CN108277446A - A kind of isometric helix milling method of large scale high temperature alloy ultra fine grained steel bar - Google Patents

Abstract

The present invention relates to an equidistant spiral rolling method for large-sized superfine-grained superalloy rods, which belongs to the technical field of mechanical processing, and specifically relates to a method for equidistant spiral rolling of large-sized superfine-grained superalloy rods, comprising the following steps : S1: Select a superalloy billet with a diameter of 40‑150mm and a length of 300‑5000mm; S2: place the above superalloy billet in a heating furnace and heat it to 920‑1120°C; S3: heat the superalloy billet from The heating furnace is transferred to the guide groove of the skew rolling mill, and the transfer time is 5-20s; S4: feeding in the guide groove of the skew rolling mill, and the high-temperature alloy billet moves spirally in the deformation zone until the deformation is completed; S5: repeat the above S2- Step S4; the beneficial effect of the present invention is that: the deformation zone has a large penetration depth, and multi-pass rolling can be reciprocated. Continuous and stable local deformation, combined with compression-torsion three-dimensional severe deformation, can obtain ideal grain refinement effect.

Description

A method for equidistant spiral rolling of large-size superalloy ultra-fine-grained rods

technical field

The invention belongs to the technical field of mechanical processing, and relates to a method for spiral rolling with conical rolls and equal roll spacing of large-size GH4169 high-temperature alloy overall ultra-fine-grained rods, in particular to an equidistant spiral rolling method for large-sized high-temperature alloy ultra-fine-grained rods rolling method.

Background technique

Ultrafine crystal/nanocrystalline materials are one of the hot topics in current material science research. Compared with traditional coarse-grained metal materials, ultra-fine-grained/nanomaterials show more excellent or unique properties in some aspects, such as higher strength and hardness, better fatigue performance and superplasticity, better Corrosion resistance, wear resistance and biological characteristics, etc. These excellent properties make ultra-fine-grained materials have broad application prospects in engineering fields such as aviation, aerospace, automobiles, marine, and biology, and also make people pay more attention to the development of ultra-fine-grained/nano-prepared technologies.

For ultra-fine-grain GH4169 with a grain size of 1.5um, its tensile strength at room temperature has been significantly improved. For the coarse-grained GH4169 in the solid solution state, its tensile strength is 853Mpa, and after ultra-fine grain processing, its tensile strength can reach 1060Mpa. For the high-temperature tensile properties at 650°C, the tensile properties of the coarse-grained GH4169 alloy are 1100Mpa, while the ultra-fine-crystalline GH4169 has a high-temperature tensile properties of up to 1530Mpa. It can be seen that large-scale superalloy ultra-fine-grained rods have great potential in industrial applications.

When preparing nano-scale materials, the equivalent strain should usually be greater than 6, which is difficult to achieve by traditional plastic processing methods, but can be achieved by applying Severe Plastic Deformation (SPD). Modern SPD started from the combined forming method of large pressure and shear deformation proposed by Bridgemen, and its rapid development began in the mid-1970s in the former Soviet Union and Western countries. Segal developed the Equal-Channel Angular Pressing (ECAP) technology. , marking the arrival of the microstructural era of SPD research.

The definition of SPD generally recognized after 2006: a metal forming method that produces super large strains in the block but does not significantly change the geometric size of the block, and presents a grain refinement effect of large-angle grain boundaries, which can obtain grain sizes in the micron level ( 100-1000nm) and nanoscale (less than 100nm), both can be called nano-SPD (nanoSPD for short). Because the nanoSPD material has a large number of large-angle non-equilibrium grain boundary structures containing high-density dislocations and high internal stress, the material exhibits mechanical behavior and deformation mechanism different from traditional coarse-grained materials.

Currently available processing technology solutions: SPD typical molding technology, typical SPD methods include high pressure torsion (High Pressure Torsion, HPT), equal channel angular pressing (ECAP), cumulative stack rolling method (Accumulative Roll Bonding, ARB), torsion extrusion (Twist Extrusion, TE) and multi-directional forging (Multi-Directional Forging, MDF).

Among them, (1) High-pressure torsional deformation: apply a pressure of several GPa to the original sample (block or powder) placed in the support tank, and relatively rotate the upper and lower anvils to cause strong shear deformation of the sample and refine the grains. The characteristic of high-pressure torsion is that the workpiece is disc-shaped and small in size, generally 10-20 mm in diameter and 0.2-0.5 mm in thickness.

(2) Equal-diameter angular extrusion deformation: Through two equal-section channels intersecting at a certain angle in the mold, the material is extruded from one end to the other end, and the bending angle changes the direction of material movement to produce pure shear deformation. The forming process can be repeated, and the amount of shear strain increases with the deformation pass.

(3) Cumulative stacking rolling method: stack the original plates in double layers after surface treatment, roll and weld them together after heating, then cut them from the middle and send them back to the surface treatment before the next rolling and welding cycle. The plates can be welded together, and the reduction in each pass must not be less than 50%, but the ARB process requires strong shear stress conditions, and lubricants cannot be used, which is detrimental to the service life of the rolls.

(4) Twisting extrusion: Beygelzime et al proposed this process. This method is also a molding technique for refining grains through shear deformation. The columnar billet is extruded through a torsion die. Similar to HPT, there is a problem of uneven deformation, and the effect of grain refinement is lower than that of ECAP and HPT.

(5) Multi-directional forging: This process obtains large deformation by changing the free forging direction orthogonally several times. The grain refinement effect of this type of deformation is significantly lower than that of ECAP and HPT.

Another existing processing technology solution: the derivative method. In recent years, new SPD processes have emerged in an endless stream. The basic forming principle is the same as the above method, and many new ECAP forming technologies have been derived. These methods try to simplify tool design, reduce energy consumption, and improve yield. Increase the size of the workpiece, upgrade the degree of automation, etc., including:

(1) ECAP derivative method: repeated bending and straightening (RCS), the blank is placed between the bending devices, and as the upper die moves down, the blank is bent and becomes wavy; then two flat plates are used for straightening , and then bend, through continuous repetition, accumulate enough deformation without significantly changing the size of the blank, and refine the material structure.

(2) Cyclic Closed Die Forging (CCDF), the mold consists of a lower die with a cavity of a certain section and a punch of the same section that moves vertically in the cavity. Put the fully lubricated sample with graphite lubricant into the lower mold and heat it to a certain temperature. The workpiece is pressed into the lower mold by the punch, and after being taken out, it is rotated 90° around the Z axis in the same direction, and reinserted into the lower mold for deformation. In this way, the workpiece is rotated 90° around the Z axis between successive passes. In this way, 1, 3 and 5 compressions were subjected respectively.

(3) Reciprocating extrusion (CEC), the mold consists of two cavities, a compression belt and punches placed in the two cavities. The cross-sectional areas of the two cavities are equal, on the same axis, and connected by the middle compression belt. During the extrusion process, the sample reaches the compression zone under the action of the punch. At this time, the sample will be subjected to positive extrusion deformation, and the extruded workpiece will be upset under the action of the punch of another cavity. out of shape. Then, the punch on the other side presses the workpiece back in reverse according to the above process, completing an extrusion cycle. Repeat the above process until the desired strain is obtained.

(4) Continuous shear deformation of the plate. The device uses the upper mold, the lower mold and the lower roller to form two intersecting channels with a small difference in cross-sectional area. The sheet is fed into the cavity, and the sheet undergoes strong plastic deformation at the corner of the cavity, and then extrudes from the other side of the cavity. Grooves are machined on the surface of the feed roller for increased friction. Due to the fact that the cross-sectional area of the material remains unchanged before and after deformation, it is possible to repeatedly perform multiple passes of plastic deformation on the plate in the same mold.

(5) Elliptical spiral equal channel extrusion method (ECEA), under the action of extrusion force, the billet undergoes upsetting (circle-ellipse transformation), torsion (elliptical cross-section twisting) and reverse upsetting (elliptical —circle transformation) the process changes back to a round bar. Metals flow plastically primarily in cross-section, and accumulate strain. The shape of the mold utilizes the particularity of the round and elliptical shapes, and there are no sharp corners in the cavity, which makes the metal flow easily. The combination of multiple deformation modes in one process is realized.

(6) Continuous Friction Angular Extrusion (CFAE), the drive roller rotates and applies pressure P to the workpiece against its support. The first extrusion channel is formed between the drive roller and the workpiece support, and the second channel is a short slot in the stationary die assembly. After one to eight processings of the sheet-shaped workpiece, the maximum equivalent true strain can reach 5.3, and the orientation of the sheet remains constant.

(7) An HPT-derived method for high-pressure torsion (HPT) of tubes, where the tube is located inside a rigid disk, and a mandrel is placed in the tube, which is compressed in its elastic state with a compressor. Due to the axial compression of the mandrel, it expands in the radial direction, and the expansion is limited by the tube and the disk, forming a large hydrostatic stress in the tube and generating a large friction force on both sides of the tube. While keeping the mandrel fixed, deformation of the tube is achieved by rotating the disk with external torque. During the torsion process, the deformation mode is local shear, the normal direction of the shear plane is the radial direction of the tube, and the shear direction is parallel to the circumferential direction.

(8) A TE-derived method, superhigh torsion (STS), localizes the torsional strain (TS) region by localized heating and cooling to make this region less resistant to deformation than the other two parts. Simultaneously with the generation of the TS zone, the rod is moved along the longitudinal axis, thus continuously producing super large plastic strains throughout the rod. This new process, STS, involves a bar that creates a localized soft zone relative to the rest of the bar and the movement of the zone in the longitudinal direction. An important feature of STS is that the cross-sectional dimension of the rod remains constant under strain.

Superalloy is a metal material that can work for a long time above 600°C and under certain stress conditions. It has excellent high temperature strength, good oxidation resistance and thermal corrosion resistance, good fatigue performance, fracture toughness and other comprehensive properties. It has become It is an irreplaceable key material for the hot end parts of military and civilian gas turbine engines. There are relatively few patent reports on the superfine grain process of superalloys at home and abroad. People such as Fu Rui of the General Institute of Iron and Steel Research proposed a process for producing high-temperature alloy ultra-fine-grained rods using a multi-directional forging and drawing process in the patent [CN 106862447 A]. This process uses multi-directional upsetting for deformation, but its deformation zone is small, the strain penetration is small, and it is difficult for ultra-fine grains to cover all areas of the blank. Although the maximum diameter that can be recorded for the forged bar is 420mm, the overall deformation is difficult to cover all areas of the billet, the deformation permeability is poor, and the unevenness is serious, which cannot meet the actual production needs. . As far as this kind of forming method is concerned, the overall ultra-fine crystallization is difficult to achieve. Luo Junting of Yanshan University and others proposed in the patent [CN 104294197 A] that the ultra-fine grain refinement of superalloy plates is carried out by using cold rolling deformation of 70-80%. From the perspective of cold deformation, if the deformation reaches 70-80%, the size that can be formed is greatly constrained by the forming load. In addition, rolling deformation belongs to the process of two-dimensional plastic deformation, which has a great impact on the quality of both the roll and the billet, and the degree of deformation is difficult to achieve. Finally, it can be seen from the examples that the whole process is a single-pass deformation, and the degree of refinement is limited. Baosteel Zhang Junbao et al. in the patent [CN 103008659 A] method for manufacturing ultra-fine-grained high-temperature-resistant alloy disk blanks used powder metallurgy spray forming method to form aviation high-temperature alloy turbine disks. The grain size of superalloys obtained by powder metallurgy is about 3-5um, and there are certain requirements for the grain size of raw materials, so the degree of refinement is limited and cannot fully meet industrial needs. Dong Jianxin of Beijing University of Science and Technology and others proposed an ultra-fine-grained nickel-based superalloy and its preparation method in the patent [CN 101307402 A]. The patent did not propose what parameters and methods should be used to prepare the ultra-fine-grained superalloy. Its remarkable advantages put forward the characteristics of low tonnage requirements, but the deformation load here still greatly exceeds the continuous local deformation method involved in this patent under the same deformation conditions. Therefore, compared with the patented method in this paper, its characteristics of low tonnage requirement, small loss and cost reduction are not remarkable. Secondly, the shape of the raw material mentioned in the patent does not mention what kind of shape, such as rod, plate and wire, so it cannot be compared with the patent herein. Yang Gang mentioned in the research progress of ultra-large plastic deformation in special steel technology-the grain refinement mechanism of nanomaterials that the use of surface mechanical ball milling (SAMT) to perform severe plastic deformation on Inconel 600 nickel-based superalloys to produce ultra-fine grains. Such deformation can only produce ultra-fine or nano-powder, which cannot be compared with the large-size GH4169 ultra-fine-grained rod mentioned in this patent.

Comprehensive analysis shows that most of the ultra-fine-grained processes mentioned in existing papers or patents use powder forming or forming ultra-fine/nano-powder, which is different from the large-scale superalloy integral ultra-fine-grained rods mentioned in this patent. No analogy can be made. However, the multi-directional upsetting process for preparing ultra-fine grains proposed in some patents has a small deformation zone and poor penetration. Cold rolling also belongs to the process of two-dimensional plastic deformation, which has a great influence on the quality of both the roll and the billet, and the degree of deformation is difficult to achieve. Finally, the whole process is a single-pass deformation, and the degree of refinement is limited. At present, it is only limited to laboratory research, and it is difficult to prepare large-sized materials with industrial-grade overall ultra-fine grains.

Contents of the invention

The purpose of the present invention is to provide a method of spiral rolling with conical rolls and equal roll pitch for large-scale GH4169 superalloy overall ultra-fine-grained rods, so as to solve the problems of limited size and refinement and low efficiency in the above-mentioned background technology .

The invention discloses a method for equidistant spiral rolling of a large-size high-temperature alloy ultra-fine-grained rod, comprising the following steps:

S1: Select a superalloy blank with a diameter D of 40-150mm and a length of 300-5000mm;

S2: Place the above-mentioned superalloy billet in a heating furnace and heat it to 920-1120°C. The heating time is: diameter of the superalloy billet D×(0.6-0.8) min;

S3: transfer the heated high-temperature alloy billet from the heating furnace to the guide groove of the skew rolling mill, and the transfer time is 5-20s;

S4: Feed the material in the guide groove of the cross rolling mill, and send the superalloy into the deformation zone between the entrance and the exit of the cross rolling mill, and the superalloy billet moves spirally in the deformation zone until the deformation is completed, and a superalloy rod with a diameter of Dm is obtained material, where m is the number of rolling;

S5: repeating the above steps S2-S4, performing 2-6 times of spiral rolling on the superalloy billet to obtain GH4169 superalloy overall ultra-fine-grained bar;

The skew rolling mill is a two-roll skew rolling mill, and the rolls are all single-tapered rolls, the cone angle γ1 is 15-17 degrees, and the arc radius r of the rolls biting into the high-temperature alloy billet is 80-450mm, and the feed angle of the rolls is α is 19-21 degrees, the rolling angle β of the rolls is 15-17 degrees, the roll spacing Dg between the two rolls is 84%-96% of the diameter D of the superalloy billet, and the roll speed n is 20-40r/min ;

The high-temperature alloy blank is a large-size GH4169 high-temperature alloy rod;

In step S5, the heating time for the repeated rolling process is: the diameter of the superalloy rod Dm×(0.3-0.4) min.

Preferably, the small end surface of the roll is set as an arc surface, and the radius of the arc surface is 80-450mm.

Preferably, the pass ellipticity coefficient is the ratio of the guide plate distance _Dd to the roll distance Dg, and in step S4, the superalloy billet is rolled in the deformation zone with a pass ellipticity coefficient of 1.18-1.35.

Preferably, during the rolling process of the high-temperature alloy billet, the roll distance Dg between the two rolls is constant, which is beneficial to realize multi-pass repeated rolling.

Preferably, during the repeated rolling process of step S5, the shape of the deformation zone remains unchanged.

Compared with prior art, the beneficial effect of the present invention is:

(1) The penetration depth of the deformation zone is large, and a large-scale overall ultra-fine grain structure can be obtained. The plastic deformation inside the material during the cross rolling process consists of two parts, one is the compression deformation between the rolls, which is a periodic intermittent deformation, and the other is the continuous torsional deformation. The superimposition of compression and torsional deformation produces three-dimensional severe plastic deformation in the deformation zone during the cross rolling process, which is obviously different from conventional forging; (2) The diameter of the bar before and after cross rolling remains unchanged and can be reciprocated for multi-pass rolling. There is widening in the cross-rolling process, and the equivalent diameter in the cross-section of the superalloy billet remains unchanged; (3) Continuous and stable local deformation, small rolling load, and smooth deformation process. In the cross rolling process, the actual contact area between the workpiece and the superalloy billet is only a small part of the surface area of the superalloy billet, which is a local contact deformation, so the load is small; (4) The compression-torsion combined three-dimensional severe deformation can obtain ideal crystal grains Refinement effect.

Description of drawings

Fig. 1 is a schematic diagram of a roll of the present invention.

Figure 2 is a schematic diagram of the original structure grains.

Fig. 3 is a schematic diagram of embodiment 1 of the present invention that the number of rolling is 2 times.

Fig. 4 is a schematic diagram of embodiment 1 of the present invention that the number of rolling times is 6.

Fig. 5 is the relative position of each die in the cross rolling process of the present invention.

Fig. 6 is a top view of the relative positions of the molds in the skew rolling process of the present invention.

Fig. 7 is a left side view of the relative positions of the molds in the skew rolling process of the present invention.

Fig. 8 is a schematic diagram of the deformation zone in the cross rolling process of the present invention.

Reference signs: 1-roller, 2-high temperature alloy billet, 3-guide plate.

Detailed ways

The invention discloses a method for equidistant spiral rolling of a large-size high-temperature alloy ultra-fine-grained rod, comprising the following steps:

S1: Select a superalloy blank 2 with a diameter D of 40-150 mm and a length of 300-5000 mm;

S2: Place the above-mentioned superalloy billet 2 in a heating furnace and heat it to 920-1120°C. The heating time is: the diameter of the superalloy billet 2 is D×(0.6-0.8) min;

S3: transfer the heated superalloy billet 2 from the heating furnace to the guide groove of the skew rolling mill, and the transfer time is 5-20s;

S4: Feed in the guide groove of the skew rolling mill, and send the superalloy into the deformation zone between the entrance and the exit of the skew rolling mill, and the superalloy billet 2 spirally moves in the deformation zone until the deformation is completed, and a superalloy with a diameter of Dm is obtained Bar, where m is the number of rolling times, the diameter of the superalloy bar obtained by rolling once is D1, the diameter of the superalloy bar obtained by rolling twice is D2, and so on;

S5: Repeating the above steps S2-S4, performing 2-6 times of spiral rolling on the superalloy blank 2 to obtain the GH4169 superalloy overall ultra-fine-grained bar;

The skew rolling mill is a two-roll skew rolling mill, the rolls 1 are all single-tapered rolls 1, the cone angle γ1 is 15-17 degrees, and the arc radius r of the roll 1 biting into the superalloy billet 2 is 80-450 mm, The feeding angle α of the roll 1 is 19-21 degrees, the rolling angle β of the roll 1 is 15-17 degrees, and the distance Dg between the two rolls 1 is 84%-96% of the diameter D of the superalloy billet 2, Roller 1 speed n is 20-40r/min;

The high-temperature alloy blank 2 is a large-size GH4169 high-temperature alloy rod;

In step S5, the heating time of the repeated rolling process is: the diameter of the superalloy rod Dm×(0.3-0.4) min, where m is the number of rolling times, and the diameter of the superalloy rod obtained by rolling once is D1, and the diameter of the superalloy rod after rolling is D1. The diameter of the superalloy rod obtained by making twice is D2, and so on.

The small end face of the roll 1 is set as an arc surface, and the radius of the arc surface is 80-450mm.

The pass ellipticity coefficient is the ratio of the guide plate 3 distance D _d to the roll distance Dg. In step S4, the superalloy billet 2 is rolled in the deformation zone with a pass ellipticity coefficient of 1.18-1.35.

During the rolling process of the superalloy billet 2, the roll distance Dg between the two rolls 1 is constant, which is beneficial to realize multi-pass repeated rolling.

During the repeated rolling process in step S5, the shape of the deformation zone remains unchanged.

This patent adopts conical rollers to carry out equidistant rolling of GH4169 superalloy rods. The advantage of this type of overall ultra-fine grain process is that the deformation zone is controlled by the size of the roll 1, and the longer the roll 1, the larger the size of the deformation zone. Secondly, the deformation process is helical feeding, so there are three-dimensional strain effects in the axial, radial and circumferential directions, and the penetration of the deformation zone has obvious advantages. After the high-temperature alloy billet 2 is pulled into the roll 1, the cross section becomes elliptical. During the spiral advance process, because the radius of the major axis of the ellipse is greater than the distance between the rolls 1, the high-temperature alloy billet 2 has been subjected to the small deformation compression of the roll 1, and the deformation zone Rotate one circle at any point, and be compressed twice by roll 1; spiral rolling can be realized many times. Due to the large ellipticity, the diameter of the bar after spiral rolling is larger than the roll distance, and the deformed rolled piece can be rolled repeatedly. Under the condition of the same deformation parameter, it is rolled repeatedly, so that a larger deformation can be obtained; the use of a large feeding angle and a large rolling angle can obtain a more stable spiral forward power to meet the needs of large plastic deformation, which can Production of high-temperature alloy overall ultra-fine-grained rods with a diameter of 40-150mm and a length of 300-5000mm. Therefore, this patent provides a realistic choice for the industrialized production of large-size GH4169 superalloy rods.

Generally, the type of material processing is distinguished by the recrystallization temperature. Above the recrystallization temperature is hot processing, and below the recrystallization temperature is cold processing. In the prior art, cold processing is used to prepare ultra-fine grains. Due to insufficient deformation, relatively small amounts can only be obtained by accumulating dislocations. Small grains, but such grains have poor thermal stability and cannot be heat treated. The purpose of this patent is to obtain grains that can be heat treated, that is, to obtain ultra-fine grains by accumulating large deformation and recrystallization, so as to distinguish them from traditional cold working.

Embodiment one:

Adopt above-mentioned technical parameter, design and process roll 1 as shown in Figure 1;

S1: The main deformation parameters are superalloy GH4169, the diameter D is 100mm, and the length is 500mm; the radius r of the biting arc of the spiral roll shape is 100mm, the feeding angle α is 19°, the rolling angle β is 15°, and the cone angle γ1 is 15°, the spacing Dg of roll 1 is 86% of the billet diameter D, the pass ellipticity coefficient is 1.22, and the speed n of roll 1 is 22r/min;

S2: Heating the cylindrical billet to 945°C in a heating furnace for 70 minutes;

S3: transfer the billet heated to temperature from the heating furnace to the guide groove of the skew rolling mill, and the transfer time is 10s;

S4: The blank moves spirally in the deformation zone until the deformation ends.

S5: Repeat steps S2-S4, repeat rolling 2 times and 6 times sampling analysis, it has a significant effect on grain refinement of superalloy, the grain size is small, and the heating time of repeated rolling process is: superalloy bar Diameter Dm × (0.3-0.4) min, where m is the number of rolling times, the diameter of the superalloy rod obtained by rolling once is D1, the diameter of the superalloy rod obtained by rolling twice is D2, and so on.

Based on the above examples, the original structure is as shown in Figure 2, and the average grain size is about 80um; it adopts the method of the present invention, and Figure 3 is a grain diagram of 2 rolling times, wherein the grain size is about 25um, and the grain size is fine. The degree of refinement is 68.75%; Figure 4 is the grain diagram of the superalloy with rolling times of 6, in which the grain size is about 2.9um, and the degree of grain refinement is 96.375%. Its working principle is shown in FIG. 8 , and the positional relationship between the roll 1 and the guide plate 3 is shown in FIG. 5 , FIG. 6 and FIG. 7 .

In summary: the overall ultra-fine grain preparation method for superalloy rods provided by the present invention is carried out by designing the shape of the conical roll, keeping the roll distance in the deformation zone constant, and adopting the ellipticity coefficient of the pass in the super large deformation zone. Repeated multi-pass rolling to gradually accumulate super large plastic deformation; moreover, based on this method, the range of raw material size changes is small, so multi-pass spiral rolling can be performed. For different types of superalloys, the number of rolling times is between 2- Within the range of 6, the grain refinement effect is remarkable, and it is suitable for continuous severe plastic deformation of high-temperature alloy rods of various sizes and types under low load. It is used to prepare overall fine-grained or ultra-fine-grained rods of 1000-3000nm. And it can overcome the disadvantage that the existing severe plastic deformation process has a large load and can only process small-sized workpieces.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, any person familiar with the technical field within the technical scope disclosed in the present invention, according to the technical solution of the present invention Any equivalent replacement or change of the inventive concepts thereof shall fall within the protection scope of the present invention.

Claims (5)

1. a kind of isometric helix milling method of large scale high temperature alloy ultra fine grained steel bar, which is characterized in that include the following steps：

S1：It is 40-150mm to choose diameter dimension D, and length is the high temperature alloy blank of 300-5000mm（2）；

S2：By above-mentioned high temperature alloy blank（2）It places in heating furnace and is heated to 920-1120 DEG C, heating time is：High temperature alloy Blank（2）Diameter D ×（0.6-0.8）min；

S3：By the high temperature alloy blank after heating（2）It is transported in skew rolling mill deflector chute from heating furnace, transhipment time 5-20s；

S4：Feeding is carried out in the deflector chute of skew rolling mill, and high temperature alloy is sent into the deformed area between skew rolling mill entrance and exit, High temperature alloy blank（2）In deformed area, inside spin movement terminates until deforming, and obtains the high temperature alloy bar of a diameter of Dm, wherein M is rolling number；

S5：Above-mentioned S2-S4 steps are repeated, to high temperature alloy blank（2）It carries out 2-6 screw rolling and obtains GH4169 high temperature alloys Whole ultra fine grained steel bar；

The skew rolling mill is two-roller skew-rolling machine, the roll（1）It is single cone-shaped roll, cone angle gamma 1 is 15-17 degree, and roll （1）Bite high temperature alloy blank（2）Arc radius r be 80-450mm, roll（1）Feed angle α is 19-21 degree, roll（1）'s Roll off angle beta is 15-17 degree, two rolls（1）Between roll（1）Space D g is high temperature alloy blank（2）The 84%- of diameter D 96%, roll（1）Rotating speed n is 20-40r/min；

The high temperature alloy blank（2）For large scale GH4169 high temperature alloy bars；

In S5 steps, the heating time for repeating the operation of rolling is：High temperature alloy bar diameter Dm ×（0.3-0.4）min.

2. a kind of isometric helix milling method of large scale high temperature alloy ultra fine grained steel bar as described in claim 1, feature exist In the roll（1）Small end face is set as arc surface, and circular arc radius surface is 80-450mm.

3. a kind of isometric helix milling method of large scale high temperature alloy ultra fine grained steel bar as described in claim 1, feature exist In Groove Ovality Factor is guide plate（3）Away from D_dThe ratio between with roll spacing Dg, S4 step high temperature alloy blanks（2）In deformed area Groove Ovality Factor is used to be rolled for 1.18-1.35.

4. a kind of isometric helix milling method of large scale high temperature alloy ultra fine grained steel bar as described in claim 1, feature exist In in high temperature alloy blank（2）In the operation of rolling, two rolls（1）Between roll spacing Dg immobilize.

5. a kind of isometric helix milling method of large scale high temperature alloy ultra fine grained steel bar as described in claim 1, feature exist In in S5 steps repeat the operation of rolling, deformed area shape remains unchanged.