Preparation method of long crescent stepped boss for fusion reactor and molding bed

Abstract

The invention discloses a preparation method of a long crescent stepped boss for a fusion reactor and a molding bed. The heating and forging temperatures and the heat preservation time are controlled, the deformation amount of each heating number is designed and controlled, crystal grains are made to be uniform and refined, a pre-forming tire mold and a forming mold are designed, and the arc-shaped stepped boss is formed step by step. According to the method, the initial forging temperature of 1180 DEG C is adopted in the large-deformation forging stage of a steel ingot, the initial forging temperature of 1150 DEG C is adopted in the small-deformation stage of a blank, and 20%-30% of deformation is reserved at the forming heating number of 1150 DEG C. According to the method, a long-crescent-shaped product with the stepped boss can be forged and formed on a forming die, the thickness of a forged section is reduced, uniform austenite grains and good performance are obtained, the grain size is larger than or equal to grade 4, and the yield is high. All-directional attenuation of ultrasonic flaw detection bottom waves is reduced, and material loss, machining loss and cost are reduced.

Description

TECHNICAL FIELD

[0001] The application relates to the field of plastic forming of metal materials, and particularly relates to a preparation method of a long crescent-shaped stepped boss for a fusion reactor and a forming mold. BACKGROUND

[0002] The TF coil box in a compact fusion energy experimental device (BEST) is a magnetic field system structure required for maintaining plasma discharge, and is made of 316LN austenitic stainless steel and subjected to complex working conditions of cooling, excitation, discharge and the like. A long crescent-shaped stepped boss structure product is an important part of the BEST TF coil box, and a structural diagram is shown in the figure. Figure 1 The crescent arc is longer than 4m, the thickness is relatively thick, and the forging forming has the difficulties of long heating time, poor forging penetration, large difference between sections, great forming difficulty, difficult grain size control and large attenuation in ultrasonic flaw detection. Meanwhile, the TF coil box is a key part of the magnetic system, and the magnetic property is very strict, so the ferrite content and the magnetic permeability need to be controlled, and the forging forming cannot be performed at low temperature.

[0003] A disc forging piece mold blank forming method with upper and lower bosses is disclosed in Chinese patent CN111761017B, in which a titanium alloy bar blank is heated to below the beta transformation temperature in stages, the first time is 0.6-0.8 min / mm*Dmm, wherein D is the diameter of the titanium alloy bar blank, and the diameter of the forging piece is used for stage heat preservation. Chinese patent CN103492099B discloses a manufacturing method of stepped forging material, in which the steps of obtaining a primary forging material, heating an austenitic stainless steel columnar raw material to 1000-1080 DEG C, then forging the full length of the raw material into a cylindrical shape by reciprocating forging with a forging ratio of 1.5 or more without heating the raw material, the step of obtaining a secondary forging material, gradually forming a small-diameter shaft portion by reciprocating forging without reheating the primary forging material, and ending the forging before the surface temperature of the final forging portion is reduced to 300 DEG C or more from the heating temperature of the raw material, thereby forming a large-diameter flange portion and a small-diameter shaft portion, and the step of performing solid solution heat treatment, heating the secondary forging material to 1040-1100 DEG C for 30 minutes or more. The above two patents achieve forming from different directions, but the above two processes cannot achieve the effect for important parts such as the BEST TF coil box. SUMMARY

[0004] The application aims to provide a preparation method of a long crescent-shaped stepped boss for a fusion reactor and a forming mold.

[0005] The technical scheme of the present application is a preparation method of a long crescent-shaped stepped boss for a fusion reactor, comprising the following steps, Step 1: The steel ingot is preheated to 800-850 DEG C in the first stage, and is kept at 0.4-0.6 min / mm according to the cross-sectional thickness; and is preheated to 1180±20 DEG C in the second stage, and is kept at 0.6-0.8 min / mm according to the cross-sectional thickness; Step 2: Forming a square block, cutting off the ingot head and tail, and performing upsetting and drawing, forging and rolling and forging square processing to obtain a square block with a size of LxWxT; Step 3: Preforming the stepped boss, placing the square block into the boss mold, and pressing down along the length L direction to form a stepped boss blank with a small end height H1 and a large end height H; Step 4: Forming a crescent-shaped curve, placing the stepped boss blank on the horse frame, pressing the center of the large end with a hydraulic machine, and bending into a crescent-shaped blank; Step 5: Final forging and filling, placing the crescent-shaped blank into the forming mold, pressing the large end height H part into two-step ladder with a large punch, and making the total height of the two-step ladder 0.7H-0.8H to make the blank fill the forming mold.

[0006] Further, the material needs to be kept at 350-450 DEG C in the heating furnace for 3h before the first stage of step 1.

[0007] Further, after the three processes of step 2 are completed, when the blank temperature is less than or equal to 850 DEG C, immediately return to the furnace and heat to 1180 DEG C and keep for 0.4 min / mm.

[0008] Further, when the square block temperature of step 3 is less than or equal to 850 DEG C, return to the furnace and heat to 1150 DEG C and keep for 0.4 min / mm.

[0009] Further, when the crescent-shaped blank temperature of step 4 is less than or equal to 850 DEG C, return to the furnace and heat to 1150 DEG C and keep for 0.3 min / mm.

[0010] Further, the grain size of the product after final forging is greater than or equal to 4 levels (according to ASTM E112 standard), and the ultrasonic flaw detection has no bottom wave attenuation.

[0011] A forming device comprises a boss mold and a forming mold, The boss mold is assembled by a plurality of detachable sliding blocks, and the inside is provided with two stepped boss grooves; the forming mold has a crescent-shaped cavity, and three stepped boss grooves are arranged at the bottom, and the total depth matches the product size.

[0012] Further, the height of the boss groove in the boss mold is H and H1.

[0013] Further, the upper end step height of the shaped tire membrane is H1, and the height sum of the second step and the third step is 0.7-0.8H.

[0014] Advantages of the present application: 1. The process of the present application controls the heating and forging temperature and the holding time, designs to control the deformation amount of each heating, and makes the grain uniform and refined.

[0015] 2. The present application designs a pre-shaped tire membrane and a shaping die to gradually shape the arc-shaped stepped boss. In the large deformation forging stage of the ingot, the initial forging temperature is 1180℃, in the small deformation stage of the blank, the initial forging temperature is 1150℃, and the initial forging temperature of the forming heating is 1150℃, which reserves 20%-30% deformation amount. This method can make the long crescent-shaped strip with stepped boss product in the tire membrane forging and forming, reduce the forging section thickness, get uniform austenite grain and good performance, the grain size is ≥4 levels, reduce the attenuation of the bottom wave of ultrasonic flaw detection in all directions, reduce material loss and processing loss and cost, the magnetic permeability μ is detected between 1.002-1.006, which meets the requirement of μ≤1.03. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0017] Figure 1 is a preparation method flowchart of a long crescent-shaped strip with stepped boss for fusion reactor; Figure 2 is a three-dimensional schematic diagram of the present application using boss tire mold to form square block into stepped boss; Figure 3 is a front view of the present application using boss tire mold to form square block into stepped boss; Figure 4 is a top view of the present application using boss tire mold to form square block into stepped boss; Figure 5 is a three-dimensional schematic diagram of the boss tire mold of the present application; Figure 6 is a three-dimensional schematic diagram of the shaped tire membrane of the present application; Figure 7 is a three-dimensional schematic diagram of the final forging of the shaped tire membrane in the present application; Figure 8 is a product grain size diagram of embodiment 1 of the present application Figure 1 ; Figure 9 is a product grain size diagram of embodiment 2 of the present application Figure 2 ; Figure 10 Product grain size of Example 3 of the present application Figure 3 ; Figure 11 Product magnetic permeability of Example 1 of the present application Figure 1 ; Figure 12 Product magnetic permeability of Example 2 of the present application Figure 2 ; Figure 13 Product magnetic permeability of Example 3 of the present application Figure 3 ; Reference numerals: 1 - shaped tire membrane; 2 - boss tire membrane. DETAILED DESCRIPTION

[0018] The present application will be further described below in conjunction with the accompanying drawings and specific examples, but should not be understood as limiting the scope of the subject matter described herein to the following examples, and any modifications, substitutions and changes made according to ordinary technical knowledge and conventional means in the art without departing from the above technical idea of the present application are included in the scope of the present application.

[0019] Reference Figures 1-7 , Example 1: A method for preparing a long crescent-shaped band with stepped boss for a fusion reactor, comprising the following steps: Step 1: material pretreatment Put the steel ingot made of 316LN austenitic stainless steel into a 350℃ heating furnace for 3h; First stage heating to 800, 0.4 min / mm according to cross-sectional thickness, and holding; Second stage heating to 1180, 0.6 min / mm according to cross-sectional thickness, and holding; Step 2: blank forming Cut off the ingot head and tail, and perform upsetting and drawing, forging and rolling, and forging square treatment to obtain a square block with size L x W x T; At this time, when the blank temperature is 800℃, immediately reheat to 1180℃ and hold for 0.4 min / mm; Step 3: stepped boss preforming Put the square block into the boss die, 1, and press it along the length direction to form a stepped boss blank with small end height H1 and large end height H; the boss die is assembled by a plurality of detachable sliding blocks, and has two stepped boss grooves inside with depths of H and H1; at this time, the blank temperature is 800℃, reheat to 1150℃ and hold for 0.4 min / mm; Step 4: crescent bending forming Put the stepped boss blank on the horse frame, press the center of the large end with the hydraulic machine upper anvil, and bend it into a crescent-shaped blank; At this time, the blank temperature is 800℃, and the furnace is heated to 1150℃ and kept for 0.3 min / mm; Step 5: final forging filling Put the crescent-shaped blank into the forming mold 2, and press the large end height H to two stepped types with a total height of 0.7H~0.8H, a deformation of 20%~30%, so that the blank fills the crescent-shaped stepped boss groove, The forming mold: the cavity is crescent-shaped, and three stepped boss grooves are set at the bottom, and the total depth matches the product size.

[0020] The reheat operation in steps 2, 3, and 4 is immediately executed when the blank temperature drops to ≤850℃.

[0021] Reference Figure 8 The grain size of the product after final forging is 5, and according to the ASTM E112 standard, and there is no bottom wave attenuation in ultrasonic flaw detection, according to Figure 11 The magnetic permeability of the product after final forging is less than 1.03.

[0022] Example 2: A preparation method of a long crescent-shaped stepped boss for a fusion reactor, comprising the following steps: Step 1: material pretreatment Put the 316LN austenitic stainless steel into a 450℃ heating furnace for 3h; The first stage is heated to 850℃, and the section thickness is kept at 0.6 min / mm; The second stage is heated to 1200℃, and the section thickness is kept at 0.8 min / mm; Step 2: blank forming Cut off the ingot head and tail, and perform upsetting and lengthening, forging and rolling, and square processing to obtain a square block with a size of L×W×T; When the blank temperature is ≤850℃, immediately reheat to 1180℃ and keep for 0.4 min / mm; Step 3: stepped boss preforming Put the square block into the boss mold and press it in the length L direction to form a stepped boss blank with a small end height H1 and a large end height H; The boss mold is assembled by a plurality of detachable sliding blocks, and two stepped boss grooves are arranged inside, with depths of H and H1 respectively; At this time, the blank temperature is 850℃, and the furnace is heated to 1150℃ and kept for 0.4 min / mm; Step 4: crescent bending forming Put the stepped boss blank on the horse frame, press the center of the large end with the hydraulic upper anvil, and bend it into a crescent-shaped blank; At this time, the blank temperature is 850℃, and the furnace is heated to 1150℃ and kept for 0.3 min / mm; Step 5: final forging Put the crescent-shaped blank into the forming mold, and press the large end height H to two stepped types with a total height of 0.7H~0.8H and a deformation of 20%~30%, so that the blank fills the crescent-shaped stepped boss groove, The furnace heating operation described in steps 2, 3, and 4 is immediately performed when the blank temperature drops to ≤850℃.

[0023] Reference Figure 9 The grain size of the product after final forging is 5 levels, and the ultrasonic flaw detection has no bottom wave attenuation according to ASTM E112 standard, and Figure 12 The magnetic permeability of the product after final forging is less than 1.03.

[0024] Example 3: A preparation method of a long crescent-shaped stepped boss for a fusion reactor, comprising the following steps: Step 1: material pretreatment Put the 316LN austenitic stainless steel into a 400℃ heating furnace for 3h; The first stage is heated to 810℃, and the section thickness is kept for 0.5 min / mm; The second stage is heated to 1190℃, and the section thickness is kept for 0.5 min / mm; Step 2: blank forming Cut off the ingot head and tail, perform upsetting and lengthening, forging and rolling, and square treatment to obtain a square block with size L×W×T; When the blank temperature is ≤850℃, immediately heat the furnace to 1180℃ and keep for 0.4 min / mm; Step 3: stepped boss preforming Put the square block into the boss mold and press it along the length direction to form a stepped boss blank with a small end height H1 and a large end height H; the boss mold is assembled by several detachable sliding blocks, and two stepped boss grooves are arranged inside, with depths of H and H1 respectively; at this time, the blank temperature is 780℃, and the furnace is heated to 1150℃ and kept for 0.4 min / mm; Step 4: crescent bending forming Put the stepped boss blank on the horse frame, press the center of the large end with the hydraulic upper anvil, and bend it into a crescent-shaped blank; At this time, the blank temperature is 780℃, and the furnace is heated to 1150℃ and kept for 0.3 min / mm; Step 5: final forging The crescent-shaped blank is put into the forming die, and the large punch is used to press the height H of the large end into two stepped types, the total height is 0.7H~0.8H, the deformation amount is 20%~30%, so that the blank fills the crescent-shaped stepped boss groove, The re-melting heating operations in steps 2, 3 and 4 are all executed immediately when the blank temperature is reduced to ≤850℃.

[0025] Referring to Figure 10 The grain size of the product after finish forging is 5 levels according to the ASTM E112 standard, and there is no bottom wave attenuation in ultrasonic flaw detection, referring to Figure 13 The magnetic permeability of the product after finish forging is less than 1.03.

[0026] The preparation method of the long crescent-shaped stepped boss for fusion reactors and the forming die are described in detail above, and specific examples are applied to describe the structure and working principle of the present application. The above examples are only used to help understand the method and core idea of the present application. It should be pointed out that for ordinary skilled persons in the technical field, some improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A method for manufacturing a long crenel-shaped band with stepped bosses for a fusion reactor, characterized by: It comprises the following steps, Step 1: the ingot is preheated to 800-850 DEG C in the first stage, and is kept for 0.4-0.6 min / mm according to the cross-sectional thickness; and is preheated to 1180 DEG C ± 20 DEG C in the second stage, and is kept for 0.6-0.8 min / mm according to the cross-sectional thickness; Step 2: the square block is formed, the ingot head and tail are cut off, upsetting and elongation, forging and rolling and forging square treatment are carried out, and the square block with the size of LxWxT is obtained; Step 3: the stepped boss is preformed, the square block is placed into the boss mold, and is pressed in the length L direction, and the stepped boss blank with the small end height H1 and the large end height H is formed; Step 4: the crescent bending is formed, the stepped boss blank is placed on the horse frame, the center of the large end is pressed by the hydraulic machine upper anvil, and the crescent blank is bent; Step 5: the final forging is filled, the crescent blank is placed into the forming mold, the large end height H part is pressed into two-step ladder by the large punch, the total height of the two-step ladder is 0.7H-0.8H, and the blank is filled into the forming mold; The step 1 and the step 2 are large deformation forging of the ingot, the initial forging temperature is 1180 DEG C, the steps 3-5 are small deformation forging of the blank, the initial forging temperature is 1150 DEG C, and 20%-30% deformation is reserved during the small deformation forging.

2. The method according to claim 1, wherein the long crenel-shaped band with stepped bosses for fusion reactors is characterized in that: The material needs to be kept in the heating furnace at 350 DEG C-450 DEG C for 3h before the first stage of the step 1.

3. The method of claim 1, wherein the long crenel-shaped band with stepped bosses is prepared by the following steps: After the three processes of the step 2 are completed, the blank is immediately returned to the furnace and heated to 1180 DEG C and kept for 0.4 min / mm when the temperature is less than or equal to 850 DEG C. ​ 4. The method of claim 1, wherein the long crenel-shaped band with stepped bosses is prepared by the steps of: The square block is returned to the furnace and heated to 1150 DEG C and kept for 0.4 min / mm when the temperature is less than or equal to 850 DEG C in the step 3. ​ 5. The method of claim 1, wherein the long crenel-shaped band with stepped bosses is prepared by the steps of: The crescent blank is returned to the furnace and heated to 1150 DEG C and kept for 0.3 min / mm when the temperature is less than or equal to 850 DEG C in the step 4. ​ 6. The method of claim 1, wherein the long crenel-shaped band with stepped bosses is prepared by the steps of: The grain size of the product after the final forging is greater than or equal to 4 levels, and the ultrasonic flaw detection has no bottom wave attenuation. ​ 7. A forming device for carrying out the method according to any one of claims 1 to 6, characterized in that The boss mold and the forming mold are included, The boss mold is assembled by a plurality of detachable sliding blocks, and the internal two-step boss grooves are arranged; the forming mold is crescent-shaped, and three-step boss grooves are arranged at the bottom, and the total depth is matched with the product size.

8. The forming apparatus of claim 7 wherein: The height of the boss groove in the boss mold is H and H1.

9. The forming apparatus of claim 7 wherein: The height of the upper end step of the forming mold is H1, and the height sum of the second step and the third step is 0.7-0.8H.

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