Welding method and application of iron-nickel-based alloy

Abstract

The invention discloses a welding method and application of an iron-nickel-based alloy. The invention belongs to the field of welding. The problem that in the prior art, a welding joint of an iron-nickel-based alloy is prone to cracking in an extreme environment is solved. The method comprises the following welding steps: selecting a base material and a welding material, forming a V-shaped groove in a connecting part of a test plate, performing TIG (Tungsten Inert Gas) welding surfacing, preheating the test plate, performing TIG welding backing welding, performing TIG welding filling, performing cosmetic welding and performing postweld heat treatment. According to the iron-nickel-based alloy welded through the welding method, liquidation cracks are effectively restrained, welding defects are reduced, the quality and reliability of a welding joint are improved, the strength and toughness of the precipitation strengthening type iron-nickel-based high-temperature alloy casting welding joint can be effectively guaranteed, and the welding quality of the precipitation strengthening type iron-nickel-based high-temperature alloy casting welding joint is improved. The method is simple in process, easy to operate and suitable for welding of precipitation strengthening type iron-nickel-based superalloy castings of various shapes and sizes, and has wide application prospects.

Description

Technical Field

[0001] The invention belongs to the field of welding, and in particular relates to a welding method and application of an iron-nickel based alloy. Background Art

[0002] Precipitation-strengthened iron-nickel-based high-temperature alloys have broad application prospects in aerospace, nuclear energy industry, petrochemical industry and other fields due to their excellent high-temperature strength, good oxidation resistance and corrosion resistance. In order to meet the needs of practical applications, their welded joints need to have strength, plasticity and toughness that are quite matched with the parent material 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 such alloys, affected 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, and welded joints are often difficult to achieve performance levels comparable to those of the parent material, which limits their scope of application to a certain extent. In order to give full play to the performance advantages of such alloys, it is urgent to propose a special welding process to ensure their welding quality.

[0003] Different welding methods and process parameters have a significant impact on the welding quality of precipitation-strengthened iron-nickel-based high-temperature alloy castings. Therefore, in order to propose a welding process that can adapt to the characteristics of this type of alloy, it is necessary to select a suitable welding method, 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 many aspects such as alloy property requirements, weld joint performance requirements, process adaptability requirements and actual application requirements, developing an efficient and reliable welding process is of great significance to promoting the application and development of precipitation-strengthened iron-nickel-based high-temperature alloy castings in various fields. Summary of the invention

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

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

[0007] One of the purposes of the present invention is to provide a method for welding an iron-nickel based alloy, wherein:

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

[0009] S2: Make a V-shaped groove on the connection part of the test plate and clean it;

[0010] S3: Use TIG welding to build up the groove of S2, build up two layers, welding parameters: current 125-135A, arc voltage 12-13V, wire feeding speed 600mm / min, welding speed 120mm / min, shielding gas Ar, gas flow 13-15L / min, interpass temperature 50℃-60℃;

[0011] S4: preheating of test plate;

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

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

[0014] S7: Post weld heat treatment.

[0015] It is further defined that the base material in S1 is an iron-nickel based alloy aged base material, and the tensile strength at room temperature and 700°C is ≥655MPa, the yield strength is ≥240MPa, and the elongation after fracture is ≥35%; the chemical composition of the welding wire 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 .03%, Co: 10.0-15.0, Cu≤0.5%, Al: 0.8~1.5%, and the rest are Ni and inevitable impurities; and when the welding parameters are current 175~185A, arc voltage 13~15V, wire feeding speed 100mm / min, welding speed 10mm / min, shielding gas Ar, gas flow rate 15L / min, interpass temperature ≥60℃, the tensile strength of the cladding metal obtained by TIG welding the base material and the welding wire is ≥600MPa, and the elongation after fracture is ≥25%.

[0016] It is further defined that the V-shaped groove in S2 is 60°.

[0017] It is further defined that the first layer of surfacing welding in S3 is 5 passes.

[0018] It is further defined that in S3, the second layer of surfacing welding is performed in 4 passes.

[0019] It is further defined that the preheating temperature of S4 is 60-70°C.

[0020] It is further defined that the root gap of the S5 root weld is 3 mm.

[0021] It is further defined that the S7 heat treatment temperature is 800-1000°C and the heat treatment time is 2-4h.

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

[0023] A third object of the present invention is to provide a welding method for use in welding precipitation-strengthened iron-nickel-based high-temperature alloy castings.

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

[0025] (1) By optimizing the state of the base material and the selection of welding materials, improving the welding parameters of the transition layer, adjusting the welding parameters of the test plate, 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 is performed to effectively inhibit the generation of liquefaction cracks, reduce welding defects, and improve 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%, meeting the actual use requirements.

[0027] (3) The welding process provided by the present invention can effectively ensure the strength and toughness of the welded joints of precipitation-strengthened iron-nickel-based high-temperature alloy castings, and no cracks will occur in the joints under high-temperature environments. The method is simple in process and easy to operate, and is suitable for welding precipitation-strengthened iron-nickel-based high-temperature alloy castings of various shapes and sizes, and has broad application prospects. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are conventional materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained through commercial channels by those skilled in the art.

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

[0031] When equivalent, concentration or other value or parameter is represented by the range limited by range, preferred range or a series of upper preferred value and lower preferred value, this should be understood as specifically disclosing all ranges formed by any pairing of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether the scope is disclosed separately. For example, when disclosing range "1 to 5", described range should be interpreted as including range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5" etc. When numerical range is described in this article, unless otherwise stated, the scope is intended to include its end value and all integers and fractions within the scope. In the present application specification and claims, range limitation can be combined and / or interchanged, if these ranges are not otherwise stated, include all sub-ranges contained therein.

[0032] The indefinite articles "a" and "an" before the elements or components of the present invention have no limitation on the quantity requirements (i.e. the number of occurrences) of the elements or components. Therefore, "a" or "an" should be interpreted as including one or at least one, and the elements or components in the singular form also include the plural form, unless the quantity obviously refers to the singular form only.

[0033] The "one embodiment" or "embodiment" of the present invention refers to a specific feature, structure or characteristic that can be included in at least one implementation of the present invention. The "in one embodiment" that appears in different places in this specification does not refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

[0034] The endpoints and any values ​​of the ranges disclosed in the 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this article.

[0035] Embodiment 1:

[0036] The base material is an iron-nickel alloy aged base material, and the chemical composition weight percentage is 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%, and the balance is other inevitable impurities. At room temperature, its tensile strength is 746MPa, its yield strength is 521MPa, and its elongation after fracture is 43.8%. At 700℃, its tensile strength is 692MPa, and its yield strength is 4 03MPa, elongation after fracture is 46.8%; the chemical composition of the welding wire 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%, the rest is Ni and unavoidable impurities; the base material and the welding wire are welded by TIG welding, the welding parameters are: current is 170A, arc voltage is 14V, wire feeding speed is 100mm / min, welding speed is 10mm / min, shielding gas is Ar, gas flow rate is 15L / min, and the interpass temperature is controlled to be ≥60℃. The tensile strength of the cladding metal obtained is 729MPa, and the elongation after fracture is 42.4%;

[0037] A 60° V-shaped groove is made at the connection part of the parent material, and the groove and the surrounding area are cleaned to remove oil, scale and impurities;

[0038] TIG welding was used to build up the groove. The welding parameters were as follows: current 130A, arc voltage 12.5V, wire feeding speed 600mm / min, welding speed 120mm / min, shielding gas Ar, gas flow 13-15L / min, and two build-up layers. The first layer had 5 passes, and the second layer had 4 passes. The interpass temperature was 50-60℃, and the weld was naturally cooled to room temperature after welding.

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

[0040] The heat input range is 0.8-1.0 kJ / cm, TIG welding is used for filling and capping 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 cooling to room temperature after welding.

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

[0042] Comparative Example 1:

[0043] The base material is an iron-nickel alloy aged base material, and the chemical composition weight percentage is 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%, and the balance is other inevitable impurities. At room temperature, its tensile strength is 746MPa, its yield strength is 521MPa, and its elongation after fracture is 43.8%. At 700℃, its tensile strength is 692MPa, and its yield strength is 4 03MPa, elongation after fracture is 46.8%; the chemical composition of the welding wire 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%, the rest is Ni and unavoidable impurities; the base material and the welding wire are welded by TIG welding, the welding parameters are: current is 170A, arc voltage is 14V, wire feeding speed is 100mm / min, welding speed is 10mm / min, shielding gas is Ar, gas flow rate is 15L / min, and the interpass temperature is controlled to be ≥60℃. The tensile strength of the cladding metal obtained is 729MPa, and the elongation after fracture is 42.4%;

[0044] A 60° V-shaped groove is made at the connection part of the parent material, and the groove and the surrounding area are cleaned to remove oil, scale and impurities;

[0045] TIG welding was used to build up the groove. The welding parameters were as follows: current 130A, arc voltage 12.5V, wire feeding speed 600mm / min, welding speed 120mm / min, shielding gas Ar, gas flow 13-15L / min, and two build-up layers. The first layer had 5 passes, and the second layer had 4 passes. The interpass temperature was 50-60℃, and the weld was naturally cooled to room temperature after welding.

[0046] The preheating temperature of the test plate is ≥60℃, and TIG welding is used for base welding. The heat input range is 0.8-1.0kJ / cm2. The welding parameters are: current 130A, arc voltage 12.5V, welding speed 120mm / min, shielding gas is Ar, gas flow rate is 13-15L / min, and interpass temperature ≥60℃;

[0047] The heat input range is 0.8-1.0 kJ / cm, TIG welding is used for filling and capping 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 cooling to room temperature after welding.

[0048] Comparative Example 2:

[0049] The base material is an iron-nickel based alloy solid solution base material, and the chemical composition weight percentage is 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%, and the balance is other inevitable impurities. At room temperature, its tensile strength is 554MPa, the yield strength is 354MPa, and the elongation after fracture is 22%. At 700°C, its tensile strength is 484MPa, the yield strength is 286MPa, and the elongation after fracture is 23.7%. The chemical composition of the welding wire 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%, and the rest is Ni and inevitable impurities; the base material and the welding wire are welded by TIG welding, and the welding parameters are: current is 175-185A, arc voltage is 13-15V, wire feeding speed is 100mm / min, welding speed is 10mm / min, shielding gas is Ar, gas flow rate is 15L / min, and the interpass temperature is controlled to be ≥60°C. The tensile strength of the cladding metal obtained is 729MPa, and the elongation after fracture is 42.4%;

[0050] A 60° V-shaped groove is made at the connection part of the parent material, and the groove and the surrounding area are cleaned to remove oil, scale and impurities;

[0051] The groove was surfacing welded by pulse 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 of 13-15L / min, one surfacing layer, and naturally cooled to room temperature after welding;

[0052] The test plate was preheated to 20°C, and hot wire TIG welding was used for base welding. The welding parameters were as follows: welding current was 120A, hot wire current was 30A, arc voltage was 10.5V, and welding speed was 120mm / min.

[0053] Hot wire TIG welding is used for filling and capping welding. The welding parameters are: welding current is 130A, hot wire current is 20A, arc voltage is 10.5V, welding speed is 120mm / min, shielding gas is Ar, gas flow rate is 13-15L / min, and interpass temperature is ≥40℃.

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

[0055] Non-destructive testing includes X-ray testing + ultrasonic testing:

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

[0057] Ultrasonic testing shall be carried out in accordance with GB / T 11345 Ultrasonic testing technology, testing levels and assessment for non-destructive testing of welds.

[0058] Mechanical properties test:

[0059] Mechanical properties testing is carried out in accordance with GB / T 2651 metal material weld destructive test and transverse tensile test.

[0060] Table 1 Performance test of Example 1 and Comparative Example 1 From Table 1, we can see the difference in mechanical properties between Example 1 and Comparative Example 1. The overall mechanical properties of Example 1 are much higher than those of Comparative Example 1. This is because the last step of heat treatment is omitted in Comparative Example 1 compared with Example 1. Heat treatment has the effect of removing hydrogen and stress, and can effectively improve the mechanical properties of the metal. Comparative Example 2 selects solid solution base material, pulse TIG welding for surfacing welding of grooves, wire TIG welding for base welding, hot wire TIG welding for filling and capping welding, and no post-weld heat treatment, which leads to cracks in the alloy of Comparative Example 2 and cannot be used. Through the embodiments and comparative examples, it can be proved that the welding method of the present invention can inhibit cracks in welded joints and can effectively improve the mechanical properties of welded joints.

[0061] The above are only preferred specific embodiments of the present invention, which are all different implementations based on the overall concept of the present invention, and the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A welding method for an iron-nickel based alloy, characterized in that: The method comprises the following steps: S1: Selection of base material and welding wire; S2: Make a V-shaped groove on the connection part of the test plate and clean it; S3: Use TIG welding to build up the groove of S2, build up two layers, welding parameters: current 125-135A, arc voltage 12-13V, wire feeding speed 600mm / min, welding speed 120mm / min, shielding gas Ar, gas flow 13-15L / min, interpass temperature 50℃-60℃; S4: preheating of test plate; S5: Base welding: heat input range 0.8 ~ 1.0 kJ / cm, TIG welding, welding parameters: current 125 ~ 135A, arc voltage 12 ~ 13V, welding speed 120mm / min, shielding gas Ar, gas flow 13 ~ 15L / min, interpass temperature ≥ 60 ℃; S6: Filling and capping welding: heat input range 0.8 ~ 1.0 kJ / cm, TIG welding, welding parameters: current 125 ~ 135A, arc voltage 12 ~ 13V, welding speed 100mm / min, shielding gas Ar, gas flow 13 ~ 15L / min, interpass temperature ≥ 60 ℃; S7: Post weld heat treatment.

2. The welding method according to claim 1, characterized in that: The base material in S1 is an iron-nickel alloy aged base material, and the tensile strength at room temperature and 700°C is ≥655MPa, the yield strength is ≥240MPa, and the elongation after fracture is ≥35%; the chemical composition of the welding wire 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≤0.03 %, Co: 10.0-15.0, Cu≤0.5%, Al: 0.8~1.5%, and the rest are Ni and inevitable impurities; and when the welding parameters are current 175~185A, arc voltage 13~15V, wire feeding speed 100mm / min, welding speed 10mm / min, shielding gas Ar, gas flow rate 15L / min, interpass temperature ≥60℃, the tensile strength of the cladding metal obtained by TIG welding the base material and the welding wire is ≥600MPa, and the elongation after fracture is ≥25%.

3. The welding method according to claim 1, characterized in that: S2 has a V-shaped groove of 60°.

4. The welding method according to claim 1, characterized in that: In S3, the first layer of surfacing welding is 5 passes.

5. The welding method according to claim 1, characterized in that: In S3, the second layer of surfacing is performed in 4 passes.

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

7. The welding method according to claim 1, characterized in that: The root gap of S5 base welding is 3mm.

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

9. A welded joint prepared by the welding method according to any one of claims 1 to 8, characterized in that: Tensile strength ≥625MPa, yield strength ≥240MPa, elongation after break ≥25%.

10. Use of the welding method according to claims 1 to 8 in welding of precipitation-strengthened iron-nickel-based high-temperature alloy castings.

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