Welding process for tank body material of molten salt heat storage tank

Abstract

The invention discloses a welding process of a molten salt heat storage tank body material. According to the welding technology of the fused salt heat storage tank body material, the fused salt heat storage tank body material welded through the welding technology has good mechanical performance and corrosion resistance, and high reliability is achieved in industrial practical application.

Description

Technical Field

[0001] The invention relates to a welding process for a tank body material of a molten salt heat storage tank. Background Art

[0002] With the proposal of the "dual carbon" strategic goal, the concepts of energy conservation, emission reduction and sustainable development have attracted attention in my country and even the world. Concentrating Solar Power (CSP) technology is considered to be the clean energy with the greatest development potential in the future due to its green, pollution-free and continuously adjustable output characteristics, and has become a new direction for future energy development in countries around the world. Salt storage and transmission salt devices are the core components of the CSP system, and the molten salt corrosion resistance of the materials used directly determines the safety and service life of the device. However, molten salt acts as an electrolyte in the corrosion system that corrodes metal containers, which will accelerate the corrosion damage of pipelines and container materials. At present, no material can fully meet the service requirements.

[0003] By adding a certain amount of Al element to ordinary 310S (0Cr25Ni20) heat-resistant steel and reducing the Cr element content, the production cost is reduced while obtaining a single-phase austenite matrix 310S heat-resistant steel. Technicians have studied the effects of different Al contents on the corrosion behavior and corrosion mechanism of high-aluminum 310S in high-temperature carbonate molten salts. The results show that it has excellent corrosion resistance in high-temperature molten salts and is expected to become a material for salt storage and transmission pipelines in the next generation of solar thermal power generation systems (CSP).

[0004] Any material cannot be separated from the welding process in the actual assembly application of engineering. The welding process of 310S heat-resistant steel is mature, but aluminum-containing 310S heat-resistant steel is a newly developed steel type and there is currently no suitable welding process. Therefore, how to improve the welding performance of aluminum-containing 310S heat-resistant steel needs to be studied. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defect that there is no clear welding process for aluminum-containing 310S heat-resistant steel in the prior art and that the conditions for commercial use cannot be met, and a welding process for aluminum-containing 310S heat-resistant steel is provided. The welding process of the present invention ensures that the aluminum-containing 310S heat-resistant steel still has good mechanical properties and corrosion resistance after welding, and has high reliability in practical industrial applications.

[0006] The present invention solves the above technical problems through the following technical solutions.

[0007] The invention provides a welding process for a tank body material of a molten salt heat storage tank, which comprises the following steps: welding a base material, wherein the welding adopts an argon arc welding process; the base material is aluminum-containing 310S heat-resistant steel, and the wire feeding speed of the welding process is 5.0-9.5m / min, the welding speed is 5-6mm / s, the welding current is 170-190A, and the arc voltage is 18-25V.

[0008] In the present invention, if the welding parameters of the welding process, such as wire feeding speed, welding speed, welding current and arc voltage, are within a specific range, the welded molten salt heat storage tank body material will have excellent mechanical properties and molten salt corrosion resistance. Therefore, the welding parameters within a specific range are crucial to solving the technical problem of the present invention; otherwise, the welded molten salt heat storage tank body material will not have excellent mechanical properties and molten salt corrosion resistance.

[0009] In the present invention, preferably, the welding wire feeding speed may be 6.5-7 m / min; for example, 6.5 m / min or 7 m / min.

[0010] In the present invention, preferably, the welding speed is 70 / 12 mm / s.

[0011] In the present invention, preferably, the welding current may be 176-187A; for example, 176A or 187A.

[0012] In the present invention, preferably, the arc voltage may be 20.8-21.3A; for example, 20.8 or 21.3A.

[0013] In the present invention, preferably, the aluminum-containing 310S heat-resistant steel comprises the following components in percentage by mass: C: 0.02-0.1%, Si: 0.5-3%, Mn: 1.1-3%, Cr: 4-12%, Ni: 11-22% and Al: 1.3-4%, with the remainder being Fe.

[0014] In the present invention, the matrix structure of the aluminum-containing 310S heat-resistant steel is single-phase austenite.

[0015] In the present invention, the content of C may be 0.05-0.1%, for example 0.075%.

[0016] In the present invention, the content of Si may be 1-2.5%, for example, 1.97%.

[0017] In the present invention, the content of Mn may be 1.5-2.5%, for example 2.08%.

[0018] In the present invention, the Cr content may be 6-13%, for example, 10.22%.

[0019] In the present invention, the Ni content may be 11-22%, for example, 19.29%.

[0020] In the present invention, the Al content may be 1.5-3.5%, for example 3.03%.

[0021] In some preferred embodiments of the present invention, the chemical composition and mass percentage of the aluminum-containing 310S heat-resistant steel include: C: 0.075%, Si: 1.97%, Mn: 2.08%, Cr: 10.22%, Ni: 19.29%, Al: 1.3-4%, and the balance is Fe.

[0022] In a preferred embodiment of the present invention, the chemical composition and mass percentage of the aluminum-containing 310S heat-resistant steel include: C: 0.075%, Si: 1.97%, Mn: 2.08%, Cr: 10.22%, Ni: 19.29%, Al: 3.03%, and the balance is Fe.

[0023] In the present invention, C refers to the element carbon, Si refers to the element silicon, Al refers to the element aluminum, Cr refers to the element chromium, Ni refers to the element nickel, Mn refers to the element manganese, and Fe refers to the element iron.

[0024] In the present invention, the aluminum-containing 310S heat-resistant steel may be in a hot-rolled state.

[0025] In the present invention, the aluminum-containing 310S heat-resistant steel can be obtained by adding Al element and reducing Cr element in the composition of 310S (0Cr25Ni20) heat-resistant steel.

[0026] In the present invention, the size of the aluminum-containing 310S heat-resistant steel may be 30 mm×15 mm×6.8 mm, and the required size may be obtained by wire cutting.

[0027] In the present invention, the welding process may further include pre-welding treatment, which can remove impurities such as oil stains during the processing.

[0028] The pre-welding treatment may include grinding and / or wiping, wherein acetone or ethanol is preferably used for the wiping.

[0029] In the present invention, the welding may further include an operation of opening a welding groove.

[0030] Wherein, the welding groove is a V-shaped groove.

[0031] The groove angle of the V-shaped groove is preferably 60°. The blunt edge size of the V-shaped groove is preferably 2 mm.

[0032] In the present invention, the welding material may be Inconel 625 welding wire.

[0033] Wherein, the diameter of the Inconel 625 welding wire is preferably 2.4 mm.

[0034] In the present invention, the welding method can adopt Tungsten Inert Gas Welding (TIG for short). TIG welding has fewer defects and a stable arc. Even if the current is less than 10A, it can still maintain stable combustion. The weld pool is always protected by argon gas during the welding process, so it can effectively isolate the surrounding air. Argon gas itself is insoluble in metal and does not react with metal, thereby ensuring the stability of the welding process and obtaining a high-quality weld.

[0035] The inert gas may be pure argon.

[0036] In the present invention, preferably, the gas flow rate of the inert gas (such as argon) is 7-16 L / min, such as 10 L / min.

[0037] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0038] The reagents and raw materials used in the present invention are commercially available.

[0039] The positive progressive effect of the present invention is that the welding process of the aluminum-containing 310S heat-resistant steel provided by the present invention enables the aluminum-containing 310S heat-resistant steel to still have good mechanical properties and corrosion resistance after welding, and has higher reliability in practical industrial applications.

[0040] The present invention can provide a useful reference for the actual welding of energy storage structural materials for high-temperature molten salt (salt storage alloy materials such as nitrates and chlorides for solar thermal power generation). BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is the metallographic structure of the parent material.

[0042] Figure 2 Metallographic structure of weld.

[0043] Figure 3 This is the surface morphology after welding in Example 1.

[0044] Figure 4 This is the surface morphology after welding in Example 2.

[0045] Figure 5 This is the surface morphology after welding in Example 3. DETAILED DESCRIPTION

[0046] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0047] The parent material used in the embodiment of the present invention is aluminum-containing 310S heat-resistant steel, and its chemical composition is shown in Table 1.

[0048] Table 1 Base material (chemical composition (wt.%)

[0049] Element C Si Mn Cr Ni Al Fe content 0.075 1.97 2.08 10.22 19.29 3.03 margin

[0050] The welding wire used in the embodiment of the present invention is Inconel 625 welding wire, and its chemical composition is shown in Table 2.

[0051] Table 2 Chemical composition of welding wire (wt.%)

[0052]

[0053] Examples 1-3

[0054] The size of the base material is 30mm×15mm×6.8mm, the groove is V-shaped, the groove angle is 60°, and the blunt edge size is 2mm. Before welding, the groove is polished and cleaned with sandpaper and wiped with acetone to remove impurities such as oil stains during processing. A solid core welding wire Inconel 625 with a diameter of 2.4mm is selected, and the shielding gas is pure argon. The argon arc welding process parameters are shown in Table 3:

[0055] Table 3

[0056]

[0057] Effect Example 1 Organizational Structure

[0058] The matrix structure of the aluminum-containing 310S heat-resistant steel used in the present invention is single-phase austenite, and its metallographic structure is as follows: Figure 1 shown. Figure 1 It can be seen that its structure is an austenite structure with clear grain boundaries and a small amount of twins.

[0059] The welded plate was sampled perpendicular to the weld, the longitudinal surface of the weld joint was polished, and metallographic corrosion was carried out using FeCl3 + 50% hydrochloric acid aqueous solution for 30-40s. The metallographic structure of the weld was observed using a ZEISS Observer.LSM800 metallographic microscope. Figure 2 shown. Figure 2 a, b, c correspond to embodiments 1-3 respectively. Figure 2It can be observed that the structure of the base material is an austenite structure with an FCC crystal structure. No obvious defects such as pores and thermal cracks are observed in the weld area, and the weld is well fused with the base material.

[0060] from Figure 2 (a) It can be observed that the grains near the fusion line of the welded joint of Inconel 625 welding wire are small, and the grains in the heat affected zone are growing.

[0061] The surface morphology after welding of Example 1-3 is as follows Figure 3-5 shown.

[0062] Effect Example 2 Mechanical Properties

[0063] The welded specimens of the materials of Example 1 were processed into tensile specimens according to the national standard GB / T 228.1-2010. The instrument used for the room temperature tensile test was a Shimadzu AGS-X 300kN electronic universal testing machine. The tensile rate was 2mm / min. The displacement loading method was adopted. Three groups of parallel experiments were performed on each component specimen.

[0064] The load-displacement curve is measured, and the corresponding stress and strain values ​​are calculated based on the load-displacement curve data. The average value is obtained to obtain the corresponding mechanical property data. These performance data can illustrate the feasibility of welding.

[0065] The mechanical properties are obtained after welding by argon arc welding process. The mechanical properties after welding are shown in Table 4. These mechanical properties can illustrate the reliability and rationality of the welding process.

[0066] Table 4

[0067]

[0068]

[0069] Effect Example 3 Molten Salt Corrosion Resistance

[0070] The weld of the material in Example 1 was subjected to a static immersion corrosion test to measure the corrosion rate of the weld area in the ternary carbonate molten salt.

[0071] Table 5 shows the corrosion rate and unit area mass change of aluminum-containing 310S weld in carbonate at different corrosion times.

[0072] Table 5

[0073] time 72h 144h 216h 300h Mass change (mg / cm2) 0.758 2.428 2.534 3.926 Corrosion rate (μm / year) 118.212 189.390 131.750 146.969

[0074] It can be seen from Table 5 that the welded alloy plate has excellent molten salt corrosion resistance.

Claims

1. A welding process for the body material of a molten salt heat storage tank, characterized in that: The method comprises the following steps: welding the parent material, wherein the welding adopts an argon arc welding process; The base material is aluminum-containing 310S heat-resistant steel, the welding wire feeding speed is 5.0-9.5m / min, the welding speed is 5-6mm / s, the welding current is 170-190A and the arc voltage is 18-25V.

2. The welding process according to claim 1, characterized in that: It meets one or more of the following conditions: (1) The welding wire feeding speed is 6.5-7 m / min; for example, 6.5 m / min or 7 m / min; (2) The welding speed is 70 / 12 mm / s; (3) The welding current is 176-187A; for example, 176A or 187A; (4) The arc voltage is 20.8-21.3A; for example, 20.8 or 21.3A; (5) The aluminum-containing 310S heat-resistant steel comprises the following components in percentage by mass: C: 0.02-0.1%, Si: 0.5-3%, Mn: 1.1-3%, Cr: 4-12%, Ni: 11-22% and Al: 1.3-4%, with the balance being Fe; (6) The matrix structure of the aluminum-containing 310S heat-resistant steel is single-phase austenite.

3. The welding process according to claim 2, characterized in that: It meets one or more of the following conditions: (1) The C content is 0.05-0.1%, for example 0.075%; (2) The Si content is 1-2.5%, for example 1.97%; (3) The Mn content is 1.5-2.5%, for example 2.08%; (4) The Cr content is 6-13%, for example 10.22%; (5) The Ni content is 11-22%, for example 19.29%; (6) The Al content is 1.5-3.5%, for example 3.03%.

4. The welding process according to claim 3, characterized in that: The aluminum-containing 310S heat-resistant steel includes the following components in percentage by mass: C: 0.075%, Si: 1.97%, Mn: 2.08%, Cr: 10.22%, Ni: 19.29%, Al: 3.03%, and the balance is Fe.

5. The welding process according to claim 1, characterized in that: It meets one or more of the following conditions: (1) The aluminum-containing 310S heat-resistant steel is in a hot-rolled state; (2) The aluminum-containing 310S heat-resistant steel is prepared by adding Al element and reducing Cr element in the composition of 310S (0Cr25Ni20) heat-resistant steel.

6. The welding process according to claim 1, characterized in that: The size of the aluminum-containing 310S heat-resistant steel is 30 mm×15 mm×6.8 mm.

7. The welding process according to claim 1, characterized in that: The welding process also includes pre-welding treatment.

8. The welding process according to claim 1, characterized in that: The pre-welding treatment includes grinding and / or wiping; the wiping is preferably performed using acetone or ethanol.

9. The welding process according to claim 1, characterized in that: The welding also includes the operation of opening a welding groove; Wherein, the welding groove is a V-shaped groove; the groove angle of the V-shaped groove is preferably 60°; the blunt edge size of the V-shaped groove is preferably 2 mm; The welding material is Inconel 625 welding wire; the diameter of the Inconel 625 welding wire is preferably 2.4 mm.

10. The welding process according to claim 1, characterized in that: The welding method adopts non-melting inert gas shielded welding (TIG); wherein the inert gas is pure argon gas; preferably, the gas flow rate of the pure argon gas is 7-16 L / min, for example, 10 L / min.

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