CN114505428A - Forging process of near-isotropic, high-strength and high-plasticity Mg-Gd-Y-Zr alloy material - Google Patents
Forging process of near-isotropic, high-strength and high-plasticity Mg-Gd-Y-Zr alloy material Download PDFInfo
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Abstract
The invention discloses a forging process of a near-isotropic, high-strength and high-plasticity Mg-Gd-Y-Zr alloy material, belonging to the technical field of plastic processing of metal materials. The process comprises the following steps: cutting solid solution Mg- (0.1-16) Gd- (0.1-12) Y- (0-1.0) Zr (wt.%) alloy into block ingots (six-sided cuboids or other scalene bodies (3 axial direction), hexagonal prisms, equilateral or scalene octahedrons (4 axial direction), cylinders or equilateral or scalene polyhedrons (5 axial direction and above) larger than octahedrons) with certain shapes), circularly hammering and forging the blocks along multiple axial directions (axial direction is more than or equal to 3) of the blocks at a high speed at a certain temperature, annealing for 5-600min for 30 or more axial forging, and then continuously forging until the total number reaches more than 100 times after continuous several times of forging. The Mg-Gd-Y-Zr alloy material forged by the method has weak texture, near isotropy, high strength and high plasticity.
Description
Technical Field
The invention relates to the technical field of plastic processing of metal materials, in particular to a forging process of a near-isotropic, high-strength and high-plasticity Mg-Gd-Y-Zr alloy material.
Background
Because of the advantages of small density, high specific strength, excellent damping performance, good heat-conducting performance and the like, the magnesium alloy has wide application prospect in the fields of automobiles, electronics, communication, aerospace and the like. However, the magnesium alloy with the close-packed hexagonal structure has only two independent basal plane slip systems at room temperature, and the critical shear stress is small (10 MPa), so that the room-temperature strength and plasticity of the magnesium alloy are limited. The comprehensive mechanical property of the magnesium alloy can be obviously improved by adding the rare earth element into the magnesium alloy, and the rare earth magnesium alloy with high strength and good high-temperature creep resistance can be prepared, so that the magnesium alloy can partially replace aluminum alloy materials in the medium-temperature (300 ℃) environment in the fields of weaponry and aerospace. The recently developed new Mg-Gd-Y-Zr based alloys have stronger age strengthening ability than commercial WE43 and WE54 alloys. However, the traditional rolled, extruded and forged Mg-Gd-Y-Zr alloy material has the defects of low processing yield, strong base texture or wire texture, anisotropy, poor secondary processing performance and the like. In order to overcome the defects of the traditional rolling, extruding and forging of the rare earth magnesium alloy, multidirectional forging is used as a novel deformation process for processing the rare earth magnesium alloy materials commonly in recent times.
The document { B.B.Dong, Journal of Alloys and Compounds,2020,823.} proposes a quantitative cooling multidirectional forging process, which adopts cooling forging with deformation temperatures of 480, 460, 440 and 420 ℃, the single-pass strain capacity of 100%, the forging speed of 5mm/s and the strain rate of 0.04s-1And forging for 4 times, wherein initial coarse grains (60 um) are gradually changed into a uniform fine grain structure with the average grain size of 5um after forging, and the tensile strength, yield strength and elongation of the forged rare earth alloy can reach 357MPa, 294MPa and 18.1 percent respectively. According to the method, the rare earth magnesium alloy with weak texture, fine grains and high performance is successfully prepared by four-pass forging, but because the forging temperature required in each pass is different (480, 460, 440 and 420 ℃), the forged sample needs to be reheated to the specified temperature for heat preservation, and the graphite lubricant needs to be coated on the preheated die repeatedly, so that the sample heating process is complicated and is not easy to operate.
The document X.S.Xia, Journal of Alloys and Compounds 623(2015)62-68 proposes a cooling multidirectional forging with a single pass strain of 50%, a forging speed of 10mm/s and a strain rate of 0.08s-1The initial temperature of 530 ℃ is discharged from the furnace and then forged for 6 times, the original coarse grains (200 um) after forging processing are refined into a uniform fine grain structure with the average grain size of 5um, and the tensile strength, the yield strength and the elongation can respectively reach 320MPa, 253MPa and 7.5 percent. The forging method adopts cooling multidirectional forging without repeatedly heating a mold and a sample, simplifies the processing flow to a certain extent, but changes the single-pass into the multi-passThe shape quantity is big, and other faces of cuboid sample become the drum-shaped after forging for the first time, and this has increased the degree of difficulty of forging operation afterwards, has seriously reduced production efficiency, restricts the forging machining efficiency of rare earth magnesium alloy. The forging conditions in the above work (the temperature is more than or equal to 480 ℃, the pass deformation is more than or equal to 50 percent, and the strain rate is less than or equal to 0.1s-1) The middle {10-12} twin crystal is not easy to nucleate, a small amount of {10-12} twin crystal rapidly expands after nucleation, and then the whole mother crystal grain is swallowed, so that the contribution to recrystallization generation and tissue refinement is very limited.
Chengrongshi et al, the institute of Metal research of Chinese academy of sciences, reported a forging method of forging magnesium alloy by multidirectional, cyclic and high-speed hammering (patent publication No. CN103805923A), the control of the deformation and the rotation direction of the patent mainly depends on the shape and size of the forging stock, belonging to the preparation process of magnesium alloy forging products, and the specific forging process parameters are as follows: the strain amount of each hammering is 2.5-30%, and the strain rate of the forged material is 1-1000 s-1The hammering forging temperature is 200-550 ℃, the technological parameters are too wide, the processing method is only suitable for processing some magnesium alloys with non-rare earth or low rare earth content, such as AZ80, AZ31, Mg-2.0Zn-0.8Gd and other alloys, and the technology with the wide parameters is not suitable for processing high rare earth magnesium alloys; recently, Chenrongshi et al reported a hammer forging cogging method of a high-strength heat-resistant magnesium alloy ingot (patent publication No. CN105441840A), which adopts an as-cast alloy with the rare earth element content of Gd + Y + Nd more than or equal to 8 percent, and cuts the as-cast alloy into block blanks after solution treatment, wherein the specific forging technological parameters are as follows: the total forging pass is 20-200 times, the forging pass of the initial pass is 1-5 times, the deformation of each forging pass is 1-5%, the total deformation is 1-10%, and the strain rate is 1-200 s-1(ii) a Forging for 1-10 times in each pass after the initial pass, wherein the deformation amount of forging for each time is 1-10%, and the strain rate is 1-200 s-1The elongation at break of the finally prepared high-strength heat-resistant magnesium alloy blank under the same test condition at high temperature can be improved to 100-1000%, and the yield is higher than 80%, so that the cogging process can realize high-speed large-strain processing in the subsequent processes of re-forging, rolling, extruding and the like.
The above studies can prove that the hammer is multidirectionalThe forging can be used for processing non-rare earth magnesium alloy materials, and is optimized and used for a magnesium alloy cogging process with the content of rare earth elements Gd, Y and Nd being more than or equal to 8 percent through forging process parameters. For magnesium alloy with non-rare earth or low rare earth content, coarse eutectic phase at the grain boundary is dissolved back to the matrix after solution treatment, the plasticity is obviously improved, the recrystallization temperature is lower (approximately equal to 250 ℃) in the plastic processing process, and the processing window is wider. And the multidirectional forging at high temperature activates various twin crystals, so that the coarse crystal structure can be quickly segmented. In addition, dislocation movement is effectively hindered by extensive two-dimensional surface defects such as twin boundaries, grain boundaries and the like, a large number of dislocations are accumulated in micro regions of the twin boundaries and the grain boundaries, recovery recrystallization occurs under the action of a thermal effect, and secondary refinement occurs to tissues. Different from Mg-Al-Zn alloy which is easy to recrystallize, the rare earth magnesium alloy after solution treatment has poor room temperature plasticity because a large amount of rare earth elements are redissolved to a matrix, the recrystallization temperature is higher (more than or equal to 400 ℃), and the processing window is very narrow. After the rare earth magnesium alloy is subjected to solution treatment, a large number of solute atoms are redissolved to a matrix, the rare earth atoms block the movement of dislocation slip, climbing, cross slip and the like in the thermal deformation process, and finally the dislocation induced recovery and recrystallization effects in the high rare earth magnesium alloy are strongly inhibited. In addition, a large number of rare earth atoms tend to be segregated near the grain boundary in the high rare earth magnesium alloy structure, which has a more obvious effect of inhibiting dislocation-induced recrystallization at the grain boundary, so that the advantage of promoting recrystallization nucleation by the grain boundary in the high rare earth magnesium alloy structure disappears. For the high rare earth magnesium alloy lacking dislocation induced recrystallization, the twin crystal and the recrystallization thereof become the main way for refining the structure, firstly, the twin crystal carries out primary refinement on the structure through division and intersection, a large amount of dislocations can be accumulated along with further forging of extensive twin crystal boundary and crystal boundary, and the newly formed twin crystal boundary has no solute atom segregation and can be used as the preferential nucleation position of the recrystallization, and finally, the secondary refinement of the structure is realized. Previous studies have shown that the {10-12} twin is the most dominant twin mechanism in the multidirectional forging process of high rare earth magnesium alloys ({10-11} twin and {10-11} - {10-12} secondary twin hardly occur). Therefore, in order to fully utilize the {10-12} twin crystal and the refining effect of recrystallization on the structure, special process conditions are designed according to the property of the {10-12} twin crystal. For example, designing six-sided cubesOr special-shaped samples such as other scalenohedron (3-axis), hexagonal prism, equilateral or other scalenohedron (4-axis), cylinder or equilateral or scalenohedron (5-axis or above) larger than octahedron, and the like, and {10-12} twin crystals are easier to activate in the multiaxial loading process. The forging temperature (350--1) And the parameters of deformation amount (1-10%) are also selected to be favorable for the activation of {10-12} twin crystal.
In the aspect of alloy component design, the work optimizes the components of the Mg-Gd-Y alloy. Nodooshan et al { h.j. Nodooshan, Materials Science and Engineering: a 615(2014) } 79-86. study Mg-xGd-3Y-0.5Zr (x ═ 3-12, wt.%) alloys with different Gd contents for age hardening and mechanical properties, and found that GW103K alloy has the greatest yield strength and tensile strength, further increasing Gd content without strength increase and decrease. Wang et al { j.wang, Materials Science and Engineering: a 456(1-2) (2007)78-84.} investigated the effect of different Y contents on Mg-10Gd-xY-0.4Zr (x ═ 1,3,5 wt.%) alloys, and found that the strength and age-hardening ability of the alloys increased and the plasticity gradually decreased with increasing Y content.
The comprehensive mechanical property of the forged Mg-Gd-Y-Zr rare earth magnesium alloy is greatly improved, and the forged Mg-Gd-Y-Zr rare earth magnesium alloy has stronger aging strengthening capability, namely the Mg-Gd-Y-Zr rare earth magnesium alloy can be used for preparing the near-isotropic high-strength high-plasticity magnesium alloy.
Therefore, the forging process is optimized from the aspects of forged alloy composition design, sample shape design, forging temperature, strain rate, deformation and the like, {10-12} twin crystals are widely activated, and the tissue refinement is finally realized, and the efficient and low-cost forging method for preparing the near-isotropic, high-strength and high-plasticity Mg-Gd-Y-Zr rare earth magnesium alloy and the preparation method thereof are provided, so that the requirements of the national weapons and equipment and the aerospace field on the high-performance rare earth magnesium alloy are met.
Disclosure of Invention
Aiming at the defects of low production efficiency, high cost, poor comprehensive mechanical property and the like of rare earth magnesium alloy forging, the invention provides a forging process of a near-isotropic, high-strength and high-plasticity Mg-Gd-Y-Zr alloy material, and the process has low cost and high forging efficiency.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a forging technology of near-isotropy, high-strength and high-plasticity Mg-Gd-Y-Zr series alloy materials is characterized in that after the Mg-Gd-Y-Zr series magnesium alloy blanks are forged by circulating continuous multi-fire, the obtained block magnesium alloy materials have optimized matching of near-isotropy, high strength and high plasticity; wherein: in each forging process, performing axial multi-axial (axial is more than or equal to 3) continuous high-speed forging on the magnesium alloy blank in a variable manner, wherein the total number of times of multiple axial hammering is not less than 30 times, and then performing annealing for 5-600 min; then continuous high-speed forging and annealing of next fire forging are carried out, and the continuous fire forging is circulated for several times until the total pass reaches more than 100 passes.
The magnesium alloy blank is in the shape of a block, specifically, a hexahedral cube, a scalene hexahedron (3 axial direction), a hexagonal prism, an equilateral octahedron (4 axial direction), a scalene octahedron (4 axial direction), a cylinder, an equilateral polyhedron (5 axial directions and above) larger than the octahedron, or a scalene polyhedron (5 axial directions and above) larger than the octahedron.
In the forging process of the magnesium alloy blank, firstly forging the magnesium alloy blank once along one axis of a block body, then overturning the magnesium alloy blank to the other axis for continuous forging, wherein the specific overturning rotating axis and overturning angle are determined according to the shape of the blank; the strain amount of each forging is 1-10%; the hammering forging temperature is 350-550 ℃, the annealing temperature is the same as the forging temperature, and the annealing time is determined according to the size of a sample.
The high-speed forging is hammering for 10-100 times per minute, and the strain rate of the corresponding forged material is more than or equal to 10s-1。
The magnesium alloy blank is subjected to solid solution treatment before forging at the treatment temperature of 400-550 ℃ for 8-24h, and then is subjected to air cooling or water cooling to obtain a uniform solid solution alloy blank.
The Mg-Gd-Y-Zr alloy comprises the following chemical components in percentage by weight: 0.1-16% of Gd, 0.1-12% of Y, 0-1.0% of Zr and the balance of Mg.
The design principle of the invention is as follows:
for rare earth magnesium alloy, the addition of rare earth elements has strong inhibition effect on dislocation-dominated recrystallization, and especially at grain boundaries, the enrichment of a large number of rare earth atoms has strong inhibition effect on continuous and discontinuous recrystallization processes near the grain boundaries. Different from dislocation dominant recrystallization, twin crystal induced recrystallization can weaken the texture while refining the crystal grains, is not inhibited by rare earth elements, and can simultaneously improve the strength and the plasticity of the magnesium alloy. Recently, by designing samples in the shapes of cuboids or other scalene hexahedrons (3 axial directions), hexagonal prisms or other scalene octahedrons (4 axial directions) and cylinders or equilateral or scalene polyhedrons (5 axial directions and above) larger than octahedrons, more {10-12} twin crystals are activated in sample tissues in the forging axial direction, crystal grains can be refined efficiently, textures can be regulated, and the aims of grain refinement, texture regulation and performance remarkable improvement of the magnesium rare earth alloy are finally achieved through multidirectional high-speed forging. The intrinsic advantages of {10-12} twin recrystallization mechanism for refining the rare earth magnesium alloy structure: the rare earth magnesium alloy has lower stacking fault energy, and {10-12} twin crystal is usually used as a main deformation mechanism; the {10-12} twin crystal in the coarse crystal structure of the solid solution magnesium alloy is easily and widely activated; the {10-12} twin crystal has a two-dimensional twin crystal boundary, and the division of the mother crystal grains to form three-dimensional crystal nuclei does not have difficulty in dimension jumping; twin crystal boundaries formed in the crystal in the deformation process do not have the problem of segregation of rare earth elements, and the crystal boundaries can be used as recrystallization preferred nucleation positions; the {10-12} twin crystal induction recrystallization nucleation starts in the crystal, and has the advantages of high refining efficiency, no inhibition by misconvergence rare earth elements at the crystal boundary and the like. The multiaxial (not less than 3), high strain rate and small strain loading of the invention can fully activate {10-12} twin crystal and excite twin crystal recrystallization, and the invention has the following advantages of external conditions: multidirectional loading helps all crystal grains of the sample to start a {10-12} twin mechanism; basal plane and non-basal plane dislocations are activated in the twin crystal grains, and the extensive interaction of twin crystal and dislocation can effectively inhibit the expansion of twin crystal and pin twin crystal boundary; the high strain rate is also beneficial to widely activate {10-12} twin crystals; the small strain is favorable for {10-12} twin nucleation but unfavorable for twin expansion growth. On the other hand, by forging a sample in the shape of a cubic block or other scalene hexahedron (3 axial direction), hexagonal prism, equilateral or other scalene octahedron (4 axial direction), cylinder or equilateral or scalene polyhedron (5 axial direction and above) larger than octahedron, etc., wide {10-12} twin crystals are activated, and during subsequent annealing treatment, static recrystallization nucleation of {10-12} twin crystals is facilitated, and finally, tissue homogenization regulation and control are realized.
Therefore, whether the forging process or the intermediate annealing after forging, a plurality of axial (axial is more than or equal to 3) forging activation {10-12} twin crystals have obvious effects on tissue refinement and texture regulation. In addition, the influence of alloy chemical components on the forging performance and the mechanical property is comprehensively considered, the Mg-Gd-Y-Zr rare earth magnesium alloy in the range of Mg- (3-10) Gd- (1-3) Y- (0.4-1.0) Zr (wt.%) is preferably selected to have the highest strength and the best plasticity matching, the comprehensive mechanical property of the alloy after forging is greatly improved, and the alloy has stronger aging strengthening capability, namely the Mg-Gd-Y-Zr rare earth magnesium alloy with the components can be used for preparing the near-isotropic, high-strength and high-plasticity magnesium alloy after forging.
The invention has the following advantages:
1. the selection of the components of the forging alloy is optimized, and the alloy has good plasticity in the forging process and enough aging precipitation strengthening capacity after forging, so that the Mg-Gd-Y-Zr rare earth magnesium alloy in the range of Mg- (3-10) Gd- (1-3) Y- (0.4-1.0) Zr (wt.%) is preferably selected, and the comprehensive mechanical property of the alloy is greatly improved after forging, namely the near-isotropic, high-strength and high-plasticity Mg-Gd-Y-Zr rare earth magnesium alloy is obtained.
2. The invention only needs to heat before and during forging processing, and the forging tool does not need to be preheated, thereby reducing the cost. In addition, the single-pass small-strain forging method is adopted, the problems that the rare earth magnesium alloy is poor in plastic deformation capability and cracks are easily generated in the forging process are solved, the using steps of mineral oil and graphite lubricant are omitted, large strain accumulation is guaranteed, uniform and fine recrystallization structures are obtained, and the method is favorable for marketization and application of the rare earth magnesium alloy.
3. The equipment adopted by the invention is an industrial hammer forging machine, the equipment is simple, the operation is convenient, a die is not needed, the forging speed is high, the forging time is shortened, the heat loss of a forged sample is reduced, the continuous forgeability is ensured, the repeated heating of each pass is not needed, the shape and the size of the sample are not greatly changed, the shape of the sample is not needed to be modified, and the forging processing of the rare earth magnesium alloy is simple and controllable.
4. The magnesium rare earth alloy prepared by the method has the advantages of weak/non-basal texture, near isotropy, high strength and high plasticity, and is optimally matched.
Drawings
FIG. 1 is a schematic diagram of the principle of multi-axial (axial direction is more than or equal to 3) forging activation {10-12} twin crystal of the solid solution state rare earth magnesium alloy of the invention; wherein: (a) since the {10-12} twin crystal and basal plane slip critical shear stresses are similar, assuming that the critical shear stresses are equal, the {10-12} twin crystal schmidt factor is maximum for the crystal grains with c-axis at 70-110 ° to the loading direction under unidirectional loading, (b) the {10-12} twin crystal is easily activated for the crystal grains with c-axis at 70-110 ° to the loading direction under unidirectional loading (yellow region 34.2%), (c) the crystal grain distribution of the {10-12} twin crystal is easily activated for triaxial forging (yellow and red regions 79.8%), (d) the crystal grain distribution of the {10-12} twin crystal is easily activated for tetraaxial forging (yellow and red regions 89.8%), (e) the crystal grain distribution of the {10-12} twin crystal is easily activated for five axial forging (yellow and red regions 100.0%).
FIG. 2 is a schematic diagram of a forging process of a rare earth magnesium alloy designed based on the multi-axial (3 ≦ axial ≦ 5) activating {10-12} twin crystal principle in FIG. 1; wherein: (a) cubic specimen triaxial forging, (b) hexagonal prism specimen tetraaxial forging, and (c) cylindrical specimen pentaaxial forging.
FIG. 3 is the macro sample morphology, structure, and mechanical property curves before and after the alloy GW63K of the present invention is forged; wherein: (a) sample 1, (b) forged sample 2, (c) sample 1 optical microstructure, (d) forged sample 2 optical microstructure, (e) sample 1 room temperature tensile mechanical property curve, (f) forged sample 2 room temperature tensile mechanical property curve.
FIG. 4 is the optical microstructure and mechanical properties of an initial solid solution GW52K alloy of the present invention; wherein: (a) an optical microstructure; (b) mechanical properties.
FIG. 5 is a macroscopic morphology of a cubic GW52K alloy sample after forging; wherein: (a) sample 2, (b) sample 3, (c) sample 4, (d) sample 5.
FIG. 6 is an optical microstructure of a sample of a wrought GW52K alloy; wherein: (a) sample 2, (b) sample 3, (c) sample 4, (d) sample 5.
FIG. 7 is a sample {0002} macrostructure of a GW52K alloy after forging; wherein: (a) sample 4, (b) sample 5.
FIG. 8 is a plot of room temperature tensile and compressive mechanical properties of alloy sample 5 of GW52K as forged and as aged; wherein: (a) sample 5 tensile mechanical property curve, (b) sample 5 tensile and compressive mechanical property curve.
Detailed Description
The invention is described in detail below with reference to the figures and examples.
The invention provides a forging process of a near-isotropic, high-strength and high-plasticity Mg-Gd-Y-Zr alloy material, which selects Mg- (3-10) Gd- (1-3) Y-0.5Zr (wt.%) alloy with optimized components, designs a forging sample into a hexahedral cubic or other scalene hexahedrons (3 axial direction), a hexagonal prism, an equilateral or scalene octahedron (4 axial direction), a cylinder or an equilateral or scalene polyhedron (5 axial direction and above) with more than eight directions and other shapes, strictly controls the forging pass to be more than or equal to 30 passes, then carries out annealing for 5-600min (the temperature is the forging temperature, the time length depends on the size of the sample), and activates {10-12} twin crystals and dynamic or static recrystallization thereof through multi-axis forging to realize refinement of the texture, and has the advantages of short production flow, short production process, low cost, high yield, high strength and high plasticity, The equipment is simple, the efficiency is high, the cost is low, and two block rare earth magnesium alloy forging stocks with weak texture, uniformity, fine grains and near isotropy, namely Mg-6.0Gd-3.0Y-0.5Zr (GW63K) and Mg-5.0Gd-2.0Y-0.5Zr (GW52K), are successfully prepared.
The weak/non-basal plane texture near-isotropic rare earth magnesium alloy is prepared by the following steps:
1) preparing a blank: the Mg- (0.1-16) Gd- (0.1-12) Y- (0.1-1.0) Zr (wt.%) alloy ingot blanks produced by adopting methods of gravity casting, antigravity casting, continuous casting and the like are cut from the ingot blanks to obtain hexahedral cubes or other scalene bodies (3 axial direction), hexagonal prisms, equilateral or scalene octahedrons (4 axial direction), cylinders or equilateral or scalene polyhedrons (5 axial direction and above) which are larger than the octahedrons, and the blanks are chamfered to prevent stress concentration and cracking in the process of forging sharp corners.
2) Solution treatment: the block blank is subjected to solution treatment for 8-24h at 400-550 ℃, and then is subjected to air cooling or water cooling to obtain a uniform solid solution alloy blank.
3) Hammer forging: heating the block blank subjected to solution treatment to the deformation temperature of 350-550 ℃, preserving heat for 30-60min, and then performing continuous and cyclic hammer forging on the block blank in multiple directions by using an air hammer forging machine, wherein the hammer forging in each direction is performed once, the direction is changed once per time, the strain of the single-time hammer forging is controlled to be 2-10%, and the average strain rate is 10-200s-1Continuously hammering until the number of times is more than or equal to 30, directly annealing for 5-600min, then rapidly forging for the second time until the number of times of hammering exceeds 100, stopping hammering and air cooling.
In the following examples, multidirectional forging is performed according to the shape of a block material, wherein hexagonal cubes or other scalenohedrons are subjected to 3-axis forging, hexagonal prisms, equilateral or scalenohedrons are subjected to 4-axis forging, and cylinders or equilateral or scalenohedrons larger than eight are subjected to 5-axis and above forging, as shown in fig. 1-2.
Example 1
In the embodiment, Mg-6.0Gd-3.0Y-0.5Zr (GW63K) alloy is adopted, and the weight percentage of the alloy components is Gd: 6.0%, Y: 3.0%, Zr: 0.5% and balance magnesium, abbreviated as GW 63K. Cutting 2 70X 70mm cubic block materials into GW63K alloy ingots, performing solid solution at 480 ℃ for 8h for air cooling, preserving heat at 420 ℃ for 60min, then performing multidirectional hammer forging processing on an industrial air hammer, namely performing cyclic loading in three directions of 1, 2 and 3, performing hammer forging on a block sample 2 for 160(70+70+20) passes, wherein the symbol "+" represents short-time annealing for 5min in the forging process, the time used in the whole process is about 15min, the forging finishing temperature is 300-350 ℃, and finally performing air cooling on the sample. The surface sample after hammer forging had no defects, and the difference between the three dimensions of the sample and the original sample size was not more than 20%, as shown in fig. 3(a) and 3(b), and fig. 3(c) is the optical microstructure of sample 1. After hammer forging, a fine and uniform substructure structure is formed, the grain size is reduced from 100um before processing to 5-20 um after processing, and no microcrack exists, as shown in fig. 3 (d). Yield strength sigmayNot less than 235MPa and tensile strength sigmabNot less than 307MPa, elongation not less than 14%, aging at 200 deg.C for 100hAfter, yield strength σyNot less than 290MPa, tensile strength sigmabMore than or equal to 372MPa and the elongation rate is more than or equal to 13.5 percent.
TABLE 1 mechanical properties of GW63K magnesium alloy before and after 430 ℃ multi-shaft forging processing
Example 2
In the embodiment, Mg-5.0Gd-2.0Y-0.5Zr (GW52K) alloy is adopted, and the weight percentage of the alloy components is Gd: 4.96%, Y: 2.44%, Zr: 0.43 percent, and the balance of magnesium, abbreviated as GW 52K. Five cubic samples of 70X 70mm are cut out from a GW52K magnesium alloy ingot, and the sample is dissolved at 480 ℃ for 8h and air-cooled. The sample is kept at 430 ℃ for 60min before forging, then multidirectional hammer forging processing is carried out on an industrial air hammer, the cubic block sample 2 is subjected to hammer forging 170(70+70+30) passes, the symbol "+" represents short-time annealing carried out in the forging process to be carried out for 5min, the block sample 4 is subjected to hammer forging 200 passes, the block samples 3 and 5 are subjected to hammer forging 200(100+100) passes, the whole process takes about 15min, the forging finishing temperature is 300 + 350 ℃, and the surface of the sample is intact and has no cracks, as shown in figure 5. The grain size after hammer forging is reduced from 100 mu m before processing to 5-20 mu m after processing, and no microcrack exists, as shown in FIG. 6. The forged GW52K magnesium alloy has a texture strength of less than 4 in the (0002) basal plane pole figure, and a texture peak position that is more than 30 degrees off-angle from the pole figure center, as shown in FIG. 7. Yield strength sigmayNot less than 250MPa and tensile strength sigmabNot less than 313MPa, elongation not less than 8.0%, and yield strength sigma after aging at 200 deg.C for 100hyNot less than 332MPa, tensile strength sigmabNot less than 360MPa, elongation not less than 8.1%, and tensile-compressive yield strength ratio in forging direction about 1, as shown in FIG. 8(a) and FIG. 8 (b).
TABLE 2 mechanical properties of GW52K magnesium alloy before and after 430 ℃ multi-shaft forging processing
Claims (7)
1. A forging process of near-isotropy, high-strength and high-plasticity Mg-Gd-Y-Zr alloy materials is characterized by comprising the following steps of: the method is characterized in that after the Mg-Gd-Y-Zr magnesium alloy blank is forged by circulating continuous several fire, the obtained block magnesium alloy material has the optimized matching of near isotropy, high strength and high plasticity; wherein: in each forging process, performing axial multi-axial (axial is more than or equal to 3) continuous high-speed forging on the magnesium alloy blank in a variable manner, wherein the total number of times of multiple axial hammering is not less than 30 times, and then performing annealing for 5-600 min; then continuous high-speed forging and annealing of next fire forging are carried out, and the continuous fire forging is circulated for several times until the total pass reaches more than 100 passes.
2. The forging process of the near-isotropic, high-strength and high-plasticity Mg-Gd-Y-Zr alloy material according to claim 1, characterized in that: the magnesium alloy blank is in the shape of a block, specifically, a hexahedral cube, a scalene hexahedron (3 axial direction), a hexagonal prism, an equilateral octahedron (4 axial direction), a scalene octahedron (4 axial direction), a cylinder, an equilateral polyhedron (5 axial directions and above) larger than the octahedron, or a scalene polyhedron (5 axial directions and above) larger than the octahedron.
3. The forging process of the near-isotropic, high-strength and high-plasticity Mg-Gd-Y-Zr alloy material according to claim 2, characterized in that: in the forging process of the magnesium alloy blank, firstly forging the magnesium alloy blank once along one axis of a block body, then overturning the magnesium alloy blank to the other axis for continuous forging, wherein the specific overturning rotating axis and overturning angle are determined according to the shape of the blank; the strain amount of each forging is 1-10%.
4. The forging process of the near-isotropic, high-strength and high-plasticity Mg-Gd-Y-Zr alloy material according to claim 1, characterized in that: the high-speed forging is hammering for 10-100 times per minute, and the strain rate of the corresponding forged material is more than or equal to 10s-1。
5. The forging process of the near-isotropic, high-strength and high-plasticity Mg-Gd-Y-Zr alloy material according to claim 1, characterized in that: the hammering forging temperature is 350-550 ℃, the annealing temperature is the same as the forging temperature, and the annealing time is determined according to the size of a sample.
6. The forging process of the near-isotropic, high-strength and high-plasticity Mg-Gd-Y-Zr alloy material according to claim 1, characterized in that: the magnesium alloy blank is subjected to solid solution treatment before forging at the treatment temperature of 400-550 ℃ for 8-24h, and then is subjected to air cooling or water cooling to obtain a uniform solid solution alloy blank.
7. The forging process of the near-isotropic, high-strength and high-plasticity Mg-Gd-Y-Zr alloy material according to claim 1, characterized in that: the Mg-Gd-Y-Zr alloy comprises the following chemical components in percentage by weight: 0.1-16% of Gd, 0.1-12% of Y, 0-1.0% of Zr, and the balance Mg.
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