High-toughness austenitic stainless steel solid welding wire for 5Ni steel and preparation method

Abstract

The invention relates to the technical field of welding wire preparation, in particular to a high-toughness austenitic stainless steel solid welding wire for 5Ni steel and a preparation method. The invention relates to a high-toughness austenitic stainless steel solid welding wire for 5Ni steel. The welding wire comprises the following components: 0.14-0.26% of C; 0.24% to 0.56% of Si; 16.3% to 19.3% of Cr; 0.5 Mn + Ni: 18.5%-20.5%, and the content of Mn is greater than 4.5%; 4.0%-7.0% of Mo + 1.5 W, and at the same time, Mo is less than or equal to 3.0%; 0.03% to 0.12% of N; 0.03%-0.1% of 0.5 Nb + Ti + 1.2 V; 0.02% to 0.08% of rare earth Ce + La; s + P < = 0.008%; o < = 0.003%; and the balance of Fe and inevitable impurities. The high-toughness austenitic stainless steel solid welding wire for the 5Ni steel has the advantages that the low-temperature toughness is improved, the hot crack sensitivity is reduced, the work hardening is weakened, the welding wire is easy to machine, the pore sensitivity is reduced, and the requirements of efficient and low-defect welding of the 5Ni steel are met.

Description

Technical Field

[0001] The present invention relates to the technical field of wire preparation, and particularly to a high-toughness austenitic stainless steel solid wire for 5Ni steel and a preparation method thereof. Background Art

[0002] 5Ni steel is an alloy steel with a Ni content of 4.75% - 5.25%, and is generally supplied in a quenched and tempered state. It is widely used in low-temperature storage devices such as liquefied petroleum gas (LPG), liquefied ethylene (LEG), and liquefied ethane (LEC). Due to the low service temperature, relatively stringent requirements are imposed on the matching welding materials, especially for high low-temperature toughness requirements, with the requirement that KV2 ≥ 27J at -140°C. To ensure the low-temperature toughness of the welded joint, nickel-based welding materials are commonly used for welding at present. However, nickel-based welding materials have a high viscosity of the weld metal, poor gas permeability, and are prone to defects such as porosity, slag inclusion, and lack of fusion. At the same time, they are expensive, increasing the construction cost. Therefore, it is urgent to develop low-cost and high-toughness welding materials. Austenitic stainless steel solid wires have high welding efficiency and a price much lower than that of nickel-based welding materials. Therefore, they have good market prospects for welding 5Ni steel.

[0003] There are many literatures on the preparation of stainless steel wires. For example, the publication number CN102363251A discloses a high-strength and tough fully austenitic stainless steel wire. The wire composition is: C: 0.03 - 0.10%, Si: 0.3 - 0.90%, Mn: 2.0 - 4.5%, Cr: 13.0 - 16.0%, Ni: 21 - 25%, Mo: 3.5 - 5.5%, N: 0.10 - 0.30%, S ≤ 0.010, P ≤ 0.015%, H ≤ 5 ppm, and the rest is Fe. The wires prepared according to the composition components and their proportions in this patent usually have poor low-temperature toughness, high sensitivity to hot cracks, serious work hardening, difficult processing, and relatively high porosity sensitivity, and cannot meet the requirements of efficient and low-defect welding of 5Ni steel. Summary of the Invention

[0004] In view of this, the present invention aims to provide a high-toughness austenitic stainless steel solid wire for 5Ni steel. The composition includes: C: 0.14% - 0.26%; Si: 0.24% - 0.56%; Cr: 16.3% - 19.3%; 0.5Mn + Ni: 18.5% - 20.5%, and at the same time, the Mn content is greater than 4.5%; Mo + 1.5W: 4.0% - 7.0%, and at the same time, Mo ≤ 3.0%; N: 0.03% - 0.12%; 0.5Nb + Ti + 1.2V: 0.03% - 0.1%; rare earth Ce + La: 0.02% - 0.08%; S + P ≤ 0.008%; O ≤ 0.003%; the rest is Fe and inevitable impurities. The wire solves the problems of poor low-temperature toughness, high sensitivity to hot cracks, serious work hardening, difficult processing, high porosity sensitivity, and inability to meet the requirements of efficient and low-defect welding of 5Ni steel, etc.

[0005] To solve the above problems, the present invention provides a high-toughness austenitic stainless steel solid wire for 5Ni steel. The composition of the wire includes: C: 0.14% - 0.26%; Si: 0.24% - 0.56%; Cr: 16.3% - 19.3%; 0.5Mn + Ni: 18.5% - 20.5%, and at the same time, the Mn content is greater than 4.5%; Mo + 1.5W: 4.0% - 7.0%, and at the same time, Mo ≤ 3.0%; N: 0.03% - 0.12%; 0.5Nb + Ti + 1.2V: 0.03% - 0.1%; rare earth Ce + La: 0.02% - 0.08%; S + P ≤ 0.008%; O ≤ 0.003%; the rest is Fe and inevitable impurities.

[0006] A preparation method of a high-toughness austenitic stainless steel solid wire for 5Ni steel as described above includes:

[0007] S100, blank preparation: After mixing the components of the wire in proportion, vacuum melting and electroslag remelting are used for melting, and then an ingot is prepared by casting after melting.

[0008] S200, forging treatment: The forging temperature is 1000 - 1200 °C.

[0009] S300, hot rolling treatment: The hot rolling temperature is 1000 - 1200 °C to form a hot-rolled wire rod.

[0010] S400, solution treatment: After maintaining for a preset time at a preset temperature, it is cooled.

[0011] S500, cleaning the wire rod: Degreasing and cleaning the wire rod.

[0012] S600. Drawing treatment: The wire rod is drawn by a wire drawing machine or a wire rolling machine to form a welding wire with a preset diameter according to process requirements. After drawing, the welding wire is wound layer by layer.

[0013] S700. Final treatment: The welding wire is finally cleaned, dried and packaged.

[0014] Further, in step S200, the forging heating temperature is 1120 - 1200 °C, and the final forging temperature is 1000 - 1080 °C.

[0015] Further, in step S300, the hot rolling heating temperature is 1120 - 1200 °C, and the final rolling temperature is 1000 - 1080 °C.

[0016] Further, in step S400, the preset temperature is 1120 - 1200 °C, and the preset time is 1 - 2 h.

[0017] Further, in step S500, the method for cleaning the wire rod includes caustic washing and pickling, and finally, it is soaked in a sodium carbonate solution for 3 - 5 min for acid-base neutralization treatment.

[0018] Further, the caustic washing method includes:

[0019] Prepare an alkaline degreaser. The components of the alkaline degreaser include: 5 - 10% sodium hydroxide, 2 - 4% sodium carbonate, 1 - 3% sodium silicate, 0.5 - 1% alkylphenol polyoxyethylene ether, and the rest is water.

[0020] Use the alkaline degreaser with a concentration of 6 - 12% and a temperature of 70 - 90 °C, soak for 15 - 40 min, and then perform ultrasonic cleaning.

[0021] Further, the pickling method includes:

[0022] Use a mixed solution of 6 - 12% nitric acid and 1 - 5% hydrofluoric acid, soak for 7 - 15 min at a temperature of 30 - 60 °C, and then use high-pressure water to wash away the residual acid.

[0023] Further, in step S600, the relaxed diameter of the welded wire after winding is ≥ 1000 mm, and the warp distance is ≤ 10 mm.

[0024] Further, in step S700, the final treatment method includes:

[0025] S710. Cleaning step: Use electrolytic caustic washing, and then perform high-pressure water cleaning.

[0026] S720. Drying step: The drying temperature is 60 - 90 °C, and the drying time is 3 - 10 min.

[0027] S730. Packaging step: Use vacuum packaging.

[0028] Compared with the prior art, the high-toughness austenitic stainless steel solid wire for 5Ni steel of the present invention has the following advantages:

[0029] The advantages of this technical solution lie in that the composition includes: C: 0.14% - 0.26%; Si: 0.24% - 0.56%; Cr: 16.3% - 19.3%; 0.5Mn + Ni: 18.5% - 20.5%, and at the same time, the Mn content is greater than 4.5%; Mo + 1.5W: 4.0% - 7.0%, and at the same time, Mo ≤ 3.0%; N: 0.03% - 0.12%; 0.5Nb + Ti + 1.2V: 0.03% - 0.1%; rare earth Ce + La: 0.02% - 0.08%; S + P ≤ 0.008%; O ≤ 0.003%; the rest is Fe and inevitable impurities. The prepared wire improves the low-temperature toughness, reduces the hot crack sensitivity, weakens the work hardening, is easy to process, reduces the porosity sensitivity, and meets the requirements of high-efficiency and low-defect welding of 5Ni steel. Specific embodiments

[0030] To make the above objects, features, and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below.

[0031] In the present invention, the descriptions involving "first", "second", "upper", "lower", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", "upper", "lower" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the technical solutions between embodiments can be combined, they are all within the protection scope required by the present invention.

[0032] The present invention will be described in detail below in conjunction with embodiments.

[0033] A high-toughness austenitic stainless steel solid wire for 5Ni steel, the composition of the wire includes: C: 0.14% - 0.26%; Si: 0.24% - 0.56%; Cr: 16.3% - 19.3%; 0.5Mn + Ni: 18.5% - 20.5%, and at the same time, the Mn content is greater than 4.5%; Mo + 1.5W: 4.0% - 7.0%, and at the same time, Mo ≤ 3.0%; N: 0.03% - 0.12%; 0.5Nb + Ti + 1.2V: 0.03% - 0.1%; rare earth Ce + La: 0.02% - 0.08%; S + P ≤ 0.008%; O ≤ 0.003%; the rest is Fe and inevitable impurities.

[0034] The idea of the technical solution adopting the above components and proportions lies in:

[0035] (1) Control the nitrogen content of the welding wire to reduce the porosity sensitivity; adopt the Nb, Ti, V composite strengthening technology to form a large number of fine carbides in the weld metal, significantly improving the strength without deteriorating the plasticity and low-temperature toughness.

[0036] (2) Adopt the technical route of high-carbon C. While achieving good strengthening, through the synergistic effect of Mn and Ni, the stability of austenite at low temperature can be significantly improved, and the low-temperature toughness can be enhanced.

[0037] (3) The atomic radius of W is much larger than that of Mo, so it has a better strengthening effect. Partially replace Mo with W with better solid solution effect, which can improve the strength while avoiding the decrease of low-temperature toughness caused by the segregation of Mo.

[0038] (4) Using rare earths La and Ce can purify the weld metal, reduce the harmful effects of low-melting-point impurities such as S and P, improve the low-temperature toughness while reducing the hot crack sensitivity; at the same time, strictly control the S and P contents to further reduce the hot crack sensitivity.

[0039] By comprehensively using the above technologies, a solid welding wire with low porosity and hot crack sensitivities, relatively high strength of the deposited metal, and excellent low-temperature toughness can be obtained.

[0040] To better elaborate the technical approach of the present invention, the main functions of each component are elaborated in detail below.

[0041] C: It is the main strengthening element. Through solid solution strengthening and precipitation strengthening with Nb, Ti, and V, the strength of the weld metal can be significantly improved; at the same time, as a strong austenite-forming element, it can significantly improve the stability of austenite at low temperature, and significantly increase the plasticity and low-temperature toughness of the weld metal. When the carbon content is lower than 0.14%, its strengthening effect is insufficient; when the content is higher than 0.26%, a large number of carbides are formed with Cr, Mo, and W, deteriorating the low-temperature toughness.

[0042] Si: Its main function is to improve the spreading and wettability of the weld metal, and reduce defects such as slag inclusions and lack of fusion. When the Si content is lower than 0.24%, the weld spreading is poor, and defects such as slag inclusions and lack of fusion are likely to occur; when the Si content is greater than 0.56%, Si is prone to segregation, forming low-melting-point compounds, and the weld is prone to cracking when the restraint is large.

[0043] Cr: It is the main strengthening element. When the Cr content is lower than 16.3%, the strength of the weld metal is low and the hot crack sensitivity is high; when the Cr content is greater than 19.3%, as a ferrite-forming element, the stability of austenite is significantly reduced, and the low-temperature toughness deteriorates.

[0044] Mn and Ni: They are austenite-forming elements and are key elements to ensure the low-temperature toughness of the weld metal. Mn has a greater stability for austenite at temperatures below -100°C than Ni. To improve the low-temperature toughness, the Mn content should be greater than 4.5%. When 0.5Mn + Ni is less than 18.5%, the low-temperature toughness of the weld metal is poor; when 0.5Mn + Ni is greater than 20.5%, the hot cracking sensitivity of the weld metal increases.

[0045] W and Mo: They are important strengthening elements. However, when the Mo content is greater than 3.0%, it is prone to segregation, forming brittle second phases, significantly reducing the plasticity and low-temperature toughness of the weld metal. When Mo + 1.5W is less than 4.0%, the strength of the weld metal is insufficient; when Mo + 1.5W is greater than 7.0% and the Mo content is greater than 3%, the low-temperature toughness of the weld metal decreases and the hot cracking sensitivity increases.

[0046] N: It is an important strengthening element. When N is less than 0.03%, the strength of the weld metal is insufficient; when N is greater than 0.12%, the porosity sensitivity of the weld metal increases, and at the same time, the arc stability decreases.

[0047] Nb, Ti, and V are important strengthening elements. When 0.5Nb + Ti + 1.2V is less than 0.03%, their strengthening effect is insufficient; when 0.5Nb + Ti + 1.2V is greater than 0.12%, their low-temperature toughness decreases severely.

[0048] Rare earth Ce + La: Its main function is to purify the weld metal, improve the low-temperature toughness of the weld metal, and at the same time, it is easy to combine with low-melting-point substances such as S, reducing the hot cracking sensitivity. When its content is less than 0.02%, the effect of improving low-temperature toughness and reducing hot cracking sensitivity is insufficient; when it is greater than 0.08%, a large number of oxide inclusions are formed, reducing the plasticity and toughness of the weld metal.

[0049] S, P: They are impurity elements, which are easy to form low-melting-point compounds, increasing the hot cracking sensitivity of the weld metal. To ensure that the weld metal has good crack resistance, it is necessary to control S + P ≤ 0.008%.

[0050] O: It is an impurity element. When the content is greater than 0.003%, it is easy to form non-metallic oxide inclusions, deteriorating the low-temperature hot toughness of the weld metal.

[0051] The welding wire prepared from the above components has improved low-temperature toughness, reduced hot cracking sensitivity, weakened work hardening, is easy to process, reduced porosity sensitivity, and meets the requirements of high-efficiency and low-defect welding of 5Ni steel.

[0052] A preparation method of a high-toughness austenitic stainless steel solid welding wire for 5Ni steel as described above, including:

[0053] S100. Blank preparation: After mixing the components of the welding wire in proportion, vacuum melting and electroslag remelting are used for melting, and then an ingot is prepared by casting after melting.

[0054] S200. Forging treatment: The forging temperature is 1000 - 1200°C. Specifically, the preferred forging heating temperature is 1120 - 1200°C, the final forging temperature is 1000 - 1080°C, and the single-hammer deformation amount ≤ 12%.

[0055] S300. Hot rolling treatment: The hot rolling temperature is 1000 - 1200°C. Specifically, the preferred hot rolling heating temperature is 1120 - 1200°C, the final rolling temperature is 1000 - 1080°C, a hot rolled wire rod is formed, and the final size of the formed wire rod is Φ5.5mm or Φ6.5mm, or it can also be wire rods of other specifications.

[0056] S400. Solution treatment: After maintaining for a preset time at a preset temperature, it is cooled. Preferably, the preset temperature is 1120 - 1200°C, the preset time is 1 - 2h, to fully dissolve carbides and the second phase, and then water cooling is carried out.

[0057] S500. Cleaning the wire rod: The wire rod is degreased and cleaned. The methods for cleaning the wire rod include caustic washing and pickling, and finally, it is soaked in a soda ash solution for 3 - 5min for acid-base neutralization treatment to avoid further corrosion.

[0058] The caustic washing method includes:

[0059] Preparing an alkaline degreasing agent. The components of the alkaline degreasing agent include: 5 - 10% sodium hydroxide, 2 - 4% soda ash, 1 - 3% sodium silicate, 0.5 - 1% alkylphenol polyoxyethylene ether, and the rest is water.

[0060] Using the alkaline degreasing agent with a concentration of 6 - 12% and a temperature of 70 - 90°C, soaking for 15 - 40min, and then ultrasonic cleaning.

[0061] The pickling method includes:

[0062] Using a mixed solution of 6 - 12% nitric acid and 1 - 5% hydrofluoric acid, soaking for 7 - 15min at a temperature of 30 - 60°C, and then using high-pressure water to wash to remove the residual acid.

[0063] S600. Drawing treatment: The wire rod is drawn through a wire drawing machine / rolling mill, and a welding wire with a preset diameter is formed according to the process requirements, reduced in diameter to Φ1.2mm or other sizes, the area reduction rate for each pass is 5 - 15%, and after drawing, the welding wire is wound in layers, and the relaxation diameter of the wire after winding ≥ 1000mm, and the warp distance ≤ 10mm.

[0064] S700. Final treatment: The welding wire is finally cleaned, dried, and packaged. The final treatment method includes:

[0065] S710. Cleaning step: Electrolytic alkaline cleaning is adopted, followed by high-pressure water cleaning to remove wire drawing powder, oil stains, etc. on the surface of the welding wire, aiming to stabilize the arc and reduce slag inclusion defects.

[0066] S720. Drying step: The drying temperature is 60 - 90 °C, and the drying time is 3 - 10 min.

[0067] S730. Packaging step: Vacuum packaging is adopted.

[0068] The following uses specific embodiments to illustrate the welding wire of the present application.

[0069] As an embodiment, the welding wire is prepared by vacuum melting + electroslag remelting to obtain ingots of the compositions of 3 embodiments. After processes such as forging, hot rolling into a wire rod with a diameter of Φ5.5 mm, solution treatment at 1160 °C for 2 h, alkaline cleaning + acid cleaning, etc., it is drawn and reduced in diameter to 1.2 mm by a straight-line wire drawing machine. Finally, after alkaline cleaning + high-pressure water cleaning and drying, the welding wire of the embodiment is obtained. The specific composition is shown in Table 1.

[0070] The deposited metal of the welding wire of the embodiment is used for multi-position (flat welding, horizontal welding, and vertical welding) butt joint test plate welding with 5Ni steel. The welding parameters used are shown in Table 2, the mechanical properties of the deposited metal are shown in Table 3, and the mechanical properties of the joint are shown in Table 4. The results show that the strength of the deposited metal is moderate, and the low-temperature toughness of the deposited metal and the joint at -140 °C is excellent. According to the crack test method of the T-joint weld in GB / T 41107.2, no cracks are generated. The welding joints of the welding wire of the embodiment at the flat, horizontal, and vertical welding positions are analyzed for defects according to GB / T 13298 and subjected to radiographic inspection according to GB / T 3323. The results are shown in Table 5, and the results show that there are no defects such as pores, slag inclusions, and lack of fusion in the joints, and the radiographic inspection is all Grade I.

[0071] Table 1

[0072]

[0073] Table 2

[0074]

[0075] Table 3

[0076]

[0077] Table 4

[0078]

[0079] Table 5

[0080]

[0081] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A high-toughness austenitic stainless steel solid wire for 5Ni steel, characterized in that the wire composition components include: C: 0.14% - 0.26%; Si: 0.24% - 0.56%; Cr: 16.3% - 19.3%; 0.5Mn + Ni: 18.5% - 20.5%, and at the same time the Mn content is greater than 4.5%; Mo + 1.5W: 4.0% - 7.0%, and at the same time Mo ≤ 3.0%; N: 0.03% - 0.12%; 0.5Nb + Ti + 1.2V: 0.03% - 0.1%; rare earth Ce + La: 0.02% - 0.08%; S + P ≤ 0.008%; O ≤ 0.003%; the rest is Fe and unavoidable impurities.

2. A preparation method of a high-toughness austenitic stainless steel solid wire for 5Ni steel as described in claim 1, characterized in that, Including: S100. Blank preparation: After mixing the wire composition components in proportion, melt them by vacuum melting and electroslag remelting, and prepare an ingot by casting after melting. S200. Forging treatment: The forging temperature is 1000 - 1200 °C. S300. Hot rolling treatment: The hot rolling temperature is 1000 - 1200 °C to form a hot-rolled wire rod. S400. Solution treatment: Keep it at a preset temperature for a preset time and then cool it. S500. Clean the wire rod: Degrease and clean the wire rod. S600. Drawing treatment: Draw the wire rod through a wire drawing machine / wire rolling machine, form a wire with a preset diameter according to process requirements, and wind the wire after drawing. S700. Final treatment: Finally clean, dry and package the wire.

3. The preparation method of the high-toughness austenitic stainless steel solid wire for 5Ni steel according to claim 2, characterized in that in step S200, the forging heating temperature is 1120 - 1200 °C, and the final forging temperature is 1000 - 1080 °C.

4. The preparation method of the high-toughness austenitic stainless steel solid wire for 5Ni steel according to claim 2, characterized in that in step S300, the hot rolling heating temperature is 1120 - 1200 °C, and the final rolling temperature is 1000 - 1080 °C.

5. The preparation method of the high-toughness austenitic stainless steel solid wire for 5Ni steel according to claim 2, characterized in that in step S400, the preset temperature is 1120 - 1200 °C, and the preset time is 1 - 2 h.

6. The preparation method of the high-toughness austenitic stainless steel solid wire for 5Ni steel according to claim 2, characterized in that in step S500, the method for cleaning the wire rod includes alkali cleaning and acid cleaning, and finally soak it in a soda ash solution for 3 - 5 min for acid-base neutralization treatment.

7. The preparation method of the high-toughness austenitic stainless steel solid wire for 5Ni steel according to claim 6, characterized in that the alkali cleaning method includes: Prepare an alkaline degreasing agent, and the components of the alkaline degreasing agent include: 5 - 10% sodium hydroxide, 2 - 4% soda ash, 1 - 3% sodium silicate, 0.5 - 1% alkylphenol polyoxyethylene ether, and the rest is water; Use the alkaline degreasing agent, with a concentration of 6 - 12%, a temperature of 70 - 90 °C, soak for 15 - 40 min, and then perform ultrasonic cleaning.

8. The preparation method of the high-toughness austenitic stainless steel solid wire for 5Ni steel according to claim 6, characterized in that The pickling method includes: Using a mixed solution of 6-12% nitric acid and 1-5% hydrofluoric acid, soaking for 7-15 minutes at a temperature of 30-60 °C, and then using high-pressure water cleaning to remove the residual acid.

9. The preparation method of the high-toughness austenitic stainless steel solid wire for 5Ni steel according to claim 2, characterized in that In step S600, the relaxation diameter of the wire after layer winding is ≥1000 mm, and the warp distance is ≤10 mm.

10. The preparation method of the high-toughness austenitic stainless steel solid wire for 5Ni steel according to claim 2, characterized in that In step S700, the final treatment method includes: S710, a cleaning step, using electrolytic alkali cleaning and then high-pressure water cleaning; S720, a drying step, the drying temperature is 60-90 °C, and the drying time is 3-10 minutes; S730, a packaging step, using vacuum packaging.

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