A method for ultra-fine grain rolling of large-size superalloy rods with reverse-cone helical rolls

Abstract

The invention relates to the field of machining, in particular to a reverse conical spiral roller ultra-fine grain rolling method of large high-temperature alloy bars. The method includes the following steps that design of rolling tools specifically includes roller design and guiding plate design, and rollers are set to be double-curved-surface type truncated-cone-shaped spiral rollers; a deformation zone is constructed as follows: curved surfaces of two guiding plates are placed oppositely, the two rollers are placed between the guiding plates, and the zone defined by the two guiding plates and the two rollers is the deformation zone; an equal-ellipticity deformation zone is constructed as follows: the ellipticity is unchanged in the deformation zone; the rolling feeding manner is selected as follows: the back feeding type rolling manner is selected. According to the method, the double-curved-surface type truncated-cone-shaped spiral rollers and the curved guiding plates are designed,and the equal-ellipticity deformation zone is constructed, so that severe plastic deformation can be produced on the premise that the core Mannesmann effect can be suppressed remarkably.

Description

technical field [0001] The invention relates to the field of mechanical processing, in particular to an ultra-fine-grain rolling method of a large-size high-temperature alloy bar with a reverse-cone helical roll. 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 def...

AI Technical Summary

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) There are the following problems in the rolling method of spiral conical rolls with equal roll spacing for large-size high-temperature ultra-fine grain bars (application number 201810172370.1): 1) The shape of the rolls in the original technology is conical. The diameter of the roll increases gradually, and the speed of the contact area between the roll and the billet increases gradually, 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 ultra-fine-grain process of superalloys mentioned in existing patents or papers, limited by the volume of the deformation zone, can only produce small-sized ultra-fine-grained materials, and it is difficult to prepare large-scale (Φ60~ Φ500mm) material

Images