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CN-121972595-A - Hot extrusion preparation method and die for large-scale inclined tee joint of G115 heat-resistant steel

CN121972595ACN 121972595 ACN121972595 ACN 121972595ACN-121972595-A

Abstract

A preparation method of a large-scale inclined tee joint hot extrusion of G115 heat-resistant steel comprises the following steps of 1) forging blanks, namely homogenizing and forging at a high temperature, 2) hot extrusion, wherein the heating temperature of the forging blanks is 1200-1260 ℃, the extrusion ratio is more than or equal to 6.0, the extrusion speed is 20-45 mm/s, the extrusion force is 38000-48000 tons, an inclined tee joint hot extrusion die is adopted in extrusion, in the extrusion process, upsetting is carried out on the forging blanks in a die cavity of the inclined tee joint hot extrusion die by using an upsetting punch, the die cavity is initially filled with the blanks, when the die cavity of a main pipe is filled with 90%, punching is carried out on the blanks in the die cavities of the main pipe and a branch pipe by using a punching punch, so that the die cavities are completely filled with the blanks, and three blind hole structures (namely, 2 main pipes and 1 branch pipe) are finally formed, 3) heat treatment is carried out, the inclined tee joint forging is annealed in 2h after extrusion and demoulding, the annealing temperature is 770-45 ℃ and the annealing time is 10-20 h, and after annealing is finished, the annealing is cooled to below 200 ℃ along with a furnace, and the furnace is discharged and cooled to the room temperature.

Inventors

  • ZHAO HAIPING
  • LIU JUNZHAN
  • ZHAO XIN
  • ZHAO HAIYAN
  • SUN QIANG
  • WANG TINGTING

Assignees

  • 宝武特种冶金有限公司

Dates

Publication Date
20260505
Application Date
20260303

Claims (7)

  1. 1. The preparation method of the large-scale inclined tee joint of the G115 heat-resistant steel by hot extrusion is characterized by comprising the following steps of: 1) Blank forging Comprises high-temperature homogenization and forging; Heating the G115 large-size continuous casting round billet, firstly heating to 600-650 ℃ at the rate of 50-80 ℃ per hour, preserving heat for 5-8 hours, continuously heating to 1000-1050 ℃ at the rate of 50-80 ℃ per hour, preserving heat for 3-5 hours, continuously heating to 1240-1280 ℃ at the rate of 50-80 ℃ per hour, and preserving heat for 70-80 hours; forging comprises at least three upsetting steps and three drawing steps, wherein the height delta H which is less than or equal to H 0 /2,H 0 under each upsetting step is the original height of a G115 large-specification continuous casting round billet, the upsetting ratio is 2.3-2.7, the drawing step adopts a WHF method, the forging ratio of drawing is 2.7-3.2, the total forging pressure ratio is ensured to be more than or equal to 6, and a forging billet is obtained; 2) Hot extrusion The heating temperature of the forging stock is 1200-1260 ℃, the extrusion ratio is more than or equal to 6.0, the extrusion speed is 20-45 mm/s, 38000-48000 tons of extrusion force; The extrusion adopts an inclined tee joint hot extrusion die, a main pipe die cavity and a branch pipe die cavity which is obliquely arranged and communicated with the middle part of the main pipe die cavity are arranged in the inclined tee joint hot extrusion die, and the bottoms of the main pipe die cavity and the branch pipe die cavity are protruded to form a cylindrical male die; in the extrusion process, upsetting is carried out on forging blanks in a die cavity of an inclined tee hot extrusion die by using an upsetting punch, so that the die cavity is initially filled with blanks, when the die cavity is filled with 90-95%, the die cavity is punched by using a punching punch, so that the die cavity is completely filled with blanks in a main pipe die cavity and a branch pipe die cavity, and three blind hole structures, namely 2 main pipes and 1 branch pipe are finally formed, and an inclined tee forging is obtained; 3) Heat treatment of Annealing treatment is carried out within 2 hours after extrusion and demolding of the inclined tee forging, the annealing temperature is controlled to 770-790 ℃, and the annealing time is 10-20 hours; And (3) tempering heat treatment, namely heating to 900-1000 ℃ at the speed of 50-80 ℃ per hour, preserving heat for at least 2 hours, continuously heating to 1070+/-10 ℃ at the speed of 50-80 ℃ per hour, normalizing for 8-12 hours, air cooling to room temperature, heating to 770-790 ℃ at the speed of 50-80 ℃ per hour, tempering for 10-15 hours, and air cooling to room temperature.
  2. 2. The method for preparing the large-scale inclined tee joint hot extrusion of the G115 heat-resistant steel, as claimed in claim 1, wherein the inclined tee joint hot extrusion die is fully preheated before extrusion in the step 2), the preheating temperature is more than or equal to 600 ℃, and the preheating time is more than or equal to 2 hours.
  3. 3. The method for preparing the large-scale inclined tee joint hot extrusion of the G115 heat-resistant steel according to claim 1 or 2, wherein the glass powder and the carbon powder are used for lubrication before and during the extrusion in the step 2).
  4. 4. The method for preparing the large-scale inclined tee hot extrusion of the G115 heat-resistant steel as claimed in claim 1,2 or 3, wherein the inclined tee hot extrusion in the step 2) is carried out by adopting a 50000 ton extruder.
  5. 5. The method for preparing the large-scale inclined tee joint hot extrusion of the G115 heat-resistant steel according to claim 1, wherein in the high-temperature homogenization treatment in the step 1), an anti-oxidation coating is sprayed on the surface of the large-scale continuous casting round billet of the G115.
  6. 6. The method for preparing the large-scale inclined tee joint hot extrusion of the G115 heat-resistant steel according to claim 1, wherein in the step 1), the components of the large-scale G115 continuous casting round billet are ：C 0.060~0.100%,Si≤0.55%,Mn 0.27~0.73%,P≤0.020%,S≤0.010%,Cr 8.40~9.60%,W 2.33~3.17%,Co 2.80~3.25%,Cu 0.40~1.20%,V 0.13~0.27%,Nb 0.03~0.10%,N 0.005~0.019%,B 0.008~0.022%,Ni≤0.13%,Ti≤0.02%,Al≤0.015%,O≤0.0040%,As≤0.015%,Sb≤0.015%,Bi≤0.005%,Sn≤0.020%,Pb≤0.015%,As+Sb+Bi+Sn+Pb≤0.035%, weight percent, and the balance is Fe and unavoidable impurity elements.
  7. 7. The large-scale inclined tee joint hot extrusion die of the G115 heat-resistant steel is characterized by comprising a body, wherein a main pipe die cavity and a branch pipe die cavity which is obliquely arranged and communicated with the middle part of the main pipe die cavity are arranged in the body, and cylindrical male dies are respectively formed by bulges at the bottoms of the main pipe die cavity and the sub pipe die cavity.

Description

Hot extrusion preparation method and die for large-scale inclined tee joint of G115 heat-resistant steel Technical Field The invention relates to the technical field of steel hot working, in particular to a method for preparing a large-scale inclined tee joint hot extrusion of G115 heat-resistant steel and a grinding tool. Background Along with the rapid development of economy, the demand for energy sources is higher and higher, and thermal power generation is an important component of energy sources in China, so the demand for high-efficiency and low-emission high-parameter thermal power units is urgent and urgent. The higher the steam temperature and pressure parameters of the coal-fired power generation, the lower the energy consumption of the coal-fired power generation, the lower the pollutant emission, but the higher the performance requirements on the materials. The P92 used by the 600 ℃ parameter ultra-supercritical unit can not meet the requirement of a higher parameter unit, and the high temperature resistance requirement of the material must reach 650 ℃ when the ultra-supercritical unit with the parameter of 630 ℃ is built. G115 is martensitic heat-resistant steel, as disclosed in China patent CN103045962B, the heat-resistant steel adopts a composite strengthening principle, contains W, co, cu, B, N and other strengthening elements, has high-temperature long-term structure stability, high-temperature durable strength and oxidation resistance which are all greatly higher than those of P92, is suitable for long-term use under the high-pressure working condition with the temperature below 650 ℃, and is superior to those of P92 under the temperature of 600 ℃ in the G115 through comparative study. However, because the G115 alloy has high content and complex strengthening elements, more than 25 tons of ingot shape cannot be selected for controlling segregation, but the demonstration project needs to use a large-scale inclined tee joint with the phi of 1000mm according to design requirements, and according to the existing inclined tee joint preparation process, steel ingots with the diameter of more than 40 tons are needed, the processing efficiency is low, and especially the continuity of metal streamline can be broken during machining, the overall performance is influenced, if the traditional inclined tee joint extrusion process is adopted, namely seamless steel pipes are used as blanks for extrusion, and the weight and the size of the blanks cannot meet the requirements. Therefore, development of a large G115 inclined tee joint preparation process adopting solid blanks and integrally formed by one-time extrusion is urgently needed, and the use requirement of a 1000 MW-level 630 ℃ ultra-supercritical thermal power generating unit is met. In the prior art, the chinese patent CN103045962B mainly relates to aspects of component design, reinforcement concept, manufacturing method, performance characteristics and the like of G115, but does not relate to a manufacturing method of a G115 tee bend. Chinese patent CN108998650a relates to a method for manufacturing a seamless steel pipe with large diameter and thick wall for G115 in 630 ℃ ultra supercritical unit, which only relates to an extrusion pipe making process for the seamless steel pipe with large diameter and thick wall for G115, and does not relate to the manufacture of a bevel tee. Chinese patent CN108950148a relates to a method for improving radial organization and performance uniformity of G115 large-caliber thick-wall pipe, and the technology also does not relate to a method for manufacturing G115 inclined tee. Chinese patent CN100400192C relates to a forging method of large-scale inclined tee, and does not relate to extrusion preparation of G115 large-scale inclined tee. Chinese patent CN107876677A relates to a large-scale inclined tee die forging production process and a die, wherein blanks are put into the die, upsetting, punching a main hole and reaming the main hole are respectively carried out by three punches to carry out inclined tee die forging, a ten-thousand-ton die forging hydraulic press is adopted to carry out forging, specific specifications are not involved, the production specifications are estimated according to forging force, are less than DN600, and the production of a G115 large-scale inclined tee is not involved. Chinese patent CN112775631a relates to a method for extrusion forming of pressure pipe tee, which uses a construction forming mode to extrude continuous casting billet, and sequentially extrudes tee branch pipe and main pipe, including forward extrusion and backward extrusion, forward extrusion tee branch pipe, backward extrusion tee main pipe, the material involved is 316H, the shape is symmetrical "trousers" tee, and large-scale inclined tee and G115 heat-resistant steel are not involved. Disclosure of Invention The invention aims to provide a hot extrusion preparation method and a die for a large G115 heat-resist