A method for making a large-scale cross wedge rolling die surface uniform hardening

Abstract

The application provides a manufacturing method of a large-scale cross wedge rolling die surface uniform hardening, comprising: obtaining a to-be-rough-turned die; rough turning the to-be-rough-turned die to obtain a rough-turned die, the rough-turned die comprising a main body part and end parts located at two ends of the main body part, the end part having a diameter larger than that of the main body part, and the difference between the diameter of the end part and that of the main body part being a first preset threshold; performing first heat treatment on the rough-turned die to obtain a heat-treated die; performing finish turning on the heat-treated die so that the diameters of the main body part and the end part are both target diameters to obtain a finish-turned die; and performing second heat treatment on the finish-turned die to obtain a cross wedge rolling die. The diameter of the end part of the rough-turned die is increased, and then the rough-turned die is heat treated, and then the rough-turned die is processed to remove the amount, so that the hardness of the outer surface of the finish-turned die is uniform.

Description

Technical Field

[0001] This application relates to the field of steel mold manufacturing technology, and in particular to a method for manufacturing a large wedge cross rolling die with uniform surface hardening. Background Technology

[0002] Wedge cross rolling, a new steel rolling technology that emerged in 1961, is suitable for rolling variable cross-section rotating bodies. Two rolls with wedge-shaped passes rotate in the same direction along the wedge's advance, gradually rolling the billet into a variable cross-section rotating body. The wedge pass consists of three sections: wedge entry, forming, and finishing. Wedge cross rolling is a new process and technology for forming shaft parts. Scientifically, this process belongs to the intersection of metallurgy and mechanical engineering. Compared with traditional cutting and forging processes, it has advantages such as high production efficiency, material savings, and low production costs, and is widely recognized as an integral part of modern advanced manufacturing.

[0003] A wedge cross-rolling die includes a first roll and a second roll with a wedge. The first roll and the second roll rotate in the same direction, driving the cylindrical billet to rotate. Under the rolling action of the wedge, the billet forms a stepped shaft. Currently, large wedge cross-rolling dies have a diameter and height of over 1 meter. During the hardening process, the hardening results at both ends and the middle of the wedge cross-rolling die differ significantly; the ends are hard, while the middle is relatively soft, failing to achieve uniform hardening and thus not meeting technical requirements. Summary of the Invention

[0004] In view of this, the purpose of this application is to propose a method for manufacturing a large wedge cross rolling die with uniform surface hardening.

[0005] To achieve the above objectives, this application provides a method for manufacturing a large wedge cross rolling die with uniformly hardened surface, comprising:

[0006] Obtain the roughing mold;

[0007] The rough-machined mold is rough-machined to obtain a rough-machined mold. The rough-machined mold includes a main body and end portions located at both ends of the main body. The diameter of the end portions is larger than the diameter of the main body. The difference between the diameter of the end portions and the diameter of the main body is a first preset threshold.

[0008] The rough-machined die is subjected to a first heat treatment to obtain a heat-treated die;

[0009] The heat treatment mold is precision machined so that the diameter of the main body and the end portion are both the target diameter, so as to obtain the precision machined mold. The difference between the diameter of the main body and the target diameter is a second preset threshold, and the second preset threshold is less than the first preset threshold.

[0010] The precision-machined die is subjected to a second heat treatment to obtain a wedge cross rolling die.

[0011] Furthermore, the first heat treatment includes:

[0012] The rough mold is placed into a high-temperature kiln, so that the temperature of the rough mold rises to 860-870°C and is held for 5-7 hours to obtain a high-temperature mold.

[0013] The high-temperature mold is lifted out of the high-temperature kiln and placed in a room-temperature water tank for rapid cooling and hardening for 5-10 minutes to obtain a cooled mold.

[0014] The cooling mold is lifted out and placed in a room temperature oil bath for quenching until the temperature of the cooling mold is 120-180℃, thus obtaining the quenched mold.

[0015] The quenched mold is placed in a low-temperature kiln, where the temperature rises to 400-500°C and is held for 12-15 hours. It is then removed and cooled to 100-110°C for hardening treatment until the hardness is qualified, thus obtaining a heat-treated mold.

[0016] Furthermore, the second heat treatment also includes:

[0017] The precision-machined mold is placed into a low-temperature kiln, so that the temperature of the precision-machined mold rises to 400-500℃ and is held for 12-15 hours to obtain a low-temperature precision-machined mold.

[0018] The mold, after being precision machined at low temperature, is lifted out and cooled to 100-110℃;

[0019] Repeat the above steps 2-3 times to obtain the wedge cross rolling die.

[0020] Furthermore, the roughing die is composed of the following elements by mass percentage: carbon C 0.52-0.60, silicon Si 0.60-0.80, manganese Mn 1.30-1.50, sulfur S ≤0.035, phosphorus P ≤0.035, chromium Cr 0.30-0.40, nickel Ni ≤0.30, copper Cu ≤0.25, with the remainder being iron Fe and unavoidable impurities.

[0021] Furthermore, the roughing die also includes a transition section located between the end portion and the main body portion to connect the end portion and the main body portion, and the diameter of the transition section is larger than the diameter of the main body portion and smaller than the diameter of the end portion.

[0022] Furthermore, the outer edge of the transition section in the axial cross-section of the roughing die is an arc.

[0023] Furthermore, the outer edge of the transition section in the axial cross-section of the roughing die is a straight line.

[0024] Furthermore, the length of the connected end and the transition portion is 300 mm.

[0025] Furthermore, the first threshold is 10-15 mm.

[0026] Furthermore, the second threshold is 3-5 mm.

[0027] As can be seen from the above, the method for manufacturing a large wedge cross rolling die with uniform surface hardening provided by this application involves increasing the diameter of the end of the rough-turned die, and then performing a first heat treatment to achieve hardening. After the first heat treatment, the die is then precision-turned to make the hardness of the outer surface of the precision-turned die uniform. On this basis, a second heat treatment is performed on the precision-turned die to obtain a large wedge cross rolling die with uniform surface hardening. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in this application or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic flowchart illustrating the manufacturing method of uniformly hardening the surface of a large wedge cross rolling die according to an embodiment of this application.

[0030] Figure 2 This is a schematic diagram of the axial cross-sectional structure of the roughing die according to an embodiment of this application;

[0031] Figure 3 This is a schematic diagram showing the diameter and length of the axial cross-sectional structure of the roughing die in an embodiment of this application.

[0032] In the diagram: 1. Main body; 2. End; 3. Transition section. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0034] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this application should have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," and similar terms used in the embodiments of this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0035] As described in the background section, wedge cross rolling is a new steel rolling technology that emerged in 1961. It is suitable for rolling variable cross-section rotating bodies. Two rolls with wedge-shaped passes rotate in the same direction along the direction of wedge advance, gradually rolling the billet into a variable cross-section rotating body. The wedge pass consists of three sections: wedge entry, forming, and finishing. Wedge cross rolling is a new process and technology for forming shaft parts. Scientifically, this process belongs to the intersection of metallurgy and mechanical engineering. Compared with traditional part forming processes such as cutting and forging, it has advantages such as high production efficiency, saving raw materials, and low production costs, and is recognized as an integral part of modern advanced manufacturing.

[0036] A wedge cross-rolling die includes a first roll and a second roll with a wedge. The first roll and the second roll rotate in the same direction, driving the cylindrical billet to rotate. Under the rolling action of the wedge, the billet forms a stepped shaft. Currently, large wedge cross-rolling dies have a diameter and height of over 1 meter. During the hardening process, the hardening results differ significantly between areas within 300mm of the end face and areas beyond 300mm of the end face. The ends are hard, while the middle is relatively soft, failing to achieve uniform hardening and thus not meeting technical requirements.

[0037] To solve the above problems, this application increases the diameter of the end of the roughing die and then performs a first heat treatment to harden it. After the first heat treatment, it is then subjected to a de-weighting process to make the hardness of the outer surface of the finished die uniform, thereby obtaining a large wedge cross rolling die with uniform surface hardening.

[0038] The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0039] refer to Figure 1 A method for manufacturing a large wedge cross-rolling die with uniformly hardened surface, comprising:

[0040] Step S101: Obtain the roughing mold;

[0041] In this step, the roughing die is a wedge cross rolling die formed by centrifugal casting.

[0042] In some embodiments, the roughing die is composed of the following elements in the following mass percentages: carbon (C) 0.52–0.60, silicon (Si) 0.60–0.80, manganese (Mn) 1.30–1.50, sulfur (S) ≤0.035, phosphorus (P) ≤0.035, chromium (Cr) 0.30–0.40, nickel (Ni) ≤0.30, copper (Cu) ≤0.25, with the remainder being iron (Fe) and unavoidable impurities.

[0043] Specifically, the above-mentioned elemental composition structure is the composition structure of 55Mn material, that is, the roughing die is made of 55Mn material. 55Mn material has poor hardenability, and the hard layer formed on the outer surface of the die after hardening is about 10mm. Therefore, on this basis, the roughing die made of 55Mn material is subjected to uniform surface hardening treatment so that the outer surface of the final wedge cross rolling die is uniformly hardened, that is, the hardness is uniform.

[0044] Step S102: Roughly machine the mold to be rough machined to obtain a rough machined mold. The rough machined mold includes a main body 1 and end portions 2 located at both ends of the main body. The diameter of the end portions 2 is larger than the diameter of the main body 1. The difference between the diameter of the end portions 2 and the diameter of the main body 1 is a first preset threshold.

[0045] In this step, the mold to be rough-machined is rough-machined so that the diameter of the two ends 2 of the mold after rough machining is larger than the diameter of the main body 1. That is, the outer circle size of the ends 2 is increased so that after the mold is hardened in the subsequent rough machining, the increased part on the ends 2 is the part with greater hardness after hardening, thereby making the part on the ends 2 with the same diameter as the main body 1 have the same hardness.

[0046] In some embodiments, the first threshold is 10-15 mm.

[0047] Specifically, taking advantage of the poor hardenability of 55Mn material, the hard layer formed on the outer surface of the mold after hardening is about 10mm. The value of the diameter of the end 2 being greater than the diameter of the main body 1, i.e. the first threshold, is set at 10-15mm. This can further ensure that after hardening, the enlarged part on the end 2 is the part with greater hardness after hardening, thereby making the part on the end 2 with the same diameter as the main body 1 have the same hardness.

[0048] Step S103: Perform a first heat treatment on the rough-machined mold to obtain a heat-treated mold;

[0049] In this step, the roughing die undergoes a first heat treatment, including quenching and tempering, to harden the roughing die. This is an essential step to obtain a wedge cross rolling die with uniform surface hardening and deformation resistance.

[0050] In some embodiments, the first heat treatment includes:

[0051] The rough mold is placed into a high-temperature kiln, so that the temperature of the rough mold rises to 860-870°C and is held for 5-7 hours to obtain a high-temperature mold.

[0052] The high-temperature mold is lifted out of the high-temperature kiln and placed in a room-temperature water tank for rapid cooling and hardening for 5-10 minutes to obtain a cooled mold.

[0053] The cooling mold is lifted out and placed in a room temperature oil bath for quenching until the temperature of the cooling mold is 120-180℃, thus obtaining the quenched mold.

[0054] The quenched mold is placed in a low-temperature kiln, where the temperature rises to 400-500°C and is held for 12-15 hours. It is then removed and cooled to 100-110°C for hardening treatment until the hardness is qualified, thus obtaining a heat-treated mold.

[0055] In this embodiment, the first heat treatment steps are quenching and tempering. The quenching uses water and oil to perform dual-liquid quenching on the rough-machined mold. Taking advantage of the principle that water has a higher cooling capacity than oil, the hardenability and hardenability of the quenched mold are improved, and the slow cooling operation is ensured when approaching the martensitic transformation in the later stage. This prevents the quenched mold from cracking and solves the problem of poor hardenability and hardenability of the quenched mold.

[0056] The tempering temperature is lower than the quenching temperature, which allows for hardening treatment of the quenched mold to obtain a heat-treated mold with qualified hardness. This ensures the hardness of the heat-treated mold and makes it meet the hardness requirements of the subsequent precision machining steps.

[0057] Step S104: Perform precision machining on the heat treatment mold so that the diameters of the main body 1 and the end 2 are both target diameters, to obtain a precision-machined mold. The difference between the diameter of the main body 1 and the target diameter is a second preset threshold, which is less than the first preset threshold.

[0058] In this step, the heat treatment mold is precision-machined to remove excess material from the end portion 2 and the main body portion 1. The amount removed from the end portion 2 is greater than that removed from the main body portion 1 because the area of ​​the end portion 2 in contact with the liquid during quenching is larger than that of the main body portion 1. Therefore, the hardness of the outer surface of the end portion 2 is greater than that of the outer surface of the main body portion 1. During the precision machining process, in order to make the diameters of the end portion 2 and the main body portion 1 the same and both the target diameter, the diameter reduction of the end portion 2 must be greater than that of the main body portion 1. The excess material removed from the end portion 2 is the part with increased hardness, so that the outer surface hardness of the end portion 2 and the main body portion 1 is the same after precision machining. Therefore, the outer surface hardness of the mold is the same after precision machining, achieving uniform hardening, that is, obtaining a large wedge cross rolling mold with uniform surface hardening.

[0059] In some embodiments, the second threshold is 3-5 mm.

[0060] In this embodiment, the second threshold is the difference between the diameter of the main body 1 and the target diameter. The second threshold is set to further ensure the smoothness of the outer surface of the precision-machined mold, so that the precision-machined mold has higher accuracy and is closer to the finished product. The accuracy of the rough-machined mold is less than that of the precision-machined mold, so the second threshold needs to be reserved to allow operating space for the precision machining operation.

[0061] Step S105: Perform a second heat treatment on the precision-machined die to obtain a wedge cross rolling die.

[0062] In this step, the precision-machined die is subjected to multiple tempering operations to completely eliminate the casting stress of the precision-machined die, thereby obtaining the deformation-resistant wedge cross rolling die.

[0063] In some embodiments, the second heat treatment further includes:

[0064] Step (1): The precision-machined mold is placed into a low-temperature kiln, and the precision-machined mold is heated to 400-500℃ and kept at that temperature for 12-15 hours to obtain a low-temperature precision-machined mold.

[0065] Step (2): The mold after low-temperature precision machining is lifted out and cooled to 100-110℃;

[0066] Repeat steps (1) and (2) above 2-3 times to obtain the wedge cross rolling die.

[0067] In this embodiment, the second heat treatment step is multiple tempering. The multiple tempering method is used to completely eliminate the casting stress of the precision-machined mold and obtain the wedge cross rolling mold that is resistant to annular deformation.

[0068] In some embodiments, the roughing die further includes a transition portion 3, which is located between the end portion 2 and the main body portion 1 to connect the end portion 2 and the main body portion 1, and the diameter of the transition portion 3 is larger than the diameter of the main body portion 1 and smaller than the diameter of the end portion 2.

[0069] In this embodiment, the transition portion is used to complete the transition from the main body portion 1 to the end portion 2. During the heat treatment process, the transition portion 3 is located between the end portion 2 and the main body portion 1, and its hardness is also between the end portion 2 and the main body portion 1. Therefore, setting the diameter of the transition portion 3 between the diameter of the end portion 2 and the diameter of the main body portion 1 can further ensure that the hardness of the outer surface of the precision-machined mold is uniform after precision machining.

[0070] In this embodiment, there are two ends 2, which are located at both ends of the main body 1. Therefore, there are also two transition parts 3, which connect the two ends 2 to the main body 1 respectively.

[0071] In some embodiments, the outer edge of the transition portion 3 in the axial cross-section of the roughing die is an arc.

[0072] In this embodiment, the diameter of the transition portion 3 increases with the distance from the main body portion 1, and the rate of change of its diameter becomes slower and slower. This makes the outer edge of the axial tangent of the transition portion 3 an arc, which can serve to transition between the main body portion 1 and the end portion 2. It can also further ensure that the hardness of the inner diameter of the transition portion 3 is comparable to that of the target diameter position, which lays the foundation for obtaining uniform hardness of the outer surface of the mold after precision machining.

[0073] In some embodiments, the outer edge of the transition portion 3 in the axial section of the roughing die is a straight line.

[0074] In this embodiment, the diameter of the transition portion 3 increases with the distance from the main body portion 1, and the rate of change of its diameter is the same. That is, the outer edge of the axial tangent of the transition portion 3 is a straight line, which realizes the function of uniformly transitioning the main body portion 1 and the end portion 2, ensuring that the hardness of the position where the inner diameter of the transition portion 3 is the target diameter is comparable, thus laying the foundation for the uniform hardness of the outer surface of the mold after precision machining.

[0075] In some embodiments, the length of the connected end portion 2 and the transition portion 3 is 300 mm.

[0076] Specifically, in the existing large wedge cross rolling die, the hardness after quenching within 300mm of its end face is greater than that in the middle position, that is, greater than that of the main body 1. Therefore, in order to achieve uniform quenching, the diameter of the end 2 is increased. The transition part 3 is used to realize the transition from the main body 1 to the end 2. That is, the length of the increased diameter should be 300mm from the end face. Setting the length of the connected end 2 and the transition part 3 to 300mm can ensure that the hardness of the outer surface of the die after precision turning is uniform, thus achieving uniform surface quenching.

[0077] Specifically, the roughing mold has symmetrically provided end portions 2 and transition portions 3 at both ends.

[0078] For example, such as Figure 2 and Figure 3 The diagram shows the axial cross-sectional structure of the roughing die. The target diameter is d, the main body diameter is D1, the end diameter is D2, the transition diameter is D3, the transition length is L1, the end length is L2, and the length of the connected transition and end is L1 + L2 = L, which is 300 mm. The first threshold is the difference between D2 and D1, and the second threshold is the difference between D1 and d. The first threshold is 10-15 mm, and the second threshold is 3-5 mm, meaning that the difference between D2 and D1 is between 10-15 mm, and the difference between D1 and d is between 3-5 mm.

[0079] Specifically, the determination of the first threshold was based on a large number of experiments, and the specific experimental data is shown in Table 1:

[0080] Table 1

[0081] 5 5～7 10 2～3 12 0～2 15 -2～0 20 -5～3

[0082] As can be seen from the table above, when the first threshold is 10, 12 and 15, the hardness of the end part 2 and the main body 1 are closest after precision turning, that is, the difference is small. This can achieve the technical effect of the same hardness of the outer surface of the mold after precision turning, that is, to achieve uniform hardening of the outer surface of the large wedge cross rolling mold.

[0083] It should be noted that the method in this embodiment can be executed by a single device, such as a computer or server. The method can also be applied in a distributed scenario, where multiple devices cooperate to complete the task. In such a distributed scenario, one of these devices may execute only one or more steps of the method in this embodiment, and the multiple devices will interact with each other to complete the method described.

[0084] It should be noted that the above description describes some embodiments of this application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in a different order than that shown in the above embodiments and still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0085] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this application (including the claims) is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the embodiments of this application as described above, which are not provided in the details for the sake of brevity.

[0086] Additionally, to simplify the description and discussion, and to avoid obscuring the embodiments of this application, the well-known power / ground connections to integrated circuit (IC) chips and other components may or may not be shown in the provided drawings. Furthermore, the apparatus may be shown in block diagram form to avoid obscuring the embodiments of this application, and this also takes into account the fact that the details of the implementation of these block diagram apparatuses are highly dependent on the platform on which the embodiments of this application will be implemented (i.e., these details should be fully understood by those skilled in the art). While specific details (e.g., circuits) have been set forth to describe exemplary embodiments of this application, it will be apparent to those skilled in the art that the embodiments of this application can be implemented without these specific details or with variations thereof. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0087] Although this application has been described in conjunction with specific embodiments thereof, many substitutions, modifications and variations of these embodiments will be apparent to those skilled in the art from the foregoing description.

[0088] The embodiments of this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of this application should be included within the protection scope of this application.

Claims

1. A method for manufacturing a large wedge cross-rolling die with uniformly hardened surface, characterized in that, include: Obtain the roughing mold; The rough-machined mold is rough-machined to obtain a rough-machined mold. The rough-machined mold includes a main body and end portions located at both ends of the main body. The diameter of the end portions is larger than the diameter of the main body. The difference between the diameter of the end portions and the diameter of the main body is a first preset threshold. The rough-machined die is subjected to a first heat treatment to obtain a heat-treated die; The heat treatment mold is precision machined so that the diameter of the main body and the end portion are both the target diameter, so as to obtain the precision machined mold. The difference between the diameter of the main body and the target diameter is a second preset threshold, and the second preset threshold is less than the first preset threshold. The precision-machined die is subjected to a second heat treatment to obtain a wedge cross rolling die; The roughing die further includes a transition section located between the end portion and the main body portion to connect the end portion and the main body portion. The diameter of the transition section is larger than the diameter of the main body portion and smaller than the diameter of the end portion. The first preset threshold is 10-15mm, and the second preset threshold is 3-5mm. The rough-machined mold is rough-machined so that the diameter of the two ends of the mold after rough machining is larger than the diameter of the main body. That is, the outer diameter of the ends is increased so that after the mold is hardened in the subsequent process, the increased portion on the ends will be the part with greater hardness after hardening, thus making the part on the ends with the same diameter as the main body have the same hardness. The heat-treated mold is then finish-machined to remove excess material from the ends and the main body. The amount removed from the ends is more than the amount removed from the main body. The excess material removed from the ends is the part with increased hardness, so that the outer surface hardness of the ends and the main body is the same after finish machining.

2. The method for manufacturing a large wedge cross-rolling die with uniform surface hardening according to claim 1, characterized in that, The first heat treatment includes: The rough-carved mold is placed into a high-temperature kiln, so that the temperature of the rough-carved mold rises to 860-870℃ along with the temperature inside the high-temperature kiln and is held for 5-7 hours to obtain a high-temperature mold. The high-temperature mold is lifted out of the high-temperature kiln and placed in a room-temperature water tank for rapid cooling and hardening for 5-10 minutes to obtain a cooled mold. The cooling mold is lifted out and placed in a room temperature oil bath for quenching until the temperature of the cooling mold is 120-180℃, thus obtaining the quenched mold. The quenched mold is placed in a low-temperature kiln, where the temperature rises to 400-500°C and is held for 12-15 hours. It is then removed and cooled to 100-110°C for hardening treatment until the hardness is qualified, thus obtaining a heat-treated mold.

3. The method for manufacturing a large wedge cross-rolling die with uniform surface hardening according to claim 2, characterized in that, The second heat treatment includes: The precision-machined mold is placed into a low-temperature kiln, so that the temperature of the precision-machined mold rises to 400-500℃ and is held for 12-15 hours to obtain a low-temperature precision-machined mold. The mold, after being precision machined at low temperature, is lifted out and cooled to 100-110℃; Repeat the above steps 2-3 times to obtain the wedge cross rolling die.

4. The method for manufacturing a large wedge cross-rolling die with uniformly hardened surface according to claim 1, characterized in that, The roughing die is composed of the following elements by mass percentage: carbon (C) 0.52-0.60, silicon (Si) 0.60-0.80, manganese (Mn) 1.3-1.50, sulfur (S) ≤0.035, phosphorus (P) ≤0.035, chromium (Cr) 0.30-0.40, nickel (Ni) ≤0.30, copper (Cu) ≤0.25, with the remainder being iron (Fe) and unavoidable impurities.

5. The method for manufacturing a large wedge cross-rolling die with uniform surface hardening according to claim 1, characterized in that, The outer edge of the transition section in the axial section of the roughing die is an arc.

6. The method for manufacturing a large wedge cross-rolling die with uniform surface hardening according to claim 1, characterized in that, The outer edge of the transition section in the axial section of the roughing die is a straight line.

7. The method for manufacturing a large wedge cross-rolling die with uniform surface hardening according to claim 1, characterized in that, The length of the connected end and the transition portion is 300 mm.

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