TWI851193B - Welding wire and manufacturing method the same - Google Patents

Abstract

The invention provides a welding wire and a manufacturing method thereof. The manufacturing method includes the following steps: providing a steel billet, wherein the composition of the steel billet is: the carbon content ranging from 0.02 to 0.10 wt.%, the manganese content ranging from 2.00 to 3.00 wt.%, the silicon content ranging from 0.01 to 0.25 wt.%, the chromium content ranging from 0.10 to 0.5 wt.%, the titanium content ranging from 0.10 to 0.3 wt.%, and residual balanced iron and inevitable impurity elements, based on 100wt.% of the total weight of the steel billet, the composition of the steel billet conforms to the judgment formula: (manganese content/2 + titanium content + chromium content / 1.33) / silicon content is greater than 5; performing a heating procedure for the steel billet; performing a hot rolling procedure to the heated steel billet to form a hot rolled steel; performing a slow cooling procedure for the hot rolled steel; and performing a cold drawing procedure for the cooled steel to make a welding wire.

Description

Welding wire and manufacturing method thereof

The present invention relates to a welding wire and a method for manufacturing the same, and in particular to a welding wire composition with excellent electroplating properties and a method for manufacturing the same.

Gas shield welding is a welding method that uses an inert gas to protect the arc. Compared with other welding methods, gas shield welding has a faster welding speed and is convenient for use in automated processes, so it is the most common welding process in industry.

However, the choice of inert gas will affect the arc pattern and change the shape of the molten droplet during welding.

If 100% carbon dioxide is used as the shielding gas, the carbon dioxide will decompose the gas molecules in the ultra-high temperature environment of the arc. When carbon dioxide decomposes, it will absorb heat energy and have the effect of cooling the arc, so that the arc is only concentrated on a small area of the welding wire, and the droplets will form a globular transfer, which also makes the welding channel molten area narrower.

If 100% argon is used as the protective gas, because argon is a monatomic inert gas that does not participate in the reaction, the arc will be long, unstable, and easy to move and swing. Therefore, the industry often uses a small amount of carbon dioxide mixed with argon to combine the advantages of both to achieve good weld quality.

However, carbon dioxide will decompose under the action of the arc, and the freed oxygen will also be mixed into the weld. Silicon, a common alloying element in steel, easily reacts with oxygen. Therefore, during the welding process, silicon will react with oxygen before iron and carbon to form silicon oxide, which is welding slag. If welding slag is generated during welding, removing oxygen can prevent the large-scale oxidation of iron and carbon in the weld.

Welding slag will adhere to the surface of the weld, which will affect the appearance of the weld. In addition, the welding slag based on silicon is acid-resistant and alkali-resistant and non-conductive. When the welded workpiece undergoes subsequent processes (such as pickling), the area with welding slag adhesion will be difficult to wash off. When electroplating is performed later, the area containing silicon oxide on the surface will form unplated spots.

In addition, due to the large difference in thermal expansion coefficient and lattice between silicon oxide and steel, residual stress gradually accumulates between silicon oxide and steel after the workpiece is used for a period of time, resulting in reduced adhesion of silicon oxide and further detachment, exposing the steel surface. Corrosion usually occurs where silicon oxide detaches. Therefore, once there is residual slag on the surface of the welded workpiece, the corrosion resistance will deteriorate.

0.3，(Si+Mn/5)/(Ti+Al)

3之條件式。但是，若合金中錳含量為2%以上，則矽含量需控制為0.15%以下，同樣於鋼鐵冶煉製程中不易控制。 In order to reduce the generation of slag, the existing technology adopts a similar approach, which is to reduce the silicon content. For example, the silicon content is reduced to below 0.15%. By reducing the silicon content, the generation of silicon-containing slag can be reduced. However, silicon is a common deoxidizer in molten iron and a slag-forming element, so it is difficult to control the silicon content to below 0.15%. In addition, the existing technology also controls the alloy composition of the welding wire to meet Si×Mn

0.3, (Si+Mn/5)/(Ti+Al)

3. However, if the manganese content in the alloy is above 2%, the silicon content must be controlled below 0.15%, which is also difficult to control in the steel smelting process.

In order to increase the composition range of silicon and avoid the generation of welding slag, the composition of the welding wire needs to be designed. In addition, the welding wire needs to go through multiple drawing processes, so the hot rolling structure also needs to be controlled.

Therefore, it is necessary to provide a welding wire with excellent electroplating properties and a manufacturing method thereof to solve the problems existing in the conventional technology.

One of the purposes of the present invention is to provide a welding wire composition with excellent electroplating properties and a manufacturing method thereof. By designing the alloy, the silicon content in the welding wire composition can be increased, making steel smelting easier.

Another purpose of the present invention is to provide a welding wire composition with excellent electroplating properties and a manufacturing method thereof, by designing the composition of alloying elements such as manganese, chromium, and titanium, and then modifying the welding slag, so that there is no obvious silicon-containing welding slag on the surface of the welding path, so that the subsequent electroplating will not produce unplated points and thus affect the product quality.

To achieve the above-mentioned object, the present invention provides a method for manufacturing a welding wire, comprising the following steps: providing a steel billet, wherein the steel billet comprises: based on the total weight of the steel billet being 100wt.%, a carbon content of 0.02 to 0.10wt.%, a manganese content of 2.00 to 3.00wt.%, a silicon content of 0.01 to 0.25wt.%, a chromium content of 0.10 to 0.5wt.%, and a titanium content of 0.10 to 0.3wt.%, and inevitable impurities, the rest being iron, wherein the composition of the steel billet meets the judgment formula of (manganese content/2+titanium content+chromium content/1.33)/silicon content greater than 5; the steel billet is subjected to a heating process; the heated steel billet is subjected to a hot rolling process to form a wire rod; the hot rolled wire rod is subjected to a slow cooling process; and the wire rod subjected to the slow cooling process is subjected to a cold drawing process to produce a welding wire.

In some embodiments of the present invention, the ratio of silicon content to manganese content of the steel blank is between 0.02 and 0.1.

In some embodiments of the present invention, the heating process is to heat and control the steel embryo to a temperature between 1000 and 1050°C.

In some embodiments of the present invention, the rolling temperature of the hot rolling process is 820 to 1000°C, and the finishing temperature is controlled to be between 800 and 850°C.

In some embodiments of the present invention, the cooling rate of the slow cooling process is between 0.1 and 5°C per second.

In some embodiments of the present invention, the proportion of ferrite in the welding wire is less than 5%.

In addition, the present invention also provides a welding wire, comprising: the welding wire composition is: based on the total weight of the welding wire as 100wt.%, the carbon content is between 0.02 and 0.10wt.%, the manganese content is between 2.00 and 3.00wt.%, the silicon content is between 0.01 and 0.25wt.%, the chromium content is between 0.10 and 0.5wt.%, the titanium content is between 0.10 and 0.3wt.%, and inevitable impurities, and the rest is iron, wherein the welding wire composition meets the judgment formula of (manganese content/2+titanium content+chromium content/1.33)/silicon content greater than 5.

In some embodiments of the present invention, the ratio of silicon content to manganese content of the welding wire is between 0.02 and 0.1.

In some embodiments of the present invention, the proportion of ferrite in the welding wire is less than 5%.

In some embodiments of the present invention, the welding wire contains nano-scale titanium carbide precipitates.

S100: Welding wire manufacturing method

S101~S105: Steps

[Figure 1]: Schematic flow chart of the method for manufacturing the welding wire of an embodiment of the present invention.

[Figure 2]: Oxide free energy diagram (Ellingham diagram) of an embodiment of the present invention.

[Figure 3]: Electron microscope schematic diagram of the hot-rolled structure of an embodiment of the present invention.

[Figure 4]: Schematic diagram of the surface of the weld after welding in an embodiment of the present invention using an electron microscope.

[Figure 5]: Electron microscope schematic diagram of the surface of the weld after welding in the embodiment of the present invention.

[Figure 6]: Schematic diagram of the internal structure and distribution of intermediaries in the embodiment of the present invention.

In order to make the above and other purposes, features and advantages of the present invention more clearly understandable, the following will specifically cite the preferred embodiments of the present invention and provide a detailed description in conjunction with the attached drawings. Furthermore, the directional terms mentioned in the present invention, such as top, bottom, top, bottom, front, back, left, right, inside, outside, side, periphery, center, horizontal, transverse, vertical, longitudinal, axial, radial, topmost or bottommost, etc., are only referenced to the directions of the attached drawings. Therefore, the directional terms used are used to explain and understand the present invention, not to limit the present invention.

0且

2的其他任何實值。 As used herein, reference to a numerical range for a variable is intended to mean that the variable is equal to any value within the range. Thus, for a variable that is itself discontinuous, the variable is equal to any integer value within the numerical range, including the endpoints of the range. Similarly, for a variable that is itself continuous, the variable is equal to any real value within the numerical range, including the endpoints of the range. By way of example, and not limitation, a variable described as having a value between 0-2 takes on a value of 0, 1, or 2 if the variable is itself discontinuous, and takes on a value of 0.0, 0.1, 0.01, 0.001, or 2 if the variable is itself continuous.

0 and

Any other real value of 2.

In order to make it easier to understand the design principle of the present invention, the following is an explanation of the effects of the various components of the welding wire of the present invention on welding:

Carbon (C): Carbon can affect the strength after welding. Generally speaking, the higher the carbon content, the higher the hardness after welding. If the carbon content is less than 0.02%, the hardness after welding may be insufficient; if the carbon content is too high, the hardness is high due to the high ratio of hard and brittle structures after welding, but there may be problems with poor toughness. Although the toughness after welding can be improved by heat treatment after welding, heat treatment will increase the cost, extend the workpiece processing time, and increase the production cost. Therefore, the present invention sets the upper limit of the carbon content of the welding wire to about 0.15%.

Silicon (Si): Silicon is a common deoxidizer. During the welding process, silicon will react with oxygen before iron to form silicon oxide. Therefore, the existing technology reduces the silicon content to avoid the formation of silicon-containing slag and improve corrosion resistance. On the other hand, after adding silicon, the hardness of the weld can be improved by solid solution strengthening. As described below, by designing the composition of manganese, chromium, and titanium, the alloy smelting margin can be improved after the slag is modified. Therefore, the silicon content of the present invention is designed to be between 0.01 and 0.25wt.%.

Manganese (Mn): During welding, manganese can capture sulfur to form manganese sulfide (MnS) and prevent the formation of iron sulfide (FeS); due to the low melting point of iron sulfide, coupled with the large temperature changes during welding, thermal stress is caused by shrinkage and expansion. Once there is a low-melting-point liquefied phase such as iron sulfide in the structure, thermal cracking will occur during welding. Manganese can delay the transformation of manganese phase, so the weld structure can be adjusted to improve the strength after welding. In addition, manganese also has a deoxidation effect. In addition, referring to the Ellingham diagram in Figure 2, it can be found that the deoxidation ability of manganese is only slightly inferior to that of silicon. If manganese oxide is generated, since the conductivity of manganese oxide falls within the scope of conductors, manganese oxide will not affect the subsequent electroplating process and will not form unplated spots. However, when the manganese content is too high, the structure after welding will produce stray iron, making the weld hardness too high, the toughness decreased, and cold cracking is prone to occur. Therefore, the manganese content of the present invention is designed to be between 2.00 and 3.00wt.%.

Chromium (Cr): Chromium can delay the transformation of the ferrous iron phase, so it can adjust the weld structure and improve the strength after welding. Chromium also has a deoxidation effect. However, the conductivity of chromium oxide is slightly poor, so it is only used as an auxiliary. Therefore, the chromium content of the present invention is designed to be between 0.10 and 0.5wt.%.

Titanium (Ti): Titanium has a strong deoxidation effect. In addition, in the weld channel, the oxides generated by titanium can promote the formation of needle-shaped ferrite groups, thus helping to improve the mechanical strength and toughness of the weld channel. However, if the titanium content is too high, titanium will combine with carbon after hot rolling to form nano-scale titanium carbide (TiC) precipitates, which greatly improves the strength of the steel. Since the welding wire needs to go through a large deformation wire drawing process when making it, high-strength welding wire will make cold drawing difficult, cause mold damage, and even wire drawing cracks. Therefore, the titanium addition amount designed in the present invention is between 0.10 and 0.3wt.%.

According to the above design principle, the present invention proposes a method for manufacturing a welding wire, comprising the following steps: providing a steel billet, wherein the steel billet composition is: based on the total weight of the steel billet being 100wt.%, the carbon content is between 0.02 and 0.10wt.%, the manganese content is between 2.00 and 3.00wt.%, the silicon content is between 0.01 and 0.25wt.%, the chromium content is between 0.10 and 0.5wt.%, and the titanium content is between 0.1 0 to 0.3wt.%, and inevitable impurities, the rest is iron, wherein the composition of the steel billet meets the judgment formula of (manganese content/2+titanium content+chromium content/1.33)/silicon content greater than 5; the steel billet is subjected to a heating process; the heated steel billet is subjected to a hot rolling process to form a wire rod; the hot rolled wire rod is subjected to a slow cooling process; and the wire rod subjected to the slow cooling process is subjected to a cold drawing process to produce a welding wire.

By designing the composition of manganese, chromium and titanium, the welding slag can be modified. Therefore, a uniform iron oxide film can be formed on the surface of the weld after welding, avoiding the formation of silicon-based welding slag on the surface, thereby improving the electroplating performance. The modified composition increases the silicon margin in the welding wire composition, making it easier to smelt steel.

The welding wire manufacturing of an embodiment of the present invention is carried out in two steps: (1) hot rolling the steel billet into a wire coil; and (2) cold drawing the wire into the welding wire. During the hot rolling, the steel billet (e.g., a small steel billet) needs to be reheated through a heating process, and the reheating temperature is between 1000 and 1050°C (e.g., about 1030°C). If the reheating temperature is too high, titanium carbide will undergo solid solution. Titanium combines with carbon after hot rolling to produce nano-scale titanium carbide precipitates, which will greatly increase the strength of the steel, and make the cold drawing process difficult and increase mold wear. If the reheating temperature is too low, the hot rollers will be damaged too much and the roller load will increase, resulting in uneven rolling.

During the hot rolling process, the rolling temperature used is between 820 and 1000°C, and the final rolling temperature is set between 800 and 850°C (for example, about 820°C). If the final rolling temperature is too high, the grains of the hot rolled structure will be coarse, which is not conducive to the subsequent wire drawing. In addition, because the composition contains 2 to 3% manganese, the coarse hot rolled structure will also lead to the formation of island-like scattered iron, which will easily cause wire breakage after wire drawing. If the final rolling temperature is too low, it is easy to increase the rolling machine load, resulting in uneven rolling. The slow cooling process after hot rolling is to spread the hot rolled wires on the Stelmor cooling conveyor for slow cooling. The cooling rate is designed to be about 0.1 to 5°C per second. If the cooling rate is too high, the wires will form tough iron and loose iron, which is not conducive to subsequent wire drawing. If the cooling rate is too low, the production yield is too low, resulting in increased production costs. The wires produced by hot rolling can be made into welding wires after multiple cold drawing processes.

Implementation example:

The oxidation reaction during welding produces the following reaction: Si+O ₂ →SiO ₂

4/3Cr+O ₂ →2/3Cr ₂ O ₃

Ti+O ₂ →TiO ₂

2Mn+O ₂ →2MnO

Therefore, the present invention designs an index α, which is used to represent the ratio of oxygen captured by manganese, chromium, and titanium relative to that captured by silicon, where α=(Mn/2+Ti+Cr/1.33)/Si. It is expected that the larger the α value, the higher the ratio of oxygen captured by manganese, chromium, and titanium. The composition of the smelting embodiment of the present invention is shown in Table 1. The present invention controls the α value to be greater than 5, and the performance of the weld after welding is excellent. The detailed results are shown in the following examples.

As shown in Figure 3, it shows the hot-rolled structure of the embodiment of the present invention after hot rolling, which contains more than 95% volume fraction of granular iron and less than 5% of the Ma Tian scattered iron structure.

Therefore, optionally, the proportion of the iron ore in the welding wire is designed to be less than 5%.

FIG4 shows an electron microscope schematic diagram of the weld surface after welding in the embodiment of the present invention. As shown in FIG4, it can be visually observed that there is no welding slag on the surface.

FIG5 shows an electron microscope schematic diagram of the surface of the weld after welding of the embodiment of the present invention. Example 1 with the lowest α value was selected to analyze the weld surface. As shown in FIG5, no silicon-rich oxide was found. FIG6 shows a schematic diagram of the structure inside the weld of the embodiment of the present invention and the distribution of intermediates. As shown in FIG6, many intermediates (i.e., oxides) can be observed. The composition of the oxide is evaluated by measuring the composition of the intermediates. The silicon/manganese (Si/Mn) ratio of the embodiment of the present invention is about 0.02 to 0.1. The silicon/manganese (Si/Mn) ratio of the comparative example is about 1.5 or more.

Therefore, optionally, the ratio of silicon content/manganese content of the welding wire is designed to be between 0.02 and 0.1.

By adjusting the composition of the welding wire according to the embodiment of the present invention, the slag property is improved, and silicon oxide is not easily generated, thereby improving the surface quality and electroplating properties.

The present invention improves the soldering slag through the composition design of alloy elements such as manganese, chromium, and titanium. The soldering wire composition design uses 2 to 3% manganese, 0.1 to 0.3% titanium, and 0.1 to 0.5% chromium for auxiliary effect, so the silicon content can reach about 0.25wt.%. In addition, the alloy composition meets α>5, where α=(manganese content/2+titanium content+chromium content/1.33)/silicon content. After the experiment, the surface can reach a surface without obvious silicon-containing soldering slag. In this way, no unplated spots will be generated during subsequent electroplating.

In addition, when manufacturing the welding wire of the present invention, a low furnace temperature between 1000 and 1050°C (for example, about 1030°C) is used for solid solution to reduce the solid solution of titanium carbide; if a large amount of titanium carbide is solid-solved, titanium will combine with carbon after hot rolling to produce nano-scale titanium carbide precipitates, and the strength of the welding wire will be easily too high. The hot rolling temperature is about 820 to 1000°C, and the final rolling temperature is controlled to be between about 800 and 850°C (for example, about 820°C) to promote the formation of granular iron. If the final rolling temperature is too high, an island-like hemp field scattered iron structure will appear, and the hemp field scattered iron structure will cause wire drawing to break. If the temperature out of the furnace or the temperature after rolling is too low, the rolling machine will have difficulty bearing the load.

After rolling, the wire is spread out and cooled on the Stelmor cooling conveyor at a cooling rate of 0.1 to 5°C per second. If the cooling rate is too high, high-strength tantalum and loose iron will be produced, which will make subsequent wire drawing difficult. If the cooling rate is too low, the yield will be too low.

In addition, the present invention also provides a welding wire, comprising: the welding wire composition is: based on the total weight of the welding wire as 100wt.%, the carbon content is between 0.02 and 0.10wt.%, the manganese content is between 2.00 and 3.00wt.%, the silicon content is between 0.01 and 0.25wt.%, the chromium content is between 0.10 and 0.5wt.%, the titanium content is between 0.10 and 0.3wt.%, and inevitable impurities, and the rest is iron, wherein the welding wire composition meets the judgment formula of (manganese content/2+titanium content+chromium content/1.33)/silicon content greater than 5.

In some embodiments of the present invention, the ratio of silicon content to manganese content of the welding wire is between 0.02 and 0.1.

In some embodiments of the present invention, the proportion of ferrite in the welding wire is less than 5%.

In some embodiments of the present invention, the welding wire contains nano-scale titanium carbide precipitates.

S100: Welding wire manufacturing method

S101~S105: Steps

Claims (6)

A method for manufacturing a welding wire comprises the following steps: providing a steel billet, wherein the steel billet comprises: based on the total weight of the steel billet being 100wt.%, a carbon content of 0.02 to 0.10wt.%, a manganese content of 2.00 to 3.00wt.%, a silicon content of 0.01 to 0.25wt.%, a chromium content of 0.10 to 0.5wt.%, and a titanium content of 0.10 to 0.3wt.%. % and unavoidable impurities, the rest being iron, wherein the composition of the steel blank meets the judgment formula of (manganese content/2+titanium content+chromium content/1.33)/silicon content greater than 5; the steel blank is subjected to a heating process; the heated steel blank is subjected to a hot rolling process to form a wire rod; the hot rolled wire rod is subjected to a slow cooling process; and the wire rod subjected to the slow cooling process is subjected to a cold drawing process to produce a welding wire. The manufacturing method as described in claim 1, wherein the heating process is to heat and control the steel blank to a temperature between 1000 and 1050°C. The manufacturing method as described in claim 1, wherein the rolling temperature of the hot rolling process is 820 to 1000°C, and the finishing temperature is controlled to be between 800 and 850°C. The manufacturing method as described in claim 1, wherein the cooling rate of the slow cooling process is between 0.1 and 5°C per second. A welding wire, comprising: the welding wire composition is: based on the total weight of the welding wire as 100wt.%, the carbon content is between 0.02 and 0.10wt.%, the manganese content is between 2.00 and 3.00wt.%, the silicon content is between 0.01 and 0.25wt.%, the chromium content is between 0.10 and 0.5wt.%, the titanium content is between 0.10 and 0.3wt.%, and inevitable impurities, and the rest is iron, wherein the welding wire composition meets the judgment formula of (manganese content/2+titanium content+chromium content/1.33)/silicon content greater than 5. A welding wire as described in claim 5, wherein the welding wire contains nano-scale titanium carbide precipitates.