CN108277446B - Equidistant spiral rolling method for large-size high-temperature alloy ultrafine-grained bar - Google Patents
Equidistant spiral rolling method for large-size high-temperature alloy ultrafine-grained bar Download PDFInfo
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Abstract
The invention discloses an equidistant spiral rolling method of a large-size high-temperature alloy ultrafine-grained bar, belongs to the technical field of machining, and particularly relates to an equidistant spiral rolling method of a large-size high-temperature alloy ultrafine-grained bar, which comprises the following steps: s1: selecting a high-temperature alloy blank with the diameter dimension D of 40-150mm and the length of 300-5000 mm; s2: placing the high-temperature alloy blank in a heating furnace and heating to 920-1120 ℃; s3: transferring the heated high-temperature alloy blank from the heating furnace into a guide chute of a skew rolling mill for 5-20 s; s4: feeding in a guide chute of the skew rolling mill, and spirally moving the high-temperature alloy blank in a deformation zone until the deformation is finished; s5: repeating the steps S2-S4; the invention has the beneficial effects that: the deformation zone has large penetration depth and can carry out multi-pass rolling repeatedly. Continuous and stable local deformation and three-dimensional severe deformation of the composite pressing-twisting can obtain ideal grain refining effect.
Description
Technical Field
The invention belongs to the technical field of machining, and relates to a conical roller equal-roller-spacing spiral rolling method for a large-size GH4169 high-temperature alloy whole ultrafine-grained bar material, in particular to an equidistant spiral rolling method for the large-size high-temperature alloy ultrafine-grained bar material.
Background
Ultra-fine grain/nano-grain materials are one of the hot topics for current material science research. Compared with the traditional coarse-grained metal material, the ultra-fine grained/nano material has more excellent or unique properties in certain aspects, such as higher strength and hardness, better fatigue performance and superplasticity, better corrosion resistance, wear resistance, biological characteristics and the like. The excellent characteristics lead the ultra-fine grain material to have wide application prospect in the engineering fields of aviation, aerospace, automobiles, oceans, biology and the like, and lead people to pay more attention to the development of the ultra-fine grain/nano preparation technology.
For the ultra-fine crystal GH4169 with the crystal grain size of 1.5um, the tensile strength at room temperature is remarkably improved. As for the coarse crystal GH4169 in a solid solution state, the tensile strength is 853Mpa, and after the ultra-fine crystal process treatment, the tensile property can reach 1060 Mpa. The tensile property of the coarse crystal GH4169 alloy is 1100MPa for the high-temperature tensile property of 650 ℃, and the high-temperature tensile property of the ultra-fine crystal GH4169 alloy can reach 1530 MPa. Therefore, the large-size high-temperature alloy ultrafine-grained bar has great potential in the field of industrial application.
When the nano-scale material is prepared, the equivalent strain is usually more than 6, the traditional Plastic processing method is difficult to realize, and the Super Plastic Deformation (SPD) can be realized. Modern SPD starts from the combination of high pressure and shear deformation forming method proposed by Bridgemen, the rapid development starts from soviet union and western countries before the middle of the 70 th 20 th century, and Segal develops Equal-Channel Angular Extrusion (ECAP), which marks the arrival of the microstructure era of SPD research.
Definition of SPD generally accepted after 2006: the metal forming method can obtain the grain size of micron (100-1000 nm) and nanometer (less than 100 nm), which can be called nano SPD (nano SPD for short). The nano SPD material has a large amount of large-angle non-equilibrium grain boundary tissues containing high-density dislocation and high internal stress, so that the material shows mechanical behavior and a deformation mechanism different from those of the traditional coarse-grained material.
The current processing technical scheme is as follows: typical SPD forming techniques include High Pressure Torsion (HPT), Equal Channel Angular Pressing (ECAP), cumulative rolling (ARB), Twist Extrusion (TE), and Multi-Directional Forging (MDF).
Wherein, (1) high-pressure torsional deformation: the original sample (block or powder) placed in the supporting groove is applied with a plurality of GPa pressures, and the upper anvil and the lower anvil are relatively rotated, so that the sample is subjected to strong shearing deformation to refine grains, and the high-pressure torsion is characterized in that the workpiece is in a disc shape, the size is small, the diameter is generally 10-20 mm, and the thickness is 0.2-0.5 mm.
(2) Equal channel angular extrusion deformation: the material is extruded from one end to the other end through two equal-section channels intersecting at a certain angle in the die, the material is subjected to pure shear deformation through the change of the motion direction of the material by the bending angle, the forming process can be repeated, and the shear strain amount is increased along with deformation passes.
(3) Cumulative pack rolling method: the method comprises the steps of carrying out double-layer stacking on an original plate after surface treatment, heating, carrying out roll welding together, then carrying out next roll welding circulation after cutting from the middle and returning to the surface treatment, wherein in order to ensure that the plate can be welded together after rolling, the reduction of each pass is not less than 50%, but strong shear stress conditions are required in the ARB processing process, a lubricant cannot be used, and the service life of a roller is not favorable.
(4) Torsion extrusion: beygelzime et al teach this process. The method also adopts a forming technology of thinning crystal grains through shearing deformation, and the columnar blank is extruded through a torsion die, so that the method has the similar problem of uneven deformation as HPT, and the effect of thinning the crystal grains is lower than that of ECAP and HPT.
(5) Multidirectional forging: the process changes the free forging direction through multiple orthogonal operations to obtain large deformation. The grain refining effect of such deformation is significantly lower than that of ECAP and HPT.
Another existing processing technical scheme is as follows: the derivation method, the new SPD technology in recent years is endlessly developed, the basic forming principle is the same as the above method, many ECAP forming new technologies are derived, the methods try to simplify the tool design, reduce the energy consumption, improve the yield, promote the workpiece size, upgrade the automation degree, and the like, wherein, the method comprises the following steps:
(1) ECAP derivatization method: repeated bending and straightening (RCS), wherein the blank is placed between the bending devices and is bent into a wavy shape along with the downward movement of the upper die; the material structure is then refined by straightening with 2 plates and bending again, with repeated iterations, accumulating sufficient deformation without significantly changing the dimensions of the blank.
(2) A Circular Closed Die Forging (CCDF) is composed of a lower die with a cavity with a certain cross section and a punch with the same cross section, which vertically moves in the cavity. And (3) putting the fully lubricated sample with the graphite lubricant into a lower die, and heating to a certain temperature. And pressing the workpiece into the lower die through the punch, taking out the workpiece, rotating the workpiece by 90 degrees around the Z axis in the same direction, and reinserting the lower die for deformation. Thus, the workpiece is rotated 90 about the Z-axis between successive passes. In this way, 1,3 and 5 compressions were respectively experienced.
(3) Reciprocating extrusion (CEC), a die is made up of two die cavities, a compression band and punches placed in the two die cavities. The two die cavities have equal sectional areas and are connected through a middle compression belt on the same axis. During the extrusion process, the sample reaches the compression belt under the action of the punch, at the moment, the sample is subjected to positive extrusion deformation, and the extruded workpiece is subjected to upsetting deformation under the action of the punch of the other die cavity. Then, the punch on the other side reversely presses the workpiece back according to the process to complete an extrusion cycle. The above process is repeated until the desired strain is obtained.
(4) The plate is continuously sheared and deformed, and the device utilizes an upper die, a lower die and a lower roller to form two mutually crossed channels with small difference in cross-sectional area. The plate is fed into the die cavity, and the plate is strongly shaped and deformed at the corner of the die cavity and then extruded from the other side of the die cavity. Grooves are machined on the surface of the feeding roller for increasing the friction force. Due to the characteristic that the cross-sectional area of the material is kept unchanged before and after deformation, the plate can be subjected to multi-pass plastic deformation repeatedly in the same die.
(5) The method is characterized in that a blank is converted into a round bar stock through upsetting-drawing (round-oval transformation), twisting (oval cross section twisting) and reverse upsetting-drawing (oval-round transformation) processes under the action of extrusion force. Metals produce plastic flow primarily in cross-section and accumulate strain. The shape of the die utilizes the particularity of a circular shape and an oval shape, and a sharp corner area does not exist in a cavity of the die, so that metal can flow easily. The combination of multiple deformation modes in one technological process is realized.
(6) Continuous Friction Angle Extrusion (CFAE), the drive roller rotates and applies pressure P to the workpiece against its support. A first extrusion channel is formed between the drive roller and the workpiece support member and a second channel is a short slot in the stationary die assembly. The sheet workpiece is processed for one to eight times, the maximum equivalent real strain can reach 5.3, and the orientation of the sheet material is always kept constant.
(7) An HPT derivatization method is adapted for High Pressure Torsion (HPT) of a tube, the tube being positioned within a rigid disk, a mandrel being placed within the tube and compressed in its elastic state by a compressor. Due to the axial compression of the mandrel, which expands radially, the expansion is limited by the tube and the discs, creating large hydrostatic stresses in the tube, creating large friction forces on both sides of the tube. The deformation of the tube is achieved by an external torque rotating disc, with the mandrel held stationary. During the twisting process, the deformation mode is local shearing, the normal direction of the shearing surface is the radial direction of the tube, and the shearing direction is parallel to the circumferential direction.
(8) One TE derivatization method, ultra-high torsion (STS), localizes the Torsional Strain (TS) region by locally heating and cooling to make the region less resistant to deformation than the other two portions. While the TS zone is created, the rod moves along the longitudinal axis, thereby continuously creating an ultra-large plastic strain throughout the rod. This new process STS includes a rod that creates localized soft zones and movement of the regions in the longitudinal direction relative to the rest of the rod. An important feature of STS is that the cross-sectional dimensions of the rod remain unchanged when strained.
The high-temperature alloy is a metal material capable of working for a long time at the temperature of more than 600 ℃ and under a certain stress condition, has excellent high-temperature strength, good oxidation resistance and hot corrosion resistance, good fatigue performance, fracture toughness and other comprehensive properties, and becomes an irreplaceable key material for hot-end parts of military and civil gas turbine engines. Patent No. CN 106862447 a by the ministry of iron and steel research institute proposes a process for producing high-temperature alloy ultrafine-grained bar by using a multidirectional forging and drawing process. The process adopts a multidirectional upsetting-drawing mode for deformation, but the deformation area is small, the strain penetrability is small, and the superfine grains are difficult to cover each area of the blank. Although the maximum diameter size recorded by the forged bar stock is 420mm, the whole deformation is difficult to cover each area of the blank, the deformation permeability is poor, the nonuniformity is serious, and the actual production requirement cannot be met. . With such a forming method, it is difficult to achieve the entire grain refinement. Luojunting et al, Yanshan university, in patent [ CN 104294197A ], proposed ultra-fine grain refinement of high temperature alloy sheet using cold rolling deformation of 70-80%. From the cold deformation point of view, if the deformation reaches 70-80%, the forming size is greatly restricted by the forming load. In addition, rolling deformation belongs to the history of bidirectional plastic deformation, and has great influence on the quality of both a roller and a blank, so that the deformation degree is difficult to achieve. Finally, as can be seen from the examples, the whole process is single-pass deformation, and the degree of refinement is limited. The patent of Zjunbao, Bao Steel, et al (CN 103008659A) discloses a method for forming a high-temperature alloy turbine disk piece for aviation by powder metallurgy spray forming in a manufacturing method of an ultra-fine grain high-temperature alloy disk blank. The grain size of the high-temperature alloy obtained by the powder metallurgy method is about 3-5um, and the high-temperature alloy has certain requirements on the grain size of raw materials, so the refinement degree is limited, and the industrial requirement cannot be completely met. The patent of "CN 101307402 a" by the new creation of the university of beijing technology proposes an ultra-fine grain nickel-based superalloy and a preparation method thereof, and the patent does not propose what parameters and methods are used for preparing the ultra-fine grain nickel-based superalloy. The characteristic of low tonnage requirement is provided for the remarkable advantages, but the deformation load still greatly exceeds the continuous local deformation mode related to the patent under the same deformation condition. Thus, the low tonnage requirements, low losses and reduced costs are not significant compared to the methods of the patents herein. Secondly, the shape of the raw material mentioned in this patent does not mention what kind of shape, such as bars, plates and wires, and therefore does not resemble the patent herein. Research progress of ultra-large plastic deformation of poplar steel in the special steel technology-a grain refinement mechanism of nano materials refers to that surface mechanical ball milling (SAMT) is adopted to carry out severe plastic deformation on Inconel 600 nickel-based high-temperature alloy to generate ultra-fine grains. Such deformation can only produce ultrafine or nano-powders, which cannot be analogized to the large-size GH4169 ultrafine grained bars mentioned in this patent.
The comprehensive analysis shows that: the ultra-fine grain processes mentioned in the prior papers or patents, which mostly use powder forming or shaping ultra-fine/nano-powder, cannot be compared with the large-size high-temperature alloy monolithic ultra-fine grain bars mentioned in the present patent. The processes for preparing ultrafine crystals by multi-directional upsetting and drawing proposed in some patents have smaller deformation zone and poorer penetrability. Cold rolling also belongs to the history of two-way plastic deformation, and the deformation degree is difficult to achieve no matter the quality of a roller or a blank is greatly influenced. Finally, the whole process is single-pass deformation, the refining degree is limited, the current process is only limited to laboratory development, and the industrial-grade integral ultrafine-grained large-size material is difficult to prepare.
Disclosure of Invention
The invention aims to provide a conical roller equal-spacing spiral rolling method for a large-size GH4169 high-temperature alloy whole ultrafine grain bar material, which aims to solve the problems of limited size and refinement degree, low efficiency and the like in the background technology.
The invention relates to an equidistant spiral rolling method of a large-size high-temperature alloy ultrafine crystal bar, which comprises the following steps:
s1: selecting a high-temperature alloy blank with the diameter dimension D of 40-150mm and the length of 300-5000 mm;
s2: placing the high-temperature alloy blank in a heating furnace, heating to 920-1120 ℃ for the following time: the diameter of the high-temperature alloy blank is Dx (0.6-0.8) min;
s3: transferring the heated high-temperature alloy blank from the heating furnace into a guide chute of a skew rolling mill for 5-20 s;
s4: feeding materials in a guide chute of a skew rolling mill, feeding high-temperature alloy into a deformation zone between an inlet and an outlet of the skew rolling mill, and spirally moving the high-temperature alloy blank in the deformation zone until the deformation is finished to obtain a high-temperature alloy bar with the diameter Dm, wherein m is the rolling frequency;
s5: repeating the steps S2-S4, and carrying out 2-6 times of spiral rolling on the high-temperature alloy blank to obtain a GH4169 high-temperature alloy whole ultrafine crystal bar material;
the skew rolling mill is a two-roller skew rolling mill, the rollers are single conical rollers, the cone angle gamma 1 is 15-17 degrees, the radius r of an arc of the high-temperature alloy blank which is bitten into the rollers is 80-450mm, the feeding angle β of the rollers is 19-21 degrees, the rolling angle beta of the rollers is 15-17 degrees, the roller distance Dg between the two rollers is 84-96 percent of the diameter D of the high-temperature alloy blank, and the roller rotating speed n is 20-40 r/min;
the high-temperature alloy blank is a large-size GH4169 high-temperature alloy bar;
in step S5, the heating time for repeating the rolling process is: the diameter Dm (0.3-0.4) of the high-temperature alloy bar is multiplied by 0.3-0.4 min.
Preferably, the small end surface of the roller is provided with a circular arc surface, and the radius of the circular arc surface is 80-450 mm.
Preferably, the pass ovality factor is the guide plate distance DdAnd the ratio of the roll spacing Dg to the pass ovality coefficient of 1.18-1.35 is adopted for rolling the high-temperature alloy blank in the deformation zone in the step S4.
Preferably, in the rolling process of the high-temperature alloy blank, the roll distance Dg between the two rolls is fixed, which is beneficial to realizing multi-pass repeated rolling.
Preferably, the shape of the deformed region is maintained during the repeated rolling at step S5.
Compared with the prior art, the invention has the beneficial effects that:
(1) the deformation zone has large penetration depth, and large-size integral ultrafine grain structure can be obtained. The plastic deformation in the material during the skew rolling process is composed of two parts, namely compression deformation between rollers, which is periodic discontinuous deformation, and continuous torsional deformation. The superposition of compression and torsional deformation enables three-dimensional severe plastic deformation which is obviously different from that of conventional forging to be generated in a deformation area in the skew rolling process; (2) the diameter of the bar material before and after the skew rolling is kept unchanged, and the bar material can be repeatedly rolled for multiple times. The width expansion exists in the skew rolling process, and the equivalent diameter in the cross section of the high-temperature alloy blank remains unchanged; (3) continuous and stable local deformation, small rolling load and stable deformation process. The actual contact area of the workpiece and the high-temperature alloy blank in the skew rolling process is only a very small part of the surface area of the high-temperature alloy blank, and the workpiece and the high-temperature alloy blank are in local contact deformation, so that the load is small; (4) the pressing-twisting composite three-dimensional severe deformation can obtain ideal grain refinement effect.
Drawings
FIG. 1 is a schematic view of a roll of the present invention.
FIG. 2 is a schematic diagram of original structure grains.
FIG. 3 is a schematic view of 2 rolling passes according to an embodiment of the present invention.
FIG. 4 is a schematic diagram of 6 rolling passes according to an embodiment of the present invention.
FIG. 5 shows the relative positions of the dies during skew rolling according to the present invention.
FIG. 6 is a top view of the relative positions of the dies during skew rolling in accordance with the present invention.
FIG. 7 is a left side view of the relative positions of the dies during cross-piercing in accordance with the present invention.
FIG. 8 is a schematic view of the deformation zone of the skew rolling process of the present invention.
Reference numerals: 1-roller, 2-high temperature alloy blank and 3-guide plate.
Detailed Description
The invention relates to an equidistant spiral rolling method of a large-size high-temperature alloy ultrafine crystal bar, which comprises the following steps:
s1: selecting a high-temperature alloy blank 2 with the diameter dimension D of 40-150mm and the length of 300-5000 mm;
s2: placing the high-temperature alloy blank 2 in a heating furnace to be heated to 920-1120 ℃, wherein the heating time is as follows: 2 diameters Dx (0.6-0.8) min of the high-temperature alloy blank;
s3: transferring the heated high-temperature alloy blank 2 from the heating furnace into a guide chute of a skew rolling mill for 5-20 s;
s4: feeding materials in a guide chute of a skew rolling mill, feeding high-temperature alloy into a deformation zone between an inlet and an outlet of the skew rolling mill, and spirally moving the high-temperature alloy blank 2 in the deformation zone until the deformation is finished to obtain a high-temperature alloy bar with the diameter Dm, wherein m is the rolling frequency, the diameter of the high-temperature alloy bar obtained by one-time rolling is D1, the diameter of the high-temperature alloy bar obtained by two-time rolling is D2, and the like;
s5: repeating the steps S2-S4, and carrying out 2-6 times of spiral rolling on the high-temperature alloy blank 2 to obtain a GH4169 high-temperature alloy whole ultrafine crystal bar;
the skew rolling mill is a two-roller skew rolling mill, the rollers 1 are single tapered rollers 1, the taper angle gamma 1 is 15-17 degrees, the arc radius r of the high-temperature alloy blank 2 which is bitten into the rollers 1 is 80-450mm, the feeding angle β of the rollers 1 is 19-21 degrees, the rolling angle beta of the rollers 1 is 15-17 degrees, the distance Dg between the two rollers 1 is 84-96 percent of the diameter D of the high-temperature alloy blank 2, and the rotating speed n of the rollers 1 is 20-40 r/min;
the high-temperature alloy blank 2 is a large-size GH4169 high-temperature alloy bar;
in step S5, the heating time for repeating the rolling process is: the diameter Dm of the high-temperature alloy bar is multiplied by (0.3-0.4) min, wherein m is the rolling times, the diameter of the high-temperature alloy bar obtained by one-time rolling is D1, the diameter of the high-temperature alloy bar obtained by two-time rolling is D2, and the like.
The small end surface of the roller 1 is arranged to be an arc surface, and the radius of the arc surface is 80-450 mm.
Pass ovality coefficient is 3-distance D of guide platedAnd the ratio of the roll spacing Dg, rolling the high-temperature alloy blank 2 in the deformation zone by adopting the pass ovality coefficient of 1.18-1.35 in the step S4.
In the rolling process of the high-temperature alloy blank 2, the roll distance Dg between the two rollers 1 is fixed, which is beneficial to realizing multi-pass repeated rolling.
During the repeated rolling in step S5, the deformed zone shape remains unchanged.
The constant-roll-spacing rolling method adopts the conical rolls to roll the GH4169 high-temperature alloy bar material at the same roll spacing. The advantage of such an integrated ultra-fine grain process is that the deformation zone is controlled by the size of the roll 1, the longer the roll 1, the larger the size of the deformation zone. And the second deformation process is spiral feeding, so that the axial, radial and circumferential three-way strain action exists, and the penetration advantage of the deformation zone is obvious. After the high-temperature alloy blank 2 is pulled into the roller 1, the cross section is changed into an ellipse, in the process of spiral advancing, because the radius of the major axis of the ellipse is larger than the distance between the rollers 1, the high-temperature alloy blank 2 always bears the small deformation compression of the rollers 1, and any point of a deformation area rotates for one circle and is compressed twice by the rollers 1; the spiral rolling can be repeatedly realized, because of large ovality, the diameter of the rod after the spiral rolling is larger than the roller distance, and the deformed rolled piece can be repeatedly rolled under the condition of the same deformation parameter for multiple times, so that larger deformation can be obtained; by adopting a large feeding angle and a large rolling angle, more stable spiral advancing power can be obtained to meet the requirement of large plastic deformation, and the high-temperature alloy integral superfine crystal bar with the diameter size of 40-150mm and the length size of 300-5000mm can be produced. Therefore, the method provides a practical choice for the industrial production of the large-size GH4169 high-temperature alloy bar.
Generally, the type of material processing is distinguished by the recrystallization temperature, hot processing is carried out above the recrystallization temperature, cold processing is carried out below the recrystallization temperature, cold processing is adopted in the prior art for preparing ultra-fine crystals, small grains can be obtained only by accumulating dislocation due to insufficient deformation, but the grains have poor thermal stability and cannot be subjected to heat treatment. The object of this patent is to obtain grains that can be heat-treated, i.e. ultra-fine grains by means of recrystallization through accumulation of large deformations, thus being distinguished from conventional cold working.
The first embodiment is as follows:
designing the processing roller 1 as shown in figure 1 by adopting the technical parameters;
s1, selecting high-temperature alloy GH4169 as a main deformation parameter, wherein the diameter D is 100mm, the length is 500mm, the radius r of a gripping arc of the spiral roller shape is 100mm, the feed angle α is 19 degrees, the rolling angle β degrees, the cone angle gamma 1 is 15 degrees, the distance Dg between rollers 1 is 86 percent of the blank diameter D, the pass ovality coefficient is 1.22, and the rotating speed n of the roller 1 is 22 r/min;
s2: heating the cylindrical blank to 945 ℃ in a heating furnace for 70 minutes;
s3: transferring the blank heated to the temperature from the heating furnace into a guide chute of the skew rolling mill for 10 s;
s4: the blank spirally moves in the deformation zone until the deformation is finished.
S5: repeating the steps S2-S4, and repeatedly rolling for 2 times and 6 times for sampling analysis, wherein the effect on grain refinement of the high-temperature alloy is remarkable, the grain size is small, and the heating time of the repeated rolling process is as follows: the diameter Dm of the high-temperature alloy bar is multiplied by (0.3-0.4) min, wherein m is the rolling times, the diameter of the high-temperature alloy bar obtained by one-time rolling is D1, the diameter of the high-temperature alloy bar obtained by two-time rolling is D2, and the like.
Based on the above example, the original structure is shown in fig. 2, and the average size of crystal grains is about 80 um; by adopting the method of the invention, FIG. 3 is a crystal grain diagram with the rolling frequency of 2, wherein the size of the crystal grain is about 25um, and the grain refinement degree is 68.75%; FIG. 4 is a grain diagram of a superalloy with a rolling number of 6, wherein the grain size is around 2.9um and the grain refinement is 96.375%. The operation principle is shown in fig. 8, and the positional relationship between the roll 1 and the guide plate 3 is shown in fig. 5, 6, and 7.
In summary, the following steps: according to the preparation method of the integral ultrafine crystal for the high-temperature alloy bar, the appearance of the conical roller is designed, the roller distance in the deformation zone is kept unchanged, and the pass ovality coefficient of the ultra-large deformation zone is adopted for repeated multi-pass rolling so as to gradually accumulate ultra-large plastic deformation; moreover, the raw material size variation range is smaller based on the method, so that the spiral rolling can be carried out in multiple passes, the rolling frequency is within the range of 2-6 for different types of high-temperature alloys, the grain refining effect is obvious, and the method is suitable for low-load continuous severe plastic deformation of high-temperature alloy bars with various size specifications and types. Used for preparing 1000-3000nm integral fine crystal or ultra-fine crystal bar. And can overcome the defects that the existing severe plastic deformation process has large load and only can process small-sized workpieces.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (5)
1. An equidistant spiral rolling method of a large-size high-temperature alloy ultrafine crystal bar is characterized by comprising the following steps:
s1: selecting a high-temperature alloy blank (2) with the diameter dimension D of 40-150mm and the length of 300-5000 mm;
s2: placing the high-temperature alloy blank (2) in a heating furnace to be heated to 920-1120 ℃, wherein the heating time is as follows: the diameter Dx (0.6-0.8) of the high-temperature alloy blank (2) is min;
s3: transferring the heated high-temperature alloy blank (2) from the heating furnace into a guide chute of a skew rolling mill for 5-20 s;
s4: feeding materials in a guide chute of the skew rolling mill, feeding the high-temperature alloy into a deformation zone between an inlet and an outlet of the skew rolling mill, and performing spiral motion on the high-temperature alloy blank (2) in the deformation zone until the deformation is finished to obtain a high-temperature alloy bar with the diameter Dm, wherein m is the rolling frequency;
s5: repeating the steps S2-S4, and carrying out 2-6 times of spiral rolling on the high-temperature alloy blank (2) to obtain a GH4169 high-temperature alloy whole ultrafine crystal bar;
the skew rolling mill is a two-roller skew rolling mill, the rollers (1) are single-cone rollers, the taper angle gamma 1 is 15-17 degrees, the arc radius r of the high-temperature alloy blank (2) which is bitten into the rollers (1) is 80-450mm, the feeding angle β of the rollers (1) is 19-21 degrees, the rolling angle beta of the rollers (1) is 15-17 degrees, the roller distance Dg between the two rollers (1) is 84-96 percent of the diameter D of the high-temperature alloy blank (2), and the rotating speed n of the rollers (1) is 20-40 r/min;
the high-temperature alloy blank (2) is a large-size GH4169 high-temperature alloy bar;
in step S5, the heating time for repeating the rolling process is: the diameter Dm (0.3-0.4) of the high-temperature alloy bar is multiplied by 0.3-0.4 min.
2. The method for equidistantly spirally rolling the large-sized high-temperature alloy ultrafine grained bar according to claim 1, wherein the small end surface of the roll (1) is configured as a circular arc surface with a radius of 80-450 mm.
3. The method of claim 1, wherein the pass ovality factor is the guide plate distance DdAnd the ratio of the roll spacing Dg to the pass ovality coefficient of 1.18-1.35 is adopted for rolling the high-temperature alloy blank (2) in the deformation zone in the step S4.
4. The method for equidistantly spirally rolling a large-sized superalloy ultra-fine grain bar according to claim 1, wherein a roll gap Dg between the two rolls (1) is constant during rolling of the superalloy blank (2).
5. The method of equidistant helical rolling of large-sized superalloy ultrafine grained rod material according to claim 1, wherein the shape of the deformation zone is maintained during the repeated rolling in step S5.
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