Gas shielded solid wire rod and wire for full position weld form uniformity

Abstract

The application discloses a gas protection solid wire rod and welding wire for full position welding forming uniformity, which contains Fe and inevitable impurity elements, and the following chemical elements with mass percentage: C: 0.03-0.11%; Si: 0.6-1.1%; Mn: 1.3-2.1%; S: 0.005-0.018%; P: 0.004-0.015%; Ti: 0.04-0.22%; Ni: 0.4-1.5%; Mo: 0.05-0.4%; Cu: 0.03-0.45%; and Zr: 0.02-0.08%. The welding wire has good spreading and forming uniformity under the condition of automatic girth welding of the pipe in full position, and can avoid the spreading deterioration and welding defects such as welding toe undercut and edge un-melting caused by complex space welding position change, thereby ensuring the full position welding quality.

Description

Technical Field

[0001] This invention relates to a welding wire rod and welding wire, and more particularly to a gas-shielded solid welding wire rod and welding wire. Background Technology

[0002] Solid wire gas metal arc welding is a common welding method for the construction of various engineering structures. By matching different types of welding materials and implementing welding processes, it can meet the requirements of joint performance and structural integrity in various service environments, including conventional static mechanical properties, dynamic fatigue properties, corrosion resistance, and high temperature resistance, and is therefore widely used.

[0003] However, in the manufacturing process of specific industrial welded structures, complex spatial welding positions are often involved, such as all-position welding of pipelines, welding of energy medium storage tanks and spherical tanks in complex spatial positions, and vertical and overhead welding of important steel structures. In these non-flat and horizontal welding positions, the spreadability of the weld pool is deteriorated due to the effect of gravity, resulting in uneven weld formation and easy formation of undercut defects and incomplete fusion at the weld toe, which adversely affects the weld quality.

[0004] The current solution is to repair and weld these welding defects during the on-site manufacturing process. This not only increases the workload and construction costs, but excessive welding can also lead to a deterioration in the overall performance of the joint, posing a significant hidden danger to the construction of the engineering structure.

[0005] Based on this, it is desirable to provide a gas-shielded solid welding wire rod and welding wire that can improve the uniformity of forming in all-position welding. Summary of the Invention

[0006] One of the objectives of this invention is to provide a gas-shielded solid welding wire rod for all-position welding to ensure uniformity of forming. This wire can produce welding wire with good spreadability and uniform forming under all-position automatic circumferential welding conditions in pipelines. It can also avoid the deterioration of spreadability and welding defects such as weld toe undercut and edge incomplete fusion caused by complex spatial welding position changes, thus ensuring the quality of all-position welding.

[0007] To achieve the above objectives, the present invention provides a gas-shielded solid welding wire rod for uniform forming in all-position welding, which contains Fe and unavoidable impurity elements, and further contains the following chemical elements in the following mass percentages:

[0008] C: 0.03~0.11%; Si: 0.6~1.1%; Mn: 1.3~2.1%; S: 0.005~0.018%; P: 0.004~0.015%; Ti: 0.04~0.22%; Ni: 0.4~1.5%; Mo: 0.05~0.4%; Cu: 0.03~0.45%; Zr: 0.02~0.08%.

[0009] This invention also provides a gas-shielded solid welding wire rod for all-position welding to ensure uniformity of forming, wherein the mass percentage content of each chemical element is as follows:

[0010] C: 0.03–0.11%; Si: 0.6–1.1%; Mn: 1.3–2.1%; S: 0.005–0.018%; P: 0.004–0.015%; Ti: 0.04–0.22%; Ni: 0.4–1.5%; Mo: 0.05–0.4%; Cu: 0.03–0.45%; Zr: 0.02–0.08%; balance Fe and unavoidable impurities.

[0011] Furthermore, the mass percentage content of each chemical element in the gas-shielded solid welding wire rod of the present invention further satisfies at least one of the following:

[0012] C: 0.05–0.07%;

[0013] Si: 0.7–0.9%;

[0014] Mn: 1.5–1.7%;

[0015] S: 0.01~0.015%;

[0016] P: 0.008~0.012%

[0017] Ti: 0.09–0.12%;

[0018] Ni: 0.8–1.2%;

[0019] Mo: 0.08–0.2%;

[0020] Cu: 0.15–0.25%;

[0021] Zr: 0.03~0.05%.

[0022] Specifically, the design principles of each chemical element in this invention are as follows:

[0023] C: Carbon plays a decisive role in ensuring the strength of the welding wire. Furthermore, as a significant element that expands the austenite region, a certain carbon content is beneficial for forming more low-temperature phase transformation structures during the solidification phase transformation of the weld metal, avoiding the formation of bulk proeutectoid ferrite at high temperatures, and also contributing to the toughness of the weld metal. Based on this, the present invention controls C to be 0.03–0.11%.

[0024] Silicon (Si): Silicon is a crucial deoxidizer, ensuring the purity of the weld metal. In this invention, silicon significantly reduces the surface tension of the molten pool, improving weld metal fluidity and promoting uniform weld metal spreading. Furthermore, the large difference in thermal expansion coefficients between silicon oxides and weld metal facilitates slag removal after welding, minimizing negative impacts on weld quality. However, silicon is a strong ferrite-forming element; higher levels can promote the formation of high-temperature phase transformation structures, which is detrimental to ensuring weld metal toughness. Therefore, this invention controls the Si content to 0.6–1.1%.

[0025] Mn: Manganese is an important solid solution strengthening element in C-Mn type low alloy steel welds, second only to carbon in its contribution to weld strength. Simultaneously, manganese can significantly expand the austenite region; increasing the manganese content within a certain range helps delay the solid-state phase transformation to a lower temperature range, ensuring strength while improving weld metal toughness. However, in this invention, the presence of manganese increases the surface tension of the molten pool, which is detrimental to its spreadability, especially in complex spatial positions such as all-position welding. It reduces the wettability of the weld edges, negatively impacting weld uniformity. Therefore, this invention controls the Mn content to be 1.3–2.1%.

[0026] Sulfur is typically controlled as a harmful element during normal flat or horizontal welding to prevent hot cracking and weld metal embrittlement. However, in this invention, sulfur significantly improves the surface tension of the molten pool, increasing its wettability to the weld edges during all-position welding, thereby reducing undercut and lack of fusion defects. In this invention, the harmful effect of sulfur on hot cracking can be controlled using high-melting-point sulfide-forming elements such as manganese and zirconium. Therefore, this invention controls sulfur content to 0.005–0.018%.

[0027] P: Phosphorus is also strictly limited as a harmful element in conventional low-alloy steel welding wire. However, in this invention, phosphorus has a positive effect from the perspective of improving the surface tension of the molten pool. Appropriate addition of phosphorus improves the wettability of the molten pool during all-position welding and is beneficial for optimizing weld formation quality. Based on this, the P content is controlled at 0.004% to 0.015%.

[0028] Titanium (Ti): As a chemical element with strong affinity for oxygen, carbon, and nitrogen, titanium plays a role in deoxidation, carbon fixation, and nitrogen fixation during the molten pool reaction stage, improving the purity of the weld metal and ensuring the overall performance of the weld joint. Simultaneously, in this invention, titanium also significantly reduces the surface tension of the liquid metal, which is beneficial for the uniform spreading of the weld toe edge and ensures the forming quality during all-position welding. Furthermore, titanium has a relatively low ionization potential, making it an element that can be directly added to welding metallurgy with a significant arc-stabilizing effect. Based on this, the Ti content in this invention is controlled at 0.04–0.22%.

[0029] Ni (Ni): The infinite solid solution of nickel and iron significantly improves the toughness of the metal. Simultaneously, nickel significantly expands the austenite region, which is beneficial for low-temperature solid-state phase transformation, thus improving the weld metal properties from a microstructural perspective. Therefore, the addition of nickel plays a positive role in ensuring the service performance of the joint. However, in this invention, the presence of nickel significantly increases the viscosity and surface tension of the liquid weld metal, greatly affecting weld spreadability, especially in complex spatial locations, where the combined effect with gravity is detrimental to weld uniformity. Therefore, this invention controls the Ni content to 0.4–1.5%.

[0030] Mo (Mo): Molybdenum significantly improves the strength of weld metal during the solid-state phase transformation process. It delays the austenite transformation temperature and expands the low-temperature phase transformation temperature range, while also promoting the formation of a finer, more resilient low-temperature phase transformation microstructure, ensuring weld metal toughness. Therefore, it is a crucial element for regulating the overall performance of welded joints. However, molybdenum can significantly increase the surface tension of the molten pool. Higher molybdenum content worsens the spreadability of the molten pool and the uniformity of the final weld formation, especially increasing the tendency for undercut at weld edges when welding in complex spatial locations.

[0031] Mo: 0.05–0.4%;

[0032] Cu: Copper dissolved in ferrite can significantly improve strength, while also leveraging the numerous slip systems of face-centered cubic metals to enhance matrix toughness. However, copper significantly increases the surface tension of the molten pool. In this invention, excessively high Cu content is detrimental to uniform pool spreading and weld formation quality. Therefore, this invention controls the Cu content to 0.03–0.45%.

[0033] Zirconium (Zr) is not only an important carbide-forming element, playing a role in carbon fixation and promoting heterogeneous nucleation and grain refinement during solid-state phase transformation, but it is also a high-melting-point, stable sulfide-forming element. In this invention, the combined action of Zr and manganese can avoid welding hot cracking problems in situations with high sulfur content, thereby maximizing the role of sulfur in reducing the surface tension of the molten pool and improving the uniformity of weld formation. Based on this, the Zr content is controlled at 0.02% to 0.08%.

[0034] Furthermore, the mass percentage of unavoidable impurity elements in the gas-shielded solid welding wire rod of the present invention satisfies the following conditions: O≤0.008%, N≤0.008%.

[0035] The unavoidable impurities in this invention are mainly O and N, and it is desirable that their content be as low as possible.

[0036] While increased oxygen content can improve molten pool activity and surface tension, which is beneficial for molten pool spreading and weld appearance, it also leads to reduced molten pool reaction stability and increased slag content. Furthermore, excessive oxide inclusions can cause weld embrittlement. Excessive nitrogen content can form nitride aggregates with related alloying elements, and excessive nitrogen dissolved in ferrite can also cause severe weld embrittlement.

[0037] Furthermore, in the gas-shielded solid welding wire rod described in this invention, it also satisfies: the surface tension factor ST of the molten pool. f The value is 0.40–0.70; the hot crack control factor HC f Above 230; among which:

[0038]

[0039] In the formula, each chemical element is replaced with the value before the percentage sign of its mass percentage content.

[0040] The gas-shielded solid welding wire rod of the present invention is achieved through optimized design and strict control of the surface tension factor of the molten pool. This surface tension factor of the molten pool is set by systematically considering the influence of major chemical elements on the surface tension of the molten pool and thus on the spreadability of the weld. Through the correlation of chemical elements with strong correlation of molten pool surface tension, the adverse effects of welding position factors and gravity on the spreadability and uniformity of weld formation are overcome, and stable all-position automatic welding is achieved.

[0041] Furthermore, to ensure good weld spreadability and uniformity under all-position welding conditions, the weld pool surface tension factor is crucial for the design and optimization of welding wire composition. The weld pool surface tension factor is determined by systematically considering the influence of key chemical elements during the molten pool's chemical reaction and solidification stages on the surface tension, and consequently, on weld spreadability. Through the correlation between the surface tension of these chemical elements and their strong correlation with weld pool surface tension, reducing the surface tension of the weld pool increases weld metal spreadability and edge wettability, thereby improving weld formation quality.

[0042] Different chemical elements exhibit varying degrees of correlation with surface tension during the molten pool stage. This invention reflects this difference in the effect on the molten pool surface tension factor ST. fBased on the contribution coefficient, the surface tension factor of the molten pool was designed. Therefore, the relevant chemical elements in this invention do not play a role independently, but have a clear correlation.

[0043] In this invention, although sulfur has a very positive effect on improving the surface tension of the molten pool, it readily forms low-melting-point eutectics with iron, thus widening the solidification temperature range of the molten pool and strongly increasing the tendency of the weld metal to hot crack. Therefore, it is necessary to control the hot cracking tendency of the weld metal by using chemical elements that can fix sulfur at high temperatures. Accordingly, this invention also designs a hot cracking control factor HC that reflects the synergistic addition relationship of Mn, Zr, and S. f .

[0044] For this invention, only by simultaneously controlling the surface tension factor ST of the molten pool can... f and hot crack control factor HC f Only in this way can a balance be achieved between improving the surface tension of the molten pool and avoiding welding hot cracks.

[0045] Furthermore, in the gas-shielded solid welding wire rod described in this invention, the microstructure of its deposited metal includes a low-temperature phase transformation structure dominated by bainite, and the total volume content of the bulk proeutectoid ferrite and side strip ferrite formed during the high-temperature phase transformation process is less than 5%.

[0046] Furthermore, in the gas-shielded solid welding wire rod described in this invention, the properties of the deposited metal meet the following requirements: tensile strength ≥ 625 MPa, yield strength ≥ 550 MPa, and low-temperature impact energy KV2 ≥ 68 J at -10℃.

[0047] Another object of the present invention is to provide a gas-shielded solid welding wire for uniform forming of all-position welding, which is made from gas-shielded solid welding wire rod as described above.

[0048] In the preparation process, the wire rod is first smelted, refined, cast, hot rolled, and annealed in a vacuum electric furnace to obtain the wire rod. Then, the finished welding wire is prepared by drawing and winding the welding wire.

[0049] Furthermore, the surface of the gas-shielded solid welding wire of the present invention has a copper plating layer.

[0050] The present invention can also improve the welding arc stability by increasing the conductivity and wire feeding stability of the welding wire by plating copper on the surface of the welding wire.

[0051] During preparation, copper plating is performed after the wire drawing step.

[0052] Since the preparation process of the wire rod and welding wire in this case is not an improvement over the prior art, that is, conventional processes in the field can be used, the preparation process of the wire rod and welding wire will not be described in detail in this invention.

[0053] The gas-shielded solid welding wire rod and welding wire for uniform forming in all-position welding described in this invention have the following beneficial effects:

[0054] Using the gas-shielded solid welding wire rod described in this invention, a welding wire with good spreadability and uniform forming can be obtained under the condition of automatic circumferential welding of pipelines in all positions. It can avoid the deterioration of spreadability and welding defects such as weld toe undercut and edge non-fusion caused by complex changes in spatial welding position, and ensure the quality of welding in all positions.

[0055] The gas-shielded solid welding wire rod and welding wire of the present invention ensure the basic mechanical properties of the weld metal through alloy element design, and can meet the service requirements of all-position welded structural engineering.

[0056] Furthermore, the gas-shielded solid welding wire of the present invention has a moderate strength level, good toughness, tensile strength ≥625MPa, yield strength ≥550MPa, and low-temperature impact energy KV2 ≥68J at -10℃. Therefore, it has a wide range of applications and solves the problem of matching welding materials in multiple industrial fields with requirements for uniformity of welding quality in spatial positions. Detailed Implementation

[0057] The following will provide a further explanation and description of the gas-shielded solid welding wire rod and welding wire for uniform welding in all positions, based on specific embodiments. However, this explanation and description do not constitute an undue limitation on the technical solution of the present invention.

[0058] Examples 1-7

[0059] Table 1 lists the mass percentage of each chemical element in the gas-shielded solid welding wire rods and welding wires of Examples 1-7.

[0060] Table 1. (wt%, balance Fe and other unavoidable impurities besides O and N)

[0061]

[0062]

[0063] The gas-shielded solid welding wires described in Examples 1 to 7 of this invention are all prepared using the following steps:

[0064] The ingots are smelted, refined, and cast in a vacuum electric furnace to obtain ingots with the chemical composition shown in Table 1. Then, the wire rods are hot rolled, annealed, drawn, copper-plated, wound, and packaged to finally obtain finished welding wire with a diameter of 1.0 mm.

[0065] This invention conducts all-position welding process performance tests on gas-shielded solid welding wires from Examples 1 to 7 to evaluate the final all-position weld formation quality. The process performance of each example welding wire is comprehensively evaluated based on weld toe transition smoothness (used to assess weld pool spread and edge incomplete fusion sensitivity), weld toe edge micro-area filling ability (used to assess resistance to edge undercut), and weld hot cracking sensitivity. The evaluation results are listed in Table 2.

[0066] In the performance evaluation test of all-position welding process for pipelines, since the edge characteristics of multi-layer, multi-pass filler welds are not easily observed, only the quality of the cap weld formation is evaluated. The cap weld current is 200–230A, the welding voltage is 22–24V, and the welding speed is 320–380mm / min. Appropriate welding torch oscillation is performed according to the bevel width before cap weld to ensure the coverage of the single-pass cap weld.

[0067] The performance evaluation results of all-position welding process of gas-shielded solid welding wires in Examples 1 to 7 are shown in Table 2.

[0068] Table 2.

[0069]

[0070]

[0071] Note: In Table 2, ○ indicates excellent, ● indicates good, and × indicates poor. Excellent weld toe transition smoothness means the transition angle between the weld toe and the base metal is greater than 150° and there are no edge incomplete fusion defects; good means the transition angle between the weld toe and the base metal is between 150° and 120° and there are no edge incomplete fusion defects; poor means the transition angle between the weld toe and the base metal is less than 150° and there are obvious edge incomplete fusion defects. Excellent weld toe edge micro-area filling ability means the weld toe undercut depth is less than 0.4mm and there are no more than one such area within any 300mm weld length; good means the weld toe undercut depth is between 0.4mm and 0.7mm and there are no more than two such areas within any 300mm weld length; poor means the weld toe undercut depth exceeds 0.7mm and there are more than two such areas within any 300mm weld length. Excellent weld hot crack sensitivity means that there are no hot crack defects under normal welding process conditions; good means that there is a certain tendency to hot crack under normal heat input conditions, and the tendency to hot crack can be avoided by reducing the welding heat input or increasing the cooling rate; poor means that the tendency to weld hot crack cannot be avoided even by improving the welding process conditions.

[0072] As can be seen from Table 2, all embodiments exhibit good adaptability in terms of the uniformity of weld formation in all positions.

[0073] Furthermore, this invention also conducted welding tests on the gas-shielded solid welding wires of Examples 1-7 according to the requirements of GB / T 8110-2008 standard, and evaluated the strength and impact toughness of the welded metal to assess its mechanical adaptability during service. Table 3 lists the mechanical properties of the welded metal of the gas-shielded solid welding wires of Examples 1-7.

[0074] During the solid wire fusion metal welding test, the welding current was 230-250A, the welding voltage was 24-26V, and the welding speed was 340mm / min.

[0075] Table 3.

[0076] Example Yield strength (MPa) Tensile strength (MPa) Impact toughness (KV2, -10℃) 1 560 638 80 2 586 640 113 3 592 655 155 4 580 641 159 5 597 668 84 6 599 665 68 7 594 667 95

[0077] As shown in Table 3, the gas-shielded solid welding wires of Examples 1-7 of this invention all meet the following mechanical properties of their deposited metal: tensile strength > 625 MPa, yield strength > 550 MPa, and -10℃ low-temperature impact energy (KV) > 70 J. In terms of the mechanical properties of the deposited metal of the solid welding wires, Examples 3 and 4 have superior mechanical properties, with tensile strength > 640 MPa, yield strength ≥ 580 MPa, and -10℃ low-temperature impact energy (KV) > 150 J.

[0078] It should be noted that the combination of the technical features in this case is not limited to the combination methods described in the claims of this case or the combination methods described in the specific embodiments. All technical features described in this case can be freely combined or combined in any way, unless they contradict each other.

[0079] It should also be noted that the embodiments listed above are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made thereto are those that can be directly derived or easily conceived by those skilled in the art from the content disclosed in the present invention, and should all fall within the protection scope of the present invention.

Claims

1. A gas-shielded solid welding wire rod for all-position welding to ensure uniform forming, characterized in that, Its mass percentage content of each chemical element is as follows: C: 0.03~0.11%; Si: 0.6~1.1%; Mn: 1.3~2.1%; S：0.005~0.018%； P：0.004~0.015%； Ti: 0.04~0.22%; Ni: 0.4~1.5%; Mo: 0.05~0.4%; Cu: 0.03~0.45%; Zr: 0.02~0.08%; balance is Fe and unavoidable impurities; It also satisfies: molten pool surface tension factor ST f The value is 0.40~0.70; the hot crack control factor HC f Above 230; in: ； ； In the formula, each chemical element is replaced with the value before the percentage sign of its mass percentage content.

2. The gas-shielded solid welding wire rod as described in claim 1, characterized in that, Its mass percentage content of each chemical element further satisfies at least one of the following conditions: C：0.05~0.07%； Si: 0.7~0.9%; Mn: 1.5~1.7%; S：0.01~0.015% ； P：0.008~0.012% Ti: 0.09~0.12%; Ni: 0.8~1.2%; Mo: 0.08~0.2%; Cu: 0.15~0.25%; Zr：0.03~0.05%。 3. The gas-shielded solid welding wire rod as described in claim 1, characterized in that, The unavoidable impurity element mass percentage content must meet the following requirements: O≤0.008%, N≤0.008%.

4. The gas-shielded solid welding wire rod as described in claim 1, characterized in that, The microstructure of the deposited metal includes a low-temperature phase transformation structure dominated by bainite, and the total volume content of the bulk proeutectoid ferrite and side strip ferrite formed during the high-temperature phase transformation process is less than 5%.

5. The gas-shielded solid welding wire rod as described in claim 1, characterized in that, Its deposited metal properties meet the following requirements: tensile strength ≥625MPa, yield strength ≥550MPa, and low-temperature impact energy KV2 ≥68J at -10℃.

6. A gas-shielded solid welding wire for achieving uniformity in all-position welding, characterized in that, It is made from gas-shielded solid welding wire rod as described in any one of claims 1-5.

7. The gas-shielded solid welding wire as described in claim 6, characterized in that, Its surface has a copper plating layer.

Images