CN1102480C - Process for manufacturing welding wire - Google Patents
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- CN1102480C CN1102480C CN97102700A CN97102700A CN1102480C CN 1102480 C CN1102480 C CN 1102480C CN 97102700 A CN97102700 A CN 97102700A CN 97102700 A CN97102700 A CN 97102700A CN 1102480 C CN1102480 C CN 1102480C
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Abstract
The present invention relates to a process for manufacturing a non-crack flux-cored welding wire for welding high strength steel and a steel structure for bearing large restraining force, and the non-crack flux-cored welding wire has the diameter of 0.8 to 4mm and excellent crack resisting force and ground coating paint protection quality and comprises little diffusible hydrogen. The process for manufacturing a non-crack flux-cored welding wire by using a high temperature heating process to carry out hydrogen relief treatment comprises the following steps: a straight welding wire of the diameter of 8 to 15mm is heated to the temperature of 620 to 1100 DEG C through the direct electric heating process of first and second roller electrodes and a ring transformer arranged between the first and the second roller electrodes, and the first roller electrode is separated from the second roller electrode with 2 to 5 m; the electric heated welding wire is cooled to the temperature which is not higher than 500 DEG C by using a coefficient of heat transfer which is not higher than 250 kcal/m2 h DEG C; the diameter of the welding wire is stretched to the wishful diameter. Therefore, each 100 g of deposited metal comprises not more than 5 ml of the diffusible hydrogen in a welding member formed by the obtained welding wire.
Description
The invention relates to a process for manufacturing a flux-cored wire for low-hydrogen welding, which has high crack resistance and bottom coating protection quality and is suitable for welding high-strength steel and other high-quality steel and steel structures bearing restraining force.
The dehydrogenation treatment in the seamless flux-cored wire manufacturing process is generally carried out as follows: the tube flux cored wire drawn from 10 to 13mm in diameter to 2 to 4mm is heated to 600 to 800 ℃ in a bell-type furnace or a tunnel-type arch furnace. The heat dehydrogenation process is used for small diameter wires of 2 to 4mm for the following reasons: (1) there is no effective heat dehydrogenation treatment process for larger diameter welding wires; and (2) the small diameter wire is easily coiled or looped, which is required to shorten the total length of the bell-type furnace or tunnel-type arch furnace.
In addition, the hardness of the skin must be controlled to satisfy the filling ratio and other technical conditions of each flux-cored wire, thereby ensuring good wire feeding efficiency of 0.8 to 4mm diameter wire during automatic welding and preventing breakage of the wire during manufacturing. Thus, the diameter of the wire to be heated must be determined by taking into account the skin cold hardening that occurs when the wire is subjected to stretching after the softening annealing. In this way, one heating can serve two different purposes, namely dehydrogenation and softening of the skin. In addition, the conventional bell-type furnaces and tunnel-type arch furnaces are not completely satisfactory because the productivity of the bell-type furnace is low and the thermal efficiency of the tunnel-type arch furnace is low, the materials, structures and service lives of the tunnel-type arch furnaces are not allowed to be used at temperatures higher than 800 ℃ and they require a large installation space.
As automatic welding has become widespread, the use of bare wires, flux-cored wires has increased, and flux-cored wires with slit skins have become the mainstream. Such a wire has a tendency to be troublesome in that hydrogen-induced cracks are formed in the welding of high-strength steel or in a steel structure subjected to a large restraining force, since about 7ml of diffusible hydrogen is generated from 100g of deposited metal. When used to weld primed steel panels, hydrogen-rich welding wires have a tendency to form air gaps, craters, and other welding defects.
The reason why it is difficult to manufacture a low-hydrogen welding wire with a slit skin is as follows: (1) the filled flux contains binding moisture; (2) unless heated above 500 ℃, the water of crystallization cannot be removed from certain inorganics contained in the flux fill; (3) certain metal powders contained in the flux fill contain hydrogen that cannot be removed unless heated above 300 ℃; (4) when heated to high temperatures, oxygen entering through the skin gaps degrades the quality of the filled flux by accelerating oxidation; and (5) wetting through the skin gap makes it impossible to produce a low hydrogen flux-cored wire.
Thus, seamless flux cored wires have been developed to enable the manufacture of low hydrogen flux cored wires. This type of low-hydrogen flux-cored welding wire is manufactured by filling a steel pipe with flux. The filled steel tube is heated to a temperature between 600 and 800 ℃ for dehydrogenation. The water in the filled flux becomes atomichydrogen by the chemical reaction given below and diffuses through the skin.
In the formula, Me: flux and reducing agent or other metal components in the inner wall of the skin
H2O-water in the filled flux
To reduce water and other hydrogen sources (potential hydrogen), the wire must be heated to a higher temperature. On the other hand, in order to obtain good wire feeding performance, it is necessary to appropriately control the conditions of skin softening annealing. However, the conventional process with one heating cannot provide a welding wire with a flux satisfactorily dehydrogenated and a skin satisfactorily softened. Performing a strong dehydrogenation process causes excessive softening of the skin, which may impair the wire feeding during welding, depending on the wire specifications. Softening annealing a wire with proper skin hardness at lower temperatures results in insufficient dehydrogenation, increased amounts of diffusible hydrogen, and reduced weld metal crack resistance. Conventional heating processes are unable to meet the ever-increasing demands for lower hydrogen content welding wires and for higher wire feed speeds.
In order to solve the above problems, the inventors provide a new process for manufacturing a welding wire, which allows a strong dehydrogenation process and provides an optimal wire feeding speed by optimizing the heating for the two heating processes of dehydrogenation and skin softening, rather than the conventional one-time heating. The main features of the invention are as follows:
(1) a process for manufacturing a seamless flux cored welding wire dehydrogenated by high temperature heating, the process comprising the steps of: directly electrically heating a straight welding wire at a temperature between 620 and 1100 ℃, the straight welding wire being a metal tube filled with a flux and having a diameter of 8 to 15mm, by passing the welding wire through a first and a second pair of roller electrodes arranged 2 to 5m apart along a path of travel of the welding wire and through an opening in a ring-core transformer arranged between the two pairs of roller electrodes; by using250kcal/m2h℃(≈214.98W/(m2K), the same below) cools the heated wire to below 500 ℃; and drawing the cooled wire to a diameter of between 0.8 and 4 mm.
(2) A process for manufacturing a seamless flux cored welding wire dehydrogenated by high temperature heating, the process comprising the steps of: directly electrically heating a straight welding wire at a temperature between 620 and 1100 ℃, the straight welding wire being a metal tube filled with a flux and having a diameter of 8 to 15mm, by passing the welding wire through a first and a second pair of roller electrodes arranged 2 to 5m apart along a path of travel of the welding wire and through an opening in a ring-core transformer arranged between the two pairs of roller electrodes; heating the preheated wire to a temperature between 600 and 800 ℃ in a gas or electric furnace with 250kcal/m2The heat transfer coefficient below h ℃ cools the heated welding wire to below 500 ℃; and drawing the cooled wire to a diameter of between 0.8 and 4 mm.
(3) A process for manufacturing a seamless flux cored welding wire dehydrogenated by high temperature heating, the process comprising the steps of: directly electrically heating a straight welding wire at a temperature between 620 and 1100 ℃, the straight welding wire being a metal tube filled with a flux and having a diameter of 8 to 15mm, by passing the welding wire through a first and a second pair of roller electrodes arranged 2 to 5m apart along apath of travel of the welding wire and through an opening in a ring-core transformer arranged between the two pairs of roller electrodes; using 250kcal/m2Below h DEG CThe heat transfer coefficient of (a) cools the heated wire to below 500 ℃; drawing the cooled wire to a diameter of between 2 and 7 mm; heating the drawn wire in a gas or electric furnace to a temperature between 600 and 800 ℃; using 250kcal/m2The heat transfer coefficient below h ℃ cools the heated welding wire to below 500 ℃; and drawing the cooled wire to a diameter between 0.8 and 4 mm.
The above-described processes according to the present invention can manufacture a flux cored wire having a diameter of 0.8 to 4mm by simply drawing a wire having a diameter of 8 to 15 after flux dehydrogenation and skin softening processes. Directly and electrically heating a straight seamless flux-cored wire having a diameter of 8 to 15mm by a continuous water-flowing process without generating sparks and using 250kcal/m2heat transfer coefficient below h DEG CThe heated wire is cooled to below 500 ℃ to obtain a seamless flux-cored wire containing not more than 5ml of diffusible hydrogen per 100g of deposited metal. The dehydrogenated wire of 8 to 12mm diameter is then drawn into a seamless flux cored wire of 2 to 4mm diameter with the hardness of the skin controlled to a vickers hardness of 180 to 250 Hv. When the diameter of the raw welding wire is limited to about 8 to 12mm, a seamless flux-cored welding wire having a diameter of 0.8 to 1.6mm and a skin hardness controlled to 200 to 250Hv Vickers hardness can be obtained. Furthermore, the diameter of the raw welding wire to be heat treated and the hardness of the processed welding wire can be selected from a wide range according to the chemical composition of the steel strip used to manufacture the raw pipe.
Ultra-low hydrogen welding wire can be manufactured by subjecting a raw welding wire having a diameter between 8 and 15mm to dehydrogenation and skin softening heat treatment and drawing the wire diameter to between 2 and 7 mm. First, a raw wire having a diameter between 8 and 15mm is dehydrogenated by direct electrical heating. The wire drawn to a diameter of 2 to 7mm is then heated in a continuous gas or electric furnace for skin softening and dehydrogenation treatment. The obtained product is an ultra-low hydrogen flux-cored wire containing not more than 3ml of diffusible hydrogen per 100g of deposited metal and having a skin hardness controlled to 150 to 250Hv Vickers hardness.
The processes according to the present invention eliminate the need for pre-baking fill flux. Even if the flux contains a lot of water, no pre-baking or other strong drying treatment is required. An ultra-low hydrogen flux cored wire having diffusible hydrogen of not more than 3ml per 100g of deposited metal can be obtained without any such pre-bake strong drying treatment by subjecting a raw tube having a diameter of 8 to 15mm to dehydrogenation treatment and subjecting a tube drawn to a diameter of 2 to 7mm to additional dehydrogenation treatment.
The processes of the present invention also eliminate the conventionally encountered trouble of adjusting flux materials containing crystal water or hydrogen. The combination of a dehydrogenation treatment at a temperature of at most 1100 ℃ for a wire having a diameter of between 8 and 15mm and a subsequent dehydrogenation treatment for a wire drawn to a diameter of 2 to 7mm allows the production of an ultra-low hydrogen flux cored wire containing no more than 3ml of diffusible hydrogen per 100g of deposited metal without adjusting the crystal water or hydrogen contained in the filler flux.
Further, performing dehydrogenation heating and skin softening heating in separate processes may select an optimum condition for each heating. The provision of optimum heating for dehydrogenation and skin softening in the separation process may still ensure improved dehydrogenation and stable wire feed under conditions where severe bending of the hose occurs during welding.
Fig. 1 shows the principle of direct electrical heating of a welding wire passing through a toroidal transformer according to the present invention.
FIG. 2 is a graphical representation of the relationship between the zone of controlled skin hardness after softening annealing and the skin hardness of a wire of 8 to 15mm diameter.
Fig. 3 is a graph showing the relationship between the skin hardness control region after softening annealing and the skin hardness of the welding wire heated and stretched to a diameter of 2 to 7 mm.
Fig. 4 graphically represents the relationship between heating time and temperature in a combination of direct electrical heating and heating in a tunnel-arch furnace.
FIG. 5 is a graph showing the relationship between heating time and temperature when heating in a continuous tunnel-type arch furnace.
FIG. 6 graphically illustrates the relationship between the amount of diffusible hydrogen versus horizontal position and the incidence of hydrogen induced cracking in fillet welds.
FIG. 7 is a graph showing the relationship among the amount of diffusible hydrogen, the number of formed shrinkage cavities and the occurrence of air voids.
Fig. 8 is a graph showing the relationship among the heating time, the skin temperature of the flux-cored wire, and the flux temperature in example 1.
Fig. 9 graphically illustrates the relationship between the heating time, the skin temperature of the flux-cored wire, and the flux temperature in example 2.
Fig. 10 is a graph showing the relationship among the heating time, the skin temperature of the flux-cored wire, and the flux temperature in example 3.
Fig. 11 is another graph showing the relationship among the heating time, the skin temperature of the flux cored wire, and the flux temperature in example 3.
Fig. 12 graphically shows the relationship between the heating time and the amount of diffusible hydrogen in each example.
The following paragraphs describe the details of the present invention with reference to the drawings.
Fig. 1 shows the principle of direct electrical heating of a welding wire passing through a toroidal transformer according to the present invention. As shown in fig. 1, a pair of roller electrode devices 2 and 3 are arranged with a given distance therebetween, and a welding wire 1 is sandwiched between opposed roller electrodes 2a and 2b and 3a and 3b constituting the roller devices 2 and 3. The welding wire 1 is advanced while being kept in contact with the circumferential surfaces of the paired roller electrodes 2a and 2b and 3a and 3 b.
A toroidal transformer 4 is centrally disposed between the pair of roller electrode assemblies 2 and 3 such that the welding wire passes through the opening in the transformer. The transformer comprises, for example, a core consisting of hollow square electrical steel sheets with the desired properties of forming a magnetic circuit, which are laminated to the desired thickness, forming a square leak opening in the centre. The transformer 4 has a long-wire primary coil 5 wound on each of four sides arranged at 90 ° from the adjacent sides. Both ends of the primary coil 5 are connected to a power supply E. The roller electrodes 2 and 3 are electrically connected to each other by means of a conductive member 6. The connection end of the conductive member 6 is held in slidable contact with the roller electrode by a slider 7.
Since the conductive member 6The cross-sectional area and material can be selected as desired, so that the resistance R of the heated wire can be easily adjusted1Resistance R to conductive member2The ratio of (A) to (B) is maintained at R1＞＞R2. The current through the circuit rapidly and efficiently heats the wire to temperatures as high as 1100 ℃. At very low spark rates, the power efficiency is as high as 90 to 95%, compared to about 50% in high frequency induction heating. Since the secondary impedance can be kept lower than the primary impedance, the voltage fluctuation is small. The first and second roller electrode arrangements have substantially equal potentials as the supply voltage is dissipated to heat the wire between the first and second roller electrodes. Since the first and second roll electrode means can thus be grounded, no current can escape from between the first and second roll electrode means. Further, the arrangement of the roller electrode devices at intervals not exceeding 2 to 5m contributes to making the heating device compact.
Rapid direct electrical heating can be performed by a toroidal transformer to achieve optimal dehydrogenation and skin softening simultaneously or separately. In a separate process step, the dehydrogenation heating to between 620 and 1100 ℃ is carried out in a preceding stage in order to reduce the amount of diffusible hydrogen. The skin softening heating to between 600 and 800 c is performed in a post-stage to control the hardness of the skin (increase wire feed speed and prevent wire breakage). If the dehydrogenation in the previous stage is performed on a larger diameter wire that is moving slower, the subsequent drawing and surface treatment will be sufficient to obtain the desired product. Therefore, it is desirable to dehydrogenate larger diameter wires between diameters 8 and 15.
If the dehydrogenation process is performed in the previous stage on a larger diameter wire between 8 and 15mm which moves slower than the finer, a wire containing no more than 5ml of diffusible hydrogen can be obtained without any other process than the subsequent drawing. Manufacturing ultra-low hydrogen welding wires with a bound flux that contains more water than the unbound flux is ineffective because excess water must be removed by pre-baking or other strong drying treatment. In contrast, the dehydrogenation process of larger diameter wires between 8 and 15mm in diameter, followed by heating of the reduced diameter wire of 2 to 7mm in diameter, which heating is primarily intended to soften the skin but at the same time will also effect some additional dehydrogenation process in combination, an ultra-low hydrogen wire containing no more than 3ml of diffusible hydrogen can be produced with a binding flux that is only slightly dry.
Fig. 2 shows the relationship between the skin hardness of the wire having a diameter of 8 to 15mm and the skin hardness control region after softening annealing, and fig. 3 shows the relationship between the skin hardness of the wire drawn to a diameter of 2 to 7mm after heating and the skin hardness control region after softening heating. As shown in fig. 2 and 3, the stable wire feeding zone is different between the welding wire having a diameter of 8 to 15mm and the welding wire having a diameter of 2 to 7 mm. The wire feeder and the welding point are separated by several meters or dozens of meters and are connected by a hose. When the hose has to be bent to meet the conditions at the work site, such as welding a bend line in a confined space, the resulting large resistance between the inner wall of the hose and the passing welding wire impairsthe stability of the wire feed.
Since the resistance value varies depending on the bending condition of the hose and the diameter of the welding wire, it is necessary to prepare the welding wire having a suitable skin hardness to satisfy the work site conditions. As the filling ratio is increased, the skin hardness is decreased, as shown in fig. 3. Welding wire having a skin hardness exceeding 250Hv is prone to breakage and makes it difficult to wind the end around the reel. This is the bend-off limit. On the other hand, welding wire having a skin hardness of less than 150Hv is liable to warp between the wire feed roller and the hose or at the inlet end of the power supply tip and impairs the smoothness of wire feeding. This is the warpage limit. Thus, a stable wire feed zone is obtained when the skin hardness is maintained between the bend-break limit of 250Hv and the warp limit of 150 Hv.
Fig. 4 shows the relationship between heating time and temperature in the step of combining direct electric heating and heating in a tunnel-type arch furnace. It can be seen that direct electrical heating rapidly increased the skin temperature to 800 ℃. The temperature of the portion of the flux in contact with the inner surface of the skin then rises to 400 c and continues to rise along the flux temperature curve a. As heat is transferred through the flux, the temperature of the central portion of the flux rises along the flux temperature curve B with some time lag to reach substantially the same value as the skin temperature in about 5 minutes. Fig. 5 shows the relationship between heating time and temperature in the heating process using the continuous tunnel-type arch furnace. Unlike the situation shown in fig. 4, the skin temperature gradually rose to 800 ℃ in 2 to 3 minutes. The flux temperature also slowly rose to 800 c within about 8 minutes. As can be seen from the above, the direct electric heating can rapidly heat to a hightemperature, can perform continuous flowing water heating by directly connecting several processes, and can heat a welding wire having a large diameter or a thin skin with high thermal efficiency.
FIG. 6 shows the relationship between the amount of diffusible hydrogen and hydrogen induced cracking in horizontal and fillet welds. In other words, this graph shows the relationship between the amount of diffusible hydrogen contained in 100g of deposited metal and the tensile strength of the weld metal. When the content of diffusible hydrogen was 5ml, the tensile strength of the weld metal was sharply reduced to 60kgf/mm2(＝60×9.8×106Pa) is added. When the content exceeds 7ml, the tensile strength is lowered to 50kgf/mm2(＝50×9.8×106Pa) and the probability of hydrogen induced cracking increases. Therefore, it is preferable to keep the diffusible hydrogen content in 100g of the deposited metal to 5ml or less.
FIG. 7 shows the relationship between the amount of diffusible hydrogen, the number of craters formed and the incidence of air voids (i.e., primer protection quality). In fig. 7, the deposited metal is a metal obtained by horizontal fillet welding of a steel sheet covered with an inorganic zinc primer having a thickness of 20 μm, the amount of diffused hydrogen is a content in 100g of the deposited metal, and the number of craters and the incidence of air gaps are values in a weld bead having a length of 50 cm. As shown in fig. 7, the number of shrinkage cavities and the incidence of air voids tended to increase sharply when the diffusible hydrogen content exceeded 10 ml. In order to maintain good primer barrier qualities, the diffusible hydrogen content must be kept below 10 ml. In view of the hydrogen induced cracking resistance shown in FIG. 6 and the quality of primer protection shown in FIG. 7, the diffusible hydrogen content must be kept at least below 7ml, preferably below 5 ml. The optimal flux fill ratio for the seamless flux cored welding wire according to the present invention is 10 to 26%.
Examples of the invention
Example 1
A21 mm diameter green wire for use in JIS Z #3313 YEW-C50DR standard seamless flux cored wire, having a cavity filled with a flux to 15% by weight, is subjected to stretching to reduce to 10mm, and the cavity is filled with a flux to 1Above 00% (in bulk density) for the dehydrogenation treatment the 10mm diameter wire was directly electrically heated to 1080 ℃ at a speed of 72 ℃/S by passing the wire through a ring core transformer arranged between a first and a second roll electrode arrangement at a distance of 5m at a speed of 20m/min (≈ 0.333 m/S). Fig. 8 shows the relationship between the skin temperature and the flux temperature. More specifically, fig. 8 shows the relationship between the heating time and the flux-cored wire skin temperature and flux temperature. Immediately after electrical heating, the skin temperature rapidly increased to 1080 ℃ and the temperature of the portion of the solder in contact with the inner surface of the skin rapidly increased to 300 ℃ and continued along the solder temperature curve AAnd (5) rising. As heat is transferred through the flux, the temperature of the central portion of the flux rises along the flux temperature curve B with some time lag to reach about 950 ℃ within 1 minute, as shown in FIG. 8. The heated wire is at 50kcal/m2h(≈42.996W/(m2K), the same below) deg.C, is air cooled for 4 minutes and then water cooled below 500 deg.C at a rapid controlled cooling rate of 2.4 deg.C/S. The wire was then subjected to drawing and surface treatment procedures to obtain a finished wire of 2.4mm diameter. The 2.4mm diameter wire thus obtained was used for welding at 42V, a welding speed of 35cm/min (. apprxeq.0.058 m/s, the same applies hereinafter), a wire extension of 30mmand a wire extension of 30L/min (. apprxeq.0.5X 10)-3m3/s, same below) was welded at 550V with a bleed rate of carbon dioxide. The content of diffusible hydrogen per 100g of deposited metal obtained by gas chromatography was 4.2 ml.
Example 2
A flux-cored wire for use in a seamless flux-cored wire standardized by JIS Z3313 YEW-C50DR, in which the inner cavity is filled with a flux to 18% (by weight) of a raw wire having a diameter of 21.5mm, is subjected to drawing and surface treatment processes to reduce the diameter to 10.5mm, and the inner cavity is filled with the flux to 100% or more (by bulk density). For the dehydrogenation treatment, the 10.5mm diameter wire was directly electrically heated to 800 ℃ at a rate of 53 ℃/S by passing the wire at a speed of 20m/min through a ring core transformer disposed between first and second roller electrode assemblies spaced 5m apart. Fig. 9 shows the relationship between the skin temperature and the flux temperature. More specifically, FIG. 9 shows the heating time versus flux cored wire skin temperature and flux temperatureAnd (4) relationship. Immediately after electrical heating, the skin temperature rapidly increased to 800 ℃ and the temperature of the portion of the solder in contact with the inner surface of the skin rapidly increased to 200 ℃ and continued to increase along the solder temperature profile a. As heat is transferred through the flux, the temperature of the central portion of the flux rises along the flux temperature curve B with some time lag to reach about 800 ℃ within 1 minute, as shown in FIG. 9. The heated wire was reheated at 800 ℃ for 2 minutes in a direct-connected gas or continuous furnace at 50kcal/m2The heat transfer coefficient at h ℃ is air cooled for 2 minutes and then water cooled below 500 ℃ by rapid controlled cooling at a rate of 2.5 ℃/S. The wire was then subjected to drawing and surface treatment procedures to obtain a finished wire of 2.0mm diameter. The thus obtained 2.0mm diameter wire was used for a welding speed of 35cm/min at 38V, a wire elongation of 25mm and a wire length of 25L/min (4.167 × 10 ═ g)-4m3/s, same below) was performed at a carbon dioxide bleed rate of 500A. The content of diffusible hydrogen per 100g of deposited metal obtained by gas chromatography was 4.5 ml.
Example 3
A21 mm diameter green wire for JIS Z #3313 YEW-C50DR standard seamless flux cored wire V, having a cavity filled with a flux to 12% by weight, is subjected to stretching to reduce to 10mm, so that the cavity is filled with the flux to more than 100% (in terms of bulk density). For the dehydrogenation treatment, the 10mm diameter wire was directly electrically heated to 880 ℃ at a rate of 350 ℃/S by passing the wire through a ring core transformer arranged between first and second roller electrode assemblies spaced 2.5m apart at a speed of 60m/min (═ 1m/S, the same applies hereinafter). Fig. 10 shows the relationship between the skin temperature and the flux temperature. More specifically, fig. 10 shows the relationship between the heating time and the flux-cored wire skin temperature and flux temperature. Immediately after electrical heating, the skin temperature rapidly increased to 880 ℃ and the temperature of the portion of the solder in contact with the inner surface of the skin rapidly increased to 200 ℃ and continued to increase along the solder temperature profile a. As heat is transferred through the flux, the temperature of the central portion of the flux rises along the flux temperature curve B with some time lag to reach about 800 ℃ within 1 minute, as shown in FIG. 10. Is heated byIs 20kcal/m2h℃(≈17.16W/(m2K), the same below) was air cooled for 4 minutes and then rapidly controlled cooling water at a rate of 1.6 ℃/S at below 500 ℃. The wire was then drawnto a 3.2mm diameter wire, which was heated to 800 ℃ for 5 minutes in a tunnel arch furnace for skin softening and dehydrogenation. Fig. 11 shows the obtained relationship between the skin temperature and the flux temperature. More specifically, fig. 11 shows the relationship between the heating time and the flux core wire skin temperature and flux temperature. As shown in fig. 11, the skin temperature rose to 800 ℃ in 3 minutes. The flux temperature also rose to about 800 c in 6 minutes. The heated welding wire is at 80kcal/m2h℃(≈68.64W/(m2K), the same below) was air cooled again for 3 minutes and then cooled with rapidly controlled cooling water at a rate of 2.2 ℃/S below 400 ℃. The wire was then subjected to drawing and surface treatment to obtain a finished wire of 1.2mm diameter. The thus obtained 1.2mm diameter wire was used for welding with 270A at a welding speed of 35cm/min, a wire extension of 20mm and a carbon dioxide bleed of 25L/min at 30V. The content of diffusible hydrogen per 100g of deposited metal obtained by gas chromatography was 2.1 ml.
Fig. 12 shows the relationship between the heating time and the amount of diffusible hydrogen in each example. The amount of diffusible hydrogen in 100g of deposited metal was 4.2ml in example 1, 4.5ml in example 2, 5.0ml in example 3 in the wire directly electrically heated to 880 ℃ and water cooled at 500 ℃ after air cooling, and 2.1ml in the wire which was continuously heated and cooled in the tunnel crown furnace. It is evident that all of the wires produced by the process of the present invention contain much lower diffusible hydrogen than conventional wires, which are produced for comparison without heating. Thus, the processes according to the present invention can efficiently manufacture a low-hydrogen flux-cored welding wire having excellent crack resistance and primer protection quality by reducing the content of diffusible hydrogen, which is suitable for welding of high-strength steel and structural steel.
Claims (3)
1. A process for manufacturing a seamless flux-cored welding wire by dehydrogenating a welding wire prepared by filling a flux into a metal by high-temperature heating, comprising the steps of:
directly electrically heating a straight wire having a diameter of 8 to 15mm, the straight wire comprising a metal tube filled with a flux, to a temperature between 620 and 1100 ℃, by passing the wire through first and second pairs of roller electrodes arranged 2 to 5m apart along the wire running path and through a toroidal transformer arranged therebetween;
using not more than 250kcal/m2h℃(≈214.98W/(m2K), the same below) cools the heated wire to a temperature not higher than 500 ℃; and
the cooled wire is drawn to a diameter between 0.8 and 4 mm.
2. A process for manufacturing a seamless flux-cored wire by dehydrogenating a wire prepared by filling a flux into a metal tube by heating at a high temperature, comprising the steps of:
directly electrically heating a straight wire having a diameter of 8 to 15mm, the straight wire comprising a metal tube filled with a flux, to a temperature between 620 and 1100 ℃, by passing the wire through first and second pairs of roller electrodes arranged 2 to 5m apart along the wire running path and through a toroidal transformer arranged therebetween;
heating the wire in a gas or electric furnace at a temperature between 600 and 800 ℃;
using not more than 250kcal/m2The heat transfer coefficient of h ℃ cools the heated welding wire to the temperature of not higher than 500℃; and
the cooled wire is drawn to a diameter between 0.8 and 4 mm.
3. A process for manufacturing a seamless flux-cored wire by dehydrogenating a wire prepared by filling a flux into a metal tube by heating at a high temperature, comprising the steps of:
directly electrically heating a straight wire having a diameter of 8 to 15mm, the straight wire comprising a metal tube filled with a flux, to a temperature between 620 and 1100 ℃, by passing the wire through first and second pairs of roller electrodes arranged 2 to 5m apart along the wire running path and through a toroidal transformer arranged therebetween;
using not more than 250kcal/m2The heat transfer coefficient of h ℃ cools the heated welding wire to the temperature of not higher than 500 ℃;
drawing the cooled wire to a diameter of between 2 and 7 mm;
heating the drawn wire to a temperature between 600 and 800 ℃;
using not more than 250kcal/m2The heat transfer coefficient of h ℃ cools the heated welding wire to the temperature of not higher than 500 ℃; and
the cooled wire is drawn to a diameter of between 0.8 and 4 mm.
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| CN97102700A CN1102480C (en) | 1997-02-27 | 1997-02-27 | Process for manufacturing welding wire |
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| CN97102700A CN1102480C (en) | 1997-02-27 | 1997-02-27 | Process for manufacturing welding wire |
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| CN1102480C true CN1102480C (en) | 2003-03-05 |
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| CN104263897A (en) * | 2014-09-24 | 2015-01-07 | 河南科技大学 | Drawing and annealing system for flux cored wire production process |
| WO2016111703A1 (en) | 2015-01-09 | 2016-07-14 | Illinois Tool Works Inc. | Inline resistive heating system and method for thermal treatment of continuous conductive products |
| US11524354B2 (en) | 2017-06-09 | 2022-12-13 | Illinois Tool Works Inc. | Systems, methods, and apparatus to control weld current in a preheating system |
| CN110997218A (en) * | 2017-06-09 | 2020-04-10 | 伊利诺斯工具制品有限公司 | Coaxial laser heating filament head |
| US11344964B2 (en) | 2017-06-09 | 2022-05-31 | Illinois Tool Works Inc. | Systems, methods, and apparatus to control welding electrode preheating |
| EP3898055A2 (en) | 2018-12-19 | 2021-10-27 | Illinois Tool Works, Inc. | Contact tip, wire preheating assembly, contact tip assembly and consumable electrode-fed welding type system |
| CN110863085B (en) * | 2019-11-14 | 2022-01-04 | 中国京冶工程技术有限公司 | Stress on-line control method suitable for flux-cored wire for steel structure |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58110195A (en) * | 1981-12-22 | 1983-06-30 | Kobe Steel Ltd | Production of flux cored wire electrode for stainless steel |
| JPS5961597A (en) * | 1982-09-30 | 1984-04-07 | Nippon Steel Weld Prod & Eng Co Ltd | Production of flux cored wire for welding |
| JPS59130698A (en) * | 1983-01-14 | 1984-07-27 | Nippon Steel Corp | Production of stainless steel flux cored wire |
| JPH0481297A (en) * | 1990-07-24 | 1992-03-13 | Kawasaki Steel Corp | Production of flux cored wire for welding |
| EP0489167A1 (en) * | 1990-06-21 | 1992-06-10 | NIPPON STEEL WELDING PRODUCTS & ENGINEERING CO., Ltd. | Method of manufacturing tube filled with powder and granular material |
-
1997
- 1997-02-27 CN CN97102700A patent/CN1102480C/en not_active Expired - Fee Related
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58110195A (en) * | 1981-12-22 | 1983-06-30 | Kobe Steel Ltd | Production of flux cored wire electrode for stainless steel |
| JPS5961597A (en) * | 1982-09-30 | 1984-04-07 | Nippon Steel Weld Prod & Eng Co Ltd | Production of flux cored wire for welding |
| JPS59130698A (en) * | 1983-01-14 | 1984-07-27 | Nippon Steel Corp | Production of stainless steel flux cored wire |
| EP0489167A1 (en) * | 1990-06-21 | 1992-06-10 | NIPPON STEEL WELDING PRODUCTS & ENGINEERING CO., Ltd. | Method of manufacturing tube filled with powder and granular material |
| JPH0481297A (en) * | 1990-07-24 | 1992-03-13 | Kawasaki Steel Corp | Production of flux cored wire for welding |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111315521A (en) * | 2017-06-09 | 2020-06-19 | 伊利诺斯工具制品有限公司 | Method and system for heating welding wire to reduce hydrogen content |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1191790A (en) | 1998-09-02 |
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