CN106312454A - Method for producing main shaft forging through stacked forging of multi-element homogeneous metal - Google Patents
Method for producing main shaft forging through stacked forging of multi-element homogeneous metal Download PDFInfo
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Abstract
The invention discloses a method for producing a main shaft forging through stacked forging of multi-element homogeneous metal in order to solve the problem of large forging scrapping caused by defects such as cavities, cracks, segregation and second phases existing in the cast steel ingots because of maloperation or improper injection speed and casting temperature control in an ingot casting process in the prior art. The method comprises the steps of with rolling plate blanks meeting component requirements as metal units, fusing and welding the rolling plate blanks in a vacuum welding chamber by using a laser beam; making a reasonable forging and heating process according to a condition for closing a cavity defect inside a large forging, and synthesizing an overall blank by using the plurality of metal plate blank units through high-temperature pressure welding; and then, forging the blanks to form the main shaft forging meeting a process size requirement. By using the method, defects such as segregation, inclusion, shrinkage, loosening and cracks of large steel ingots are avoided, the overall quality of the forging is improved, the utilization ratio of the material is increased, the energy consumption is reduced, and the economic benefit is remarkable.
Description
Technical Field
The invention belongs to the technical field of forging, and particularly relates to a method for producing a main shaft forging by multi-unit homogeneous metal stack forging, wherein a plurality of metal slab unit bodies made of the same material are subjected to surface purification treatment, vacuum welding and high-temperature pressure maintaining in the forging process to eliminate the void defects among the slab unit bodies.
Background
The large-scale casting and forging industry is a very special industry, and the development level of the large-scale casting and forging industry is one of the marks for measuring the comprehensive national strength of a country. The large-scale casting and forging product is a basic component of equipment such as electric power, metallurgy, petrifaction, shipbuilding, railways, mines, aerospace, military industry, engineering and the like, is the basis of major equipment manufacturing industry, and is related to national safety and national economic life.
Because the original steel ingot of a large forging is generally cast, the metallurgical quality and the solidification property of steel inevitably bring many original defects to the steel ingot, and the common defects are as follows: segregation, inclusions, gas, bubbles, shrinkage porosity, cracks and splatter. The formation of the defects is closely related to the processes of smelting, casting, cooling and the like, and the larger the steel ingot is, the more serious the defects are, the defects are also the main reasons for scrapping the large forging, so that the blank forming rate of the steel ingot is greatly reduced; and defects inside the ingot are not visible, which are also difficult to eliminate by the improvement of the smelting process. In the traditional forging process, because the feeder head and the ingot tail of a steel ingot have more defects, the feeder head and the ingot tail are usually required to be cut off, so that the utilization rate of materials is reduced, and the energy consumption is increased.
According to the report of related patent documents, the publication No. CN101722260B discloses a free forging method of a rotating arm type forge piece, a rotary upsetting table is placed on a movable working table, a forming die is placed on the rotary upsetting table, a forge piece blank is placed in the forming die for forging, then the large circular surface of the forge piece blank is flattened, punched, rounded and finished for many times, and a rotating arm type forge piece product is manufactured. According to the method, the overall dimension of the forging can be controlled through the simple forming die and the upsetting punch, the purpose of forging the rotating arm type forging with a complex shape on free forging equipment with small equipment capacity is achieved, but the elimination capacity of the internal cavity and the porosity of the formed steel ingot is poor due to the physical shrinkage generated when molten steel is condensed into the steel ingot, the forging requirement for improving the internal quality of the large forging cannot be met, and the production efficiency is low.
CN1364667A multi-layer folding patterned steel special for knife and sword and its manufacturing method, which mainly uses semi-hard steel and hard steel with same or different proportions to heat and then to be overlapped and forged, then to be folded or twisted for many times, and finally to sandwich a layer of spring steel, and to be hammered and forged by air hammer according to required shape, so that the spring steel, the hard steel and the semi-hard steel are combined into a whole, and the multi-layer folding patterned steel with natural patterns is manufactured. The manufactured multi-layer folding pattern steel has higher sharpness maintenance, grindability and impact resistance than common clad steel, blade and clamp steel, better obdurability and abrasion resistance than common blade materials, and better corrosion resistance. However, the method is only suitable for forging sheet materials and cannot be applied to forging shaft parts.
The method for forging the steel ingot with the publication number of CN102500733B to efficiently heal the hole-type defects in the steel ingot and the method for forging the steel ingot with the publication number of CN104399854B to improve the transverse impact property of the steel are characterized in that a numerical simulation technology is adopted to research the distribution condition of internal strain of the steel ingot and the influence on the closing effect of the hole-type defects in the steel ingot in the traditional free forging process, and the forging method comprising the steps of axial pre-upsetting, radial upsetting and the like is provided on the basis. The process has the advantages that the isotropy and the uniformity of the transverse and longitudinal structures of the steel are improved to a certain extent through multiple upsetting-drawing forging processes before the steel is forged, the longitudinal performance of the steel is not reduced, the transverse performance of the steel is improved, the upsetting-drawing process is repeated once, namely, the upsetting-drawing process is repeated, the heating and the heat preservation are performed, the upsetting-drawing blank is repeated and recrystallized, and the next upsetting-drawing forging and grain refinement are facilitated. However, this method cannot effectively eliminate defects such as foreign particle inclusions which destroy the continuity of metal, cause microcracks, and reduce the forging properties and the mechanical properties after forging, and white spots and hydrogen embrittlement in the forged steel which cause the reduction of the plasticity of the steel material and are formed in the steel ingot in the form of oxides and nitrides by residual gases (such as oxygen, nitrogen, hydrogen, etc.) in the steel ingot, and thus, this method is not suitable for forged steel parts with strict quality requirements.
And "heterogeneous metal construction forming method" under publication No. CN105499459A, discloses a heterogeneous metal construction forming method comprising the steps of preparing at least one first element made of a first material and a plurality of elements made of a plurality of second elements made of a second material, stacking the plurality of elements into a predetermined shape, packaging the plurality of elements stacked into the predetermined shape into a preform, and making interfaces between the plurality of elements welded by forge welding to make the preform into a blank. The process of preparing the elements in the forming method is simply described as blanking a plurality of small-specification metal blanks into specified sizes, and the determination basis and the determination mode of the section sizes of the elements are not specifically described, so that the implementation of the method is not facilitated. The heating mode of the forming method before forging the prefabricated blank is the same as the heating mode of the common steel ingot, but the deformation of the welding seam is easily caused by the common heating mode because the stress relief annealing is not carried out on the prefabricated blank after the welding of the prefabricated blank after the forge welding, and the subsequent processing quality of the heterogeneous metal is influenced. In addition, the steps of upsetting and forge welding performed on the preform in the forming method are described, the pressing deformation of upsetting is simply described, the relation among the temperature, the heat preservation time and the welding specific pressure in the upsetting process is not involved, the full welding of internal cracks of a plurality of elements is difficult to realize, the cavity type defect of the elements cannot be completely eliminated, and the forging quality requirement of the homogeneous metal large forging cannot be met.
In the ingot casting process, due to improper operation or improper control of the injection speed and the casting temperature, the defects of cavities, cracks, segregation, second phases and the like exist in the cast steel ingot. The defects generally exist in the process of manufacturing the steel ingot, and the larger the steel ingot is, the more difficult the internal metallurgical quality of the steel ingot is to ensure; moreover, many defects are not visible and are unpredictable and difficult to eliminate by simple forging. At present, more than 80 percent of domestic large forgings are scrapped due to unqualified steel ingot quality. In particular, the mechanical property requirement of the main shaft forging piece for hydroelectric power generation is stricter. Therefore, it is necessary to improve the existing forging method of large forgings.
Disclosure of Invention
The invention aims at the problems and provides a method for producing a main shaft forging by multi-unit homogeneous metal stack forging, which eliminates the cavity defects among plate blank unit bodies by performing surface purification treatment, vacuum welding and high-temperature pressure maintaining in the forging process on a plurality of metal plate blank unit bodies made of the same material.
The technical scheme adopted by the invention is as follows: the method for producing the main shaft forging by multi-unit homogeneous metal stack forging comprises the following steps:
step one, calculating influences of factors such as strain required by welding, temperature and the like according to materials, and according to the closed conditions of macroscopic and microscopic hole type defects inside a forging stock in the production process of a large forging piece:
in the formula: gamma raysShear strain of octahedron
V0Original void fraction
Wherein,
determining the area of the cavity, determining the section size of the plate blank unit body according to the area of the cavity, and selecting a rolling plate blank with a proper size;
secondly, before a plurality of metal slab unit bodies made of the same materials are stacked, treating the contact surfaces of the slab unit bodies, firstly removing oxide skins on the surfaces of the slab unit bodies, and then cleaning the surfaces of the slab unit bodies by using an organic solvent; the high cleanness of the contact surface of the plate blank unit body needing to be welded is ensured, no impurities, oil stains, surface oxides and the like are left, and the defects of the main shaft forging are reduced as much as possible;
thirdly, stacking the cleaned plate blank unit bodies layer by layer, then quickly transferring the plate blank unit bodies into a vacuum welding chamber, and performing fusion welding on all joints of the stacked plate blank unit bodies in a mode of melting base materials by laser beams; so that the stacked plate blank unit bodies form a whole, and impurities are prevented from entering the joint to influence the forging effect;
step four, the stacked plate blank unit bodies which are welded into a whole are flatly placed on a sizing block of a heating furnace, the welding surfaces of the unit bodies are parallel to the horizontal plane, then the plate blank unit bodies are heated, and the heating process is as follows: after the temperature is preserved for 10 hours at 350 ℃, the temperature is increased to 750 ℃ at the heating rate of less than or equal to 50 ℃/hour, the temperature is preserved for 7 hours at 750 ℃, then the temperature is increased to 1080 ℃ at the heating rate of less than or equal to 50 ℃/hour, the temperature is preserved for 12 hours at 1080 ℃, the temperature is rapidly increased to 1220 ℃ according to the automatic heating power of a heating furnace, and finally the temperature is preserved for 20 hours at 1220 ℃; so as to eliminate the internal stress of the stacked plate blank unit bodies subjected to laser beam fusion welding while heating the plate blank unit bodies;
hoisting the heated stacked plate blank unit bodies to a upsetting platform of a hydraulic press, and performing upsetting pressure-maintaining welding on the stacked plate blank unit bodies, wherein the upsetting pressure-maintaining welding temperature, the heat preservation time and the welding specific pressure meet the Fick second law, so that the crack-type defects of the plate blank unit bodies are fully welded; fick's second law states that the rate of change of concentration with time at distance x during unsteady state diffusionEqual to the rate of change of diffusion flux at that location with distanceNegative value of (i.e.
Will be provided withSubstituting into the formula to obtain
In the formula: t-diffusion time(s)
C-volume concentration of diffusing species (kg/m)3)
x-distance (m)
In the upsetting pressure-maintaining welding process, the cracks of the plate blank unit bodies are finally healed through stages of crack tip passivation, crack sectioning, crack cavity spheroidization, cavity healing, quality homogenization and the like;
and step six, performing high-temperature diffusion treatment on the stacked plate blank unit bodies subjected to upsetting pressure-maintaining welding, wherein the welding of the crack-type defects is realized through atomic diffusion, the average distance traveled by the atomic diffusion is in direct proportion to the square root of diffusion time, and the following formula is generally satisfied:
in the formula: x-average distance of atoms
Tau-holding time
K-constant, dependent on material
And seventhly, upsetting, punching and reaming the bumper.
And step two, when the contact surface of the slab unit body is treated, removing the oxide skin on the surface of the slab unit body by using a milling machine.
And step two, after the contact surface of the slab unit body is treated, the surface roughness of the machined slab unit body needs to be ensured to be less than 6.3.
And step two, after removing the oxide skin on the surface of the slab unit body, the organic solvent for cleaning the surface of the slab unit body is acetone or alcohol.
And step five, when 20SiMn is used as the material of the main shaft forging, the welding temperature of the material is 1100-1150 ℃, the welding specific pressure is 5-10 MPa, and the welding time is 30-60 min.
And sixthly, the high-temperature diffusion speed of the stacked plate blank unit body main shaft forge piece is 50-70 mm/h.
The invention has the beneficial effects that: the method for producing the main shaft forging by multi-unit homogeneous metal stack forging comprises the following steps: the rolling plate blanks meeting the component requirements are used as metal unit bodies, fusion welding is carried out in a vacuum welding chamber by adopting laser beams, reasonable forging and heating processes are worked out according to the closing conditions of cavity type defects in the heavy forging, and a plurality of metal plate blank unit bodies are synthesized into an integral blank through high-temperature pressure maintaining welding; and forging the blank into a main shaft forging with the technological dimension requirement. Compared with the traditional method that steel ingots are used as forging raw materials, the method has the advantages that the mode that multiple units of homogeneous metal are welded into a forging blank in a bead welding mode avoids the defects of segregation, inclusion, gas, bubbles, shrinkage cavity, looseness, cracks and the like of a large steel ingot, and improves the overall quality of a forging; in addition, the blank does not need to remove riser materials of the water gap, so that the utilization rate of the materials is improved, the energy consumption is reduced, and the method has remarkable economic benefit. Because the metal unit bodies are generally rolling plate blanks and are stacked and welded in the special vacuum welding chamber, compared with the production process of large steel ingots, the production efficiency is high and the environmental pollution is small.
Drawings
Fig. 1 is a schematic view of a stacked slab unit cell of the present invention.
Fig. 2 is a schematic view of the welding of the unit body of the slab of the present invention using a laser beam in a vacuum welding chamber.
Fig. 3 is a schematic diagram of upsetting pressure maintaining welding of the slab unit body of the invention.
Figure 4 is a process scheme of the present invention.
Fig. 5 is a graph of the heating profile of the present invention.
The sequence numbers in the figures illustrate: 1 metal plate blank unit body, 2 vacuum welding chambers, 3 laser beam guns, 4 welding turntables, 5 hydraulic press upper beams, 6 upper upsetting plates, 7 lower upsetting plates and 8 hydraulic press lower platforms.
Detailed Description
The specific steps of the present invention are described in detail with reference to FIGS. 1 to 5. The method for producing the main shaft forging by multi-unit homogeneous metal stack forging comprises the following steps:
step one, in order to select a rolling slab with a proper size, calculating the influence of factors such as strain quantity, temperature and the like required by welding according to the material, and determining the section size of a slab unit body.
According to the change problem of the large forging voidage defect researched by jinning and the like in the plastic processing process, the pressing mechanism, conditions and criteria of the large forging voidage defect in the plastic processing process are researched by adopting a mathematical analysis method, the criteria for pressing the large forging voidage defect are deduced on the basis of cavitation mechanics, and the closing rule, the closing path and the closing speed of the large forging internal columnar cavity in the FM method, the WHF method and the V-anvil forging process are discussed according to the research results. The method is derived based on the plasticity theory and the cavity mechanics of the porous compressible material, and in the production process of the large forging, the closing conditions of macroscopic and microscopic cavity defects inside a forging stock can be expressed as follows:
in the formula: gamma raysShear strain of octahedron
V0Original void fraction
Wherein,
the area of the cavity can be determined according to the formula, the section size of the plate blank unit body is determined according to the area of the cavity, and a rolling plate blank with a proper size is selected to ensure that products with reliable quality are produced through subsequent processing.
And step two, before stacking, removing oxide skins on the surfaces of a plurality of metal slab unit bodies made of the same material by using a milling machine so as to treat the contact surfaces of the slab unit bodies and ensure that the surface roughness after machining by using the milling machine is less than 6.3. And then, cleaning the surface of the plate blank unit body by using organic solvents such as acetone or alcohol and the like to ensure that the contact surface of the plate blank unit body, which needs to be welded, is high and clean, no impurities, oil stains, surface oxides and the like are left, and the defects of the final finished product main shaft forging are reduced as much as possible.
And step three, in order to enable the stacked plate blank unit bodies to form a whole, rapidly transferring the cleaned plate blank unit bodies stacked layer by layer into a vacuum welding chamber, and performing fusion welding on all joints of the stacked plate blank unit bodies in a mode of melting a base material by using a high-energy-density laser beam as a heat source so as to prevent impurities from entering the joints and influencing the forging effect. The laser beam welding can reduce the heat input quantity to the minimum required quantity, the metallurgical change range of a heat affected zone is small, and the deformation quantity caused by heat conduction is also minimum; the laser beam can be focused on a small area, is suitable for welding parts with small intervals, and can reduce the time required for welding thick plates and even omit the use of filler metal.
And step four, hoisting and welding the stacked plate blank unit bodies into a whole, and horizontally placing the stacked plate blank unit bodies on a sizing block of a heating furnace, wherein the welding surfaces of the unit bodies are arranged in parallel to the horizontal plane. Compared with the heating curve of a common steel ingot, the heating process curve of the stacked plate blank unit bodies has the advantages that the heat preservation time of the low-temperature section, the medium-temperature forging section and the high-temperature section is relatively prolonged. Because the stress relief annealing is not carried out after the welding of the surfacing plate blank, the heat preservation time of the medium temperature section is properly prolonged in order to prevent the welding stress from causing the deformation of the welding seam. When the high-temperature section is insulated, the heat insulation time of the unit body overlaying welding piece cannot be calculated according to the size of the minimum section size of a single piece, but the heat insulation time is calculated according to the size of the stacking direction of a plurality of blanks, and the heat insulation time is calculated according to 1.5 hours of heat insulation of every 100 mm.
Because the internal stress of the stacked plate blank unit bodies welded by the laser beam in a fusion mode is eliminated, compared with the heating curve of a common steel ingot, the heating process curve of the stacked plate blank unit bodies prolongs the heat preservation time of a low-temperature section, a medium-temperature section and a high-temperature section by 1.3 times. The specific heating process comprises the following steps: firstly, after the temperature is preserved for 10 hours at 350 ℃, the temperature is increased to 750 ℃ at the heating rate of less than or equal to 50 ℃/hour, then the temperature is preserved for 7 hours at 750 ℃, then the temperature is increased to 1080 ℃ at the heating rate of less than or equal to 50 ℃/hour, after the temperature is preserved for 12 hours at 1080 ℃, the temperature is rapidly increased to 1220 ℃ according to the automatic heating power (the heating power is increased) of a heating furnace, and finally the temperature is preserved for 20 hours at 1220 ℃, thus completing the whole heating process.
And fifthly, upsetting, pressure maintaining and welding the heated stacked plate blank unit bodies. The heated stacked plate blank unit bodies are hung on a upsetting platform of a hydraulic press by iron chains, and when the unit bodies are hung, the welding surfaces of the unit bodies are always ensured to be parallel to the horizontal plane. The key point of the invention is the upsetting pressure-maintaining welding, and the crack-type defects of the plate blank unit bodies can realize sufficient welding when the temperature, the heat preservation time and the welding specific pressure meet the Fick second law. Fick's second law, which is derived on the basis of the first law, states that the rate of change of concentration with time at a distance x during unsteady diffusionEqual to the rate of change of diffusion flux at that location with distanceNegative value of (i.e.
Will be provided withSubstituting into the formula to obtain
In the formula: t-diffusion time(s)
C-volume concentration of diffusing species (kg/m)3)
x-distance (m)
In fact, the diffusion coefficient D of solute atoms in solid solution varies with concentration, and in order to make solving the diffusion equation simpler, D is often considered approximately as a constant. According to Fick's second law, the cracks of the plate blank unit bodies are finally healed through stages of crack tip passivation, crack sectioning, crack cavity spheroidization, cavity healing, quality homogenization and the like in the upsetting pressure-maintaining welding process.
The crack healing process comprises the stages of crack tip passivation, crack segmentation, crack cavity spheroidization, cavity healing, quality homogenization and the like. For the slab unit body which is already upset in place, the optimal parameters are different according to welding specific pressure (pressure maintaining pressure of a press), welding time (pressure maintaining time) of cracks and different materials. When the material of the main shaft forging is 20SiMn, the optimal welding temperature of the material is 1100-1150 ℃, the welding specific pressure is 5-10 MPa, and the welding time is 30-60 min through calculation.
Step six, the heat preservation time of high-temperature diffusion is also very important for the welding process. Under the condition of the same deformation and heat preservation temperature, the welding effect can be improved by properly prolonging the heat preservation time. The seam of crack-type defects is achieved by mechanisms such as atomic diffusion, and the average distance that atoms diffuse away is proportional to the square root of the diffusion time. The following formula is generally satisfied:
in the formula: x-average distance of atoms
Tau-holding time
K-constant, material dependent, typical alloy steels are 1.5
According to calculation, the high-temperature diffusion heat preservation time of the stacked plate blank unit body main shaft forge piece is 1.5-1.7 times of the heat preservation time of a common steel ingot forge piece. The holding time of steel ingots of general carbon steels and low alloy steels is usually calculated according to the speed of 100 mm/h.
And seventhly, performing subsequent procedures of rounding, upsetting and punching, reaming the bumper and shaping. These are the same as the forging steps of a general main shaft.
Claims (6)
1. A method for producing a main shaft forging by multi-unit homogeneous metal stack forging is characterized by comprising the following steps: the method comprises the following steps:
step one, calculating influences of factors such as strain required by welding, temperature and the like according to materials, and according to the closed conditions of macroscopic and microscopic hole type defects inside a forging stock in the production process of a large forging piece:
in the formula: gamma raysShear strain of octahedron
V0Original void fraction
Wherein,
determining the area of the cavity, determining the section size of the plate blank unit body according to the area of the cavity, and selecting a rolling plate blank with a proper size;
secondly, before a plurality of metal slab unit bodies made of the same materials are stacked, treating the contact surfaces of the slab unit bodies, firstly removing oxide skins on the surfaces of the slab unit bodies, and then cleaning the surfaces of the slab unit bodies by using an organic solvent; the high cleanness of the contact surface of the plate blank unit body needing to be welded is ensured, no impurities, oil stains, surface oxides and the like are left, and the defects of the main shaft forging are reduced as much as possible;
thirdly, stacking the cleaned plate blank unit bodies layer by layer, then quickly transferring the plate blank unit bodies into a vacuum welding chamber, and performing fusion welding on all joints of the stacked plate blank unit bodies in a mode of melting base materials by laser beams; so that the stacked plate blank unit bodies form a whole, and impurities are prevented from entering the joint to influence the forging effect;
step four, the stacked plate blank unit bodies which are welded into a whole are flatly placed on a sizing block of a heating furnace, the welding surfaces of the unit bodies are parallel to the horizontal plane, then the plate blank unit bodies are heated, and the heating process is as follows: after the temperature is preserved for 10 hours at 350 ℃, the temperature is increased to 750 ℃ at the heating rate of less than or equal to 50 ℃/hour, the temperature is preserved for 7 hours at 750 ℃, then the temperature is increased to 1080 ℃ at the heating rate of less than or equal to 50 ℃/hour, the temperature is preserved for 12 hours at 1080 ℃, the temperature is rapidly increased to 1220 ℃ according to the automatic heating power of a heating furnace, and finally the temperature is preserved for 20 hours at 1220 ℃; so as to eliminate the internal stress of the stacked plate blank unit bodies subjected to laser beam fusion welding while heating the plate blank unit bodies;
hoisting the heated stacked plate blank unit bodies to a upsetting platform of a hydraulic press, and performing upsetting pressure-maintaining welding on the stacked plate blank unit bodies, wherein the upsetting pressure-maintaining welding temperature, the heat preservation time and the welding specific pressure meet the Fick second law, so that the crack-type defects of the plate blank unit bodies are fully welded; fick's second law states that the rate of change of concentration with time at distance x during unsteady state diffusionEqual to the rate of change of diffusion flux at that location with distanceNegative value of (i.e.
Will be provided withSubstituting into the formula to obtain
In the formula: t-diffusion time(s)
C-volume concentration of diffusing species (kg/m)3)
x-distance (m)
In the upsetting pressure-maintaining welding process, the cracks of the plate blank unit bodies are finally healed through stages of crack tip passivation, crack sectioning, crack cavity spheroidization, cavity healing, quality homogenization and the like;
and step six, performing high-temperature diffusion treatment on the stacked plate blank unit bodies subjected to upsetting pressure-maintaining welding, wherein the welding of the crack-type defects is realized through atomic diffusion, the average distance traveled by the atomic diffusion is in direct proportion to the square root of diffusion time, and the following formula is generally satisfied:
in the formula: x-average distance of atoms
Tau-holding time
K-constant, dependent on material
And seventhly, upsetting, punching and reaming the bumper.
2. The method for producing a main shaft forging by multi-unit homogeneous metal stack forging according to claim 1, wherein the method comprises the following steps: and step two, when the contact surface of the slab unit body is treated, removing the oxide skin on the surface of the slab unit body by using a milling machine.
3. The method for producing a main shaft forging by multi-unit homogeneous metal stack forging according to claim 1, wherein the method comprises the following steps: and step two, after the contact surface of the slab unit body is treated, the surface roughness of the machined slab unit body needs to be ensured to be less than 6.3.
4. The method for producing a main shaft forging by multi-unit homogeneous metal stack forging according to claim 1, wherein the method comprises the following steps: and step two, after removing the oxide skin on the surface of the slab unit body, the organic solvent for cleaning the surface of the slab unit body is acetone or alcohol.
5. The method for producing a main shaft forging by multi-unit homogeneous metal stack forging according to claim 1, wherein the method comprises the following steps: and step five, when 20SiMn is used as the material of the main shaft forging, the welding temperature of the material is 1100-1150 ℃, the welding specific pressure is 5-10 MPa, and the welding time is 30-60 min.
6. The method for producing a main shaft forging by multi-unit homogeneous metal stack forging according to claim 1, wherein the method comprises the following steps: and sixthly, the high-temperature diffusion speed of the stacked plate blank unit body main shaft forge piece is 50-70 mm/h.
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