Search

CN-122007566-A - Cold crack resistant welding method for 1000 MPa-level pressure steel pipe of hydropower engineering

CN122007566ACN 122007566 ACN122007566 ACN 122007566ACN-122007566-A

Abstract

A cold crack resistant welding method for a 1000 MPa-level pressure steel pipe in hydroelectric engineering relates to the technical field of welding. A cold crack resistant welding method for a pressure steel pipe of a hydropower engineering 1000MPa level comprises the steps of respectively machining one side of two steel plates into double V grooves which are vertically symmetrical, assembling and positioning the two steel plates, arranging conical ceramic gaskets on the back surfaces of the two steel plates, preheating the two steel plates before welding after polishing the grooves, filling the single-side grooves to 1/2 by using submerged arc automatic welding after backing welding by using carbon dioxide gas shielded welding in a temperature range of 140-170 ℃, finishing welding filling of the other-side grooves by using submerged arc automatic welding when the ceramic gaskets are removed by turning the steel plates, finishing residual 1/2 welding filling of the single-side grooves by using submerged arc automatic welding when turning the steel plates again, and performing postweld heat treatment. The cold crack resistance welding method of the hydroelectric engineering 1000MPa pressure steel pipe has the advantages of excellent mechanical property and good cold crack resistance of the welded joint.

Inventors

  • ZHANG MAN
  • XIAO XIONGBING
  • HAN XUAN
  • HAN HEBING
  • FAN SHAOXUAN
  • YAN CHENGXIA
  • ZHANG YONGLI
  • LIU SHEN
  • LI TAN
  • QUAN SHUNHONG
  • LIU NING
  • ZHU HONGSHENG
  • ZHAO BIN
  • SHEN QIANG

Assignees

  • 中铁重工有限公司

Dates

Publication Date
20260512
Application Date
20260311

Claims (10)

  1. 1. The cold crack resistance welding method for the hydroelectric engineering 1000 MPa-level pressure steel pipe is characterized by comprising the following steps of: processing one side of each of the two steel plates into a double V groove which is vertically symmetrical; assembling and positioning two steel plates, and arranging a conical ceramic liner on the back surface; Preheating before welding after polishing the groove; Filling a single-side groove to 1/2 by using submerged arc automatic welding in a temperature range of 140-170 ℃ after backing welding by using carbon dioxide gas shielded welding; The ceramic liner is removed by turning the steel plate, welding and filling of the groove at the other side are completed by submerged arc automatic welding, and the remaining 1/2 of the groove at the single side is completed by turning the steel plate again by submerged arc automatic welding; And (5) performing postweld heat treatment.
  2. 2. The method for cold crack resistance welding of a pressure steel pipe of 1000MPa level in hydropower engineering according to claim 1, wherein the angle of the groove is made 20-25 ° without blunt edges when the double V groove is machined.
  3. 3. The cold crack welding method for the hydroelectric engineering 1000 MPa-level pressure steel pipe, which is characterized in that when two steel plates are assembled and positioned, the assembly clearance is 3-6mm, the assembly precision clearance is 0-1 mm, and the misalignment amount is not more than 1mm.
  4. 4. The method for cold crack resistance welding of a hydroelectric engineering 1000 MPa-level penstock according to claim 1, wherein the preheating temperature of the pre-welding is 130-150 ℃.
  5. 5. The cold crack resistant welding method for the hydroelectric engineering 1000MPa pressure steel pipe, according to claim 1, is characterized in that during carbon dioxide gas shielded welding, the polarity of a bottoming power supply is in direct current reverse connection, a CHW-95C welding wire with the diameter of 1.2mm is adopted, the welding current is 280+/-10A, and the welding voltage is 30+/-2V.
  6. 6. The method for cold crack resistance welding of a pressure steel pipe of 1000MPa level in hydroelectric engineering according to claim 5, wherein the welding speed is controlled to be 25-27cm/min, the line energy is 15-20KJ/cm, and the gas flow is 16-18L/min during carbon dioxide gas shielded welding.
  7. 7. The method for cold crack resistance welding of a pressure steel pipe of 1000MPa level in hydropower engineering according to claim 6, wherein the submerged arc welding wire CHW-S100 with the diameter of 4.0mm and the flux CHF100 are adopted in submerged arc automatic welding, the welding current is 620±30A, and the welding voltage is 32±2V.
  8. 8. The method for cold crack resistance welding of a pressure steel pipe of 1000MPa level in hydropower engineering according to claim 7, wherein the welding speed is controlled to be 40-42cm/min and the line energy is controlled to be 20-30KJ/cm during submerged arc automatic welding.
  9. 9. The method for cold crack resistance welding of a pressure steel pipe of 1000MPa level in hydropower engineering according to claim 7, wherein the inter-layer temperature is controlled at 140-170 ℃ in submerged automatic arc welding.
  10. 10. The cold crack resistant welding method for the hydroelectric engineering 1000MPa pressure steel pipe according to claim 1, wherein during postweld heat treatment, ceramic heating plates are placed on the upper surface and the lower surface of a welding line, heat preservation materials are covered and heated to 250-300 ℃, and natural cooling is performed after heat preservation is performed for more than 2 hours.

Description

Cold crack resistant welding method for 1000 MPa-level pressure steel pipe of hydropower engineering Technical Field The application relates to the field of welding, in particular to a cold crack resistance welding method for a 1000 MPa-level pressure steel pipe of a hydropower project. Background Along with the development of the hydroelectric engineering to the high water head and high capacity, the pressure steel pipe is used as a key pressure-bearing member and needs to bear higher working stress, particularly, the 1000 MPa-level ultrahigh-strength steel pipe faces remarkable challenges in welding, the traditional welding method is difficult to balance the requirements of high strength and toughness, the embrittlement of a heat affected zone is aggravated due to insufficient preheating temperature or excessive heat input, and the crack resistance of the joint is influenced. Therefore, a cold crack resistant welding method for a 1000 MPa-grade penstock for hydropower engineering is required to avoid cracks. Disclosure of Invention The application aims to provide a cold crack resistance welding method for a hydropower engineering 1000 MPa-level pressure steel pipe, which has the advantages of excellent mechanical property and good cold crack resistance of a welded joint. The application is realized in the following way: the application provides a cold crack resistance welding method of a 1000 MPa-level pressure steel pipe of a hydropower project, which comprises the following steps: processing one side of each of the two steel plates into a double V groove which is vertically symmetrical; assembling and positioning two steel plates, and arranging a conical ceramic liner on the back surface; Preheating before welding after polishing the groove; Filling a single-side groove to 1/2 by using submerged arc automatic welding in a temperature range of 140-170 ℃ after backing welding by using carbon dioxide gas shielded welding; The ceramic liner is removed by turning the steel plate, welding and filling of the groove at the other side are completed by submerged arc automatic welding, and the remaining 1/2 of the groove at the single side is completed by turning the steel plate again by submerged arc automatic welding; And (5) performing postweld heat treatment. In some alternative embodiments, the double V groove is made with a groove angle of 20-25 ° and no blunt edge. In some alternative embodiments, when two steel plates are assembled and positioned, the assembly clearance is 3-6mm, the assembly precision clearance is 0-1 mm, and the misalignment amount is not more than 1mm. In some alternative embodiments, the pre-heat temperature of the pre-heat is 130-150 ℃. In some alternative embodiments, during carbon dioxide arc welding, the polarity of the backing power supply is reversed, and a CHW-95C welding wire with the diameter of 1.2mm is adopted, so that the welding current is 280+/-10A, and the welding voltage is 30+/-2V. In some alternative embodiments, the welding speed is controlled to be 25-27cm/min, the line energy is 15-20KJ/cm, and the gas flow is 16-18L/min during carbon dioxide arc welding. In some alternative embodiments, submerged arc automatic welding is performed using a 4.0mm diameter submerged arc welding wire CHW-S100 and flux CHF100, with a welding current of 620+ -30A and a welding voltage of 32+ -2V. In some alternative embodiments, the submerged arc automatic welding is controlled to a welding speed of 40-42cm/min and a line energy of 20-30KJ/cm. In some alternative embodiments, submerged arc automated welding is controlled to an interlayer temperature of 140-170 ℃. In some alternative embodiments, during postweld heat treatment, ceramic heating plates are placed on the upper and lower surfaces of the weld joint and covered with a heat insulating material to heat to 250-300 ℃, and the weld joint is naturally cooled after heat preservation for more than 2 hours. The cold crack resistant welding method for the hydropower engineering 1000 MPa-level pressure steel pipe has the beneficial effects that one side of two steel plates is respectively processed into double V grooves which are vertically symmetrical, the two steel plates are assembled and positioned, conical ceramic gaskets are arranged on the back surfaces of the two steel plates, preheating is carried out before welding after polishing the grooves, single-side grooves are filled to 1/2 by submerged arc automatic welding in the temperature range of 140-170 ℃ after backing welding by using carbon dioxide gas shielded welding, the ceramic gaskets are removed by turning the steel plates, welding filling of grooves on the other side is completed by using the submerged arc automatic welding, remaining 1/2 of welding filling of the single-side grooves is completed by using the submerged arc automatic welding by turning the steel plates again, and postweld heat treatment is carried out. According to the cold crack resistance welding method