High-strength hydrogen embrittlement resistant stainless steel wire for arc additive manufacturing and welding and method of making

Abstract

The application relates to a hydrogen embrittlement resistant high-strength stainless steel wire for electric arc additive manufacturing and welding and a preparation method, characterized in that the alloy components and contents are as follows: C: 0.02-0.06%, Si: 0.3-0.6%, Mn: 0.4-1.0%, Mo: 0.8-1.5%, Ni: 4-7%, Cr: 12.5-15%, V: 0.1-0.25%, Cu: 0.5-0.9%, and Fe is the balance; the high-strength stainless steel wire is designed and prepared based on the concept of hydrogen embrittlement inhibition induced by electric arc additive manufacturing / welding heat cycle, has good electric arc additive manufacturing / welding formability, low hydrogen embrittlement sensitivity, and good strength and plasticity of the electric arc additive manufacturing component and the welding joint under the condition of no heat treatment.

Description

Technical Field

[0001] This invention relates to the field of electric arc additive manufacturing and welding materials technology, specifically to a high-strength stainless steel wire resistant to hydrogen embrittlement suitable for electric arc additive manufacturing and welding, and its preparation method. Background Technology

[0002] High-strength stainless steel, with its excellent strength, toughness, and corrosion resistance, is widely used in industries such as energy and chemical engineering, hydropower, and mining machinery. In practical applications, the manufacturing of high-strength stainless steel components involves extensive welding and arc additive manufacturing processes. However, the current application of arc additive manufacturing and welding with high-strength stainless steel wire systems faces the following challenges:

[0003] (1) High-strength stainless steel has a coarse structure during arc additive manufacturing and welding, resulting in relatively poor strength and plasticity and high hydrogen embrittlement sensitivity. This is especially true for large-sized complex components, which can cause cracks in additive components or welded joints, affecting service reliability and safety.

[0004] (2) In order to ensure good corrosion resistance, high-strength stainless steel contains elements such as Cr and Mo. However, during the rapid solidification process of arc additive manufacturing and welding, these elements are prone to segregation between dendrites. Segregation of elements such as Cr and Mo between dendrites will lead to the formation of high-temperature ferrite in this area, which will reduce the plasticity and toughness of high-strength stainless steel components and their resistance to localized corrosion, thereby reducing their resistance to hydrogen embrittlement.

[0005] Therefore, the development of high-strength stainless steel wire resistant to hydrogen embrittlement for high-performance arc additive manufacturing and welding is of great significance for the arc additive manufacturing and welding of high-strength stainless steel components and their reliable and safe service. Summary of the Invention

[0006] The first technical problem to be solved by the present invention is to provide a high-strength stainless steel wire resistant to hydrogen embrittlement for arc additive manufacturing and welding, in light of the current state of the art.

[0007] The technical solution adopted is as follows: The alloy composition of a high-strength stainless steel wire resistant to hydrogen embrittlement for arc additive manufacturing and welding is: C: 0.02-0.06%, Si: 0.3-0.6%, Mn: 0.4-1.0%, Mo: 0.8-1.5%, Ni: 4-7%, Cr: 12.5-15%, V: 0.1-0.25%, Cu: 0.5-0.9%, with Fe as the balance.

[0008] This invention addresses the high hydrogen embrittlement susceptibility of high-strength stainless steel wire used in arc additive manufacturing and welding. It incorporates the concept of in-situ microstructure control during the arc additive manufacturing process into the alloy design: the heat treatment effect generated by the arc additive manufacturing / welding thermal cycle induces nanoscale carbide precipitation, which suppresses grain coarsening and refines the microstructure during subsequent additive manufacturing, increasing the plastic deformation capacity of the martensitic matrix. The carbides and their interface with the martensitic matrix can trap and disperse hydrogen atoms, reducing local hydrogen content and thus lowering the hydrogen embrittlement susceptibility of high-strength stainless steel in arc additive manufacturing / welding. Simultaneously, by increasing the Ni / Cr equivalent ratio in the alloy composition and appropriately increasing the content of the austenitizing element copper, the segregation of copper dendrites suppresses the formation of high-temperature ferrite between dendrites during solidification in arc additive manufacturing / welding. This further reduces hydrogen embrittlement susceptibility while maintaining the ductility and toughness of high-strength stainless steel in arc additive manufacturing / welding, thereby solving the problem of high hydrogen embrittlement susceptibility in the arc additive manufacturing and welding of high-strength stainless steel.

[0009] The selection of alloying elements and the control of their mass fraction in this invention are based on the following criteria:

[0010] C: The main functions of carbon in this invention include: (1) Carbon atoms can generate strong interstitial solid solution strengthening, which improves the strength of arc additive manufacturing components or welded joints; (2) Under the action of arc additive manufacturing or welding thermal cycle, carbon atoms combine with vanadium to precipitate in the form of vanadium carbide, which captures hydrogen atoms and reduces hydrogen embrittlement sensitivity while generating precipitation strengthening effect; (3) Carbon is an austenitizing element, which segregates into the dendrites during arc additive manufacturing or welding solidification, inhibiting the formation of high-temperature ferrite. When the carbon content is too low, the interstitial strengthening effect is not obvious; when the amount of vanadium carbide precipitated during arc additive manufacturing or welding is insufficient or not precipitated, it cannot play the role of hydrogen trap and reduce hydrogen embrittlement sensitivity; when the amount of segregation into the dendrites during arc additive manufacturing or welding solidification is too small, the inhibitory effect on high-temperature ferrite is limited. When the carbon content is too high, the martensitic matrix becomes hard and has poor plasticity. This easily leads to the formation of coarse primary carbides during arc additive manufacturing or welding, further reducing the mechanical properties of the additive components or welded joints, especially their plasticity, increasing susceptibility to hydrogen-induced cracking, and causing excessive interdendritic segregation, resulting in the formation of retained austenite and further reducing the mechanical properties of the additive components or welded joints. Therefore, the carbon content in this invention is controlled at 0.02-0.06%.

[0011] Si: In arc additive manufacturing or welding molten pools, Si mainly plays a role in deoxidation and altering fluidity. When the Si content is too low, the deoxidation effect of the molten pool is poor, and the fluidity of the molten pool deteriorates. However, when the Si content is too high, inclusions are easily formed in the arc additive manufacturing or welding molten pool, especially in multi-layer, multi-pass additive manufacturing or welding, which easily leads to inclusions, increased fluidity, poor spatial formability, and a tendency to collapse. Furthermore, since Si is a ferritinizing element, excessive Si content will segregate into the interdendritic space during the solidification process of arc additive manufacturing or welding, promoting the formation of high-temperature ferrite. Therefore, the Si content in this invention is controlled at 0.3-0.6%.

[0012] Mn: Mn, along with Si, primarily functions as a deoxidizer and modifies the flowability of the molten pool in arc additive manufacturing or welding. Furthermore, Mn is an austenitizing element, inhibiting the formation of high-temperature ferrite. When the Mn content is too low, it fails to deoxidize or control the flowability of the molten pool, and high-temperature ferrite easily forms between dendrites. When the Mn content is too high, the number of inclusions increases, resulting in excessive fumes during additive manufacturing or welding. Moreover, excessive Mn segregation into the dendrites increases the stability of austenite in that region, leading to retained austenite in the additive component or weld joint, thus reducing its strength. Therefore, the Si content in this invention is controlled at 0.4-1.0%.

[0013] Mo (Mo): Mo can be supersaturated and dissolved into the martensitic matrix during the rapid solidification and cooling process of arc additive manufacturing or welding, improving the strength and corrosion resistance of arc additive manufactured components or welded joints. When the Mo content is too low, it does not have a significant strengthening effect. However, when the Mo content is too high, coarse carbides will be generated during arc additive manufacturing or welding, reducing strength and plasticity, increasing hydrogen embrittlement susceptibility. Furthermore, since Mo is a ferritinizing element, excessively high Mo content leads to excessive segregation into the dendrites, resulting in the formation of high-temperature ferrite in the dendrites, reducing the mechanical properties and corrosion resistance of the additive component or welded joint, and increasing hydrogen embrittlement susceptibility. Therefore, the Mo content in this invention is controlled at 0.8-1.5%.

[0014] Cr: Cr primarily forms a dense oxide film on the surface of high-strength stainless steel, improving corrosion resistance. Furthermore, Cr provides solid solution strengthening. When the Cr content is too low, the corrosion resistance and strength requirements cannot be met. When the Cr content is too high, because Cr is a ferritinizing element, it promotes the formation of high-temperature ferrite between dendrites during rapid solidification and cooling in arc additive manufacturing or welding, reducing the mechanical properties and corrosion resistance of the additive components or welded joints, and increasing hydrogen embrittlement susceptibility. Therefore, the Cr content in this invention is controlled at 12.5-15%.

[0015] Ni: Ni increases the dislocation density of martensite during the rapid cooling process of arc additive manufacturing and welding, thereby enhancing the strength of additive martensitic stainless steel through dislocation strengthening. Simultaneously, the high dislocation density in the martensitic matrix provides numerous precipitation sites for carbide precipitates. Furthermore, this invention employs a relatively high Cr content, and to ensure both high strength and good toughness, a relatively high nickel content is used for balance. However, Ni often segregates during solidification, leading to the formation of retained austenite and reducing the strength of the additive structure. Therefore, the Ni content in this invention is controlled at 4-7%.

[0016] Vanadium carbide (V) precipitates in the martensitic matrix as vanadium carbide under the thermal cycling of arc additive manufacturing, through intrinsic heat treatment. Utilizing the low mismatch between vanadium carbide and the martensitic matrix, V precipitates in large quantities within the matrix in a dispersed form. This precipitation strengthens the material, improving strength while maintaining a certain level of plasticity. Furthermore, the sodium chloride structure of vanadium carbide contains vacancies that effectively trap hydrogen atoms, reducing local hydrogen concentration and thus mitigating hydrogen embrittlement in martensitic stainless steel arc additive manufacturing. However, excessive V can cause coarsening of the carbides, leading to cracks and compromising the material's plasticity. Excessive vanadium carbide also consumes dissolved carbon in the martensitic matrix, reducing strength. Therefore, the V content in this invention is controlled at 0.05-0.25%.

[0017] Cu: In the process of arc additive manufacturing and welding, Cu element suppresses the formation of high-temperature ferrite between dendrites during solidification through interdendritic segregation. While ensuring the plasticity, toughness and resistance to localized corrosion in high-strength stainless steel arc additive manufacturing / welding, it further reduces hydrogen embrittlement sensitivity. However, when Cu element is excessive, it will increase the crack sensitivity of the weld. Therefore, the Cu content in this invention is controlled at 0.5-0.9%.

[0018] The second technical problem to be solved by the present invention is to provide a method for preparing a hydrogen-resistant high-strength stainless steel wire for arc additive manufacturing and welding.

[0019] The technical solution adopted by this invention to solve the second technical problem is: a method for preparing hydrogen-embrittlement-resistant high-strength stainless steel wire for arc additive manufacturing and welding, characterized by comprising the following processing steps:

[0020] (1) Smelting: The high-strength stainless steel alloy resistant to hydrogen embrittlement is smelted for the first time in a vacuum smelting furnace and cast to obtain a pre-melted ingot; then the pre-melted ingot is forged to prepare an electrode sample, and the electrode sample is smelted for the second time by electroslag remelting and cast to obtain the final ingot.

[0021] (2) Forging and rolling: The ingot obtained in the previous step is forged, and the bar obtained by forging is rolled to obtain wire rod;

[0022] (3) Annealing: Annealing the wire rod;

[0023] (4) Drawing: The oxide scale is removed from the annealed wire rod, and wire with a diameter of 1.1~1.3mm is obtained by multiple cold drawing and online annealing.

[0024] Since the drawing formability, mechanical properties, and welding performance of hydrogen embrittlement resistant high-strength stainless steel wire are highly sensitive to impurity elements such as P, H, and S, the impurity element content is strictly controlled through a dual smelting method of vacuum smelting and electroslag remelting to achieve the purification smelting of hydrogen embrittlement resistant high-strength stainless steel wire alloy ingots.

[0025] Preferably, in step (1), the vacuum degree of vacuum smelting is 10~20 Pa; the heating temperature of the initial melting ingot is 1150~1250℃, the holding time is 5~10h, and then it is forged into an electrode sample with a final forging temperature of not less than 950℃; the specific parameters of electroslag remelting are: electroslag speed 1.6~2.0kg / min, voltage 30~40V, and current 1.8~3.0kA. Since the high-strength stainless steel resistant to hydrogen embrittlement has poor plastic deformation ability, in order to avoid surface cracks and oxide scale inclusions during deformation, a higher initial forging and final forging temperature is used before electrode forging.

[0026] Because high-strength stainless steel has high strength but poor plastic deformation ability, in order to avoid surface cracks and oxide scale inclusions during drawing, it is preferable that the final ingot in step (2) be heated to 1100~1200℃ and held for 2~5 hours, and then forged, with the final forging temperature not lower than 950℃, followed by air cooling. In order to avoid surface and internal cracks in the wire rod caused by excessively low rolling temperature, which would reduce the wire drawing yield and wire quality, a higher rolling temperature and a longer holding time are used during rolling. In order to avoid the bar being held at 1100~1200℃ for 1~3 hours in step (2), and then rolled into wire rod through multiple hot continuous rolling passes.

[0027] In order to reduce the hardness of the wire rod and improve its plastic deformation capacity, it is preferable that in step (3), the wire rod is kept in a salt bath at 1100~1200℃ for 1~2 hours, then air-cooled and washed with water.

[0028] Pickling when removing surface oxide scale from wire rod can cause hydrogen embrittlement in ultra-high strength steel, affecting wire drawing forming ability and yield. As a preferred method, in step (4), the oxide scale of the wire rod is mechanically removed before drawing, washed and dried, and then treated with a film and dried at 80~100℃.

[0029] In order to eliminate the work hardening of the cold drawing process and the resulting poor plastic deformation ability, it is preferable to perform online annealing in step (4) during the drawing process, with an annealing temperature of 1100~1150℃. In order to avoid hydrogen embrittlement, it is preferable to perform alkali washing and water washing in step (4) in sequence.

[0030] Compared with existing technologies, the advantages of this invention are:

[0031] (1) The hydrogen embrittlement resistant high-strength stainless steel wire prepared by this invention has a scientific and reasonable composition design. The alloy design incorporates the idea of ​​in-situ control of microstructure during arc additive manufacturing and welding: the heat treatment effect generated by the arc additive manufacturing / welding thermal cycle enables the precipitation of nanoscale carbides, which can suppress grain coarsening and refine the microstructure during subsequent additive manufacturing, thereby increasing the plastic deformation capacity of the martensitic matrix; the carbides and their interface with the martensitic matrix can capture hydrogen atoms, disperse the distribution of hydrogen atoms, and reduce the local hydrogen content, thereby reducing the hydrogen embrittlement sensitivity of arc additive manufacturing / welding high-strength stainless steel. At the same time, by increasing the Ni / Cr equivalent ratio in the alloy composition, appropriately increasing the content of austenitizing element copper, and utilizing the segregation between copper dendrites, the formation of high-temperature ferrite between dendrites during the solidification process of arc additive manufacturing is suppressed. While ensuring the plasticity and toughness of high-strength stainless steel arc additive manufacturing / welding, the hydrogen embrittlement sensitivity is further reduced, thereby solving the problem of high hydrogen embrittlement sensitivity faced by high-strength stainless steel arc additive manufacturing and welding.

[0032] (2) The hydrogen embrittlement resistant high-strength stainless steel wire prepared by the present invention is suitable for the melting electrode arc additive manufacturing and welding process. It has low sensitivity to cracks caused by hydrogen embrittlement. The tensile strength of the arc additive manufacturing is as high as 1050 MPa and the elongation after fracture is as high as 10%. The tensile strength of the welded joint is as high as 1300 MPa and the elongation after fracture is as high as 12%. While ensuring high strength, it can also ensure high elongation. It is suitable for fields such as energy and chemical industry, marine engineering and shipbuilding, and weaponry. Attached Figure Description

[0033] Figure 1 Schematic diagram of the tensile specimen dimensions used in the welding experiment of high-strength stainless steel resistant to hydrogen embrittlement;

[0034] Figure 2 Schematic diagram of the sampling location for tensile specimens. Detailed Implementation

[0035] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples.

[0036] Example 1

[0037] A high-strength stainless steel wire resistant to hydrogen embrittlement for arc additive manufacturing, with the following alloy composition: C: 0.025%, Si: 0.5%, Mn: 0.7%, Mo: 0.8%, Ni: 4.3%, Cr: 13.2%, V: 0.12%, Cu: 0.6%, and Fe as the balance.

[0038] The preparation method of the above-mentioned high-strength stainless steel wire resistant to hydrogen embrittlement for arc additive manufacturing is as follows:

[0039] (1) Melting: The high-strength stainless steel wire alloy ingot was initially melted in a vacuum furnace with a vacuum degree of 12 Pa, and the ingot was cast to obtain the initial melted ingot. The initial melted ingot was held at 1170℃ for 5 hours and forged into an electrode sample with a diameter of 72 mm. The final forging temperature was not lower than 950℃. The alloy was then melted a second time using the electroslag remelting method with an electroslag speed of 1.6 kg / min, a voltage of 32 V, and a current of 2.4 kA. The final ingot was then cast.

[0040] (2) Forging: The final ingot is held at 1120°C for 4 hours and then forged into a 50mm×50mm square bar. The final forging temperature is not lower than 950°C, and then air-cooled.

[0041] (3) Rolling: The forged square bar is kept at 1100℃ for 2 hours and then rolled into Φ6.5 wire rod through multiple hot continuous rolling passes.

[0042] (4) Annealing: Keep the wire rod at 1100℃ for 1.5h, and then air cool.

[0043] (5) Drawing: The heat-treated and softened wire rod is mechanically de-scaled, washed and dried, then treated with a film, dried at 100℃ and then drawn. The drawing diameter changes as follows: Φ6.2→Φ5.9→Φ5.2→Φ4.8→Φ4.4→online annealing + alkaline washing→Φ3.7→Φ3.4→Φ3.0→Φ2.6→Φ2.2→Φ2.0→Φ1.5→Φ1.2.

[0044] (6) Alkali washing, water washing, drying, and coiling.

[0045] The prepared hydrogen embrittlement-resistant high-strength stainless steel wire was used for arc additive manufacturing experiments using an ABB robot equipped with a CMT welding power source. The substrate was made of carbon steel with a thickness of 20 mm. A shielding gas mixture of 20% carbon dioxide and 80% argon was used at a flow rate of 20 L / min. The welding mode was CMT advance + Pulse unified control, with a wire feed speed of 8 m / min and a welding torch travel speed of 3 mm / s. Tensile specimens were taken along the direction of the welding torch travel. The specimens were M10 standard tensile specimens, and tensile properties were tested. The mechanical properties are shown in Table 1.

[0046] Table 1. Test results of mechanical properties of hydrogen embrittlement-resistant high-strength stainless steel arc additive components.

[0047]

[0048] Example 2

[0049] A high-strength stainless steel wire resistant to hydrogen embrittlement for arc additive manufacturing, with the following alloy composition: C: 0.035%, Si: 0.4%, Mn: 0.42%, Mo: 1.1%, Ni: 6.2%, Cr: 14.1%, V: 0.2%, Cu: 0.7%, and Fe as the balance.

[0050] The preparation method of the above-mentioned high-strength stainless steel wire resistant to hydrogen embrittlement for arc additive manufacturing is as follows:

[0051] (1) Melting: The high-strength stainless steel wire alloy ingot was initially melted in a vacuum furnace with a vacuum degree of 18 Pa, and the ingot was cast to obtain the initial melted ingot. The initial melted ingot was held at 1200℃ for 6 hours and forged into an electrode sample with a diameter of 72 mm. The final forging temperature was not lower than 950℃. The alloy was then melted a second time using the electroslag remelting method with an electroslag speed of 1.6 kg / min, a voltage of 30 V, and a current of 1.8 kA. The final ingot was then cast to obtain the final ingot.

[0052] (2) Forging: The final ingot is held at 1200°C for 5 hours and then forged into a 50mm×50mm square bar. The final forging temperature is not lower than 950°C, and then air-cooled.

[0053] (3) Rolling: The forged square bar is kept at 1100℃ for 2 hours and then rolled into Φ6.5 wire rod through multiple hot continuous rolling passes.

[0054] (4) Annealing: Keep the wire rod at 1100℃ for 1.5h, and then air cool.

[0055] (5) Drawing: The heat-treated and softened wire rod is mechanically descaled, washed and dried, then treated with a film, dried at 100℃ and then drawn. The drawing diameter changes as follows: Φ6.2→Φ5.9→Φ5.2→Φ4.8→Φ4.6→Φ4.2→online annealing + alkaline washing→Φ3.7→Φ3.4→Φ3.1→Φ2.8→Φ2.4→Φ2.0→Φ1.8→Φ1.5→Φ1.2.

[0056] (6) Alkali washing, water washing, drying, and coiling.

[0057] The prepared hydrogen embrittlement-resistant high-strength stainless steel wire was used for arc additive manufacturing experiments with an ABB robot equipped with a CMT welding power supply. The substrate was a low-alloy high-strength steel plate with a thickness of 20 mm. 50% carbon dioxide + 50% argon was used as the shielding gas with a flow rate of 20 L / min. The welding mode was CMT + Pulse unified control, the wire feed speed was 8 m / min, and the welding torch travel speed was 2.8 mm / s. Tensile specimens were taken along the direction of the welding torch travel. The specimens were M10 standard tensile specimens, and tensile properties were tested. The mechanical properties are shown in Table 2.

[0058] Table 2. Test results of mechanical properties of hydrogen embrittlement-resistant high-strength stainless steel arc additive components.

[0059]

[0060] Example 3

[0061] A high-strength stainless steel wire for welding with resistance to hydrogen embrittlement has the following alloy composition: C: 0.026%, Si: 0.33%, Mn: 0.47%, Mo: 0.9%, Ni: 6.8%, Cr: 14.8%, V: 0.11%, Cu: 0.54%, with Fe as the balance.

[0062] The preparation method of the above-mentioned high-strength stainless steel wire resistant to hydrogen embrittlement for welding is as follows:

[0063] (1) Melting: The high-strength stainless steel wire alloy ingot was initially melted in a vacuum furnace with a vacuum degree of 17 Pa, and the ingot was cast to obtain the initial melted ingot. The initial melted ingot was held at 1200℃ for 7.5h and forged into an electrode sample with a diameter of 72mm. The final forging temperature was not lower than 950℃. The alloy was then melted a second time using the electroslag remelting method with an electroslag speed of 1.7kg / min, a voltage of 35V, and a current of 2.0kA. The final ingot was then cast to obtain the final ingot.

[0064] (2) Forging: The final ingot is held at 1200°C for 3.5 hours and then forged into a 50mm×50mm square bar. The final forging temperature is not lower than 950°C, and then air-cooled.

[0065] (3) Rolling: The forged square bar is kept at 1100℃ for 2 hours and then rolled into Φ6.5 wire rod through multiple hot continuous rolling passes.

[0066] (4) Annealing: Keep the wire rod at 1100℃ for 1.5h, and then air cool.

[0067] (5) Drawing: The heat-treated and softened wire rod is mechanically de-scaled, washed and dried, then treated with a film, dried at 100℃, and then drawn. The drawing diameter changes as follows: Φ6.2→Φ5.7→Φ5.2→Φ4.8→Φ4.2→online annealing + alkaline washing→Φ3.7→Φ3.2→Φ2.8→Φ2.4→Φ2.0→Φ1.5→Φ1.2.

[0068] (6) Alkali washing, water washing, drying, and coiling.

[0069] The prepared hydrogen-embrittlement-resistant high-strength stainless steel wire was used for welding experiments using an ABB robot equipped with a CMT welding power source. The composition of the base material used in the welding experiments is shown in Table 3. The gap was 4 mm, the plate thickness was 5 mm, and the bevel was 15° with no blunt edge. Pure carbon dioxide was used as the shielding gas, with a flow rate of 20 L / min. The welding mode was CMT unified control, the wire feed speed was 8 m / min, and the torch travel speed was 3 mm / s.

[0070] After welding, tensile and impact tests were performed on the welded joint. The tensile test samples are as follows: Figure 1 As shown, the sampling locations for tensile property testing samples are as follows: Figure 2 As shown in the figure. The tensile property test results are shown in Table 4.

[0071] Table 3. Composition of base material used in welding tests of high-strength stainless steel resistant to hydrogen embrittlement.

[0072]

[0073] Table 4 Performance of high-strength stainless steel welded joints resistant to hydrogen embrittlement (Example 3)

[0074]

[0075] Example 4

[0076] A high-strength stainless steel wire for welding with resistance to hydrogen embrittlement has the following alloy composition: C: 0.052%, Si: 0.37%, Mn: 0.44%, Mo: 1.4%, Ni: 5.2%, Cr: 13.4%, V: 0.24%, Cu: 0.82%, with Fe as the balance.

[0077] The preparation method of the above-mentioned high-strength stainless steel wire resistant to hydrogen embrittlement for welding is as follows:

[0078] (1) Melting: The high-strength stainless steel wire alloy ingot was initially melted in a vacuum furnace with a vacuum degree of 17 Pa, and the ingot was cast to obtain the initial melted ingot. The initial melted ingot was held at 1200℃ for 6 hours and forged into an electrode sample with a diameter of 72 mm. The final forging temperature was not lower than 950℃. The alloy was then melted a second time using the electroslag remelting method with an electroslag speed of 1.8 kg / min, a voltage of 37 V, and a current of 2.7 kA. The final ingot was then cast.

[0079] (2) Forging: The final ingot is held at 1100°C for 3 hours and then forged into a 50mm×50mm square bar. The final forging temperature is not lower than 950°C, and then air-cooled.

[0080] (3) Rolling: The forged square bar is kept at 1100℃ for 2 hours and then rolled into Φ6.5 wire rod through multiple hot continuous rolling passes.

[0081] (4) Annealing: Keep the wire rod at 1100℃ for 1.5h, and then air cool.

[0082] (5) Drawing: The heat-treated and softened wire rod is mechanically de-scaled, washed and dried, then treated with a film, dried at 100℃ and then drawn. The drawing diameter changes as follows: Φ6.2→Φ5.7→Φ5.2→Φ4.8→Φ4.2→online annealing + alkaline washing→Φ3.9→Φ3.4→Φ3.0→Φ2.5→Φ2.2→Φ2.0→Φ1.5→Φ1.2.

[0083] (6) Alkali washing, water washing, drying, and coiling.

[0084] The prepared hydrogen embrittlement-resistant high-strength stainless steel wire was used for welding experiments using an ABB robot equipped with a CMT welding power source. The composition of the base material used in the welding experiments is shown in Table 2. The gap was 4 mm, the plate thickness was 5 mm, and the bevel was 15° with no blunt edge. Pure carbon dioxide was used as the shielding gas, with a flow rate of 20 L / min. The welding mode was CMT unified control, the wire feed speed was 8 m / min, and the torch travel speed was 2.3 mm / s.

[0085] Tensile properties were tested on the welded joint after welding. The results of the tensile property tests are shown in Table 5.

[0086] Table 5 Performance of high-strength stainless steel welded joints resistant to hydrogen embrittlement (Example 4)

[0087]

[0088] Comparative Example 1

[0089] High-strength stainless steel wire was used as a comparative example. The wire alloy composition was: C: 0.06%, Si: 0.44%, Mn: 0.57%, Mo: 0.35%, Ni: 3.8%, Cr: 12.8%, Cu: 0.22%, with Fe as the balance. The wire diameter was 1.2 mm. Arc additive manufacturing experiments were conducted using a Furniture CMT welding power source. The wire feed speed was 6 m / min, the welding torch movement speed was 3 mm / s, and pure carbon dioxide was used as the shielding gas at a flow rate of 20 L / min. M10 standard tensile specimens were cut along the direction of the welding torch movement and subjected to room temperature tensile tests. Three measurements were taken, and the average value was calculated. Welding experiments were conducted using an ABB robot equipped with a CMT welding power source. The composition of the base material used in the welding experiments is shown in Table 3. The gap was 4 mm, the plate thickness was 5 mm, and the bevel was 15° with no blunt edge. Pure carbon dioxide was used as the shielding gas at a flow rate of 20 L / min. The welding mode was CMT unified control, the wire feed speed was 8 m / min, and the welding torch travel speed was 3 mm / s. Tensile properties of the welded joint were tested after welding. The tensile properties of the arc additive manufacturing and welded joints are shown in Table 6.

[0090] Table 6 Performance of high-strength stainless steel arc additive manufacturing deposits and welded joints (Comparative Example 1)

[0091]

[0092] This invention relates to a high-strength stainless steel wire resistant to hydrogen embrittlement. During arc additive manufacturing / welding, it generates nanoscale carbides, which inhibit grain coarsening, refine the microstructure, and enhance the plastic deformation capacity of the martensitic matrix. Simultaneously, the carbides and their interface with the martensitic matrix trap hydrogen atoms, dispersing their distribution and reducing local hydrogen content, thus lowering hydrogen embrittlement sensitivity during arc additive manufacturing / welding. Furthermore, this invention's high-strength stainless steel wire has a high Ni / Cr equivalent and a high content of the austenitizing element copper, inhibiting the formation of high-temperature ferrite between dendrites during solidification in arc additive manufacturing / welding, further reducing hydrogen embrittlement sensitivity. This results in good strength and plasticity after arc additive manufacturing and welding. Without heat treatment, the tensile strength of the arc-added component exceeds 1090 MPa, while the elongation after fracture is not less than 10%; the tensile strength of the welded joint is not less than 1300 MPa, and the elongation after fracture is not less than 12%. Comparative Example 1 has a low Ni / Cr equivalent and copper content in its high-strength stainless steel wire, and does not contain V. The tensile strength of the arc additive manufacturing component is less than 1050 MPa, and the elongation after fracture is only 7%. The tensile strength of the welded joint is less than 1150 MPa, and the elongation after fracture is only 9%, both of which are lower than the hydrogen embrittlement resistant high-strength stainless steel wire of the present invention.

[0093] The hydrogen-embrittlement-resistant high-strength stainless steel wire of this invention can be used for arc additive manufacturing and welding of high-strength stainless steel components, as well as for surfacing and repairing high-strength stainless steel components.

[0094] The technical means disclosed in this invention are not limited to those disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are all considered to be within the scope of protection of this invention.

Claims

1. A high-strength stainless steel wire resistant to hydrogen embrittlement for arc additive manufacturing and welding, characterized in that... The mass fractions of alloying elements are as follows: C: 0.02-0.06%, Si: 0.3-0.6%, Mn: 0.4-1.0%, Mo: 0.8-1.5%, Ni: 4-7%, Cr: 12.5-15%, V: 0.1-0.25%, Cu: 0.5-0.9%, and Fe is the balance.

2. A method for preparing the hydrogen embrittlement-resistant high-strength stainless steel wire for arc additive manufacturing and welding as described in claim 1, characterized by comprising the following steps: (1) Double melting: The high-strength stainless steel alloy resistant to hydrogen embrittlement is first smelted in a vacuum smelting furnace and cast to obtain a pre-melted ingot; then the pre-melted ingot is forged to prepare an electrode sample, and the electrode sample is second-melted by electroslag remelting and cast to obtain the final ingot. (2) Forging and rolling: The ingot obtained in the previous step is forged, and the bar obtained by forging is rolled to obtain wire rod; (3) Annealing: Annealing the wire rod; (4) Cold drawing: The oxide scale is removed from the annealed wire rod, and wire with a diameter of 1.1~1.3mm is obtained by multiple cold drawing and online annealing.

3. The method for preparing hydrogen-resistant high-strength stainless steel wire for arc additive manufacturing and welding according to claim 2 is characterized in that: the vacuum degree of vacuum smelting in step (1) is 10~20Pa; the heating temperature of the initial melting ingot is 1150~1250℃, the holding time is 5~10h, and then it is forged into an electrode sample, with a final forging temperature of not less than 950℃; the specific parameters of electroslag remelting are: electroslag speed 1.6~2.0kg / min, voltage 30~40V, current 1.8~3.0kA.

4. The method for preparing hydrogen embrittlement resistant high-strength stainless steel wire for arc additive manufacturing and welding according to claim 2 is characterized in that: in step (2), the final ingot should be heated to 1100~1200℃ and held for 2~5h, and then forged, with the final forging temperature not lower than 950℃ and air-cooled; subsequently, the bar is held at 1100~1200℃ for 1~3h and rolled into wire rod through multiple hot continuous rolling passes.

5. The method for preparing hydrogen-resistant high-strength stainless steel wire for arc additive manufacturing and welding according to claim 2 is characterized in that: in step (3), the wire rod is kept in a salt bath at 1100~1200℃ for 1~2h, then air-cooled and washed with water.

6. The method for preparing hydrogen embrittlement resistant high-strength stainless steel wire for arc additive manufacturing and welding according to claim 2 is characterized in that: in step (4), before drawing, the wire rod is mechanically de-oxidized, washed and dried, and then treated with a film and dried at 80~100℃; during the drawing process, online annealing is carried out at a temperature of 1100~1150℃, and after online annealing, the wire rod is successively alkali washed and water washed.

Images