KR100235919B1 - Wire for gas shield arc welding excellent in feedability and its original wire - Google Patents

Abstract

It solves the problems of deterioration of freshness and deterioration of welding workability by adding Ti, and guarantees the strength and toughness of weld metal which is indispensable as welding wire, and also excellent arc stability, so that it is excellent in the manufacturing process of welding wire. In order to provide a gas shield arc welding wire and its primitive line with excellent feedability and excellent workability without generating poor feeding and non-dreading during welding.

In the gas shield arc welding wire and its wire, C: 0.02 to 0.06%, Si: 0.45 to 1.50%, Mn: 1.0 to 2.0%, Ti: 0.10 to 0.30%, respectively, and the balance is Fe and other unavoidable impurities. In addition, Ti / C is made 4.0 or more and 50 or more carbides or carbonitrides having a particle diameter of 10 to 250 nm containing Ti are present in an average of 50 or more in the test area 2 m ^{2 in} total.

Description

Gas shield arc welding wire with excellent supplying property and its original line

1 is a schematic explanatory diagram of an apparatus used when conducting a feeding test.

* Explanation of symbols for main parts of the drawings

1: welding wire 2: wire feed roller

3: conduit tube 4: feed chip

5: wire arc

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electric wire for excellent gas shield arc welding, and a wire of the same. At the time of manufacture, it shows excellent freshness, good feeding stability without fear of feeding failure and bead running during welding, and good arc stability, resulting in very good welding. The present invention relates to a gas shield arc welding wire capable of exhibiting workability.

Gas shield arc welding is generally used for butt weld or fillet weld of various structures such as shipbuilding, vehicle, steel frame, bridge, industrial machinery, etc. As a result, high heat input welding due to a high current is directed.

Under such a situation, a gas shield arc welding wire in which an appropriate amount of Ti is contained in a low carbon steel wire has been developed, and has been popularized as a wire for high heat input welding. Therefore, the Ti content is intended to prevent the decrease in the strength and toughness of the weld metal due to the increase in the amount of heat input during welding, and to stabilize the welding arc at a high current range.

However, when Ti is added to the welding wire wire, work hardening occurs during the drawing process at the time of manufacturing the wire for welding, and the cold workability is remarkably reduced, resulting in a decrease in the freshness called wire break, and the resulting welding The excessively high strength of the molten wire causes poor feeding, which leads to deterioration of the feeding ability, and also to the nonuniformity of the wire strength, resulting in non-delineation, leading to deterioration of feeding ability and problems in welding workability.

Therefore, for the purpose of improving the freshness and lowering the wire strength, it is common to perform soft nitride annealing after the end of hot rolling or during the drawing process. However, regarding the nonuniformity of the wire strength, the improvement effect due to annealing is small, and even when the annealing of the strength increases even more due to the annealing.

In addition, as a method for lowering the strength of the low carbon steel wire containing Ti and reducing the nonuniformity of the strength, a method of controlling the rolling conditions and the cooling conditions of the hot rolled material has also been examined. For example, `` R & D Kobe Seishinshogibo '' (Vol. 35, No. 2, pages 52 to 54: hereinafter referred to as prior art documents) shows that the increase in strength after hot rolling in Ti-containing low carbon steel wire is finely deposited during ferrite. It is shown that it is due to precipitation hardening of TiC, and a method of lowering the heating temperature and slowing down the cooling rate is shown as a method of reducing the nonuniformity of the strength of the raw wire. However, even with such control rolling and control cooling techniques, the strength of the original wire still remains high, and at least one annealing is required to produce a weld wire having a moderate strength, and annealing is performed. Even if it does, the nonuniformity of the wire strength after drawing is large.

On the other hand, in order to reduce the precipitation hardening by TiC, the amount of Ti added may be reduced. However, as described above, the amount of Ti added can be reduced indefinitely from the standpoint of lowering the strength and toughness of the weld metal or stabilizing the melting point arc. There is no. In addition, when the amount of Ti added is reduced, the amount of excess C increases, the second phase such as martensite generated in the raw line increases, and various difficult points occur such as the freshness decreases backwards.

As such, no effective improvement method has been proposed with regard to strength nonuniformity. On the other hand, the automation of welding work progresses, and problems of feeding and non-detaching of the welding wire are particularly important, and excellent feeding ability without causing feeding and non-detaking. The need for a welding wire having a has been increasingly high.

SUMMARY OF THE INVENTION The present invention has been conceived in view of the above-described circumstances, and its object is to solve the problems of deterioration of freshness and deterioration of weldability due to Ti addition, and to provide excellent arc strength and toughness as well as excellent arc for welding wires. The gas shield arc has excellent freshness in the manufacturing process of the welding wire and guarantees excellent welding workability without causing a poor supply of feed and bead during welding. It is to provide a welding wire and its original line.

The wire of the present invention, that is, the gas shield arc welding wire excellent in supplyability, is capable of solving the above-mentioned problems. C: 0.02 to 0.06% (mass%, all mass% below), Si: 0.45 to 1.50%, Mn: 1.0 to 2.0%, Ti: 0.10 to 0.30%, respectively, the remainder being Fe and other inevitable impurities, and the mass ratio Ti / C of Ti to C (hereinafter simply referred to as Ti / C) is 4.0 or more. and also to present an average particle size of more than 50 in the carbide or carbonitride is the test area in an amount totaling both the 10~250mm (被檢面積) 2㎛ ² containing Ti as a base (hereinafter referred to as the first invention In addition, in the first invention, N is not actively added, but N is an element contained as an unavoidable impurity, especially in the case of carbide having a particle diameter of several tens of nm, where N-containing carbonitride is formed. Where the total number of carbides and carbonitrides is specified. The number of carbides and carbonitrides is an average value of the number in any of the 10 fields observed with a transmission electron microscope.

K₁

0.15%을 만족하도록, V, Zr, Nb, Hf 및 Ta로 이루어지는 군으로부터 선택되는 1 종 또는 2 종 이상을 함유하고, 잔부가 Fe 및 기타 불가피불순물로 이루어지고, 또한 Ti을 함유하는 입자경 30∼250mm의 탄화물 또는 탄질화물이 양자의 합계로 피검면적 2㎛²내에 평균 50∼1000개 존재하는 가스쉴드아크용접용 와이어(이하, 제2발명이라 함)를 이용해도, 신선성의 향상과 송급불량을 방지할 수 있는 점에서의 송급성의 개선이라고 하는 상기 과제를 해결할 수가 있다. (이 경우, Ti을 함유하는 입자경 20∼250nm의 탄화물 또는 탄질화물은 V, Zr, Nb, Hf 및 Ta으로 이루어지는 군으로부터 선택되는 1 종 또는 2 종이상의 원소를 함유하는 복합탄화물 또는 복합탄질화물을 형성한다.)In addition, C: 0.02 to 0.15%, Si: 0.45 to 0.50%, Mn: 1.0 to 2.0, N: 0.0010 to 0.015%, Ti: 0.05 to 0.30%, respectively, and are defined by the following formula (1) K ₁ value is 0.010

K ₁

Particles 30 to 30 containing one or two or more selected from the group consisting of V, Zr, Nb, Hf and Ta, the balance being made of Fe and other unavoidable impurities, and containing Ti so as to satisfy 0.15%. also the carbides or carbonitrides of 250mm using a (hereinafter referred to as the second invention) as the sum of both the test area ² 2㎛ present average 50-1000 gas into the shield wire for arc welding, the improvement of feeding fresh and poor The said subject of the improvement of supplyability in the point which can be prevented can be solved. (In this case, carbides or carbonitrides having a particle diameter of 20 to 250 nm containing Ti include complex carbides or complex carbonitrides containing one or two species of elements selected from the group consisting of V, Zr, Nb, Hf and Ta. Forms.)

K ₁ = (0.94 X [V] + 0.53 X [Zr] + 0.52 X [Nb] + 0.27 X [Hf] + 0.27 X [Ta] / [Ti] ··· (1)

However, [V], [Zr], [Nb], [Hf], [Ta], and [Ti] represent the contents (mass%) of V, Zr, Nb, Hf, Ta, and Ti, respectively.

In addition, C: 0.02 to 0.06%, Si: 0.45 to 1.50%, Mn: 1.0 to 2.0%, Ti: 0.10 to 0.30%, respectively, and the K ₁ value defined by the formula (1) is 1.0 or less. And one or two paper phases selected from the group consisting of V, Zr, Nb, Hf and Ta so that the K ₂ value defined by the following formula (2) satisfies 4.0 or more, and the balance is Fe and The gas shield arc welding wire which consists of an unavoidable impurity and 50 or more carbides or carbonitrides with a particle diameter of 10-250 nm containing Ti exist in an average of 50 or more within 2 micrometers ² of a test area (it is 3rd invention hereafter. May be used).

K ₂ = ([Ti] + 0.94 X [V] + 0.53 X [Zr] + 0.52 X [Nb] + 0.27 X [Hf] + 0.27 X [Ta]) / [C]

However, [C] shows content (mass%) of C.

On the other hand, the total amount of one paper element selected from the group consisting of Ca, Zn, Pb, Sn, and Bi is preferably 300 ppm or less, and in the case of forming a Cu plating layer on the surface for the purpose of improving conduction, It is recommended that the ratio of this Cu plating layer with respect to the whole welding wire shall be 0.08-0.40%, and Cu content of the whole welding wire shall be 0.08-0.50%.

Also in the case of the raw wire of the welding wire, by satisfying the same conditions as the welding wire of the above-mentioned 1 to 3 invention, it is possible to obtain a raw wire that exhibits excellent freshness during drawing processing. Specifically, C: 0.02 to 0.06%, Si: 0.45 to 1.50%, Mn: 1.0 to 2.0%, Ti: 0.10 to 0.30%, respectively, and are all composed of Fe and other unavoidable impurities, and Ti / C is The total line of carbide or carbonitride having a particle diameter of 10 to 250 nm and a Ti content of 4.0 or more may be a circular line having an average of 50 or more in the test area 2 m ² .

K₁

0.150%을 만족하도록 V, Zr, Nb, Hf 및 Ta, 으로 이루어지는 군으로부터 선택되는 1종 또는 2종이상을 함유하고, 잔부가 Fe 및 불가피불순물로 이루어지며, 또한 Ti을 함유하는 입자경 30∼250nm의 탄화물 또는 탄질화물의, 양자의 합계로 피검면적 2㎛²내에 평균 50∼1000개 존재하는 원선이라도 우수한 신선성이 얻어진다.In addition, C: 0.02 to 0.15%, Si: 0.45 to 1.50%, Mn: 1.0 to 2.0%, N: 0.0010 to 0.015%, Ti: 0.05 to 0.30%, respectively, and are defined by the above formula (1). K ₁ value is 0.010

K ₁

Particles 30-250 nm containing one or two or more selected from the group consisting of V, Zr, Nb, Hf and Ta, with a balance of Fe and an unavoidable impurity, and containing Ti to satisfy 0.150% The excellent freshness is obtained even in the case of a circular line having an average of 50 to 1000 pieces of carbide or carbonitride in the total area of 2 μm ^{2 to} be tested.

In addition, C: 0.02 to 0.06%, Si: 0.45 to 1.50%, Mn: 1.0 to 2.0%, Ti: 0.10 to 0.30%, respectively, and the K ₁ value defined by the formula (1) is 1.0 or less. And further include one or two or more selected from the group consisting of V, Zr, Nb, Hf and Ta so that the K ₂ value defined by the above formula (2) satisfies 4.0 or more, and the balance Fe and inevitable A circular line made up of impurities and having a total of 50 or more carbides or carbonitrides having a particle diameter of 10 to 250 nm containing Ti in an average of 50 or more in the test area 2 µm ² may be used.

In addition, in order to manufacture the said raw wire, it is preferable to make the heating temperature at the time of hot rolling into the austenitization temperature range of 1,000 degrees C or less, and to set the cooling rate after hot rolling to 3.0 degrees C / sec or less, and the gas produced in this way The shield arc welding wire is excellent in supplyability and produces very good welding workability without making a supply failure and non-dreading at the time of welding.

The present inventors focus on how to reduce the precipitation hardening of TiC and its nonuniformity in order to avoid the deterioration of the freshness, excessive increase in strength, and nonuniformity of strength which appear in the known Ti-containing low carbon steel welding wire as described above. Was performed.

TiC is a carbide having a crystal structure like NaCl, and its precipitation size affects strength and work hardening. The present inventors have confirmed that a large amount of fine TiC on the order of several nanometers of Ti-containing low carbon steels is precipitated. As the fine TiC is dispersed, the strength is significantly increased and the degree of work hardening is also increased. As a result, it was found that the freshness was lowered and the wire strength after the drawing was excessively released. Therefore, it is important to make such fine TiC the least. However, as long as Ti and C are added, precipitation of TiC cannot be avoided. Therefore, the present inventors have thought to generate a large amount of coarse TiC that does not increase the strength even with the same TiC, and to perform the structure control to reduce the fine TiC.

Fine precipitates of several nm are precipitated in the ferrite, but precipitated in the austenite becomes coarse. As a result, during the transformation from austenite to ferrite, Ti and C, which have been dissolved in austenite, rapidly become fine carbides in the ferrite after the transformation, and precipitation strengthening occurs due to the presence of the fine TiC. This is because the high doses of Ti and C are extremely small in ferrite compared to austenite. Therefore, in order to control the wire strength appropriately by reducing the amount of fine TiC deposition, it is precipitated by TiC in the austenite temperature range, thereby reducing the high capacity of Ti and C in austenite and controlling precipitation in ferrite. It is important.

In addition, regarding the nonuniformity in strength, the precipitation form of TiC changes immediately due to the difference in the cooling rate of the wire rod portion during cooling after hot rolling. In other words, the cooling of the wire rod after hot rolling is generally performed by Stelmore cooling, but the cooling speed is changed to the part where the wire rod overlaps (the part of the part) where the wire rod overlaps. In contrast, coarse TiC precipitates at low density at low cooling rate, and fine TiC precipitates at high cooling rate, resulting in high strength, resulting in nonuniformity in strength at the original line. In addition, the site where the fine TiC is precipitated has a higher work hardening rate than the site where the coarse TiC is precipitated, so that the unevenness of the strength is further increased with the subsequent drawing, and consequently, the unevenness of the wire strength after the drawing is remarkably increased. I realized that it would grow.

Such non-uniformity of the wire strength can be suppressed to a little smaller by performing annealing during drawing or drawing, but it is not enough that no beading occurs during welding. In addition, short time annealing may increase the intensity nonuniformity. In addition, in order to eliminate the nonuniformity of strength, softening may be excessively long when annealing is performed for a long time, and a supply failure may occur due to a decrease in the average strength. It is unavoidable and undesirable.

Therefore, in order to improve the nonuniformity of the wire strength, it is indispensable to reduce the nonuniformity of the precipitation form of TiC in the raw wire before drawing, and to reduce the degree of nonuniformity, the Ti in the austenite is also reduced. It is important to reduce the high doses of C and C. By reducing the absolute amount of TiC precipitated in the ferrite, it is possible to reduce the non-uniformity of precipitation strengthening according to the cooling rate difference. That is, not only the increase in strength but also the nonuniformity in strength can be solved by reducing the high capacities of Ti and C in austenite.

Regarding the point of decreasing the strength increase, it is a general idea that the Ti amount can be reduced and the fine TiC amount can be reduced and the strength can be lowered by reducing Ti as described in the preceding document. . According to this idea, the amount of precipitation strengthening and nonuniformity by TiC is certainly reduced by reducing the amount of Ti, but even in this case, the wire strength and nonuniformity after drawing is still increased, and the welding workability, such as non-drafting, is not improved. Do not. In addition, as described above, the amount of Ti added cannot be arbitrarily reduced from the viewpoint of decreasing the strength and toughness of the weld metal or stabilizing the weld arc. In addition, there is a demerit, that is, a disadvantage that C is left as Ti is reduced, and the amount of martensite, bainite, pearlite, etc. increases. As a result, if the Ti amount is decreased due to the decrease in strength, it is not preferable because the second phase structure such as martensite is formed to reduce the freshness. Conversely, in order to form a ferrite single phase structure, it is necessary to add Ti to remove excess C at room temperature, but as shown in the above-mentioned prior art document, the increase in strength and the increase in nonuniformity are rather increased. It is thought to cause. That is, in order to achieve the subject, the production inhibition of the second phase structure and the fine precipitation inhibition of TiC must be compatible.

As a result of the deep study by the present inventors about these points, when Ti / C became 3.5 or more, it turned out that contrary to what was known so far, the more Ti amount, the more the intensity | strength falls and the nonuniformity becomes drastically small.

In addition, by adding Ti until Ti / C is 4.0 or more and optimizing the hot rolling conditions, the amount of TiC precipitation in the ferrite phase is controlled, so that the fine TiC of several nm is extremely small, instead of 10 to 250 nm. It was found that the tissue state in which coarse TiC is dispersed is obtained. As a result, the strength and nonuniformity of the raw line is greatly lowered, and the matrix is made into a ferrite single phase. Thus, it was found that the obtained raw wire is excellent in freshness, and there is no excessive increase in strength, and yet the nonuniformity of wire strength after drawing is very small. According to the composition of the composition and the control of the structure, the present invention realizes a Ti-containing low-carbon steel welding wire which is suitable for wire strength after wire drawing, while having low nonuniformity, and excellent in supplyability.

Further, in the present invention, by containing one or two or more elements (hereinafter referred to as elements such as V) selected from the group consisting of V, Zr, Nb, Hf, and Ta, improving freshness and supplyability It is possible. V, Zr, Nb, Hf, and Ta tend to produce carbides of NaCl type like Ti, and when these elements are added, carbides containing Ti contain elements such as V and the like. Therefore, the addition of an element such as V causes the entropy term to work effectively in the mixed thermodynamic equation, resulting in the precipitation of complex carbides. Therefore, it is more thermodynamically advantageous than the precipitation of individual carbides. It becomes easy to precipitate.

Further, Zr, Nb, Hf and Ta have extremely low solubility of carbides in austenite compared with Ti, and this also works effectively for the precipitation of coarse carbides in the austenite region. In this way, by containing elements such as V, thermodynamically, the mixed entropy term works effectively, and the low solubility of the complex carbide promotes coarse precipitation of coarse carbide in austenite, and consequently, fine carbide Precipitation amount is reduced, and freshness and feeding property are improved.

Hereinafter, each of the reasons for determining the component composition of the welding wire and the original line according to the present invention will be described. First, in the welding wire of the first invention, control of the amount of C and Ti, is an extremely important requirement.

C: 0.02 to 0.06%

C is an element which is indispensable for securing the strength of the weld metal as a welding wire, and it must contain at least 0.02%. From the point of view of increasing the strength of the weld metal, the more the added amount is, the more preferable, but too much produces a second phase such as martensite that adversely affects freshness. In addition, the amount of solid solution C and Ti in austenite increases, and the amount of fine TiC precipitated in ferrite is increased to increase the line strength and increase the nonuniformity of strength. Therefore, the upper limit was set to 0.06%. The range with more preferable C content is 0.03% or more and 0.05% or less.

Ti: 0.10 to 0.30%

Ti is an essential element to secure the strength, toughness and arc stability of the deposited metal. In addition, the amount of TiC in austenite is increased to decrease the amount of fine TiC in ferrite, and the amount of solid solution C in austenite is reduced to suppress the formation of a second phase such as martensite, in an amount of 0.02 to 0.06% C. On the other hand, Ti must be contained 0.10% or more. If the amount of Ti is too small, arc stability is not secured, and the amount of solid solution Ti and C in austenite is increased, thereby increasing the amount of fine TiC precipitation in ferrite, increasing the linear strength and increasing the intensity nonuniformity. It becomes a factor. In addition, a second phase such as martensite is generated to adversely affect the freshness. On the other hand, when the amount of Ti is too large, it tends to cause solid solution hardening and deterioration of freshness, and the wire tends to be hardened and wound up by spun, etc., so it is necessary to be 0.30% or less. Preferably they are 0.20% or more and 0.25% or less.

Si: 0.45 to 1.50%

Since Si has the effect of strengthening the solid solution of ferrite, it is better to increase the strength of the weld metal, but on the other hand, the smaller one is preferable in order to increase the freshness of the wire rod. In view of the combination of strength and freshness in this manner, the Si content was set in the range of 0.45 to 1.50%. The preferable range of Si content is 0.50 to 1.2%.

Mn: 1.0 to 2.0%

Mn must be contained 1.0% or more in order to give sufficient strength to the weld metal. However, when Mn is too large, the hardenability increases and the toughness of the weld metal is adversely affected, so the upper limit is 2.0%. The range with more preferable Mn content is 1.0 to 1.8%.

Ti / C: 4.0 or higher

If the value of Ti / C is less than 4.0, the amount of C is left in excess, and a second phase such as martensite is formed, and the precipitation strengthening by TiC increases, and the intensity nonuniformity also increases. When Ti / C is 4.0 or more, the second phase is not produced but becomes a ferrite single phase, while the precipitation strengthening amount and nonuniformity of TiC is small. Moreover, when Ti / C is 4.0 or more, there exists also an advantage that the deformation resistance at the time of hot rolling becomes small. As the deformation resistance becomes smaller, rolling at low temperature is possible, and while the processing heat is reduced, the redistribution of TiC is suppressed, and as described below, the amount of precipitation strengthening and nonuniformity of TiC is small. do. In TiC of 4.0 or more, the larger this value is, the smaller the precipitation strengthening amount by TiC is, and more preferable in the case of 6.0 or more.

In addition, in the welding wire according to the first invention of the present invention and its original line, carbides or carbonitrides (hereinafter sometimes referred to as carbonitrides) having a particle diameter of 10 to 250 nm containing Ti in total It is necessary that 50 or more exist in the test area 2 m ² . Next, the reason is explained.

As described above, the carbon (nitride) size containing Ti greatly affects the freshness of the raw wire and the feeding property of the welding wire. As a result of deep research on the carbonitride size and its mechanical properties, the inventors of the present invention have satisfied that the number of carbonitrides having an average particle size of 10 to 250 nm is 50 or more within 2 μm ² of the test area. As a result, it has been found that the freshness of the raw wire and the feedability of the welding wire are significantly improved. That is, when the total size of the carbide or carbonitride is less than 50 on average within ² μm ² of the tested area, the particle size is smaller than 10 nm and fine carbides increase to increase the strength and increase the intensity nonuniformity. At the same time, bead is generated. Therefore, it is necessary that 50 or more carbon (nitrides) which have an average particle diameter of 10-250 nm size exist in the test area 2 micrometer <^2> , and 200 or more are preferable. On the other hand, when there are too many carbides of the said size, since the influence of precipitation hardening will become remarkable and supplyability will rather be inhibited, it is desired that there exist 1000 or less in the inspection area 2 micrometer <^2> .

As described above, in the wire of the present invention, by drawing one or two or more selected from the group consisting of V, Zr, Nb, Hf, and Ta so as to have a constant ratio with respect to Ti, Supply can be improved in the point of preventing a performance supply shortage (the 2nd and 3rd inventions mentioned above). However, when the content of elements such as V is too high compared to the Ti content, arc stability is impaired, resulting in deterioration of weldability and deterioration of toughness of the weld metal. Therefore, in the second invention, it is necessary to make the mole fraction with respect to the Ti addition amount of the K ₁ value (V, Zr, Nb, Hf and Ta added) represented by the following formula (1): 0.010 or more and 0.150 or less. Do.

K ₁ = (0.94 X [V] + 0.53 X [Zr] + 0.52 X [Nb] + 0.27 X [Hf] + 0.27 X [Ta]) / [Ti]

However, [V], [Zr], [Nb], [Hf], [Ta], and [Ti] represent the contents (mass%) of V, Zr, Nb, Hf, Ta, and Ti, respectively.

On the other hand, in the second invention, the content of C and Ti may satisfy the ranges of C: 0.02 to 0.15% and Ti: 0.05 to 0.30%, respectively, and even if N is contained in the range of 0.0010 to 0.015%, the object of the present invention Can be achieved.

N is an element which combines with Ti and C to produce stable carbonitrides. In the case of melting the steel of the present invention by a conventional dissolution casting method, Ti carbonitride is formed immediately after solidification, and the carbonitride containing Ti is coarsened. This is advantageous. However, when N is passed through, carbonitride becomes excessively coarse and exists as inclusions, and causes disconnection in the drawing process. Therefore, it is preferable to contain 0.0010% or more and 0.015% in the range of binomial, and 0.0035 to 0.0080% It is more preferable if it is.

Further, in the second invention, the carbon (nitride) containing Ti is required to have 50 to 1000 carbon (nitride) particles having an average particle size of 30 to 250 nm within the inspection area of 2 µm ² . It is preferable from the viewpoint of improving the freshness of the raw wire and the feeding property of the welding wire.

In the case of containing an element such as V, a composite carbide or a composite carbonitride containing Ti as a main component and one or more selected from the group consisting of V, Zr, Nb, Hf and Ta is contained. However, when the K ₂ value represented by the following Equation (2) is less than 4.0, the amount of C becomes an excess and a second phase such as martensite is produced in addition to the ferrite phase, and precipitation strengthening by carbon (nitride) containing Ti At the same time, the intensity unevenness also increases.

K ₂ = {[Ti] + 0.94 X [V] + 0.53 X [Zr] + 0.52 X [Nb] + 0.27 X [Hf] + 0.27 X [Ta] / [C]

However, [C] represents content (mass) of C.

Therefore, as defined by the third invention, the K ₂ value is preferably 4.0 or more, and the K ₂ value of 4.0 or more also has the advantage that the deformation resistance at the time of hot rolling becomes small. The smaller the deformation resistance, the lower the rolling temperature and the lower the heat generation. Therefore, the reusability of the composite carbon nitride containing Ti is suppressed, and the precipitation strengthening amount and nonuniformity of the composite carbon nitride containing Ti is small. Lose. The larger the K ₂ value is, the larger the precipitation strengthening amount due to carbide becomes, and it is preferable, and more preferably 6.0 or more.

On the other hand, when the K ₂ value is 4.0 or more, the relative amount of the elements such as V to Ti may be increased, and as defined by the third invention, the K ₁ value exceeds 0.150 to the range of 1.0 or less. Although acceptable, it is preferable to set it as 0.5 or less.

In addition, in the third invention, the carbon (nitride) containing Ti, as in the first invention, has 50 carbonaceous nitrides having an average particle size of 10 to 250 nm within a test area of 2 μm ² . If the above exists, the freshness of a raw wire and the supplyability of a welding wire can be improved.

In the present invention, in controlling the particle diameter of Ti-containing carbonitride (hereinafter, typically TiC is described), it is extremely effective to control the conditions for producing the raw wire of the welding wire. It is preferable to control the heating temperature at the time of hot rolling to 1000 degrees C or less, and also to set it at 1000 degrees C or less also about the maximum reaching temperature when the temperature rises by the process heat generation at the time of hot rolling. This is because when the heating temperature and the maximum reaching temperature are high, the high capacities of Ti and C increase, and a large amount of fine TiC easily precipitates during ferrite transformation during the cooling process after hot rolling, resulting in an increase in strength. . Preferable heating temperature range is 800-950 degreeC.

Moreover, even if the cooling rate after hot rolling is too fast, it will become easy to precipitate a large amount of fine TiC, and will raise strength. In addition, the cooling speed difference at the time of Stelmore cooling becomes large, and intensity nonuniformity becomes large. Therefore, it is preferable to slow down the cooling rate after hot rolling as much as possible, and it is recommended to control at 3.0 degrees C / sec or less.

In this way, when the heating temperature and the maximum reaching temperature are set at 1000 ° C. or lower, and hot-rolled, and the subsequent cooling rate is set at 3.0 ° C./sec or lower, TiC mainly has a size of 10 to 250 nm as described above. Is significantly controlled, resulting in a decrease in strength and a decrease in non-uniformity. In addition, it is impossible to harden excessively even in the subsequent drawing process, so it is possible to obtain a welding wire with excellent handleability without any obstacles such as spool due to stable freshness without performing soft annealing in the middle. The welding wire obtained can be a wire with moderate strength, low strength nonuniformity, and excellent welding workability.

Therefore, in the welding wire of the present invention, as described above, the total of one or two or more elements selected from the group consisting of Ca, Zn, Pb, Sn, and Bi is preferably 300 ppm or less. That is, since these trace elements reduce the precipitation driving force of the carbide according to the present invention in the austenite temperature range, it is preferable to reduce them as much as possible. For example, by carefully selecting the dissolved raw materials, the total amount of these elements is reduced to 300 ppm or less. In this case, the effect of the present invention is significantly improved. On the other hand, with the current technology, it is very difficult to reduce these elements to less than 40 ppm, but these elements may be reduced as much as possible, and the lower limit thereof is not limited in the present invention.

On the other hand, in the case of the gas shield arc welding wire of the present invention, a Cu plating layer may be formed on the surface of a circular line from the viewpoint of improving the electrical conductance of the wire. And Cu content of the plating layer with respect to the whole welding wire) are recommended. In other words, if the ratio is excessive, the amount of chips of Cu in the roller, the conduit trainer, etc. may be generated in a large amount during wire feeding, which may cause feeding failure, so it should be 0.40% or less. However, in consideration of the improvement of the electrical conductivity and the plating treatment property, the ratio is preferably 0.08% or more. However, as the Cu content of the entire wire (that is, the sum of the ratio and the Cu content in the raw wire), when it is excessive, the amount of Cu in the weld metal tends to increase and hot cracking tends to occur, so the Cu content is 0.50%. It is good to set it as follows. As mentioned above, it is desired that the lower limit be 0.08% or more in terms of the improvement of electrical conductivity and the plating treatment property.

On the other hand, a welding wire that satisfies the requirements of the present invention does not have excessive softening even when annealed, and becomes low strength when annealed, but results in a weld wire having less strength non-uniformity with minimum strength.

Moreover, the strength and toughness of the weld metal part obtained using the welding wire of this invention are comparable with the welding wire for conventional Ti addition low carbon steel, or exhibit the characteristic exceeding this.

Next, the structure and effect of the present invention will be described in more detail with reference to Examples. However, the present invention is basically not limited to the following examples, and of course, modifications can be made to the ranges suitable for the above and later purposes, and any of these are included in the technical scope of the present invention.

EXAMPLE

Example 1

Using the steel composition of the composition shown in Table 1, a circular line with a finish diameter of 5.5 mm was prepared under the hot rolling conditions described in this table. Next, cold drawing was carried out and drawn to a final wire diameter of 1.2 mm with 14 die passes. In this drawing process, the Cu-containing plated layer having the Cu content and the coating amount, as shown in Table 1, was formed in the stage of the wire diameter in the middle such as? 3.4mm and? 2.4mm.

In counting the number of Ti-containing carbon (nitride) in the raw wire before drawing and the wire after drawing, carbonized material was collected from the wire rod using an extraction replica and magnified using a transmission electron microscope. By observing ten fields of view at full magnification, carbonitrides having a diameter of 10 to 250 nm in a ² μm ² region were counted, and the average value of the number was calculated.

Regarding the strength of the circle and the wire, 100 wire rods are cut at intervals of 16 cm, the average value of these strengths are calculated, and the maximum strength and minimum strength of the wire are examined to determine the difference between the two wires in terms of the non-uniformity of the wire strength. Catch and calculate.

The freshness was evaluated as pass (circle 2 in Table 2), which was able to be drawn to ψ1.2mm without disconnection during fresh processing, and the breakage in the middle of the fresh processing was evaluated as rejected (X mark in Table 2).

The supplyability test was carried out using the apparatus shown in FIG. 1 with respect to the wire which passed the wire drawing test. In Fig. 1, reference numeral 1 denotes a welding wire, 2 a wire feeding roller, 3 a conduit tube, 4 a feeding chip, and 5 a wire arc. The supplyability was evaluated by two types of supply failure and non-detaching, and the former supply failure was not smoothly supplied to the wire during the 10 minute welding work in which gas shield arc welding was performed under the following conditions. This produced wire was made into reject (X table | surface of Table 2), and what was able to be welded without a problem was set as the pass (O table | table of Table 2, a very good thing). The latter non-dart row is a 5 m bead obtained by the welding operation, in which the wire which caused the non-dart line significantly is rejected (X in Table 2), and the non-dart row is not noticeable. The thing was set as the pass (O table | surface of Table 2, and a very favorable thing (◎ mark)). Table 2 also lists the good and bad results of arc stability during welding.

[Welding condition]

Welding method: carbon dioxide arc welding method

Welding base material: SM490

Welding Current: 300A

Welding voltage: 34V

Welding Speed: 25 ~ 30cm / min

Moreover, about the thing which passed the feedability test, the intensity | strength of the weld metal was investigated according to JIS Z3312, and the thing of strength 50kg / mm <^2> or more was made into the pass.

The measurement results of strength and the evaluation results of each characteristic are listed in Table 2 below.

TABLE 1

TABLE 2

Nos. 1 to 14 are comparative examples in which any one of the requirements of the present invention does not satisfy at least 1, and welding is performed even if the wire strength is too high and the wire freshness or supplying property is insufficient, or the wire strength is adequate and the freshness and supplying property are good. Low metal strength On the other hand, Nos. 5 to 27 are examples of the present invention (corresponding to claims 1, 4, 5, 6, 9, and 10), which satisfy all the requirements of the present invention. The wire strength and the weld metal strength are appropriate, and the non-uniformity of the wire strength is achieved. It is also small in size, excellent in freshness and supplyability, good in arc stability, and very good in welding workability.

On the other hand, Nos. 13 and 14 are comparative examples in the case where annealing treatment (10 minutes at 720 ° C.) was performed during drawing processing, and although the average wire strength was lowered and moderate, the variation in strength was large and the freshness and supplyability were insufficient. . In contrast, the inventive examples Nos. 15 to 25 are superior in freshness and supplyability to Comparative Examples 13 to 14 even without annealing. According to the present invention, the freshness and supplyability can be improved and the annealing step can be omitted. It can be seen.

Example 2

Addition of one or two paper-like elements selected from the group consisting of V, Zr, Nb, Hf and Ta. To this, a welding wire is produced as in Example 1, and the characteristics of the welding wire and the circular line Was investigated. However, the number of carbon (nitride) counted the thing of 30-250 nm in diameter. The composition and the hot rolling conditions are shown in Tables 3 to 5, and the results are shown in Tables 6 to 8. In Tables 6 to 8, "feedability" is evaluated in the same manner as in Example 1 according to the presence or absence of a supply failure.

TABLE 3

TABLE 4

TABLE 5

TABLE 6

TABLE 7

TABLE 8

Nos. 101 to 102 are conventional examples, and differ from each other in the presence or absence of annealing treatment (800 ° C. X 1 hr.). Nos. 103 to 114 and 201 to 203 are comparative examples in which none of the conditions of the present invention are satisfied, and at least any of freshness, feeding ability, and welding strength are deficient. Nos. 151 to 179 and 204 to 216 are examples of the invention (corresponding to claims 2, 4, 5, 7, 9, and 10), which substantially satisfy the present invention requirements, and have suitable wire strength and weld metal strength. It is good and excellent in supplyability in that there is no supply failure.

Example 3

A welding wire was manufactured in the same manner as in Example 1 except that one, two, or more elements selected from the group consisting of V, Zr, Nb, Hf, and Ta was added, and the properties of the welding wire and its original line Was investigated. The composition and hot rolling conditions are shown in Table 9 and the results are shown in Table 10.

TABLE 9

TABLE 10

No. 301 is a comparative example in the case where the Ti content is too small, and No. 303 is too large a K ₁ value, the average wire strength is moderate, and the arc stability is insufficient and the welding workability is low. No. 302 is a comparative example when the wire strength is too high, and lacks freshness and supply.

On the other hand, Nos. 304 to 311 are examples of the invention (corresponding to claims 3, 4, 5, 8, 9, and 10) that satisfy most of the requirements of the present invention, wire strength and weld metal strength are appropriate, and nonuniformity of wire strength. There is little, and freshness and supplyability are excellent. At the same time, the arc stability is good and the welding workability is very good.

Since the present invention is constituted as described above, the strength and toughness of the weld metal, which is indispensable as the welding wire, is guaranteed, so that the welding wire manufacturing process shows excellent freshness, and the welding failure and non-detaching It is possible to provide an excellent shield arc welding wire and its primitive line by providing excellent supplyability without sacrificing arc stability, good arc stability, and consequently exhibiting excellent welding workability.

Claims (7)

C: 0.02-0.06% (mass%, all the same below) Si: 0.45 to 1.50% Mn: 1.0 to 2.0% Ti: 0.10 to 0.30% And the remainder consisting of Fe and other unavoidable impurities, and the mass ratio Ti / C of Ti to C is 4.0 or more, and carbides or carbides having a particle diameter of 10 to 250 nm contained in Ti are both A gas shield arc welding wire having excellent supplying characteristics, characterized in that an average of 50 or more exists within a test area of 2 μm ² in total. C: 0.02 to 0.15% Si: 0.45 to 1.50% Mn: 1.0 to 2.0% N: 0.0010% to 0.015% Ti: 0.05 to 0.30% , And the K ₁ value specified in the following Formula (1) is 0.010.

fK ₁

Particle size 30 containing one or two or more selected from the group consisting of V, Zr, Nb, Hf and Ta, the balance consisting of Fe and other unavoidable impurities, and also containing Ti so as to satisfy f0.150. Carbide arc welding wire having excellent supplyability, characterized in that an average of 50 to 1000 carbides or carbides having a total thickness of -250 nm exist within 2 µm ² of the inspection area. K ₁ = (0.94 X [V] + 0.53 X [Zr] + 0.52 X [Nb] + 0.27 X [Hf] + 0.27 X [Ta]) / [Ti] ···· (1) However, [V], [Zr], [Nb], [Hf], [Ta], and [Ti] represent the contents (mass%) of V, Zr, Nb, Ta, and Ti, respectively. C: 0.02 to 0.06% Si: 0.45 to 1.50% Mn: 1.0 to 2.0% Ti: 0.10 to 0.30% , And each of V, Zr, Nb, Hf, and Ta so that the K ₁ value defined by the following formula (1) is 1.0 or less, and the K ₂ value defined by the following formula (2) satisfies 4.0 or more: Carbides or carbonitrides having a particle diameter of 10 to 250 nm containing one or two or more selected from the group consisting of Fe and other unavoidable impurities, and containing Ti; ² is excellent in feedability, characterized in that present in the average of 50 or more gas shielded arc welding wire for K ₁ = (0.94 X [V] + 0.53 X [Zr] + 0.52 X [Nb] + 0.27 X [Hf] + 0.27 X [Ta]) / [Ti] ···· (1) K ₂ = ([Ti] + 0.94 X [V] + 0.53 X [Zr] + 0.52 X [Nb] + 0.27 X [Hf] +0.27 X [Ta] / [C] However, [V], [Zr], [Nb], [Hf], [Ta], [Ti], and [C] are the contents of V, Zr, Nb, Hf, Ta, Ti, and C (mass%), respectively. ). The welding wire according to any one of claims 1 to 3, wherein the total of one or two or more elements selected from the group consisting of Ca, Zn, Pb, Sn, and Bi is 300 ppm or less. The Cu plating layer is formed in the surface, The ratio with respect to the whole welding wire of this Cu plating layer is 0.08-0.40%, and Cu content of the whole welding wire is Welding wire of 0.08 to 0.50%. It is manufactured by making the heating temperature at the time of hot rolling of the said raw wire of any one of Claims 1-3 into 1000 degrees C or less, and cooling rate after hot rolling into 3.0 degrees C / sec or less. Method for producing a wire for use. The manufacturing method of the welding wire characterized by the above-mentioned. The heating temperature at the time of annual rolling of the said raw wire of Claim 4 is 1000 degrees C or less, and the cooling rate after hot rolling is 3.0 degrees C / sec or less.

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