A method for controlling the dilution rate of a corrosion-resistant surfacing layer

Abstract

The present invention discloses a method for controlling the dilution rate of a corrosion-resistant surfacing layer, belonging to the technical field of corrosion-resistant surfacing manufacturing. A pulsed current is used to weld multiple layers of corrosion-resistant surfacing layers on the base material in sequence, and the welding material is set as a welding wire; the thickness T of the first two layers of corrosion-resistant surfacing layers is set as: T = (S w / (S t *D s ))*(A b / A p )*α; where the unit of T is mm; S t is the welding speed, with the unit of mm / min; D s is the step size, with the unit of mm; S w is the wire feeding speed, with the unit of mm / min; A b is the base current, with the unit of A; A p is the peak current, with the unit of A; α is the adjustment coefficient; the present invention can control the thickness of the first two layers of corrosion-resistant surfacing layers by using actual welding parameters, obtain qualified corrosion resistance on the basis of ensuring that the thickness of the corrosion-resistant surfacing layer is as thin as possible, ensure the quality of the corrosion-resistant surfacing layer while being economically reliable, reduce the welding difficulty, and improve the one-time surfacing qualification rate and production efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of corrosion-resistant surfacing manufacturing, and particularly relates to a method for controlling the dilution rate of a corrosion-resistant surfacing layer. Background Art

[0002] At present, the welding manufacturing industry is continuously expanding its business in fields such as oil and gas equipment, power industry, aerospace, etc. Among them, corrosion-resistant surfacing products play an important role in the welding manufacturing field. Corrosion-resistant surfacing is generally applied to core components to play the role of corrosion resistance and extend the service life of equipment. Once the corrosion-resistant layer is corroded and damaged by the medium, the consequences will be unimaginable.

[0003] In the design of corrosion-resistant surfacing process, the thickness of the surfacing layer is generally controlled within 3 - 6 mm; during the surfacing process, the Fe content (i.e., dilution rate) diffused from the molten base metal into the surfacing layer is a parameter index that must be considered. This index can measure the corrosion resistance of the corrosion-resistant layer and is a key control point; generally in the industry, it is required that the Fe content in the surfacing layer at a distance of 2.5 mm or 3 mm from the weld fusion line does not exceed 5% to prove the safety of the surfacing layer. The Fe element in the surfacing layer diffuses from the base metal during the welding process, thereby diluting the corrosion-resistant elements in the surfacing layer. This degree of diffusion is mainly affected by factors such as the magnitude of the welding heat input, the thickness of the surfacing layer, and the workpiece temperature.

[0004] At present, there is no effective and stable method in the industry to control the dilution rate of the surfacing layer. The existing methods mainly rely on experience and relatively broad parameter ranges for control, with extremely high uncertainty and certain quality and safety risks. Therefore, in order to ensure that the Fe element content in the corrosion-resistant layer does not exceed the standard, many manufacturers have to increase the surfacing thickness; since the corrosion-resistant materials used for surfacing (usually nickel-based materials) are expensive, increasing the surfacing layer thickness will increase the manufacturing cost and cause great waste.

[0005] Therefore, it is an urgent problem to be solved at present to develop and design a method for controlling the dilution rate of a corrosion-resistant surfacing layer that can accurately and effectively control the Fe element content in the surfacing layer, achieve the same corrosion resistance on the basis of reducing the thickness of the surfacing layer, and reduce the welding difficulty and surfacing cost. Summary of the Invention

[0006] For the problems existing in the prior art, the present invention provides a method for controlling the dilution rate of a corrosion-resistant surfacing layer. By using actual welding parameters, the thickness of the first two layers of the corrosion-resistant surfacing layer can be controlled. On the basis of ensuring that the thickness of the corrosion-resistant surfacing layer is as thin as possible, qualified corrosion resistance can be obtained. While ensuring the quality of the corrosion-resistant surfacing layer, it is economical and reliable, reducing the welding difficulty, and improving the one-time surfacing qualification rate and production efficiency.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] The present invention provides a method for controlling the dilution rate of a corrosion-resistant surfacing layer. A pulsed current is used to weld multiple layers of corrosion-resistant surfacing layers on the base material in sequence, and the welding material is set as a welding wire; the thickness T of the first two layers of the corrosion-resistant surfacing layer is set as: T = (S w / (S t *D s ))*(A b / A p )*α; where, the unit of T is mm; S t is the welding speed, with the unit of mm / min; D s is the step size, with the unit of mm; S w is the wire feeding speed, with the unit of mm / min; A b is the base current, with the unit of A; A p is the peak current, with the unit of A; α is the adjustment coefficient; in the actual welding process, on the premise that the wire specification is certain, the welding speed S t and the step size D s are both inversely related to the thickness T of the corrosion-resistant surfacing layer, and the wire feeding speed S w is positively related to the thickness T of the corrosion-resistant surfacing layer; and, during welding, the larger the ratio of the peak current A p to the base current A b , the more intense the heat generation, the deeper the penetration depth, the larger the molten pool volume, resulting in the thinning of the thickness T of the corrosion-resistant surfacing layer while also increasing the dilution rate, that is, the ratio of the base current A b to the peak current A p is positively related to the thickness T of the corrosion-resistant surfacing layer and inversely related to the dilution rate; on this basis, the adjustment coefficient α is set again, and the optimal value of the thickness T of the corrosion-resistant surfacing layer can be calculated through the welding speed S t , the step size D s , the wire feeding speed S w , the base current A b , and the peak current A p , so as to obtain qualified corrosion resistance on the basis of ensuring that the thickness of the corrosion-resistant surfacing layer is as thin as possible.

[0009] As a preferred technical solution, under the flat welding position, α is set to 1.

[0010] As a preferred technical solution, under the horizontal welding position, α is set to 1.2.

[0011] As a preferred technical solution, the peak current time of the pulsed current is set to 200 ms, the base current time is set to 200 ms, and the pulse width ratio is set to 50%.

[0012] As a preferred technical solution, the number of layers of the corrosion-resistant surfacing layer is not less than three layers.

[0013] As a preferred technical solution, the welding method is set as GTAW welding.

[0014] As a preferred technical solution, before welding, the oil stain and rust on the surface of the base material are cleaned and removed.

[0015] As a preferred technical solution, after welding is completed, the corrosion-resistant surfacing layer is subjected to penetrant testing, tensile testing, impact testing, bending testing, intergranular corrosion inspection, chemical composition inspection, and macroscopic cross-section inspection.

[0016] As a preferred technical solution, the welding wire is set as ER316L or ERNiCrMo-13, and the diameter of the welding wire is set as 1.2 mm.

[0017] As a preferred technical solution, the total thickness of the multi-layer corrosion-resistant surfacing layer is set as 3-6 mm.

[0018] The beneficial effects of the present invention are shown in:

[0019] 1. The present invention can calculate the thickness of the first two layers of the corrosion-resistant surfacing layer by using the actual welding parameters, thereby effectively controlling the thickness and dilution rate of the corrosion-resistant surfacing layer. On the basis of ensuring that the first two layers of the corrosion-resistant surfacing layer are as thin as possible, a corrosion-resistant surfacing layer with qualified corrosion resistance can also be obtained, effectively reducing the surfacing cost.

[0020] 2. The present invention can design the thickness arrangement of the corrosion-resistant surfacing layer according to the surfacing requirements of different products, effectively and accurately, improving the one-time surfacing qualification rate and production efficiency.

[0021] 3. The present invention can solidify the thickness of the first two layers of the corrosion-resistant surfacing layer by using the actual welding parameters, reduce the welding difficulty, realize stable welding, and ensure the welding quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic structural diagram of the first embodiment of a method for controlling the dilution rate of a corrosion-resistant surfacing layer of the present invention;

[0023] Figure 2 is a schematic structural diagram of the second embodiment of a method for controlling the dilution rate of a corrosion-resistant surfacing layer of the present invention.

[0024] In the figure: 1-base material, 2-corrosion-resistant surfacing layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] For the convenience of those skilled in the art to understand, the present invention will be further described below with reference to the accompanying drawings. Embodiment 1

[0026] Please refer to Figure 1 , which is the first embodiment of a method for controlling the dilution rate of a corrosion-resistant surfacing layer provided by the present invention. Among them, the base material 1 is a SA516 Gr.70 carbon steel plate with a thickness of 15 mm. An ER316L stainless steel corrosion-resistant surfacing layer 2 is fillet welded on the surface of the base material 1. The chemical composition of the base material 1 is shown in Table 1; the welding consumable is an ER316L welding wire with a diameter of 1.2 mm, and the chemical composition of the welding consumable is shown in Table 2.

[0027] Table 1 Chemical composition table of SA516 Gr.70

[0028]

[0029] Table 2 Chemical composition table of ER316L

[0030]

[0031] Before fillet welding, the oil stains, rust and other impurities on the surface of the base material 1 should be cleaned and removed, and no preheating is required; the welding process adopted is motorized hot wire Tig welding with pulsed welding. The specific welding process parameters are shown in Table 3;

[0032] The thickness T of the three-layer corrosion-resistant surfacing layer 2 is set as: T=(S w / (S t *D s ))*(A b / A p );Among them, S t is the welding speed, D s is the step amount, S w is the wire feeding speed, A b is the base current, A p is the peak current; since during fillet welding, the molten pool spreads horizontally, setting the adjustment coefficient α = 1 can make the thickness T of the corrosion-resistant surfacing layer 2 meet the corrosion resistance requirements; finally, the total thickness of all the corrosion-resistant surfacing layers 2 is 5.6 mm.

[0033] Table 3 Welding process parameter table

[0034]

[0035] After welding is completed, the surfacing surface of the base material 1 is subjected to penetrant testing, and samples are taken for macro cross-section inspection, intergranular corrosion inspection, bending test, impact test, chemical composition inspection, and tensile test. All the test results show that the Fe element content in the corrosion-resistant surfacing layer 2 meets the requirements, that is, the dilution of the Fe element is effectively controlled. At the same time, the quality of the corrosion-resistant surfacing layer 2 is guaranteed; the specific test results are shown in Table 4.

[0036] Table 4 Corrosion-resistant surfacing layer test table

[0037] Example Two

[0038] Please refer to Figure 2 , which is the second embodiment of a method for controlling the dilution rate of a corrosion-resistant surfacing layer provided by the present invention. Among them, the base material 1 is an A182 F22 forging, and an ERNiCrMo-13 nickel-based corrosion-resistant surfacing layer 2 is horizontally welded on the inner wall of the base material 1. The chemical composition of the base material 1 is shown in Table 5; the welding consumable is an ER ERNiCrMo-13 welding wire with a diameter of 1.2 mm, and the chemical composition of the welding consumable is shown in Table 6.

[0039] Table 5 Chemical Composition Table of A182 F22

[0040]

[0041] Table 6 Chemical Composition Table of ERNiCrMo-3

[0042]

[0043] Before horizontal welding, the oil stains, rust and other impurities on the surface of the base material 1 should be cleaned and removed, and preheating is not required; the welding process adopted is motorized hot wire Tig welding with pulsed welding. The specific welding process parameters are shown in Table 7;

[0044] The thickness T of the three-layer corrosion-resistant surfacing layer 2 is set to: T = (S w / (S t *D s ))*(A b / A p ); where S t is the welding speed, D s is the step size, S w is the wire feeding speed, A b is the base current, and A p is the peak current; since during horizontal welding, the molten pool is inclined or vertically arranged, it is necessary to slightly increase the adjustment coefficient so that the adjustment coefficient α = 1.2, which can also make the thickness T of the corrosion-resistant surfacing layer 2 meet the corrosion-resistant requirements; finally, the total thickness of all the corrosion-resistant surfacing layers 2 is 6.0 mm.

[0045] Table 7 Welding Process Parameter Table

[0046]

[0047] After welding, the surfacing surface of the base metal 1 is subjected to penetrant testing, and samples are taken for macroscopic cross-section inspection, intergranular corrosion inspection, bending test, impact test, chemical composition inspection, and tensile test. All the test results show that the Fe element content in the corrosion-resistant surfacing layer 2 meets the requirements, that is, the dilution of the Fe element is effectively controlled. At the same time, the quality of the corrosion-resistant surfacing layer 2 is guaranteed; the specific test results are shown in Table 8.

[0048] Table 8 Experimental Table of Corrosion-Resistant Surfacing Layer

[0049]

[0050] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for controlling the dilution rate of a corrosion-resistant surfacing layer, characterized in that, Using pulsed current to sequentially weld multiple layers of corrosion-resistant surfacing layers (2) on the base material (1), and the welding consumable is set as a welding wire; the thickness T of the first two layers of the corrosion-resistant surfacing layers (2) is set as: T = (S w / (S t *D s ))*(A b / A p )*α; where the unit of T is mm; S t is the welding speed, with the unit of mm / min; D s is the step size, with the unit of mm; S w is the wire feeding speed, with the unit of mm / min; A b is the base current, with the unit of A; A p is the peak current, with the unit of A; α is the adjustment coefficient; Under the flat position welding, α is set to 1; Under the horizontal position welding, α is set to 1.

2.

2. The method for controlling the dilution rate of a corrosion-resistant surfacing layer according to claim 1, characterized in that, The peak current time of the pulsed current is set to 200 ms, the base current time is set to 200 ms, and the pulse width ratio is set to 50%.

3. A method for controlling the dilution rate of a corrosion-resistant surfacing layer according to claim 1, characterized in that, The number of layers of the corrosion-resistant surfacing layer (2) is not less than three layers.

4. A method for controlling the dilution rate of a corrosion-resistant surfacing layer according to claim 1, characterized in that, The welding method is set to GTAW welding.

5. A method for controlling the dilution rate of a corrosion-resistant surfacing layer according to claim 1, characterized in that, Before welding, clean and remove the oil stains and rust on the surface of the base material (1).

6. A method for controlling the dilution rate of a corrosion-resistant surfacing layer according to claim 1, characterized in that After welding is completed, conduct penetrant testing, tensile testing, impact testing, bending testing, intergranular corrosion inspection, chemical composition inspection, and macroscopic cross-section inspection on the corrosion-resistant surfacing layer (2).

7. A method for controlling the dilution rate of a corrosion-resistant surfacing layer according to claim 1, characterized in that The welding wire is set to ER316L or ERNiCrMo-13, and the diameter of the welding wire is set to 1.2 mm.

8. A method for controlling the dilution rate of a corrosion-resistant surfacing layer according to claim 1, characterized in that, The total thickness of the multi-layer corrosion-resistant surfacing layer (2) is set to 3 - 6 mm.

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