CN114054532B - Method for improving utilization rate of nickel-based alloy bar material manufactured by extrusion - Google Patents
Method for improving utilization rate of nickel-based alloy bar material manufactured by extrusion Download PDFInfo
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- CN114054532B CN114054532B CN202110250871.9A CN202110250871A CN114054532B CN 114054532 B CN114054532 B CN 114054532B CN 202110250871 A CN202110250871 A CN 202110250871A CN 114054532 B CN114054532 B CN 114054532B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C23/00—Extruding metal; Impact extrusion
- B21C23/01—Extruding metal; Impact extrusion starting from material of particular form or shape, e.g. mechanically pre-treated
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- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C23/00—Extruding metal; Impact extrusion
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Abstract
The application relates to a method for improving the utilization rate of a nickel-based alloy bar material manufactured by extrusion, belongs to the technical field of high-temperature alloy hot working, and solves the problems of uneven deformation and low material utilization rate of a large-diameter nickel-based alloy extruded bar in the prior art. According to the method, a cylindrical gasket is arranged at the head part of a cylindrical forging stock to be extruded, and a circular gasket is arranged at the tail part of the cylindrical forging stock to be extruded. The method realizes the stable manufacture of the large-diameter nickel-based alloy bar with uniform extrusion deformation and improved material utilization rate.
Description
Technical Field
The application relates to the technical field of metal processing, in particular to a method for improving the utilization rate of nickel-based alloy bar materials manufactured by extrusion.
Background
The nickel-base alloy is a high-temperature alloy with a gamma phase containing more than 30% of nickel as a matrix, and the ageing-base alloy takes a gamma 'phase with a face-centered cubic structure and a gamma' phase with a body-centered cubic structure as precipitation strengthening phases, has excellent high strength, oxidation resistance, good toughness and ductility, good welding performance and good machining performance at the temperature of more than 600 ℃, and has extremely wide application in the fields of gas turbines, aeroengines, deep sea oil wells and the like.
The nickel-based alloy bar stock for aerospace has very high requirements on structure uniformity, grain size grade difference and the like, and the large-specification fine crystal bar stock in China is generally produced in a quick forging mode at present. Because the stress state of the extrusion process is complex, the non-uniformity of the stress can bring great influence to the tissue control, and especially the non-uniformity of the whole structure of the blank can increase the difficulty of the tissue control of the nickel-based alloy hot extrusion process. When the bar is extruded, a part of the head area is a free surface, the deformation is small, and the tail part does not completely pass through the deformation area and the bearing of the extrusion die, so that more blank tissues are reserved, the grain size difference between the head and the tail and the middle section is larger than 2 levels, and the requirement of the fine-grain bar for aerospace is difficult to meet. When in supply, a part of bar stock at the head end and the tail end needs to be cut off, so that the material utilization rate is lower, and the production cost is high due to more expensive metals such as nickel, chromium, molybdenum and the like in the superalloy.
Disclosure of Invention
In view of the above analysis, the present application aims to provide a method for improving the utilization rate of nickel-based alloy bar materials manufactured by extrusion, which is used for solving the problems of uneven deformation and low material utilization rate of nickel-based alloy extruded bars in the prior art.
The aim of the application is mainly realized by the following technical scheme:
the application discloses a method for improving the utilization rate of nickel-based alloy bar materials manufactured by extrusion.
Further, the method for improving the utilization rate of the nickel-based alloy bar material manufactured by extrusion comprises the following steps:
step 1, cogging and blanking nickel-base alloy cast ingots by adopting a free forging upsetting or closed upsetting mode;
step 2, carrying out surface machining on the nickel-based alloy blank after blank making, and turning off black skin and surface defects to obtain a cylindrical forging blank;
step 3, welding a cylindrical gasket to the head of the cylindrical forging stock, and arranging a circular ring gasket to the tail of the cylindrical forging stock to obtain a combined blank; wherein the axes of the cylindrical gasket, the cylindrical forging stock and the annular gasket are aligned;
and step 4, heating the combined blank at 930-1080 ℃, continuously preserving heat for 1-4 hours after the combined blank is thoroughly heated, and discharging from a furnace for hot extrusion.
Further, in the step 3, the diameter of the cylindrical spacer is equal to the diameter of the cylindrical forging stock.
Further, in the step 3, the height of the cylindrical spacer is 40-100 mm.
Further, in the step 3, the height of the annular gasket is 100-300 mm.
Further, in the step 3, the inner diameter of the annular gasket is 1/4-1/2 of the diameter of the cylindrical forging stock.
Further, in the step 2, the method further includes chamfering one end of the cylindrical gasket, wherein the radius of the round corner is r 20-r 50mm.
Further, in the step 3, the cylindrical gasket and the annular gasket are made of austenitic stainless steel.
Further, in the step 4, the combined blank is subjected to lubricant treatment before hot extrusion, wherein the lubricant comprises a glass mat and glass powder coated on the surfaces of the cylindrical forging blank and the cylindrical gasket, and the glass mat is arranged between the extrusion die and the cylindrical gasket.
Further, in the step 4, the extrusion ratio is 2-9 and the extrusion speed is 5-30 mm/s during hot extrusion.
Further, the cylindrical gasket, the cylindrical forging stock and the annular gasket are coaxially arranged.
Compared with the prior art, the application has at least one of the following beneficial effects:
(1) According to the method, the cylindrical gasket is arranged at the head part of the cylindrical forging stock to be extruded, and the cylindrical gasket can generate reverse acting force on the head part of the extrusion stock when extrusion starts, so that the bidirectional compressive stress and the tensile stress of the free surface area of the head part of the traditional extrusion stock are improved to be the same as the three-way compressive stress of other parts of the extrusion stock, the deformation of the head part is increased, the whole strain of the blank is more uniform, and the axial grain size difference (for example, the grain size difference between the head part, the tail part and the middle section is smaller than or equal to 1 level) is reduced.
(2) According to the method, the annular gasket is arranged at the tail part of the cylindrical forging stock to be extruded, so that the tail shrinkage phenomenon of the traditional extrusion mode is improved, the materials of the cylindrical forging stock can be extruded from the extrusion die, the utilization rate of the cylindrical forging stock (made of expensive nickel-based alloy materials) is greatly improved (for example, the utilization rate of the materials reaches over 90 percent), and the production cost is reduced.
(3) In the method, the cylindrical gasket and the annular gasket are made of austenitic stainless steel, the deformation temperature ranges of the austenitic stainless steel and the nickel-based alloy are similar, the welding is easy, and in addition, the two metal materials can use the same type of lubricant, so that the extrusion operation is convenient.
In the application, the technical schemes can be mutually combined to realize more preferable combination schemes. Additional features and advantages of the application will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the application. The objectives and other advantages of the application may be realized and attained by the embodiments of the application particularly pointed out in the written description and drawings.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the application, like reference numerals being used to refer to like parts throughout the several views.
FIG. 1 is a schematic illustration of a composite extrusion billet of the present application;
FIG. 2 is a schematic view of a double cone die of an extrusion die used in the present application;
FIG. 3 is a schematic illustration of tail end shrinkage during extrusion of a rod in a conventional manner; wherein (a) is one of the cross-sectional views; (b) is a cross-sectional view from another perspective;
fig. 4 is a schematic representation of the method of the present application during extrusion.
Reference numerals:
1-a cylindrical gasket, 2-a cylindrical forging stock, 3-a circular ring gasket, 4-a double-cone die inlet and 5-a bearing.
Detailed Description
The following detailed description of preferred embodiments of the application is made in connection with the accompanying drawings, which form a part hereof, and together with the description of the embodiments of the application, are used to explain the principles of the application and are not intended to limit the scope of the application.
The nickel-based alloy bar stock for aerospace has very high requirements on structure uniformity, grain size grade difference and the like, and the large-specification fine crystal bar stock in China is generally produced in a quick forging mode at present. Due to the complex stress state of the extrusion process, the non-uniformity of the stress can also have a great influence on the tissue control, especially the non-uniformity of the whole tissue of the blank. The existing extrusion die for extrusion of bars adopts a biconical die, as shown in the following figure 2, the die angle combination is 60 degrees and 45 degrees, arc transition is adopted between the die angles, R30mm is adopted between the die angles and the bearing, and R100mm is adopted between the die angles and the bearing. The inventors have found through intensive studies in practice that: when the bar is extruded, a part of the area of the head is a free surface, the deformation is small, the tail does not completely pass through the deformation area and the bearing of the extrusion die, so that more blank tissues are reserved, and the larger the diameter of the bar is, the more serious the tail shrinkage phenomenon is, as shown in the following figure 3. The grain size difference between the head and the tail and the middle section is larger than 2, and the requirement of the fine-grain bar for aerospace is difficult to meet. When in supply, a part of bar stock at the head end and the tail end needs to be cut off, so that the material utilization rate is lower, and the production cost is high due to more expensive metals such as nickel, chromium, molybdenum and the like in the nickel-based superalloy for aerospace.
The application discloses a method for improving the utilization rate of nickel-based alloy bar materials manufactured by extrusion, which is characterized in that a cylindrical gasket 1 is arranged at the head part of a cylindrical forging stock 2 to be extruded, and a circular gasket 3 is arranged at the tail part of the cylindrical forging stock 2 to be extruded.
Compared with the prior art, the cylindrical gasket is arranged at the head of the cylindrical forging stock to be extruded, and the cylindrical gasket can generate reverse acting force on the head of the extrusion stock when extrusion starts, so that the bidirectional compressive stress and the unidirectional tensile stress of the free surface area of the head of the traditional extrusion stock are improved to be the same as the three-dimensional compressive stress of other parts of the extrusion stock, the deformation of the head is increased, the whole strain of the blank is more uniform, and the axial grain size difference is reduced. By arranging the annular gasket at the tail part of the cylindrical forging stock to be extruded, the tail shrinkage phenomenon of the traditional extrusion mode is improved, the materials of the cylindrical forging stock can be extruded from the extrusion die, the utilization rate of the cylindrical forging stock (the materials are expensive nickel-based superalloy materials) is greatly improved, and the production cost is reduced.
Specifically, the method for improving the utilization rate of the nickel-based alloy bar material manufactured by extrusion comprises the following steps:
step 1, cogging and blanking nickel-base alloy cast ingots by adopting a free forging upsetting or closed upsetting mode;
step 2, carrying out surface machining on the nickel-based alloy blank after blank making, and turning off black skin and surface defects to obtain a cylindrical forging blank;
step 3, welding a cylindrical gasket to the head of the cylindrical forging stock, and arranging (e.g. welding) a circular ring-shaped gasket to the tail of the cylindrical forging stock to obtain a combined blank; wherein, the axes of the cylindrical gasket, the cylindrical forging stock and the annular gasket are aligned;
and step 4, heating the combined blank at 930-1080 ℃, continuously preserving heat for 1-4 hours after the combined blank is thoroughly heated, and discharging from a furnace for hot extrusion to obtain the nickel-base alloy bar stock. Wherein, before hot extrusion, the combined blank is sprayed with lubricant; as shown in fig. 4, upon extrusion, the cylindrical shim end (i.e., head) enters the extrusion die first.
Specifically, in the step 1, the blank is thermally cracked due to the excessively high heating temperature during the cogging; when the pressure is too low, the deformation resistance of the material is increased, so that the deformation is difficult, and the tonnage requirement of the press is increased. Therefore, the heating temperature at the time of cogging is controlled to 900 to 1200 ℃ (e.g., 900 ℃, 950 ℃, 1000 ℃, 1050 ℃, 1100 ℃, 1150 ℃, 1200 ℃). The blank is easy to crack due to the overlarge cogging deformation, and the blank is unstable during upsetting; too small can not break the as-cast structure, and when the deformation of a single fire is small, the deformation fire needs to be increased, so that the production cost is increased and the production efficiency is reduced. Therefore, the cogging deformation amount is controlled to be 20% to 50% (for example, 20%, 25%, 30%, 35%, 40%, 45%, 50%).
Specifically, in the step 1, the excessive temperature during blank making can cause grain growth, which brings difficulty to control grain size for subsequent extrusion; when the metal deformation resistance is too low, the metal deformation resistance is increased, and the tonnage of the required equipment is increased. Therefore, the heating temperature at the time of blank making is controlled to 1060 to 1120 ℃ (for example, 1060 ℃, 1070 ℃, 1080 ℃, 1090 ℃, 1100 ℃, 1110 ℃, 1120 ℃). The blank deformation is too large, so that the blank is unstable when deformed, the ingot body is folded and the like, and the subsequent machining and cleaning are needed, so that the material utilization rate is reduced, and the cost is increased. Therefore, the diameter of the bar after the cogging is determined according to the target extrusion billet diameter, and the deformation amount during the cogging is controlled to be less than 70%.
Specifically, in the step 2, the diameter D of the cylindrical forging stock is 300 to 900mm (e.g., 300mm, 350mm, 400mm, 450mm, 500mm, 550mm, 600mm, 650mm, 700mm, 750mm, 800mm, 850mm, 900 mm).
Specifically, in the step 2, in order to obtain a cylindrical forging stock with good surface quality, the overall finish of the cylindrical forging stock is controlled to be Ra6.3.
Specifically, in the step 3, in order to ensure that the combined billet can be extruded smoothly, the diameter of the cylindrical gasket 1 is equal to or slightly smaller than the maximum diameter of the entrance 4 of the biconical die.
Specifically, in the step 3, the diameter D of the cylindrical forging stock 2 is equal to the diameter of the cylindrical gasket 1, so that the edge of the cylindrical gasket 1 is prevented from being sheared and broken by sharp corners of the edge of the cylindrical forging stock 2 when the diameter of the cylindrical gasket 1 is too large, and the broken gasket part is clamped at the extrusion die to scratch the surface of the extrusion part (i.e. the cylindrical forging stock 2); and if the diameter of the cylindrical gasket 1 is larger than that of the cylindrical forging stock 2, the gasket can be coated on the head of the blank during extrusion, so that the diameter of the head of the nickel-based alloy bar is thinned, and the purpose of improving the material utilization rate cannot be achieved.
Specifically, in the above step 3, the height H of the cylindrical spacer 1 1 Too large can cause the gasket to wrap the head of the extrusion after extrusion, resulting in extrusionIs not sufficient in size; too small a spacer can easily deform and not serve the purpose of applying a counter force to the extrusion head. Thus, the height H of the cylindrical spacer 1 is controlled 1 The D is (1/15-1/6), specifically 40-100 mm (e.g., 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100 mm).
Specifically, in the step 3, in order to make the combined blank easier to enter the extrusion die, the phenomenon of "car-closing" is avoided, and the shell breaking force is reduced; the head of the cylindrical gasket needs to be rounded.
Specifically, in the step 3, the shell breaking force cannot be further reduced when the radius of the round angle of the cylindrical gasket 1 is too large, and meanwhile, the working time required for processing the round angle is increased, so that the production efficiency is reduced; if too small, the purpose of rounding cannot be achieved. Therefore, the fillet radius is controlled to be r20 to r50mm.
Specifically, in the step 3, the non-rounded side of the cylindrical spacer 1 is welded to one end of the cylindrical forging stock.
It should be noted that, in the above step 3, the circular ring-shaped gasket 3 is disposed at the tail of the cylindrical forging stock instead of the cylindrical gasket, because if the cylindrical gasket is disposed at the tail, the gasket enters the end-shrinking portion of the extrusion member after the extrusion is completed, and the end-shrinking portion of the extruded bar and the gasket material must be sawed from the end-shrinking vertex. The waste of materials can be caused, and the gasket cannot be added. The tail part is added with the annular gasket, so that the tail shrinkage phenomenon of extruded bars can be reduced.
Specifically, in the step 3, the inner diameter of the annular gasket 3 is too large, namely the "height-thickness ratio" of the annular part is large, and the gasket is unstable and folded under the action of huge extrusion force; too small can not achieve the purpose of reducing the extrusion tail. Therefore, the inner diameter of the circular ring-shaped gasket 3 is controlled to be eta times of the diameter of the cylindrical forging stock 2, and the range of eta value is selected to be 1/4-1/2 according to the difficulty of shrinkage of different ingot shapes and different brands of alloys.
Specifically, in the step 3, the height H of the annular gasket 3 2 Excessive size can result in unnecessary wastage of gasket material; if too small, the extrusion forging stock cannot be completely extruded from the die. In actual production, the deformation area and sizing can be adjusted according to the mouldIn-band volume estimation of the height H of the annular gasket 3 2 I.e. H 2 The following formula is required to be satisfied:
wherein: alpha is a die angle, and the biconical die is an average value of two angles; lambda is the extrusion ratio; x is the length of the bearing 5; r is the radius of the cylindrical forging stock 2. Formula (1) can be simplified as:
the above does not take into account the rounding at the inlet and outlet of the deformation zone of the die, and the height H of the annular gasket 3 is calculated in order to extrude the cylindrical forging stock 2 entirely from the die 2 And rounding up the rear part. Thus, the height H of the annular gasket 3 is controlled 2 100 to 300mm, for example 100mm,120mm,150mm,170mm,200mm,220mm,250mm,270mm,300mm.
Specifically, in the step 3, the cylindrical gasket 1 and the annular gasket 3 are made of austenitic stainless steel, and the austenitic stainless steel and the nickel-based alloy are the same or similar in deformation temperature interval (for example, the initial deformation temperatures of the two metals differ by less than 60 ℃) and are easy to weld, and in addition, the two metal materials can use the same type of lubricant, so that the extrusion operation is convenient.
Specifically, in the step 3, when the annular gasket 3 is extruded on the vertical extruder and the operation is convenient, the annular gasket 3 can not be welded with the cylindrical forging stock 2, and the heating temperature of the annular gasket 3 can be 50-100 ℃ lower than the heating temperature of the cylindrical forging stock 2, so that the strength of the annular gasket 3 can be increased, and the further reduction of shrinkage is facilitated. During extrusion, the annular gasket 3 is firstly placed on the extrusion rod and centered with the extrusion rod, then the cylindrical forging stock 2 is placed on the annular gasket 3 and centered, and then extrusion is performed.
Specifically, in the step 4, in order to prevent the cylindrical forging stock 2 and the gasket from generating oxide skin during high-temperature heating, the glass lubricant is not coated after the furnace is discharged, and meanwhile, the process of descaling can be reduced. Spraying an anti-oxidation coating on the surface of the combined blank before the combined blank is put into a furnace. The thickness of the anti-oxidation coating is moderate, and the coating is burnt when being heated in a furnace, so that the anti-oxidation coating cannot play a role in anti-oxidation, and the coating is too thick to be sintered and fall off.
Specifically, in the step 4, the combined blank is subjected to lubricant treatment before hot extrusion, wherein the lubricant comprises a glass mat and glass powder coated on the surfaces of the cylindrical forging blank 2 and the cylindrical gasket 1, and the glass mat is arranged between the extrusion die and the cylindrical gasket 1.
Specifically, in the step 4, when the extrusion ratio is too small, the advantage of refining the grain structure by large deformation of the extrusion process cannot be fully exerted; too large extrusion ratio requires a die having very high strength and hardness, and wear of the die increases, reducing die life, resulting in increased costs, and in addition, increases tonnage requirements of the extruder without universality. The extrusion speed is too slow, the heat dissipation time of the blank is increased, the surface temperature of the blank is reduced, the deformation resistance is increased, and the blank is possibly extruded in the later extrusion stage; too high a pressing speed increases the friction force, resulting in an increase in the pressing force, while too high a deformation speed is unfavorable for recrystallization refinement of the grains. Thus, the extrusion ratio at the time of hot extrusion is controlled to be 2 to 9, such as 2, 4, 6, 9, etc., and the extrusion speed is controlled to be 5 to 30mm/s, such as 5mm/s, 10mm/s, 15mm/s, 20mm/s, 25mm/s, 30mm/s.
Specifically, the nickel-base alloy bar obtained by extrusion in the step 4 has uniform and fine structure, and the grain size difference between the head part, the tail part and the middle section is less than or equal to 1 level.
Specifically, the material utilization rate of the nickel-based alloy bar obtained after extrusion in the step 4 reaches more than 90%.
Example 1
The embodiment provides a method for improving the utilization rate of nickel-based alloy bar material manufactured by extrusion, which is used for preparing nickel-based alloy fine-grain bar with the diameter of phi 300mm.
The method comprises the following steps:
step 1, cogging and forging a nickel-based alloy phi 508mm cast ingot by using a free forging hydraulic press in a free upsetting mode: the temperature of the ingot is reduced to 1100 ℃ after homogenization treatment, the ingot is discharged from a furnace to be cogged after the temperature of the ingot is uniform, the cogging deformation is 40%, the rounding is carried out after upsetting, and the diameter of the billet is ensured to be 600mm.
And 2, carrying out surface machining on the blank after blank making, turning off black skin and surface defects, and obtaining the cylindrical forging blank, wherein the overall finish of the blank is Ra6.3.
Step 3, machining a stainless steel cylindrical gasket and a stainless steel annular gasket, wherein the height of the cylindrical gasket is 60mm, one end of the cylindrical gasket is rounded, and the radius r of the rounded corner is 30mm; the height of the annular gasket is 180mm, and the inner diameter is 1/3 of the diameter of the cylindrical forging stock. One non-rounded surface of the cylindrical gasket is welded to one end of the cylindrical forging stock, and the annular gasket is welded to the other end of the cylindrical forging stock, so that the alignment of the axes of the three is ensured.
And 4, spraying an anti-oxidation coating on the surface of the welded combined blank, heating the combined blank in a furnace after the coating is dried and the heating temperature is 1020 ℃, continuously preserving heat for 3 hours after the combined blank is thoroughly heated, discharging the combined blank from the furnace for hot extrusion, coating a glass lubricant on the surface of the combined blank before extrusion, and firstly feeding one end (head) of the welded cylindrical gasket into an extrusion die, clamping the glass lubricant pad between the extrusion die and the cylindrical gasket, wherein the extrusion speed is 20mm/s, and the overall extrusion ratio is 4.
Considering that the stainless steel cylindrical gasket at the head part is easy to fall off after extrusion is finished, the arc-shaped bulge at the head part is lightened, the combined blank is extruded completely, the stainless steel backing ring is coated by part of alloy metal at the tail part, and the adhered stainless steel backing ring is completely cut off. The bar stock produced by the method has good head and tail quality, good surface quality and small machining amount, and can realize 92% material utilization rate of the cylindrical forging stock. The axial grain size of the effective area of the bar is 5-6 grade, the grain size difference is 1 grade, and the nickel-based alloy bar has good overall structure uniformity.
Example 2
This example was used to prepare fine-grained nickel-based alloy bar stock with a diameter of 150 mm.
Step 1, performing blank making by using a free forging hydraulic press in an upsetting and drawing mode after homogenizing the cast ingot, wherein the blank making heating temperature is 1080 ℃, the upsetting deformation is 50%, and drawing to phi 350mm after upsetting.
And 2, carrying out surface machining treatment on the blank, and removing black skin and defects to obtain a cylindrical forging stock (namely an extrusion stock) with a smooth surface.
Step 3, machining a cylindrical gasket and a circular gasket by austenitic stainless steel, wherein the height of the cylindrical gasket is 40mm, and one end of the cylindrical gasket is rounded; the height of the annular gasket is 150mm, and the inner diameter is 1/4 of the diameter of the extrusion blank. One side of the cylindrical stainless steel gasket, which is not rounded, is welded to one end of the extrusion blank, and the axes of the cylindrical stainless steel gasket and the extrusion blank are overlapped during welding. The annular gasket is not welded.
And 4, heating the combined blank to 990 ℃, heating the annular gasket to 930 ℃, uniformly spraying an anti-oxidation coating on the front surface of the furnace, keeping the temperature of the blank for 2 hours after the blank is subjected to uniform temperature, discharging the blank from the furnace for hot extrusion, coating the surface of the blank with a glass lubricant before extrusion, and putting one end welded with the cylindrical gasket into an extrusion die, wherein the glass lubricant pad is arranged between the extrusion die and the cylindrical gasket. The extrusion speed was 30mm/s and the extrusion ratio was 5.5.
The stainless steel cylindrical gasket at the head part automatically drops after extrusion, and the round cap-shaped bulge at the head part of the bar stock is smaller; and (3) all the combined blanks are extruded, and all the stainless steel backing rings adhered at the tail parts are cut off. The axial grain size of the effective area of the bar is 5.5-6.5 grade, and the grade difference is 1 grade. Through measurement and calculation, compared with the traditional extrusion mode without gaskets, the application can improve the material utilization rate of the nickel-based alloy to 94 percent.
It is emphasized that the method for improving the utilization rate of the nickel-based alloy bar material manufactured by extrusion is suitable for extrusion forming of nickel-based bars with various sizes, and particularly when extrusion blanks are short and extrusion is smaller and the extrusion die angle is smaller, the difference of the axial grain size of the bars can be obviously reduced, and the utilization rate of the high-temperature alloy bar material can be improved. And obtaining the alloy bar with uniform structure from beginning to end and grain size difference less than or equal to 1 level.
Example 3
This example was used to prepare nickel-base alloy bar stock with a diameter of Φ300mm.
The method comprises the following steps:
step 1, cogging and forging a nickel-base alloy phi 660mm cast ingot by using a free forging hydraulic press in a free upsetting mode: the temperature of the ingot is reduced to 1120 ℃ after homogenization treatment, the ingot is discharged from a furnace to be cogged after the temperature of the ingot is uniform, the cogging deformation is 30%, the rounding is carried out after upsetting, and the diameter of the billet is ensured to be 900mm.
And 2, carrying out surface machining on the blank after blank making, turning off black skin and surface defects, and obtaining the cylindrical forging blank, wherein the overall finish of the blank is Ra6.3.
Step 3, machining a stainless steel cylindrical gasket and a stainless steel annular gasket, wherein the height of the cylindrical gasket is 100mm, one end of the cylindrical gasket is rounded, and the radius r of the rounded corner is 50mm; the height of the annular gasket is 200mm, and the inner diameter is 1/3 of the diameter of the cylindrical forging stock. One non-rounded surface of the cylindrical gasket is welded to one end of the cylindrical forging stock, and the annular gasket is welded to the other end of the cylindrical forging stock, so that the alignment of the axes of the three is ensured.
And 4, spraying an anti-oxidation coating on the surface of the welded combined blank, heating the combined blank in a furnace after the coating is dried and the heating temperature is 1080 ℃, continuously preserving heat for 4 hours after the combined blank is thoroughly heated, discharging the combined blank from the furnace for hot extrusion, coating a glass lubricant on the surface of the combined blank before extrusion, and firstly feeding one end (head) of the welded cylindrical gasket into an extrusion die, clamping the glass lubricant gasket between the extrusion die and the cylindrical gasket, wherein the extrusion speed is 10mm/s, and the overall extrusion ratio is 9.
Considering that the stainless steel cylindrical gasket at the head part is easy to fall off after extrusion is finished, the arc-shaped bulge at the head part is lightened, the combined blank is extruded completely, the stainless steel backing ring is coated by part of alloy metal at the tail part, and the adhered stainless steel backing ring is completely cut off. The bar stock produced by the method has good head and tail quality, good surface quality and small machining amount, and can realize the material utilization rate of 90 percent of the cylindrical forging stock. The axial grain size of the effective area of the bar is 5-6 grade, the grain size difference is 1 grade, and the nickel-based alloy bar has good overall structure uniformity.
Example 4
This example was used to prepare fine-grained nickel-based alloy bar stock with a diameter of Φ400 mm.
The method comprises the following steps:
step 1, cogging and forging a nickel-base alloy phi 760mm cast ingot by using a free forging hydraulic press in a free upsetting mode: the temperature of the ingot is reduced to 1150 ℃ after homogenization treatment, the ingot is discharged from a furnace for cogging after the temperature of the ingot is uniform, the cogging deformation is 40%, the rounding is carried out after upsetting, and the diameter of the billet is ensured to be 600mm.
And 2, carrying out surface machining on the blank after blank making, turning off black skin and surface defects, and obtaining the cylindrical forging blank, wherein the overall finish of the blank is Ra6.3.
Step 3, machining a stainless steel cylindrical gasket and a stainless steel annular gasket, wherein the height of the cylindrical gasket is 80mm, one end of the cylindrical gasket is rounded, and the radius r of the rounded corner is 40mm; the height of the annular gasket is 300mm, and the inner diameter is 1/2 of the diameter of the cylindrical forging stock. One non-rounded surface of the cylindrical gasket is welded to one end of the cylindrical forging stock, and the annular gasket is welded to the other end of the cylindrical forging stock, so that the alignment of the axes of the three is ensured.
And 4, spraying an anti-oxidation coating on the surface of the welded combined blank, heating the combined blank in a furnace after the coating is dried and the heating temperature is 1000 ℃, continuously preserving heat for 3 hours after the combined blank is heated thoroughly, discharging the combined blank from the furnace for hot extrusion, coating a glass lubricant on the surface of the combined blank before extrusion, and firstly feeding one end (head) of the welded cylindrical gasket into an extrusion die, clamping the glass lubricant gasket between the extrusion die and the cylindrical gasket, wherein the extrusion speed is 15mm/s, and the overall extrusion ratio is 2.25.
Considering that the stainless steel cylindrical gasket at the head part is easy to fall off after extrusion is finished, the arc-shaped bulge at the head part is lightened, the combined blank is extruded completely, the stainless steel backing ring is coated by part of alloy metal at the tail part, and the adhered stainless steel backing ring is completely cut off. The bar stock produced by the method has good head and tail quality, good surface quality and small machining amount, and can realize the material utilization rate of 90 percent of the cylindrical forging stock. The axial grain size of the effective area of the bar is 4.5-5.5 grade, the grain size difference is 1 grade, and the whole structure uniformity of the nickel-based alloy bar is good.
Example 5
This example was used to prepare fine-grained nickel-based alloy bar stock with a diameter of Φ350mm.
The method comprises the following steps:
step 1, cogging and forging a nickel-base alloy phi 480mm cast ingot by using a free forging hydraulic press in a free upsetting mode: the temperature of the ingot is reduced to 1140 ℃ after homogenization treatment, the ingot is discharged from a furnace for cogging after the temperature of the ingot is uniform, the cogging deformation is 50%, the rounding is carried out after upsetting, and the diameter of the billet is ensured to be 700mm.
And 2, carrying out surface machining on the blank after blank making, turning off black skin and surface defects, and obtaining the cylindrical forging blank, wherein the overall finish of the blank is Ra6.3.
Step 3, machining a stainless steel cylindrical gasket and a stainless steel annular gasket, wherein the height of the cylindrical gasket is 50mm, one end of the cylindrical gasket is rounded, and the radius r of the rounded corner is 20mm; the height of the annular gasket is 200mm, and the inner diameter is 1/4 of the diameter of the cylindrical forging stock. One non-rounded surface of the cylindrical gasket is welded to one end of the cylindrical forging stock, and the annular gasket is welded to the other end of the cylindrical forging stock, so that the alignment of the axes of the three is ensured.
And 4, spraying an anti-oxidation coating on the surface of the welded combined blank, heating the combined blank in a furnace after the coating is dried and the heating temperature is 1050 ℃, continuously preserving heat for 4 hours after the combined blank is thoroughly heated, discharging the combined blank from the furnace for hot extrusion, coating a glass lubricant on the surface of the combined blank before extrusion, and firstly feeding one end (head) of the welded cylindrical gasket into an extrusion die, clamping the glass lubricant pad between the extrusion die and the cylindrical gasket, wherein the extrusion speed is 25mm/s, and the overall extrusion ratio is 4.
Considering that the stainless steel cylindrical gasket at the head part is easy to fall off after extrusion is finished, the arc-shaped bulge at the head part is lightened, the combined blank is extruded completely, the stainless steel backing ring is coated by part of alloy metal at the tail part, and the adhered stainless steel backing ring is completely cut off. The bar stock produced by the method has good head and tail quality, good surface quality and small machining amount, and can realize 91% material utilization rate of the cylindrical forging stock. The axial grain size of the effective area of the bar is 5-6 grade, the grain size difference is 1 grade, and the nickel-based alloy bar has good overall structure uniformity.
Comparative example 1
This comparative example provides a conventional method of extrusion manufacturing nickel-based alloy bar stock comprising the steps of:
step 1, cogging and forging a nickel-based alloy phi 508mm cast ingot by using a free forging hydraulic press in a free upsetting mode: the temperature of the ingot is reduced to 1100 ℃ after homogenization treatment, the ingot is discharged from a furnace to be cogged after the temperature of the ingot is uniform, the cogging deformation is 30%, the rounding is carried out after upsetting, and the diameter of the billet is ensured to be 600mm.
And 2, carrying out surface machining on the blank after blank making, turning off black skin and surface defects, chamfering one end of the head of the blank, wherein the radius of the round angle is r100mm, and the overall finish of the blank is Ra6.3, so as to obtain the cylindrical forging blank.
And 3, spraying an anti-oxidation coating on the surface of the cylindrical forging stock, heating the cylindrical forging stock in a furnace after the coating is dried and the heating temperature is 1020 ℃, continuously preserving heat for 3 hours after the blank is thoroughly heated, discharging the cylindrical forging stock to carry out hot extrusion, coating a glass lubricant on the surface of the blank before extrusion, enabling the head of the blank to enter an extrusion die, clamping a glass lubricant pad between the extrusion die and the head of the blank, wherein the extrusion speed is 20mm/s, and the integral extrusion ratio is 4.
The bar obtained in this comparative example had a 3-grade head grain size, a 5-grade intermediate grain size, a 2-grade tail grain size, and poor overall structure uniformity. The head and tail are all cut off, and the material utilization rate is 78%.
Comparative example 2
This comparative example provides a method of extrusion manufacturing nickel-base alloy bar stock, similar to example 1, except that: in step 3, the tail of the cylindrical forging stock is welded with a cylindrical gasket instead of a circular ring gasket.
The bar obtained in this comparative example had a head grain size of 5, a middle grain size of 6, a tail grain size of 3.5, and poor overall structure uniformity. The head and tail are all cut off, and the material utilization rate is 82%.
The results of examples 1-5 and comparative examples 1-2 show that the method for improving the utilization rate of the nickel-base alloy bar material manufactured by extrusion can lead the overall strain of the blank to be more uniform and reduce the axial grain size level difference (for example, the level difference is below 1); the utilization rate of the expensive nickel-based alloy material (for example, the utilization rate is more than 90 percent) can be greatly improved, and the production cost is reduced.
The present application is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present application are intended to be included in the scope of the present application.
Claims (7)
1. A method for improving the utilization rate of nickel-based alloy bar materials manufactured by extrusion is characterized in that a cylindrical gasket (1) is arranged at the head part of a cylindrical forging stock (2) to be extruded, and a circular gasket (3) is arranged at the tail part of the cylindrical forging stock (2) to be extruded;
welding a cylindrical gasket (1) to the head of a cylindrical forging stock (2), and arranging a circular ring-shaped gasket (3) to the tail of the cylindrical forging stock (2); the axes of the cylindrical gasket (1), the cylindrical forging stock (2) and the annular gasket (3) are aligned;
the diameter of the cylindrical gasket (1) is equal to the diameter D of the cylindrical forging stock (2);
height H of the cylindrical gasket (1) 1 Is (1/15-1/6) D;
one end of the cylindrical gasket is rounded, the radius of the rounded corner is r 20-r 50mm, and one non-rounded side of the cylindrical gasket (1) is welded to one end of the cylindrical forging stock (2);
the inner diameter of the annular gasket (3) is eta times of the diameter of the cylindrical forging stock (2), and the range of eta values is 1/4-1/2;
the height H of the annular gasket (3) 2 Satisfies the following formula:
wherein: alpha is a die angle, and the biconical die is an average value of two angles; lambda is the extrusion ratio; x is the length of the bearing (5); r is the radius of the cylindrical forging stock (2).
2. The method according to claim 1, characterized in that it comprises:
step 1, cogging and blanking nickel-base alloy cast ingots by adopting a free forging upsetting or closed upsetting mode;
step 2, carrying out surface machining on the nickel-based alloy blank after blank making, and turning off black skin and surface defects to obtain a cylindrical forging blank;
step 3, welding a cylindrical gasket (1) to the head of a cylindrical forging stock (2), and arranging a circular ring-shaped gasket (3) to the tail of the cylindrical forging stock (2) to obtain a combined blank; the axial centers of the cylindrical gasket (1), the cylindrical forging stock (2) and the annular gasket (3) are aligned;
and step 4, heating the combined blank at 930-1080 ℃, continuously preserving heat for 1-4 hours after the combined blank is thoroughly heated, and discharging from a furnace for hot extrusion.
3. A method according to claim 2, characterized in that in step 3, the height of the cylindrical spacer (1) is 40-100 mm.
4. A method according to claim 2, characterized in that in step 3, the height of the annular gasket (3) is 100-300 mm.
5. The method according to any one of claims 2-4, wherein in step 3, the cylindrical gasket (1) and the annular gasket (3) are both made of austenitic stainless steel.
6. The method according to claim 2, wherein in step 4, the combined blank is subjected to a lubricant treatment prior to hot extrusion, the lubricant comprising a glass mat and glass frit applied to the surfaces of the cylindrical forging blank (2) and the cylindrical gasket (1), the glass mat being interposed between the extrusion die and the cylindrical gasket (1).
7. The method according to claim 2, wherein in the step 4, the extrusion ratio is 2 to 9 and the extrusion speed is 5 to 30mm/s at the time of hot extrusion.
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| CN101134213A (en) * | 2007-09-25 | 2008-03-05 | 浙江久立特材科技股份有限公司 | Hot extrusion steel tube blank trail pad |
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