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CN-116438034-B - Method for depositing a cladding material onto a metal surface by means of electroslag strip surfacing

CN116438034BCN 116438034 BCN116438034 BCN 116438034BCN-116438034-B

Abstract

In a method for depositing a cladding material onto a metal surface by means of electroslag strip overlaying, a welding strip made of austenitic stainless steel, such as 308L or 309L alloy, and a flux material having the composition-Al 2 O 3 :20-30 wt.% -CaF 2 :55-70 wt.% -Mo 0.3-3 wt.% -Nb 1.2-2.5 wt.% -Cr 3-6 wt.% -Mn 1-3.5 wt.% -Na 2 SiO 3 :1-6 wt.% -and optionally other components, in particular-MgO: <1 wt.% -CaO.Al 2 O 3 : <1 wt.% -carbonate: <1 wt.% and unavoidable impurities is used.

Inventors

  • M. Deshelf

Assignees

  • 奥钢联伯乐焊接比利时有限公司

Dates

Publication Date
20260512
Application Date
20211110
Priority Date
20201110

Claims (20)

  1. 1. A method of depositing a cladding material onto a metal surface by means of an electroslag strip overlay, wherein the electroslag strip overlay comprises using a welded strip made of austenitic stainless steel, and a flux material having the following composition: 20-30 wt% of Al 2 O 3 -CaF 2 :55-70 wt% 0.3-3 Wt% of Mo Nb 1.2-2.5 wt.% 3-6 Wt% Cr Mn 1-3.5 wt% Na 2 SiO 3 :1-6 wt% And optionally other ingredients and unavoidable impurities, Wherein electroslag strip electrode build-up welding includes: -providing a welding strip electrode in question, -Providing a flux material of the type described, Positioning the welding strip electrode at a distance above the welding zone of the metal surface, Applying a layer of flux material to the metal surface in the soldering zone, Applying a welding current to the welding strip, thereby melting the flux material, strip and metal surface, -Continuously feeding the welding strip electrode into a layer of molten flux material while the welding strip electrode is advanced over the metal surface to produce a deposit of facing material on the metal surface along an advancing path.
  2. 2. The method of claim 1, wherein the austenitic stainless steel is a 308L or 309L alloy.
  3. 3. The method of claim 1, wherein two layers of facing material are deposited onto the metal surface.
  4. 4. A method according to claim 3, wherein the second layer of facer material deposit has a ferrite content of < 17 FN measured on its top surface, wherein the Ferrite Number (FN) is measured according to AWS a4.2 by means of FISCHER FERRITE-scope FMP 30.
  5. 5. The method of claim 4, wherein the second layer of facer material deposit has a ferrite content of < 15 FN measured on its top surface.
  6. 6. The method of claim 1, wherein the flux material has the following composition: -Al 2 O 3 :22-25 wt% -CaF 2 :58-68 wt% 0.5-2 Wt% of Mo Nb 1.5-2.3 wt.% 3-5 Wt% Cr Mn 1.2-3 wt% Na 2 SiO 3 :2-6 wt% And optionally other ingredients and unavoidable impurities.
  7. 7. The method of claim 6, wherein the flux material has the following composition: -Al 2 O 3 :23-24 wt% -CaF 2 :60-65 wt% 0.8 To 1.5% by weight of Mo Nb 1.8-2.2 wt.% 3.4-4.5 Wt% Cr Mn 1.2-2.5 wt% Na 2 SiO 3 :4-6 wt% And optionally other ingredients and unavoidable impurities.
  8. 8. The method of claim 7, wherein the flux material has the following composition: -Al 2 O 3 :24 wt% -CaF 2 :62 wt% Mo 1 wt% Nb 2 wt% -Cr 4 wt% Mn 2 wt% Na 2 SiO 3 % by weight And optionally other ingredients and unavoidable impurities.
  9. 9. The method of claim 8, wherein other components in the flux material comprise: MgO (< 1 wt.% CaO.Al 2 O 3 : < 1 wt% Carbonate, < 1% by weight.
  10. 10. The method of claim 1, wherein the welded strap has the following composition: c0.012-0.015 wt% Mn 1.65-1.75 wt% Si 0.38-0.42 wt% Cr 20-25 wt% Ni 10-15 wt% Mo 0.01-0.15 wt% And optionally other components and unavoidable impurities, the balance being iron.
  11. 11. The method of claim 10, wherein the other components in the welded strap pole include: s0.0005-0.003 wt% P0.012-0.020 wt% Nb 0.01 wt.% Cu 0.02-0.04 wt% N0.045-0.60 wt%.
  12. 12. The method of claim 1, wherein the electroslag strip overlay welding comprises applying a welding current of 400-1800A and a welding voltage of 22-26V.
  13. 13. The method of claim 12, wherein the electroslag strip overlay welding comprises applying a welding current of 1200-1300A and a welding voltage of 23-25V.
  14. 14. The method according to any one of claims 1-13, wherein a welding speed of 16-24 cm/min is used.
  15. 15. The method of claim 14, wherein a welding speed of 18-22 cm/min is used.
  16. 16. A flux material for use in a method of depositing a facing material onto a metal surface by means of electroslag strip surfacing, the flux material having the following composition: 20-30 wt% of Al 2 O 3 -CaF 2 :55-70 wt% 0.3-3 Wt% of Mo Nb 1.2-2.5 wt.% 3-6 Wt% Cr Mn 1-3.5 wt% Na 2 SiO 3 :1-6 wt% And optionally other ingredients and unavoidable impurities.
  17. 17. The flux material of claim 16, wherein the flux material has the following composition: -Al 2 O 3 :23-24 wt% -CaF 2 :60-65 wt% 0.8 To 1.5% by weight of Mo Nb 1.8-2.2 wt.% 3.4-4.5 Wt% Cr Mn 1.2-2.5 wt% Na 2 SiO 3 :4-6 wt% And optionally other ingredients and unavoidable impurities.
  18. 18. The flux material of claim 16 or 17, wherein the flux material has the following composition: -Al 2 O 3 :24 wt% -CaF 2 :62 wt% Mo 1 wt% Nb 2 wt% -Cr 4 wt% Mn 2 wt% Na 2 SiO 3 % by weight And optionally other ingredients and unavoidable impurities.
  19. 19. The flux material of claim 18, wherein other components in the flux material comprise: MgO (< 1 wt.% CaO.Al 2 O 3 : < 1 wt% Carbonate, < 1% by weight.
  20. 20. Kit for use in a method of depositing a facing material onto a metal surface by means of electroslag strip surfacing, comprising a flux material according to any one of claims 16-19 and a welding strip, wherein the welding strip is made of austenitic stainless steel.

Description

Method for depositing a cladding material onto a metal surface by means of electroslag strip surfacing The invention relates to a method for depositing a cladding material onto a metal surface by means of electroslag strip surfacing. In nuclear power applications and in the oil and gas upstream and downstream industries, a build-up layer (weld overlay) is deposited on the walls of the vessel and vessel assembly to protect the walls from corrosion, high temperature and/or chemical embrittlement. The reactor vessel is the most important structural component for the safety of a nuclear power plant. The vessel of a nuclear reactor is a cylindrical component constructed using low alloy steel with austenitic stainless steel cladding to avoid corrosion processes. Corrosion is often the cause of cracking or deformation. Therefore, austenitic stainless steel has an advantage of high corrosion resistance. The cladding material is susceptible to thermal cracking and stress corrosion cracking. Cracks in the cladding can cause catastrophic failure. The build-up process typically uses a strap electrode to create a build-up layer on the metal surface. Two of the most common methods for surfacing large assemblies are submerged arc strap surfacing (ARC STRIPCLADDING) and electroslag strap surfacing (electroslag STRIP CLADDING). In electroslag strip surfacing, strip electrodes are fed continuously into a shallow layer of conductive flux. The heat required to melt the surface layers of the weld strip, slag forming flux and base metal is generated by resistive heating generated by the welding current flowing through the molten conductive slag. The heat generated by the process is sufficient to stabilize the process and melt the weld strap into the liquid slag, thereby transferring the weld strap into the molten metal deposited on the base metal. Electroslag strip overlay is characterized by high deposition rates and low dilution. The dilution determines, among other things, the amount of iron diluted from the base metal into the deposited cladding. However, in nuclear power applications, only the less efficient submerged arc strip surfacing method is currently used. The metallurgical composition of the welded strap (WELDING STRIP electrode) greatly determines the quality of the resulting cladding in terms of corrosion resistance, temperature resistance and chemical resistance. Common alloys used for welding straps in nuclear power applications are the so-called 308L and 309L alloys. The composition of the 308L alloy is defined in AWS A5.9/A5.9M:2017 and is as follows: C is less than or equal to 0.03 weight percent Mn 1.0-2.5 wt% Si 0.30-0.65 wt% Cr 19.5-22.0 wt% Ni 9.0-11.0 wt% Mo is less than or equal to 0.75 weight percent S is less than or equal to 0.03 weight percent P is less than or equal to 0.03 weight percent Cu is less than or equal to 0.75 weight percent N is less than or equal to 0.10 weight percent The balance being unavoidable impurities and Fe. The composition of the 309L alloy is defined in AWS A5.9/A5.9M:2017, and is as follows: C is less than or equal to 0.03 weight percent Mn 1.0-2.5 wt% Si 0.30-0.65 wt% Cr 23.0-25.0 wt% Ni 12.0-14.0 wt% Mo is less than or equal to 0.75 weight percent S is less than or equal to 0.03 weight percent P is less than or equal to 0.03 weight percent Cu is less than or equal to 0.75 weight percent N is less than or equal to 0.10 weight percent The balance being unavoidable impurities and Fe. 308L and 309L alloy ribbons are sold under the different variants and various trademarks, e.g. from voestalpineWelding Soudotape L and Soudotape 309L. Electroslag strip surfacing is an advantageous welding process that provides increased productivity when compared to submerged arc strip surfacing. However, no suitable flux material is currently available to meet the specifications of nuclear applications for depositing 308L or 309L alloys by means of an electroslag strip build-up process. In particular, the current ribbon-flux combination cannot ensure an ultimate tensile strength of 520MPa while maintaining the ferrite content of the facing material around 15FN (fn=ferrite number). Only submerged arc strip overlay welding solutions currently meet this requirement. Manufacturers of structural components of nuclear power plants are reluctant to switch welding consumables to another type because product certification is a cumbersome process and changing products always involves some risk. This is especially true for varying the welding process. It is therefore an object of the present invention to provide an improved method of depositing a facing material onto a metal surface by electroslag strip overlay welding using a welded strip made of austenitic stainless steel, such as 308L or 309L alloy. In particular, it is an object of the present invention to provide a method wherein the facing material has an Ultimate Tensile Strength (UTS) above 520MPa and a ferrite content below 17 FN. To address at