARB can only prepare ultra-thin sheets

[0017] (4) Due to the serious deformation inhomogeneity of MF and TE, the grain size is uneven, the stability of the grain structure is poor, and the performance is reduced, and it is also impossible to prepare large-size forgings

[0018] (5) An equidistant spiral rolling method for large-sized titanium alloy ultra-fine-grained rods (application number 201810172305.9) has the following problems: 1) The shape of the roll in the original technology is conical, and after the billet enters the roll, due to the As the diameter gradually increases, the speed of the contact area between the roll and the billet will gradually increase, which will lead to an increase in the deformation speed difference between the core and the edge of the billet, thereby aggravating the deformation unevenness

2) The distance between the rolls is equal, the diameter reduction rate gradually decreases, and the deformation is small, so the effect of grain refinement will gradually weaken

[0019] A comprehensive analysis shows that the titanium alloy ultra-fine-grained processes mentioned in the existing patents or papers all adopt the traditional multi-pass rolling method, limited by the volume of the deformation zone, only small-sized ultra-fine-grained materials can be prepared, and it is difficult to prepare industrial-grade Large size (Φ60~Φ500mm) material with overall ultra-fine grain

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