CN115815762A - 500MPa multi-wire submerged-arc welding wire rod and welding wire capable of being welded at large heat input of 100-200kJ/cm - Google Patents

Abstract

The invention discloses a 500MPa multi-wire submerged arc welding wire rod capable of being welded at large heat input of 100 to 200kJ/cm, which comprises the following components in percentage by weight: c:0.03 to 0.12, si: less than or equal to 0.09, mn:2.30 to 2.55, P: less than or equal to 0.012, S: less than or equal to 0.005, ni:1.05 to 1.65, mo:0.20 to 0.38, ti:0.11 to 0.24, mg: less than or equal to 0.005, ce: less than or equal to 0.05, cr less than or equal to 0.05, al: less than or equal to 0.05, N: not more than 0.0065, and the balance of Fe and inevitable impurities. The invention also provides a 500MPa multi-wire submerged arc welding wire capable of welding at a large heat input of 100 to 200kJ/cm. The welding wire has the advantages of simple chemical components, high deposition efficiency, excellent low-temperature toughness and stronger adaptability to the welding heat input range.

Description

500MPa multi-wire submerged-arc welding wire rod and welding wire capable of being welded at large heat input of 100-200kJ/cm

Technical Field

The invention belongs to the field of special welding materials, is suitable for large heat input multi-wire co-melting pool submerged arc automatic welding, has deposition efficiency more than 2-5 times that of conventional single wire submerged arc automatic welding, and particularly relates to a multi-wire submerged arc welding wire rod and an automatic welding wire which can be used for large heat input high-efficiency easy-welding bridge steel Q345-Q370 qEHW with the welding speed of 100 to 200kJ/cm.

Background

In recent years, with rapid development of manufacturing industries such as shipbuilding, ocean engineering, super high-rise buildings, bridges, pipelines, pressure vessels and the like, the production scale of welding large members of medium-thickness plates is rapidly expanding. In order to ensure the strength and toughness of a welding area, the conventional medium plate produced in China at present can only adopt small heat input (less than or equal to 50 kJ/cm) to carry out multilayer multi-pass welding, so that the welding production efficiency is very low, the production cost is relatively high, and the requirements of low cost, high efficiency and reduction manufacturing required by modern economic development cannot be met. Under such circumstances, the manufacturing industry using medium steel plates has gradually started to apply a more efficient multi-wire submerged arc automatic welding high heat input welding method for the purpose of improving construction efficiency and reducing costs. During large heat input welding, because the high-temperature retention time of weld metal is prolonged, austenite grains are easily coarsened obviously, abnormal structures such as side plate ferrite, widmannstatten structures and upper bainite are easily formed, the number of M-A islands is increased and is large, the strength and toughness of the weld are seriously deteriorated, cracks are easily generated, and the defects that the service requirement cannot be met and the whole safe use of a component is influenced are caused. Therefore, research on the production process technology of the medium steel plate capable of adapting to the large heat input welding and development of the large heat input welding material are receiving much attention.

At present, a submerged-arc welding wire matched with Q345-Q370 qE bridge steel in the bridge field, such as H08MnE or H08Mn2E, is suitable for welding heat input of not more than 40kJ/cm, and the-40 ℃ low-temperature impact toughness of deposited metal is usually about 60-120J. In order to improve the production efficiency, steel structure manufacturing enterprises at the present stage adopt high heat input welding for H08MnE or H08Mn2E, and accordingly the metal toughness of a welding seam area is sharply reduced, and the problem of matching between the metal mechanical property of the welding seam area and high heat input welding is difficult to guarantee. This is because the cooling rate of the weld zone decreases with an increase in the weld line energy, and the weld metal structure is likely to coarsen. At present, most of domestic welding materials applied to the large linear energy in the fields of pipelines, ships, maritime works and the like are imported from foreign countries, and the cost is high. Therefore, the welding material with high efficiency and excellent performance is developed, the advantages of high production efficiency, environmental protection, energy conservation, beautiful forming, low pollution, easy realization of automation and the like can be achieved, and the development of the bridge steel structure industry to the high-efficiency intelligent manufacturing direction can be promoted.

In order to solve the above problems, special welding material researchers have conducted some beneficial researches on submerged arc welding automatic welding wires resistant to large heat input.

Chinese invention patent application CN201410728048.4 discloses a large heat input submerged arc welding wire suitable for welding heat input of 60 to 160kJ/cm, which adds 0.01 to 0.05 percent of Ti to form TiN to pin austenite grain boundaries and prevent austenite grain growth, and on the other hand, adds alloy elements such as Si, mn, ti, al, ce, mg and the like to promote the inclusion of composite oxides such as high melting point Si, mn, ti, al, ce, mg and the like and promote the generation of acicular ferrite. However, in the embodiment, the low-temperature impact at-40 ℃ at the center of the weld joint has a low value, probably because the addition amount of 0.01 to 0.05 percent of Ti is small in a large-heat-input welding process (more than 50 kJ/cm), the burning loss is very serious because the Ti has strong affinity with oxygen in the welding process, and the content of 0.01 to 0.05 percent of titanium element in the weld joint is low in the deposited metal or weld metal, so that the grain refinement is not enough.

The invention Chinese patent application CN200910046732.3 discloses a high-toughness submerged arc welding wire with moderate strength, high impact toughness and large linear energy resistance, which effectively improves the low-temperature toughness and the large linear energy resistance by optimizing the carbon content, controlling the upper limit of the silicon content and adopting a Mn-Ni system and has proper yield strength and tensile strength. Because the welding wire of the invention does not add elements Ti and Ce for refining the structure of the large heat input welding seam, the grain refinement is not enough in the real large heat input welding. And the toughness is improved by only adding Ni element to refine the crystal grains of ferrite phase, which increases the cost of welding wire smelting.

The Chinese invention patent application CN92105621.4 discloses a low-carbon microalloyed submerged arc welding wire, which is added with 1.2 to 1.6 percent of Mn and 0.2 to 0.4 percent of Mo to improve the strength of a welding line through solid solution strengthening; 0.02 to 0.08 percent of Ti and 0.001 to 0.008 percent of B are added to improve the toughness of the welding line through a compound action, wherein the Ti can be combined with free N. Although Ti and B elements are added, the content of Mn and Ni is low, and even though the invention is claimed to be used for high-heat input resistant and high-speed welding, the mechanical property of a welding seam, particularly the low-temperature impact toughness of a joint, is difficult to ensure in real high-heat input welding.

The Chinese patent application CN01135349.X discloses a 'large heat input submerged arc welding joint, a manufacturing method of the joint and a welding wire and a welding flux used by the joint' complete set of technology, wherein the welding wire for the large heat input submerged arc welding is composed of a welding wire consisting of C:0.03 to 0.10%, N: less than or equal to 0.0035 percent, si: less than or equal to 0.4 percent, mn:1.0 to 2.5 percent, and more than 0.03 percent of Ti, wherein the Ti/N ratio is as follows: 15 to 50. The welding wire composition also contains one or more than 2 selected from Mo, nb, B and Ni, the weld metal component of the welding joint also needs to satisfy the condition that B/N is more than or equal to 0.6 and less than or equal to 1.2, and the generation amount of grain boundary ferrite in the weld metal is controlled to be less than 10.0 percent of the area. The invention has the advantages of complex technology, higher requirement and higher implementation difficulty. The welding wire is welded under the condition of 150kJ/cm high heat input, only the numerical values of low-temperature impact values of 0 ℃ and-20 ℃ at the center of a welding seam are given to be lower, and the welding wire is conjectured to have low content of Ti element added and insufficient grain refinement.

Chinese patent application CN200710139338.5 discloses an X80 pipeline steel submerged arc welding wire, which adopts a Mn-Mo-Ti-B system, wherein 1.5 to 1.8 percent of Mn is added to obtain strength and toughness, 0.3 to 0.4 percent of Mo is added to ensure the strength and promote ferrite formation, 0.1 to 0.2 percent of Ti is added to ensure high toughness of weld metal, and 0.004 to 0.008 percent of B is added to ensure the strength and promote acicular ferrite microstructure of the weld to improve the toughness. The welding wire is suitable for welding X80 pipeline steel, and the quality of a welding seam and a heat affected zone of the welding wire can meet the requirements of relevant standards. If the welding wire is used for high heat input welding (more than 50 kJ/cm), the Si content of 0.25 to 0.35 percent in the welding wire and the Si element transitional between the base metal and the submerged arc welding flux are added, so that the high Si content of the welding seam metal is easily caused, and the low-temperature toughness of the welding seam metal is influenced. And the welding wire does not contain Ni element with stable transition coefficient, and the mechanical property of the welding line, especially the low-temperature impact toughness of the joint, is difficult to ensure under the condition of high heat input welding.

Therefore, under the condition of meeting the requirements on the mechanical properties of the welding joint in the contents of relevant standards, specifications and the like, in order to improve the welding and manufacturing efficiency of large-scale steel structures of steel structure manufacturing enterprises such as bridges and the like, a matched domestic submerged arc automatic welding wire suitable for the welding heat input of Q345-Q370 qE grades of 100 to 200kJ/cm needs to be developed, and the method is an important way for further improving the welding efficiency, reducing the cost, improving the mechanical properties of the welding joint and replacing imported products.

Disclosure of Invention

The invention aims to provide a 500MPa multi-wire submerged arc welding wire rod and a welding wire which can be welded at large heat input of 100 to 200kJ/cm, wherein the applicable heat input range is 100 to 200kJ/cm, the welding wire rod is matched with an Fe powder-containing alkaline sintered flux, and the yield strength of deposited metal is Rp0.2/MPa:463 to 536MPa, tensile strength Rm/MPa:561 to 619MPa, elongation A/%: 22 to 24 percent, impact absorption work at-40 ℃ Akv-40 ℃/J:90.4 to 155J, and the welded welding bead is neat and attractive in appearance. The submerged arc welding wire has the advantages of simple chemical components, high deposition efficiency, excellent low-temperature toughness and stronger adaptability to the welding heat input range, and is suitable for efficient and intelligent welding and manufacturing of large steel structures in the fields of bridges, ships, buildings and the like.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a500 MPa multi-wire submerged arc welding wire rod capable of being welded at large heat input of 100 to 200kJ/cm comprises the following chemical components in percentage by mass: c:0.03 to 0.12, si: less than or equal to 0.09, mn:2.30 to 2.55, P: less than or equal to 0.012, S: less than or equal to 0.005, ni:1.05 to 1.65, mo:0.20 to 0.38, ti:0.11 to 0.24, mg: less than or equal to 0.005, ce: less than or equal to 0.05, cr less than or equal to 0.05, al: less than or equal to 0.05, N: not more than 0.0065, and the balance of Fe and inevitable impurities; C. the contents of Si, mn, cr, ni, mo, ti and Ce meet that gamma is more than or equal to 0.51 and less than or equal to 0.81 and theta is more than or equal to 561 and less than or equal to 618, wherein gamma = (10 Ti +60 Ce)/(Si +2 Mn); θ =9.8 x (32 +143C +4.80Mn +11.90Cr +3.42Ni +6.64Mo + 0.96Ti).

The invention also provides a 500MPa multi-wire submerged arc welding wire capable of being welded at a large heat input of 100 to 200kJ/cm, which is prepared by drawing the wire rod.

Furthermore, under the condition of 100-200 kJ/cm heat input welding by adopting an alkaline sintered flux, the size of inclusions in deposited metal of the welding wire is more than 80 percent within the range of 0.6-1.8um, and the content of acicular ferrite in the structure is not less than 70 percent.

Further, an alkaline sintered flux is adopted and welded under the heat input of 100-200 kJ/cm, and the impact energy of the deposited metal of the welding wire in KV2 type notch at the ambient temperature of-40 ℃ is more than or equal to 80J.

Furthermore, an alkaline sintered flux is adopted and welded under the heat input of 100-200 kJ/cm, the yield strength of deposited metal of the welding wire is 463-536MPa, the tensile strength is 561-619MPa, and the elongation is 22-24%.

Further, a copper plating layer is arranged on the surface of the welding wire, and the thickness of the copper plating layer is 0.19 to 0.23um.

In the technical scheme, the action and mechanism of each component are as follows:

c: carbon is the most important element for improving the strength of the low alloy steel weld. Carbon can enlarge an austenite phase region, improve hardenability, improve the metal strength and hardness of a welding seam, and simultaneously reduce the plasticity and toughness of the welding seam. Carbon element has larger burning loss in the process of submerged-arc welding, so in order to ensure proper strength and reduce the influence of carbon on toughness and crack resistance as much as possible, the carbon content is limited to 0.03 to 0.12 percent.

Si: silicon is a ferrite forming element, and the ferrite content increases with the increase of the silicon content, mainly because silicon is an important element of a deoxidizer, and is combined with oxygen to form inclusions in a weld joint to become nucleation particles of ferrite, but the influence of the silicon element on the ferrite is mainly influenced by the manganese element, and when the manganese element is low, the influence of the silicon element on the structure transformation is large. Meanwhile, researches prove that the addition of the silicon element can enrich the silicon in inclusions, increase the size of the inclusions and reduce the toughness of welding seams, and the Si content in the welding wires needs to be controlled because the welding flux and the base metal contain higher Si which causes more serious Si increase in the welding process. The silicon content is limited to be less than or equal to 0.09 percent in the invention.

Mn: manganese is an important deoxidizing and desulfurizing element, and can improve the metal strength of a welding seam and reduce the welding heat crack tendency. Meanwhile, manganese is one of a few elements which can improve the weld strength and the weld toughness, and Mn mainly refines grains and influences the sizes of concentrated inclusions in the weld to influence the weld toughness. And when the manganese content of the weld metal is too high, the toughness is reduced. Under the condition of 200kJ/cm heat input, the burning loss of manganese is serious, and the manganese content in the welding wire components is limited to 2.30-2.55% in consideration of the large burning loss of a manganese element in the large linear energy submerged arc welding process.

Mo: in the process of high heat input welding, the transition coefficient of molybdenum is high, and a proper amount of Mo element is added into the submerged arc welding wire, so that the austenite transformation temperature of the weld metal in the cooling process after welding can be effectively reduced, the weld metal structure is refined, and the strength and the toughness are improved. But the content of Mo should be controlled to avoid the increase of the strength and hardness. Therefore, the Mo content in the welding wire components is limited to 0.20 to 0.38 percent.

Ni: the invention adds Ni element into submerged arc welding wire, which mainly improves the low temperature toughness of weld metal, and improves the weld metal strength by using the solid solution strengthening function. The mechanism of Ni to improve low temperature toughness is to lower its brittle transition temperature by toughening the ferrite matrix. Meanwhile, both Ni and Mn are austenite stabilizing elements, and can reduce the austenite phase transition temperature by adding a proper amount, but the impact toughness of the Ni and the Mn is not completely the same, so the Ni and the Mn can be added at the same time. In high heat input welding, the low-temperature toughness of weld metal is reduced greatly, meanwhile, ni has certain burning loss, and the addition amount of Ni is increased, so that the Ni content in welding wire components is limited to 1.05-1.65%.

Ti: in the invention, ti element is added into the submerged arc welding wire, the main function is that the formed oxide and nitride which are dispersed and distributed can effectively prevent austenite grains from growing, and when the volume content of the Ti element is increased in a proper range, the generation of acicular ferrite in weld metal can be obviously promoted. Meanwhile, the inclusion of Ti and composite oxides of Si, mn, al, mg and the like is beneficial to the nucleation and growth of acicular ferrite, and the low-temperature toughness of weld metal under high heat input is improved. In high heat input welding, the burning loss of Ti is serious, and the addition amount of Ti should be increased, so the Ti content in the welding wire components is controlled to be 0.11-0.24%.

Al: strong affinity with oxygen, welding seamContaining a small amount of Al ₂ O ₃ The formed composite inclusion can be used as AF nucleation particles to effectively refine weld joint structures. Meanwhile, the oxygen affinity of Al is greater than that of Ti, so that when the content of Al is excessive, the formation and distribution of Ti oxides can be influenced, and large-size Al is formed on a welding line ₂ O ₃ Impact toughness is reduced, and therefore, in terms of weld toughness, the content of Al should be as low as possible. Therefore, the Al content in the welding wire is less than or equal to 0.05 percent.

Mg: is a strong deoxidizer, reduces the oxygen content of a welding line through deoxidation reaction, wherein composite inclusions Ti-Mg-O containing Mg can pin austenite grain boundaries, inhibit grain growth and refine grains, and improve toughness. In addition, the boiling points of Al and Mg are low, so that the process problems of unstable arc, splashing and the like are easily caused. Therefore, the content of Mg in the components of the welding wire is less than or equal to 0.005 percent.

Ce: the addition of Ce to the welding wire has three main functions: firstly, the component composition of the inclusion is improved, the inclusion which is low in mismatching with acicular ferrite and rich in Ce, S, O and Al elements is formed, and the inclusion becomes acicular ferrite core particles, so that the content of acicular ferrite is increased; secondly, the size of the inclusion is refined, oxides rich in Ce are combined with larger inclusions to form large inclusions in the oxide metallurgy process carried out in the molten pool reaction, the large inclusions float upwards and are discharged out of the molten pool, the size of the inclusions is further refined, the possibility that the inclusions with larger diameters become crack sources is reduced, and the toughness is improved. Other researches show that the probability of the inclusions in weld metal with the size of 0.6-1.8um becoming acicular ferrite core particles can reach 80%, thereby further refining weld structures and improving toughness. The Ce content of the invention is controlled to be less than or equal to 0.05 percent.

S and P: the content of the P element is reduced as much as possible, and the P element is particularly contained in the steel plate. Because the use of the flux increases the P element content of the weld metal during submerged arc welding. The content of S element is required to be not more than 0.005% and the content of P element is required to be not more than 0.012%.

In actual production, strengthening of metal materials is often achieved by trying to prevent movement of dislocations in defective metal crystals to improve strength, and specific strengthening and toughening modes are solid solution strengthening, dislocation strengthening, precipitation and dispersion strengthening, and grain boundary strengthening. In weld metal, the content of Mn, si, ni and Mo causing solid solution strengthening is high, and carbide or nitride formed by trace elements such as Ti, B and the like in the weld can play a certain role in precipitation strengthening on dislocation pinning. However, the increase of strength is more remarkable particularly in solid solution strengthening and fine grain strengthening, and the body strengthening is caused by the action of atom size effect, elastic modulus effect and solid solution ordering. Meanwhile, in the process of high heat input welding, the content of each alloy element in the weld metal is greatly changed, which is related to the oxidation burning loss of the alloy element in the welding heat process. According to the theory of welding metallurgy, the affinity of each element to oxygen at 1600 ℃ is in the order from small to large: cu, ni, co, fe, W, mo, cr, mn, V, si, ti, zr, al. Since the concentration of Fe is the greatest at the weld zone, some of the Fe must be oxidized; ni is an element located on the left of Fe, and has a small affinity with oxygen, so that the oxidation loss is small. Although Mo is located on the right side of Fe, the affinity of Mo with oxygen is close to that of Fe, and the concentration of Mo in molten drops and molten pool metal is low, so that the oxidation burning loss is less, and the transition coefficient is large; although the concentrations of Mn, si and Ti are not high, the affinity with oxygen is high, so that the oxidation burning loss is serious. In addition, ti is very active and reacts with nitrogen in the arc atmosphere to generate TiN and the like, which further reduces the alloy transition coefficient. Therefore, in the large heat input welding, not only the strengthening and toughening effects of alloy elements on weld metal are considered, but also the problem of element burning caused by the large heat input welding is considered. Therefore, combining the transition margin of each alloying element after burning loss by high heat input welding with the strength increase caused by the chemical composition, the contribution to the toughness of the weld metal can be represented by the following formula θ:

in the formula, K _i Is the product of the strengthening coefficient and the transition coefficient of the i element (MPa/wt%); c _i Is the weight percentage concentration of the i element dissolved in the ferrite.Theta =9.8 x (32 +143C +4.80Mn +11.90Cr +3.42Ni +6.64Mo + 0.96Ti), wherein the content of C, mn, cr, ni, mo and Ti is equal to or more than 563 and equal to or less than or equal to theta 619. The development of welding wires has been focused on the issue of matching the toughness of the welding test plate. Generally, a large amount of alloy elements or silicon and manganese elements are added into weld metal to improve the strength through solid solution strengthening, precipitation strengthening, fine grain strengthening, precipitation strengthening and other modes, but the toughness of the weld metal is reduced to a certain extent, and the weld metal is particularly remarkable particularly under the condition of high heat input. The strength and toughness of the weld tend to exhibit a negative correlation. Therefore, for the steel plate with the tensile strength higher than 500MPa, the welding wire puts forward the requirement of the strength range on deposited metal of a welding material, and if the tensile strength of the welding material is lower than the range, the tensile strength of a welding joint cannot be ensured, and the crack resistance of the welding seam metal cannot be exerted; if the range is exceeded, the alloy material can form ultra-strong matching with a welding test plate, waste of alloy elements, damage to toughness to a certain degree and the like.

It is generally accepted that the mechanical properties of a material, whether it be strength or toughness, are largely dependent on microstructure. The acicular ferrite in the low alloy steel weld joint structure is one kind of ferrite, and is considered as a structure capable of improving the low-temperature toughness of the material by broad material researchers due to the characteristics that the crystalline grains are fine and exist in a large-angle grain boundary. Under the condition of high heat input welding, the weld metal stays for a long time at high temperature, coarse grain boundary ferrite and coarse block ferrite are easily formed in austenite grain boundaries, and the low-temperature toughness of the weld is consumed. In order to ensure the low-temperature toughness of weld metal, the wire rod and the welding wire of the invention are matched with Fe powder-MgO-SiO ₂ -CaF ₂ -Al ₂ O ₃ The flux is matched with an alkaline sintered flux, and can be used for the efficient welding of Q345 to Q370qE steel plates under the welding heat input of 100 to 200kJ/cm. Si, mn, ce and Ti are added into the submerged arc welding wire to improve the welding metallurgical quality, obtain a small compound inclusion rich in Si, mn, ce, ti and O, improve the effective inclusion ratio, further improve the content of acicular ferrite to ensure the toughness, and adjust the component proportion of Si, mn, ti and Ce to ensure that the content of the impurity meets the relation that gamma is more than or equal to 0.51 and less than or equal to 0.81, wherein gamma is not less than (10 Ti +60 Ce)/(Si + 81)2 Mn). If it is less than this range, the inclusion ratio and the number of inclusions having a size of 0.6 μm to 1.8 μm are decreased, resulting in a significant decrease in the number of nucleation sites of acicular ferrite; if the size exceeds the range, a large amount of inclusions with the size of more than 1.8 mu m appear in the welding seam, the crack sensitivity is improved, and the crack initiation work is reduced.

The manufacturing technology of the welding wire is the same as that of the prior art. Smelting the alloy components of the welding wire, casting the alloy components into steel ingots, forging, rolling wire rods, drawing the steel ingots into welding wires with corresponding sizes, plating copper and polishing, wherein the thickness of the plated copper layer is 0.19 to 0.23um, and finally coiling and packaging the welding wires into finished products.

The beneficial effects of the invention are:

(1) The welding wire metal obtained by the welding wire under the heat input of 100 to 200kJ/cm has a microstructure under a use state, wherein a small amount of blocky ferrite at an austenite crystal boundary and fine acicular ferrite inside crystal grains are arranged, a tissue matrix is provided with dispersed submicron-grade composite oxide inclusions of Si, mn, ti, ce and the like, the percentage of the inclusions in the composite oxide inclusions is more than 80 percent within the range of 0.6 to 1.8um, and the composite oxide inclusions further comprise manganese sulfur compounds. The probability of the fine inclusions becoming nucleation particles of acicular ferrite is increased, so that the proportion of the acicular ferrite in the crystal under the condition of large heat input welding is more than 70 percent by area percentage. The acicular ferrite tissue is very fine, ferrite laths grow radially, large-angle grain boundaries are formed among the laths, the crack expansion resistance is high, and the low-temperature toughness of weld metal can be obviously improved;

(2) The welding wire can be suitable for large heat input multi-wire common molten pool submerged arc automatic welding, the deposition efficiency is more than 2-5 times of that of the conventional single wire submerged arc automatic welding, the welding parameter range is wide in adjustment, the welding process performance is stable under the heat input of 100-200kJ/cm, the fluidity of the molten pool is good, the deposited metal is attractive in forming, and the crack resistance is excellent;

(3) The welding wire has the following mechanical properties under the condition of 100 to 200kJ/cm heat input of deposited metal: yield strength Rp0.2/MPa:463 to 536MPa, tensile strength Rm/MPa:561 to 619MPa, and elongation A/%: 22 to 24 percent, impact absorption work at-40 ℃ Akv-40 ℃/J:90.4 to 155J;

(4) The welding wire alloy system is reasonable in regulation and control, the coil rod smelting, rolling and welding wire drawing processes are easy to realize, the quality is stable, and the welding wire alloy system is suitable for large-scale popularization and application.

The present invention will be described in detail with reference to the accompanying drawings.

Drawings

FIG. 1a shows a microstructure of a deposited metal of example 1;

FIG. 1b shows the microstructure of the deposited metal of example 7;

FIG. 2a shows a microstructure of a deposited metal of comparative example 1;

FIG. 2b shows the microstructure of a deposited metal of comparative example 7;

FIG. 3 is a SEM electron microscopic view of inclusions in a deposited metal of example 1;

FIG. 4 is an EDS spectrum analysis chart of inclusions in example 1;

FIG. 5a is a metallographic graph showing inclusions in a deposited metal in comparative example 1;

FIG. 5b is a metallographic image showing inclusions in a deposited metal of example 1.

Detailed Description

The invention provides a 500MPa multi-wire submerged arc welding wire rod capable of being welded at a high heat input of 100 to 200kJ/cm, which comprises the following chemical components in percentage by mass: c:0.03 to 0.12, si: less than or equal to 0.09, mn:2.30 to 2.55, P: less than or equal to 0.012, S: less than or equal to 0.005, ni:1.05 to 1.65, mo:0.20 to 0.38, ti:0.11 to 0.24, mg: less than or equal to 0.005, ce: less than or equal to 0.05, cr less than or equal to 0.05, al: less than or equal to 0.05, N: not more than 0.0065, and the balance of Fe and inevitable impurities.

C. The contents of Si, mn, cr, ni, mo, ti and Ce are in accordance with that gamma is more than or equal to 0.51 and less than or equal to 0.81, and theta is more than or equal to 561 and less than or equal to 618.

Wherein γ = (10 Ti +60 Ce)/(Si +2 Mn), θ =9.8 x (32 +143C +4.80Mn +11.90Cr +3.42Ni +6.64Mo + 0.96Ti).

The invention also provides a 500MPa multi-wire submerged arc welding wire capable of being welded at a large heat input of 100 to 200kJ/cm, which is manufactured by drawing the wire rod.

The present invention will be described in detail with reference to specific examples.

Submerged arc in this embodimentThe chemical component proportion of the welding solid wire is shown in tables 1, 3 and 5, and the raw materials of P, S and low gas and inclusion content are selected according to the accurately calculated component proportion of the welding wire, and the addition amount of the alloy is calculated. Match with alkalinity (B) _ⅡW Not less than 2.0) is suitable for multi-wire submerged arc welding, wherein the welding heat input of 100-150 kJ/cm is suitable for double-wire and three-wire submerged arc automatic welding, and the welding heat input of 150-200kJ/cm is suitable for four-wire submerged arc automatic welding.

The steel for the welding wire is smelted by adopting a 75kg vacuum induction furnace, and is cast into a steel ingot after the components are qualified after charging, melting and refining. After a steel ingot is forged into a square billet, the square billet is hot-rolled into a 6.5mm wire rod, the wire rod is subjected to one-step rough wire drawing and two-step fine wire drawing to be made into a 5.0mm submerged arc welding solid core welding wire rod, and the surface of the wire rod is smooth and flat. And further carrying out copper plating on the surface of the welding wire by adopting a chemical copper plating method, wherein the copper plating thickness is controlled to be 0.19-0.23um.

TABLE 1 chemical composition ratio (mass percent) of submerged arc welding wire for example 1~3 and comparative example 1~3 of the present invention (balance Fe)

。

The six welding wires (example 1, example 2, example 3, comparative example 1, comparative example 2 and comparative example 3) are adopted to carry out a metal single wire deposited metal test according to the welding process parameters of the following table 2, the welding heat input is 100kJ/cm, and the special Fe powder-MgO-SiO powder is selected for welding ₂ -CaF ₂ -Al ₂ O ₃ Is an alkaline sintered flux, and the layer temperature is controlled to be not more than 160 ℃.

TABLE 2 groove form of deposited metal test

。

TABLE 3 chemical composition ratio (in mass percent) of submerged arc welding wire for example 4~6 and comparative example 4~6 in accordance with the present invention (the balance being Fe)

。

The five welding wires (example 4, example 5, example 6, comparative example 4, comparative example 5, comparative example 6) were used to conduct a three-wire deposited metal test in the form of a bevel as shown in the following Table 2, with a welding heat input of 150kJ/cm and a special Fe powder-MgO-SiO powder for welding ₂ -CaF ₂ -Al ₂ O ₃ Is an alkaline sintered flux, and the layer temperature is controlled to be not more than 160 ℃.

TABLE 4 groove form of deposited metal test

。

TABLE 5 chemical composition ratio (mass percent) of submerged arc welding wire for example 7~9 and comparative example 7~9 of the present invention (balance Fe)

。

Four-wire deposited metal tests were carried out using the above five kinds of welding wires (example 7, example 8, example 9, comparative example 7, comparative example 8, comparative example 9) in the form of bevels shown in Table 6 below, with a welding heat input of 200kJ/cm and a special Fe powder-MgO-SiO powder for welding ₂ -CaF ₂ -Al ₂ O ₃ Is an alkaline sintered flux, and the layer temperature is controlled to be not more than 160 ℃.

Table 6 groove form of deposited metal test

。

And (3) performing appearance inspection after the test piece is welded, performing nondestructive testing on the deposited metal by adopting an ultrasonic flaw detection technology, sampling the welded deposited metal, and performing the test according to GB/T228 specification on the sample size and the test method. The impact sample is cut from the center of the deposited metal, the longitudinal axis of the impact sample is vertical to the length direction of the deposited metal, the notch surface is vertical to the surface of the deposited metal, and the notch axis is positioned in the center of the deposited metal. The specimen size was 10X 55mm and the impact test method was carried out according to the GB/T229 specification. The results of the weld metal tensile test and the impact test are shown in table 7, in which the average values are shown in parentheses.

TABLE 7 deposited metal mechanical properties of the example and comparative example welding wires

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The chemical components of the embodiments 1 to 10 meet the requirements of the invention, the specific chemical components are shown in tables 1, 3 and 5, when theta meets 561 ≤ theta and 619, the tensile strength of the deposited metal is 561-619Mpa, the invention strength requirement is met, when gamma meets 0.51 ≤ gamma ≤ 0.81, and the impact absorption energy Akv of the deposited metal at-40 ℃ is not less than 80J. While the chemical compositions of comparative examples 1 to 10 do not satisfy the invention requirements, the strength or the height of the deposited metal does not meet the standards, and the low-temperature impact toughness of the deposited metal cannot be ensured.

The samples of the gold phase were taken from the impact test specimens of the deposited metals, and it was found that the deposited metals of examples 1 to 10 were composed mainly of acicular ferrite, a small amount of grain boundary ferrite and granular bainite as shown in FIGS. 1a and 1b, and the content of acicular ferrite was statistically shown in Table 8, and the content of acicular ferrite was not less than 70%. In contrast, the deposited metal structures of comparative examples 1 to 10 were composed mainly of bulk ferrite, a small amount of acicular ferrite, and granular bainitic ferrite as shown in fig. 2a and 2b. The acicular ferrite has fine grains and exists in a large-angle grain boundary, so that the propagation of cracks can be hindered, and the impact toughness is improved. The weld metals of the examples and the comparative examples are subjected to EDSD observation, the statistical results are shown in figure 3, and the large-angle accounts for obvious improvement of the weld metals of the examples 1 and 7.

TABLE 8 statistics of acicular ferrite fraction for examples and comparative examples

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The reason why the proportion of acicular ferrite is increased is analyzed, and the metallographic sample of example 1 is observed by an SEM electron microscope and subjected to an EDS test, as shown in FIGS. 3 and 4. The analysis found that the deposited metallic inclusion of example 1 mainly contains a complex type inclusion mainly containing Ce, ti, mn and O elements and forms acicular ferrite core particles, and that the probability of the inclusion having a size of 0.6 to 1.8um forming the core particles increases, and the sizes of the inclusions of examples and comparative examples were counted as shown in fig. 5a and 5b, and the results are shown in table 9.

TABLE 9 statistics of effective inclusion ratios for deposited metals of examples and comparative examples

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The inspection results of the above embodiments show that the submerged arc welding solid core welding wire has the deposited metal mechanical property meeting the specification requirement within the range of 100 to 200kJ/cm of heat input, namely, the submerged arc welding solid core welding wire has good strength and plasticity and also has excellent low-temperature impact toughness, and the-40 ℃ impact absorption power Akv of the weld metal is 90.4 to 155J. The method can be applied to the production and efficient welding manufacture of large-scale welding structural parts in the industries of bridges, ships, buildings and the like.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention and not to limit it; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art will understand that: modifications to the specific embodiments of the invention or equivalent substitutions for parts of the technical features may be made; without departing from the spirit of the present invention, it is intended to cover all aspects of the invention as defined by the appended claims.

Claims (6)

1. A500 MPa multi-wire submerged arc welding wire rod capable of being welded at large heat input of 100 to 200kJ/cm is characterized by comprising the following chemical components in percentage by mass: c:0.03 to 0.12, si: less than or equal to 0.09, mn:2.30 to 2.55, P: less than or equal to 0.012, S: less than or equal to 0.005, ni:1.05 to 1.65, mo:0.20 to 0.38, ti:0.11 to 0.24, mg: less than or equal to 0.005, ce: less than or equal to 0.05, cr less than or equal to 0.05, al: less than or equal to 0.05, N: not more than 0.0065, and the balance of Fe and inevitable impurities;

C. the contents of Si, mn, cr, ni, mo, ti and Ce are more than or equal to 0.51 and less than or equal to 0.81, and more than or equal to 561 and less than or equal to 618, wherein,

γ=（10Ti +60Ce）/（Si+2Mn）；

θ=9.8×（32+143C+4.80Mn+11.90Cr+3.42Ni+6.64Mo+0.96Ti）。

2. a500 MPa multiple wire submerged arc welding wire capable of welding at a large heat input of 100 to 200kJ/cm, characterized by being produced by drawing the wire rod as claimed in claim 1.

3. The 500MPa multi-wire submerged arc welding wire capable of welding at large heat input of 100 to 200kJ/cm according to claim 2, characterized in that an alkaline sintered flux is adopted, under the condition of 100 to 200kJ/cm heat input welding, the size of inclusions in deposited metal of the welding wire is more than 80 percent within the range of 0.6 to 1.8um, and the content of acicular ferrite in a structure is not less than 70 percent.

4. The 500MPa multi-wire submerged arc welding wire capable of being welded at large heat input of 100-200kJ/cm according to claim 2, characterized in that an alkaline sintered flux is adopted and the welding is carried out at the heat input of 100-200 kJ/cm, and the impact energy of a deposited metal of the welding wire in a KV2 notch at the ambient temperature of-40 ℃ is more than or equal to 80J.

5. The 500MPa multi-wire submerged arc welding wire capable of welding at large heat input of 100 to 200kJ/cm according to claim 2, which is characterized in that an alkaline sintered flux is adopted and welding is carried out at the heat input of 100 to 200kJ/cm, the yield strength of a deposited metal of the welding wire is 463 to 536MPa, the tensile strength is 561 to 619MPa, and the elongation is 22 to 24%.

6. A500 MPa multi-wire submerged arc welding wire capable of welding at a large heat input of 100 to 200kJ/cm according to any one of claims 2 to 5, which is characterized in that a copper plating layer is arranged on the surface of the welding wire, and the thickness of the copper plating layer is 0.19 to 0.23um.

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