Ultra-fine grain rolling method for large-size high-temperature alloy bar

Abstract

The invention relates to the field of mechanical processing, in particular to an ultra-fine grain rolling method for a large-size high-temperature alloy bar. The ultra-fine grain rolling method comprises the following steps that rolling tool design is carried out and specifically comprises a roller design and a guide plate design, wherein each roller is set as a hyperboloid circular truncated cone-shaped roller, and specifically, the generatrix of each roller is formed by connecting two curves; and one side of each guide plate is set as a curved surface; a deformation region is constructed, wherein the curved surfaces of the two guide plates are oppositely arranged, the two rollers are arranged between the guide plates, and the region enclosed by the two guide plates and the two rollers isthe deformation region; a deformation region with equal ovality is constructed, wherein the ovality in the deformation region remains unchanged; and a rolling feeding mode is selected, wherein a reverse rolling mode is adopted. According to the ultra-fine grain rolling method for the large-size high-temperature alloy bar, by designing the hyperboloid circular truncated cone-shaped rollers and thecurved guide plates and constructing the deformation region with equal ovality, severe plastic deformation can be generated on the premise of remarkably inhibiting the Mannesmann effect at the center.

Description

technical field [0001] The invention relates to the field of mechanical processing, in particular to an ultra-fine-grain rolling method for large-size high-temperature 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 torsional extrusion (TE), among which: [0004] (1) High-pressure torsional deformation: While loading a pressur...

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Problems solved by technology

[0009] (6) An equidistant spiral rolling method for large-sized high-temperature alloy ultra-fine-grained rods (application number 201810172810.3), using forward tapered rollers to perform equidistant rolling of round billets. Technical parameters in the forming process: The feeding angle is 19-21°, the rolling angle is 15-17°, the roll speed n is 20-40r / min, the diameter reduction rate is 4%-16%, the pass ellipticity is 1.18-1.35, etc., but, This method has shortcomings such as serious uneven deformation and small deformation, which needs to be further improved

[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 HPT forming load 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

[0021] Comprehensive analysis shows that the ultra-fine-grain process of superalloys mentioned in existing patents or papers is currently limited to laboratory research due to the degree of refinement and deformation uniformity, and it is difficult to prepare large-scale industrial-grade overall ultra-fine grains (Φ60- Φ500mm) material

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