A method of welding a ferro-nickel based alloy and applications

Abstract

A welding method and application of iron-nickel-based alloy. The invention belongs to the field of welding. The invention solves the problem that the welding joint of the iron-nickel-based alloy in the prior art is prone to cracks in an extreme environment. The welding steps of the invention include the selection of base material and welding material, the opening of a V-shaped groove on the connecting part of the test plate, TIG welding surfacing, test plate preheating, TIG welding backing welding, TIG welding filling, and post-welding heat treatment. The iron-nickel-based alloy welded by the welding method provided by the invention effectively inhibits the generation of liquid cracks, reduces welding defects, and improves the quality and reliability of the welding joint. The welding method provided by the invention can effectively ensure the strength and toughness of the welding joint of the precipitation-strengthened iron-nickel-based high-temperature alloy casting, and the joint will not produce cracks in a high-temperature environment. The method is simple in process and easy to operate, and is suitable for the welding of precipitation-strengthened iron-nickel-based high-temperature alloy castings of various shapes and sizes, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of welding, specifically relating to a welding method and application of iron-nickel based alloys. Background Technology

[0002] Precipitation-strengthened iron-nickel-based superalloys have broad application prospects in aerospace, nuclear power, and petrochemical industries due to their excellent high-temperature strength, good oxidation resistance, and corrosion resistance. To meet the demands of practical applications, their welded joints need to possess strength, plasticity, and toughness comparable to the base metal to ensure stable and reliable performance under extreme environments such as high temperature, high pressure, and strong corrosion. However, due to the relatively poor weldability of these alloys, and influenced by factors such as uneven distribution of alloying elements in the weld and welding stress, welding defects such as liquefaction cracks are prone to occur during welding. The welded joints often fail to achieve performance levels comparable to the base metal, thus limiting their application range to some extent. To fully utilize the performance advantages of these alloys, there is an urgent need to develop specialized welding processes to ensure weld quality.

[0003] Different welding methods and process parameters have a significant impact on the welding quality of precipitation-strengthened iron-nickel-based superalloy castings. Therefore, in order to develop a welding process that can adapt to the characteristics of this type of alloy, it is necessary to select appropriate welding methods, formulate reasonable welding process parameters, and take necessary welding protection measures to ensure the stability of the welding process and the consistency of welding quality.

[0004] Considering factors such as alloy properties, weld joint performance requirements, process adaptability, and practical application needs, developing an efficient and reliable welding process is of great significance for promoting the application and development of precipitation-strengthened iron-nickel-based superalloy castings in various fields. Summary of the Invention

[0005] The purpose of this invention is to solve the problem that welded joints of iron-nickel based alloys are prone to cracking under extreme environments in the prior art. This invention provides a welding method for iron-nickel based alloys.

[0006] The technical solution of the present invention is as follows:

[0007] One objective of this invention is to provide a welding method for iron-nickel based alloys, wherein the method includes:

[0008] S1: Selection of base material and welding wire;

[0009] S2: Make a V-shaped bevel at the joint of the test plate and clean it;

[0010] S3: Use TIG welding to overlay the groove of S2, with two layers of overlay welding. Welding parameters: current 125~135A, arc voltage 12~13V, wire feed speed 600mm / min, welding speed 120mm / min, shielding gas Ar, gas flow rate 13~15L / min, interpass temperature 50℃~60℃.

[0011] S4: Test plate preheating;

[0012] S5: Root pass welding: Heat input range 0.8~1.0kJ / cm, TIG welding, welding parameters: current 125~135A, arc voltage 12~13V, welding speed 120mm / min, shielding gas Ar, gas flow rate 13~15L / min, interpass temperature ≥60℃.

[0013] S6: Filler and cover welding: heat input range 0.8~1.0kJ / cm, TIG welding, welding parameters: current 125~135A, arc voltage 12~13V, welding speed 100mm / min, shielding gas Ar, gas flow rate 13~15L / min, interpass temperature ≥60℃.

[0014] S7: Post-weld heat treatment.

[0015] Further specified, the base material in S1 is an aged iron-nickel based alloy, with a tensile strength ≥655MPa, a yield strength ≥240MPa, and an elongation after fracture ≥35% at room temperature and 700℃; the chemical composition of the welding wire, by weight percentage, is: C: 0.05~0.15%, Si: 0.05~1.0%, Mn: 0.05~1.0%, Cr: 20.0~24.0%, Mo: 8.0~10.0%, Fe: ≤3.0%, Ti: ≤0.6%, S≤0.01%, P≤0. 0.03%, Co: 10.0-15.0%, Cu≤0.5%, Al: 0.8~1.5%, the remainder being Ni and unavoidable impurities; and when the welding parameters are: current 175~185A, arc voltage 13~15V, wire feed speed 100mm / min, welding speed 10mm / min, shielding gas Ar, gas flow rate 15L / min, and interpass temperature ≥60℃, the tensile strength of the cladding metal obtained by TIG welding of the base metal and welding wire is ≥600MPa, and the elongation after fracture is ≥25%.

[0016] Further specified, the V-shaped bevel in S2 is 60°.

[0017] Further specified, the first layer of S3 is welded with 5 passes.

[0018] Further specified, the second layer of S3 is welded with 4 passes.

[0019] Further specified, the preheating temperature of S4 is 60-70℃.

[0020] Furthermore, the root gap for S5 root pass welding is 3mm.

[0021] Further specified, the S7 heat treatment temperature is 800-1000℃, and the heat treatment time is 2-4 hours.

[0022] The second objective of this invention is to provide a welded joint prepared by the above-mentioned welding method, wherein the welded joint has a tensile strength ≥625MPa, a yield strength ≥240MPa, and an elongation after fracture ≥25%.

[0023] The third objective of this invention is to provide a welding method for welding precipitation-strengthened iron-nickel-based superalloy castings.

[0024] The beneficial effects of this invention are as follows:

[0025] (1) By optimizing the base material condition and welding material selection, improving the transition layer welding parameters, adjusting the test plate welding parameters, and improving the post-weld heat treatment process, a good match between the performance of the welded joint and the base material is achieved. Post-weld heat treatment effectively suppresses the generation of liquefaction cracks, reduces welding defects, and improves the quality and reliability of the welded joint.

[0026] (2) The welding process provided by the present invention can ensure that the tensile strength of the welded joint is ≥625MPa, the yield strength is ≥240MPa, and the elongation after fracture is ≥25%, which meets the actual use requirements.

[0027] (3) The welding process provided by the present invention can effectively ensure the strength and toughness of the welded joint of precipitation-strengthened iron-nickel-based high-temperature alloy castings. The joint will not crack in the high-temperature environment. The method is simple and easy to operate, and is suitable for welding precipitation-strengthened iron-nickel-based high-temperature alloy castings of various shapes and sizes. It has a wide range of application prospects. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0029] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0030] The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used in the following embodiments, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such a composition, step, method, article, or apparatus.

[0031] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including ranges “1 to 4”, “1 to 3”, “1 to 2”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range. In this specification and claims, range definitions may be combined and / or interchanged, unless otherwise stated, these ranges include all subranges contained therein.

[0032] The indefinite articles “a” and “an” preceding an element or component of this invention do not impose any limitation on the quantity (i.e., number of times) of the element or component. Therefore, “an” or “a” should be interpreted as including one or at least one, and the singular form of an element or component also includes the plural form, unless the quantity clearly refers only to the singular form.

[0033] In this invention, "an embodiment" or "embodiment" refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments.

[0034] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0035] Example 1:

[0036] The base material is an aged iron-nickel-based alloy with the following chemical composition by weight percentage: C: 0.048%, Si: 0.06%, Mn: 0.035%, S: 0.0025%, P: 0.0053%, Cr: 16.24%, Ni: 37.6%, Mo: 0.53%, Co: 0.0023%, Ti: 1.8%, Al: 1.14%, W: 0.52%, Fe: 41.32%, Nb: <0.001%, B: <0.001%, O: 0.0007%, N: 0.0039%, H: 0.00033%, with the balance being other unavoidable impurities. At room temperature, its tensile strength is 746 MPa, yield strength is 521 MPa, and elongation after fracture is 43.8%. At 700℃, its tensile strength is 692 MPa, and yield strength is 4... The tensile strength of the cladding metal was 729 MPa, and the elongation after fracture was 46.8%. The chemical composition of the welding wire, by weight percentage, was C: 0.06%, Si: 0.11%, Mn: 0.10%, Cr: 21.5%, Mo: 9.0%, Fe: ≤0.60%, Ti: 0.40%, S: 0.001%, P: 0.005%, Co: 13.0%, Cu: 0.01%, Al: 1.2%, with the remainder being Ni and unavoidable impurities. The base metal and welding wire were welded using TIG welding with the following parameters: current 170A, arc voltage 14V, wire feed speed 100mm / min, welding speed 10mm / min, shielding gas Ar, gas flow rate 15L / min, and interpass temperature ≥60℃. The resulting cladding metal had a tensile strength of 729 MPa and an elongation after fracture of 42.4%.

[0037] A 60° V-shaped bevel is cut at the connection point of the base material, and the bevel and its surrounding area are cleaned to remove oil, oxide scale and other impurities.

[0038] The bevel was surfacing using TIG welding with the following parameters: current 130A, arc voltage 12.5V, wire feed speed 600mm / min, welding speed 120mm / min, shielding gas Ar, gas flow rate 13-15L / min, two layers of surfacing, with the first layer consisting of 5 passes and the second layer consisting of 4 passes, interpass temperature 50-60℃, and the weld was allowed to cool naturally to room temperature after welding.

[0039] The test plate was preheated to 60℃. TIG welding was used for the root pass, with a heat input range of 0.8-1.0kJ / cm. Welding parameters: current 130A, arc voltage 12.5V, welding speed 120mm / min, shielding gas Ar, gas flow rate 13-15L / min, and interpass temperature ≥60℃.

[0040] The heat input range is 0.8-1.0 kJ / cm. TIG welding is used for filler and cover welding. Welding parameters: current is 130A, arc voltage is 12.5V, welding speed is 100mm / min, shielding gas is Ar, gas flow rate is 13-15L / min, interpass temperature is ≥60℃, and the weld is cooled to room temperature.

[0041] The heat treatment temperature was set at 900℃ and the time was set at 3 hours, followed by natural cooling to room temperature.

[0042] Comparative Example 1:

[0043] The base material is an aged iron-nickel-based alloy with the following chemical composition by weight percentage: C: 0.048%, Si: 0.06%, Mn: 0.035%, S: 0.0025%, P: 0.0053%, Cr: 16.24%, Ni: 37.6%, Mo: 0.53%, Co: 0.0023%, Ti: 1.8%, Al: 1.14%, W: 0.52%, Fe: 41.32%, Nb: <0.001%, B: <0.001%, O: 0.0007%, N: 0.0039%, H: 0.00033%, with the balance being other unavoidable impurities. At room temperature, its tensile strength is 746 MPa, yield strength is 521 MPa, and elongation after fracture is 43.8%. At 700℃, its tensile strength is 692 MPa, and yield strength is 4... The tensile strength of the cladding metal was 729 MPa, and the elongation after fracture was 46.8%. The chemical composition of the welding wire, by weight percentage, was C: 0.06%, Si: 0.11%, Mn: 0.10%, Cr: 21.5%, Mo: 9.0%, Fe: ≤0.60%, Ti: 0.40%, S: 0.001%, P: 0.005%, Co: 13.0%, Cu: 0.01%, Al: 1.2%, with the remainder being Ni and unavoidable impurities. The base metal and welding wire were welded using TIG welding with the following parameters: current 170A, arc voltage 14V, wire feed speed 100mm / min, welding speed 10mm / min, shielding gas Ar, gas flow rate 15L / min, and interpass temperature ≥60℃. The resulting cladding metal had a tensile strength of 729 MPa and an elongation after fracture of 42.4%.

[0044] A 60° V-shaped bevel is cut at the connection point of the base material, and the bevel and its surrounding area are cleaned to remove oil, oxide scale and other impurities.

[0045] The bevel was surfacing using TIG welding with the following parameters: current 130A, arc voltage 12.5V, wire feed speed 600mm / min, welding speed 120mm / min, shielding gas Ar, gas flow rate 13-15L / min, two layers of surfacing, with the first layer consisting of 5 passes and the second layer consisting of 4 passes, interpass temperature 50-60℃, and the weld was allowed to cool naturally to room temperature after welding.

[0046] The test plate preheating temperature is ≥60℃. TIG welding is used for the root pass. The heat input range is 0.8-1.0kJ / cm. Welding parameters: current 130A, arc voltage 12.5V, welding speed 120mm / min, shielding gas is Ar, gas flow rate is 13-15L / min, and interpass temperature is ≥60℃.

[0047] The heat input range is 0.8-1.0 kJ / cm. TIG welding is used for filler and cover welding. Welding parameters: current is 130A, arc voltage is 12.5V, welding speed is 100mm / min, shielding gas is Ar, gas flow rate is 13-15L / min, interpass temperature is ≥60℃, and the weld is cooled to room temperature.

[0048] Comparative Example 2:

[0049] The base material is a solution-treated iron-nickel alloy with the following chemical composition by weight percentage: C: 0.042%, Si: 0.068%, Mn: 0.035%, S: 0.0039%, P: 0.0039%, Cr: 16%, Ni: 36.8%, Mo: 0.54%, Co: 0.011%, Ti: 1.73%, Al: 1.2%, W: 0.56%, Fe: 42.95%, Nb: 0.0053%, B: 0.0012%, O: 0.0084%, N: 0.0062%, H: 0.00067%, with the balance being other unavoidable impurities. At room temperature, its tensile strength is 554 MPa, yield strength is 354 MPa, and elongation after fracture is 22%. At 700℃, its tensile strength is 484 MPa, yield strength is 286 MPa, and elongation after fracture is 23.7%. The chemical composition of the welding wire, by weight percentage, is: C: 0.06%, Si: 0.11%, Mn: 0.10%, Cr: 21.5%, Mo: 9.0%, Fe: ≤0.60%, Ti: 0.40%, S: 0.001%, P: 0.005%, Co: 13.0%, Cu: 0.01%, Al: 1.2%, with the remainder being Ni and unavoidable impurities. The base metal and welding wire were welded using TIG welding with the following parameters: current 175-185A, arc voltage 13-15V, wire feed speed 100mm / min, welding speed 10mm / min, shielding gas Ar, gas flow rate 15L / min, and interpass temperature ≥60℃. The resulting cladding metal had a tensile strength of 729MPa and an elongation after fracture of 42.4%.

[0050] A 60° V-shaped bevel is cut at the connection point of the base material, and the bevel and its surrounding area are cleaned to remove oil, oxide scale and other impurities.

[0051] The groove was surfacing using pulsed TIG welding with the following welding parameters: peak welding current of 180A, base welding current of 63A, arc voltage of 12V, duty cycle of 35%, frequency of 2Hz, welding speed of 70mm / min, shielding gas of Ar, gas flow rate of 13-15L / min, and one layer of surfacing. The weld was allowed to cool naturally to room temperature after welding.

[0052] The test plate was preheated to 20℃. Hot wire TIG welding was used for the root pass. The welding parameters were: welding current 120A, hot wire current 30A, arc voltage 10.5V, and welding speed 120mm / min.

[0053] Filler and cover pass welding were performed using hot wire TIG welding. Welding parameters: welding current 130A, hot wire current 20A, arc voltage 10.5V, welding speed 120mm / min, shielding gas Ar, gas flow rate 13-15L / min, and interpass temperature ≥40℃.

[0054] Nondestructive testing and mechanical property testing were performed on Example 1, Comparative Example 1, and Comparative Example 2. See Table 1 for details.

[0055] Non-destructive testing consists of radiographic testing and ultrasonic testing.

[0056] Radiographic testing was performed in accordance with GB / T 3323.1 Nondestructive testing of welds - Radiographic testing - Part 1: Film techniques for X-rays and gamma rays.

[0057] Ultrasonic testing shall be performed in accordance with GB / T 11345 Ultrasonic Testing Technology, Testing Levels and Evaluation for Non-destructive Testing of Welds.

[0058] Mechanical property testing:

[0059] Mechanical property tests were performed in accordance with GB / T 2651 Destructive testing and transverse tensile testing of welds in metallic materials.

[0060] Table 1 Performance tests of Example 1 and Comparative Example 1 Table 1 shows the difference in mechanical properties between Example 1 and Comparative Example 1. The overall mechanical properties of Example 1 are significantly higher than those of Comparative Example 1. This is because Comparative Example 1 omits the final heat treatment step compared to Example 1. Heat treatment has the effect of eliminating hydrogen and stress, which can effectively improve the mechanical properties of the metal. Comparative Example 2, due to the selection of a solution-treated base material, pulsed TIG welding for bevel surfacing, wire TIG welding for the root pass, hot-wire TIG welding for the fill and cover passes, and the absence of post-weld heat treatment, resulted in cracks in the alloy, rendering it unusable. The examples and comparative examples demonstrate that the welding method of the present invention can suppress cracking in the weld joint and effectively improve the mechanical properties of the weld joint.

[0061] The above description is merely a preferred embodiment of the present invention. These specific embodiments are different implementations based on the overall concept of the present invention, and the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A welding method for iron-nickel-based alloys, characterized in that, The method includes the following steps: S1: Selection of base material and welding wire; S2: Make a V-shaped bevel at the joint of the test plate and clean it; S3: Use TIG welding to surface the groove of S2, surfacing two layers. Welding parameters: current 125~135A, arc voltage 12~13V, wire feed speed 600mm / min, welding speed 120mm / min, shielding gas Ar, gas flow rate 13~15L / min, interpass temperature 50℃~60℃. S4: Test plate preheating; S5: Root pass welding: Heat input range 0.8~1.0kJ / cm, TIG welding, welding parameters: current 125~135A, arc voltage 12~13V, welding speed 120mm / min, shielding gas Ar, gas flow rate 13~15L / min, interpass temperature ≥60℃; S6: Filler and cover pass welding: heat input range 0.8~1.0kJ / cm, TIG welding, welding parameters: current 125~135A, arc voltage 12~13V, welding speed 100mm / min, shielding gas Ar, gas flow rate 13~15L / min, interpass temperature ≥60℃; S7: Post-weld heat treatment; The base material in S1 is an aged iron-nickel based alloy with a tensile strength ≥655MPa, a yield strength ≥240MPa, and an elongation after fracture ≥35% at room temperature and 700℃. The chemical composition of the welding wire in S1, by weight percentage, is: C: 0.05~0.15%, Si: 0.05~1.0%, Mn: 0.05~1.0%, Cr: 20.0~24.0%, Mo: 8.0~10.0%, Fe: ≤3.0%, Ti: ≤0.6%, S≤0.01%, P≤0. 0.03%, Co: 10.0–15.0%, Cu≤0.5%, Al: 0.8~1.5%, the remainder being Ni and unavoidable impurities; and when the welding parameters are: current 175~185A, arc voltage 13~15V, wire feed speed 100mm / min, welding speed 10mm / min, shielding gas Ar, gas flow rate 15L / min, and interpass temperature ≥60℃, the tensile strength of the cladding metal obtained by TIG welding of the base metal and welding wire is ≥600MPa, and the elongation after fracture is ≥25%; In S3, the first layer of welding has 5 weld passes, and the second layer of welding has 4 weld passes.

2. The welding method according to claim 1, characterized in that, S2 has a 60° V-shaped bevel.

3. The welding method according to claim 1, characterized in that, S4 preheating temperature 60~70℃.

4. The welding method according to claim 1, characterized in that, The root gap for S5 root pass welding is 3mm.

5. The welding method according to claim 1, characterized in that, S7 heat treatment temperature 800~1000℃, heat treatment time 2~4h.

6. The welded joint prepared by the welding method according to any one of claims 1-5, characterized in that, Tensile strength ≥625MPa, yield strength ≥240MPa, elongation after fracture ≥25%.

7. The application of the welding method according to any one of claims 1 to 5 in the welding of precipitation-strengthened iron-nickel-based superalloy castings.

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