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CN-121715499-B - Preparation method of large-scale ultra-long invar alloy flat material

CN121715499BCN 121715499 BCN121715499 BCN 121715499BCN-121715499-B

Abstract

The invention discloses a preparation method of a large-sized ultra-long invar alloy flat material, which adopts a four-fire forging process, and specifically comprises the steps of head riser pretreatment by a first fire, vertical ingot upsetting and octagonal shaping by a second fire, secondary vertical ingot upsetting and multi-face drawing by a third fire, and finished product forging by a fourth fire, wherein the bottleneck problem existing in the ultra-long standard forging process is broken through cooperative control of sectional heating and forging, the large-sized ultra-long invar alloy flat material with the weight of 25-30 t and the length of more than or equal to 11m is obtained, and the forging quality and the production efficiency of the large-sized ultra-long invar alloy flat material are remarkably improved.

Inventors

  • QIAN JIE
  • YANG LEI
  • WANG YU
  • JIN CHENG
  • ZHANG SHAN
  • CAI LING
  • TIAN YUXIN
  • GAO WEN
  • JIANG ZONGMING

Assignees

  • 宝武特种冶金有限公司

Dates

Publication Date
20260512
Application Date
20260213

Claims (7)

  1. 1. A preparation method of a large-scale ultra-long invar alloy flat bar is characterized by adopting a four-fire forging process and specifically comprises the following steps: S1, head riser pretreatment is carried out by first fire Hoisting an invar alloy steel ingot with the weight of 25-30 t to a working platform of a double operation machine, clamping the head and the tail of the steel ingot, and ensuring that the axis of the steel ingot coincides with the center line of a pressure head of any operation machine of the double operation machine; S2, upsetting vertical ingot and shaping octagonal ingot by using second fire The upsetting operation is carried out at a constant speed, when the high upsetting amount reaches a set amount, the upsetting operation is stopped for at least 3 seconds, then the upsetting operation is continued, the pressure head mode is rapidly switched after the upsetting operation is completed, the steel ingot is subjected to octagonal shaping, eight surfaces of the steel ingot are sequentially subjected to tapping and drawing, the steel ingot is returned to the furnace for heat preservation treatment after the octagonal shaping, and the heat preservation temperature is controlled to 900-1300 ℃; S3, performing secondary vertical ingot upsetting and multi-surface drawing by third fire Upsetting is carried out after the operation of vertical ingot forging by the second fire is repeated, the upsetting is controlled to be 1/3-2/3 of the height of the steel ingot on the same surface, the upsetting is rapidly switched to an drawing mode after the upsetting is finished, the thickness reduction of each pass is controlled to be 10-100 mm, the upsetting is gradually pressed to the target thickness, and the wide surface and the side edge of the steel ingot are alternately forged in the drawing process; S4, forging a finished product by fourth fire Chamfering the edges and corners of the steel ingot, clamping one end of the steel ingot by using a double operation machine, forging the other end of the steel ingot according to a stepped pressing mode, performing edge rolling operation according to the width of a finished product, and synchronously adjusting the positions of the steel ingot through the double operation machine in the pressing process to finally obtain the large-sized super-long invar alloy flat material with the weight of 25-30 t and the length of more than or equal to 11 m.
  2. 2. The method for manufacturing a large-scale ultra-long invar alloy flat bar according to claim 1, wherein in step S1: The diameter of the invar alloy steel ingot with the weight of 25-30 t is more than or equal to 1350mm; before clamping the head and the tail of a steel ingot, debugging the double operation machines, controlling the clamping force of the double operation machines to be 50-80N, and simultaneously starting an infrared temperature measurement system to monitor the preheating state of a working platform in real time; in the forging process of the wide face tapping and drawing and the corner chamfering, eight faces of the head of the steel ingot are alternately tapped and drawn, the rolling reduction is controlled to be 20-100 mm, and meanwhile, the eight corners of the steel ingot are tapped and chamfered, and the rolling reduction is controlled to be 20-100 mm; The diameter of the steel ingot after forging is 1250-1300 mm; The heat preservation temperature of the heating treatment is 2-5 h.
  3. 3. The method for manufacturing a large-scale ultra-long invar alloy flat bar according to claim 1, wherein in step S2: Before the upsetting operation, the verticality deviation of the steel ingot is not more than 10 degrees; During the upsetting operation, the constant speed is 2-10 mm/s, the set value of the high upsetting amount is 20-100 mm, the pause time is 3-8 s, and the total high upsetting amount is 300-400 mm; in the octagonal shaping process, the back and forth flapping times of each surface of the steel ingot are 2-10 times, and the single-sided rolling reduction is 10-100 mm; The heat preservation temperature of the heat preservation treatment is 2-5 h.
  4. 4. The method for manufacturing a large-scale ultra-long invar alloy flat bar according to claim 1, wherein in step S3: When the multiple surfaces are pulled out, the thickness of the steel ingot is pressed to the target thickness in 2-7 times; when alternately forging the wide surface and the side of the steel ingot, the first two passes finish one wide surface reduction forging and the second side finish one edge reduction forging; The heat preservation temperature of the heat preservation treatment is 2-5 h.
  5. 5. The method for manufacturing a large-scale ultra-long invar alloy flat bar according to claim 1, wherein in step S4: The rolling reduction of the chamfering treatment is 20-70 mm; in the step reduction forging process, the reduction of the first pass is 20-80 mm, the reduction of the subsequent pass is 20-50 mm, and the thickness is reduced to 260-270 mm in 4-7 passes.
  6. 6. The method for manufacturing a large-scale ultra-long invar alloy flat material according to claim 1, wherein in the step S4, the thickness of the large-scale ultra-long invar alloy flat material is 260-270 mm, and the width is 1150-1170 mm.
  7. 7. The method for producing a large-scale ultralong invar alloy flat material according to claim 1, wherein in step S4, the grain size of the large-scale ultralong invar alloy flat material reaches 4 grades or more, and the deviation of the thermal expansion coefficient is not more than 1.8x10 -6 ℃.

Description

Preparation method of large-scale ultra-long invar alloy flat material Technical Field The invention relates to the field of invar alloy forging, in particular to a preparation method of a large-scale ultralong invar alloy flat material. Background The major equipment such as domestic ultra-large LNG storage tanks and the like is developed to be large-scale and integrated, and key structural components (such as tank walls and tank bottoms) of the large-scale LNG storage tanks depend on large-scale invar alloy materials, and the large-scale invar alloy materials have low expansion coefficients, high strength and excellent low-temperature stability. At present, a large invar alloy material is prepared by adopting a five-fire forging process, wherein a first fire is used for holding the tail part of a steel ingot and is used for tapping and drawing the head part, single-sided pressing is carried out for 10-80 mm, the head part is tapped back and forth for twice, the step height difference between the ingot body and a riser is reduced, the tail part is tapped and drawn to keep the diameter of the head part and the tail part consistent, eight edges and corners are tapped and chamfered for treatment, then a furnace is returned for heat preservation, a second fire and a third fire are used for erecting the steel ingot by using a polishing clamp and are used for disc upsetting, upsetting speed and pause time are controlled, simultaneously drawing and chamfering are carried out, and furnace return for heat preservation are carried out, a fourth fire is used for preventing corner cracking by using a jaw chamfering, carrying out step pressing deformation on one end, then furnace return for heat preservation is carried out, and a fifth fire is used for forging the end which is not forged to reach the thickness of a finished product after chamfering treatment, and then the head is dropped for forging the other end to reach the thickness of the finished product, and final forming and size adjustment are completed. However, the process is only suitable for producing steel ingots with the length of less than or equal to 14 tons (the length of a finished product is about 5.3 meters), and is difficult to meet the requirements of 25-30 tons of ultra-long invar alloy flat materials, and the main limiting factors include (1) difficulty in quality control, easiness in generation of head cracking and tail shrinkage, less than 71% of finished product rate, (2) limited material performance, coarse grains caused by the traditional process, deviation of thermal expansion coefficient exceeding 0.3 multiplied by 10 -6 ℃ and influence on equipment precision, and (3) low production efficiency, lack of standardized flow, dependence on manual experience, and long single ingot forging period of up to 30 hours. If a large LNG storage tank (for example, 16 ten thousand cubic meters) is built by adopting the invar alloy prepared by the five-fire forging process, only a splicing mode can be adopted, the welding seams are more, the welding seams are easily cracked under the influence of low temperature and high pressure, and the LNG leakage risk is obviously increased. In view of the above, a method for preparing a large-scale ultra-long invar alloy is to be studied, which can realize the preparation of the large-scale ultra-long invar alloy and meet the severe requirements of the large-scale LNG storage tank and other important equipment on the alloy material in terms of specification and performance. Disclosure of Invention Aiming at the defects existing in the prior art, the invention aims to provide a preparation method of a large-sized super-long invar alloy flat material, which adopts a four-fire temperature-control forging process to carry out sectional heating and forging cooperative control, breaks through the bottleneck problem existing in the super-long specification forging process, obtains the invar alloy flat material with the weight of 25-30T and the length of more than or equal to 11m, and obviously improves the forging quality and the production efficiency of the large-sized super-long invar alloy flat material. In order to achieve the above purpose, the invention adopts the following technical scheme: the first aspect of the invention provides a preparation method of a large-scale ultra-long invar alloy flat material, which adopts a four-fire forging process and specifically comprises the following steps: S1, head riser pretreatment is carried out by first fire Hoisting an invar alloy steel ingot with the weight of 25-30 t to a working platform of a double operation machine, clamping the head and the tail of the steel ingot, and ensuring that the axis of the steel ingot coincides with the center line of a pressure head of any operation machine of the double operation machine; S2, upsetting vertical ingot and shaping octagonal ingot by using second fire The upsetting operation is carried out at a constant speed, when the high up