JPH07276086A - Flux cored wire for mag welding small in welding deformation - Google Patents

Abstract

PURPOSE:To make better the finished bead shape after welding by specifying the contents of C, Si, Mn, Ni or the like in flux as well as the components in the sheath made of steel and the parameter decided by the amt. of each elements. CONSTITUTION:The sheath made of steel is filled with metal powder type flux contg., to the total weight of the wire, 4.0 to 12.0% iron powder, 0.05 to 1.1% arc stabilizer and 0.3 to 3.5% slag forming agent other than arc stabilizers to form a wire including flux for MAG welding. The total weight of the wire in the compsn. of this wire is incorporated with 0.03 to 0.09% C, 0.2 to 1.0% Si, 0.3 to 3.0% Mn and 0.2 to 5.0% Ni. Moreover, one or >= two kinds among 0.1 to l.5% Cu, 0.1 to 3.0% Cr, 0.1 to 2.0% Mo, 0.1 to 0.7% V and 0.01 to 0.05% Nb are incorporated therein. Furthermore, the parameter T decided by the formula is regulated to <620. By using this wire, welding deformation is reduced in automatic and semiautomatic welding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding material for steel materials used in construction, civil engineering, marine structures, shipbuilding and the like, and more specifically, because there is little out-of-plane deformation occurring during welding work, The present invention relates to a highly efficient metal-powder-based mag-welding flux-cored wire capable of reducing or omitting the taking work.

[0002]

2. Description of the Related Art During welding of steel materials in various steel structures, due to solidification shrinkage of molten metal and subsequent contraction / expansion due to cooling and phase transformation, for example, in the case of fillet welded joints, out-of-plane deformation called angular deformation Deformation occurs. Such residual deformation causes a decrease in structural strength such as a decrease in buckling strength when a compressive load is applied. Further, if it is attempted to forcibly prevent this deformation with a restraint jig, excessive residual stress will be generated. Further, the dimensional accuracy becomes insufficient, which causes inconvenience in manufacturing, and spoils the aesthetic appearance.

Then, for example, Journal of Welding Society Vol. 52 (198)
3 years) As seen in "Generation and prevention of welding deformation" serialized in Nos. 4-5 and 7-9, a method of correcting residual deformation generated during welding by local heating is empirical. Have been proposed to many. However, in addition to unavoidable deterioration of the material due to reheating of the weld, the time and cost required for straightening work are serious obstacles to practical use.
It has been desired to develop a welding method capable of reducing or omitting this.

Regarding the mechanism of generation of residual stress and deformation in the welded portion, Sato's "Welding Structure Manual" 1988, (Kuroki Publishing) and K. Masubichi's "Analysi
sof Welded Structures "198
Details on 0, PERGAMON PRESS. However, the welding deformation does not pay attention to the detailed characteristics of the welding material used, such that the welding deformation is mainly determined by the geometry of the component with respect to the heat input during welding. Although it is specified in the above-mentioned book that the phase transformation temperature of the welded part of the steel structure is a factor that affects the residual stress and the deformation, the specific effect on the welding material for the steel structure. The degree of quantification and the composition have not been examined. There are also reports of studies on relaxation of residual stress and reduction of deformation, paying attention to the superplasticity phenomenon of phase transformation (Abstracts of the National Meeting of Japan Welding Society Vol. 37, p. 314-315, Vol. 38, p. 78-79,
39th p. 338-341). These are all focused on the martensitic transformation temperatures of low alloy steels and stainless steels, which contain 3.5 to 12% Ni, and are contained in the mild steel and the components of ordinary steel found in 50kg class high strength steels and It is not a finding that can be directly applied to an organization.
Further, in the case of containing such a high value of Ni, the welding material cost becomes high, and even if the strain relief work can be omitted, it is not practical from the economic knowledge. Furthermore, when this is applied to ordinary steel and low alloy steel for shipbuilding and offshore structures, the weld metal becomes electrically noble,
A selective corrosion phenomenon occurs in the heat-affected zone of welding, which causes inconvenience.

The most influential factor on the welding deformation is the welding heat input with respect to the steel plate thickness, and the phase transformation temperature of the weld metal is next. In addition to these, at the temperature at which the deformation occurs, the strength of the material against the deformation can be mentioned. The phase transformation temperature is generally in the range of 400 to 700 ° C,
It can be inferred from the knowledge of the high-temperature strength of Cr-Mo steel, for example, that the amount of deformation can be reduced by increasing the strength in this temperature range by adding elements such as Cr, Mo, V, and Nb. However, no study has been made so far to secure high-temperature strength at the transformation point temperature of the weld metal part, and since these additional elements tend to increase the transformation point temperature and increase the welding deformation as described above, The proper addition amount could not be easily determined.

As a method for solving these problems, a gas shield arc welding method has been proposed in JP-A-4-22596 and JP-A-4-22597. The welding material applied to the method of the publication is a solid wire, but when welding with a solid wire, the penetration at the time of welding is deep and it is not always satisfactory to reduce welding deformation.

[0007]

As described above, the effect of the phase transformation point temperature of the welding material on the amount of deformation generated during welding is quantified, given that the welding member / shape and the welding heat input amount are given, It is considered effective to provide design guidelines for welding material components. The present invention is intended for the welded joint of ordinary steel that is most commonly used for steel structures, paying attention to the Ar ₃ transformation point temperature of the welding material, and taking the amount of angular deformation that occurs during T-shaped fillet welding as an example. , By studying the relationship between the transformation temperature of Ar ₃ and the amount of angular deformation, the amount of angular deformation that occurs is small, and in addition to reducing the amount of angular deformation as an expanded application, the finished bead shape after welding can be greatly improved. The purpose is to provide a highly efficient welding material. Note that the amount of angular deformation is taken up as one of the measures of the amount of deformation, and the application is not limited to angular deformation.

[0008]

As a result of further experiments, the present inventors have found that the flux-cored wire can reduce the amount of welding deformation as compared with the solid wire. It was found that the solid wire has a deep penetration during welding, and the flux-cored wire has a smaller penetration than that of the solid wire, so that the amount of deformation can be further reduced.

That is, the gist of the present invention is that
Iron powder on the steel shell based on the total weight of the wire; 4.0-12.
MAG welding flux-cored wire filled with a metal powder flux containing 0%, an arc stabilizer; 0.05 to 1.1%, a slag forming agent other than the arc stabilizer; 0.3 to 3.5% And C = 0.03 based on the total weight of the wire.
~ 0.09%, Si; 0.2-1.0%, Mn; 0.3
.About.3.0%, Ni; 0.2 to 5.0%, and Cu; 0.1 to 1.5%, Cr; 0.1 to 3.0%, M
o; 0.1-2.0%, V; 0.1-0.7%, Nb;
It is characterized in that it contains any one or more of 0.01 to 0.05%, and that the parameter T determined by the following formula (1) by the weight% of each element occupying in the wire is less than 620. MAG welding flux-cored wire with less welding deformation. T = 630.0-476.5C + 56.0Si-19.7Mn-16.3Cu-26.6Ni-4.9Cr + 38.1Mo + 124.8V + 136.3Ti-19.1Nb + 198.4Al + 3315.0B ... (1 )

Furthermore, iron powder; 4.0-12.0%, arc stabilizer; 0.0 with respect to the total weight of the wire on the steel shell.
5 to 1.1%, slag forming agent other than arc stabilizer;
A mag-welding flux-cored wire filled with a metal powder-based flux containing 3 to 3.5%, wherein C: 0.03 to 0.15%, Si: 0.
2 to 1.0%, Mn; 0.3 to 3.0%, and Cu: 0.1 to 1.5%, Cr: 0.1 to 3.0.
%, Mo; 0.1 to 2.0%, V; 0.1 to 0.7%,
Nb: 0.01 to 0.50% of any one kind or two kinds or more, and the parameter T determined by the above formula (1) is 620 depending on the weight% of each element occupying in the wire.
MAG welding flux-cored wire with less welding deformation. Further, it is characterized in that Ni: 0.2 to 5.0% is further contained in the total weight of the wire.

[0011]

The Ar ₃ transformation point temperature T can be roughly estimated by the equation (1) in the range of the cooling rate of the usual arc welding method. As is clear from this equation, γ-former Ni,
It is possible to lower the Ar ₃ transformation point by adding Mn, Cu, Nb and C in a predetermined amount. Generally, the lower the transformation temperature is, the larger the transformation expansion amount is, which reduces the residual welding deformation caused by the shrinkage during cooling. Therefore, it is considered that the increase of the transformation expansion amount contributes to the reduction of the welding deformation. . However, the transformation of supercooled austenite does not simply show a clear correspondence with the transformation expansion amount due to the appearance of the bainite structure, etc. Therefore, the Ar ₃ transformation point temperature was focused here.

On the other hand, the amount of angular deformation generated in the T-shaped fillet welded joint has a clear relationship with the Ar ₃ transformation point temperature of the welding material as shown in FIG. 1, and the lower the transformation point temperature, It has been found that the amount of angular deformation that occurs is a small value.
This fact seems to be because the transformation temperature becomes low and the transformation expansion amount becomes large, and the shrinkage due to solidification is eliminated to some extent.

Further, in the case where the elements of Cu, Cr, Mo, Nb and V are contained in addition to the component system of Ni, Mn and C which are γ-formers, the value of the phase transformation temperature T given by the equation (1) is It has been found that the amount of angular deformation that occurs is small even when the value is slightly higher than when the latter is not included.
It is considered that this fact is because the elements Cr, Mo, Nb, and V all increase the mechanical strength at the temperature at which the transformation occurs to restrain the deformation. From the fact that the buckling strength against a compressive load decreases due to welding deformation, and the dimensional accuracy in joint manufacturing is considered, the transformation point temperature that gives the limit value of the angular deformation amount that does not require the above-mentioned deformation correction work is Cr, As a result of considering the effect of adding elements of Mo, Nb, and V, the relational expression (T <620) of the present invention was found.

The present invention is based on a typical welding cooling rate,
The Ar ₃ phase transformation temperature T of various components contained in the welding material is given by the equation (1). T = 630.0-476.5C + 56.0Si-19.7Mn-16.3Cu-26.6Ni-4.9Cr + 38.1Mo + 124.8V + 136.3Ti-19.1Nb + 198.4Al + 3315.0B ... (1 )

Further, by studying the relationship between the phase transformation temperature of the welding material and the amount of angular deformation that occurs, the relationship of equation (2), which is judged to be a sufficiently small amount of deformation that occurs practically, To give. T <620 ····· (2)

The specific values of the constituent elements of the welding wire in the present invention and the addition amounts thereof will be described below (the value of the addition amount of elements is% by weight based on the total weight of the wire).

C has the effect of lowering the transformation point, and 0.03% or more is required also from the viewpoint of strength. However, excessive addition leads to an increase in hot crack susceptibility of the weld metal and a decrease in toughness, so the upper limit is made 0.15%, preferably 0.09%.

Si has the effect of reducing the amount of oxygen in the weld metal and improving the bead shape, and at least 0.2
% Or more is required. Excessive addition lowers the toughness of the weld metal, so the upper limit must be 1.0%.

Mn has a large effect of lowering the transformation point, and assists Ni by at least 0.3% or more, preferably 0.8%.
% Or more must be added. Excessive addition leads to an increase in hot crack susceptibility of the weld metal and a decrease in toughness, so the upper limit must be 3.0%.

Ni is a typical gamma former and has a great effect of lowering the transformation point. In order to sufficiently obtain the effect of lowering the transformation point, it is necessary to add at least 0.2%, preferably 3.0% or more. If the addition amount is too large, the cost will increase, and in the case of offshore structures, for example, the weld metal will become too noble electrically, forming a local battery and selectively corroding the heat affected zone. Will be done. Therefore Ni
The upper limit of the amount added should be 5.0%.

The above elements are elements which are effective in lowering the transformation point, and in addition to these elements, Cu, Cr, and M, which increase the strength in the temperature range where transformation occurs,
It contains one or more elements of o, V and Nb.

Since Cu also has the effect of lowering the transformation point, it is necessary to add Cu in an amount of 0.1% or more. Excessive addition leads to a decrease in the toughness of the weld metal, so the upper limit is made 1.5%.

In order to produce the effect of increasing strength by Cr, it is necessary to add 0.1% or more. If the added amount is too large, the room temperature strength and hardness increase and the toughness deteriorates,
Further, since the weldability also decreases, the upper limit is made 3.0%.

Regarding Mo, the strength of Mo.
It is necessary to add 1% or more. Since the effect of raising the transformation temperature is great, the upper limit is made 2.0%.

Also with respect to V, addition of 0.1% or more has the effect of increasing strength. An excessive addition causes the toughness to deteriorate due to an increase in strength and hardness at room temperature and raises the transformation temperature, so the upper limit is made 0.7%.

With respect to Nb, addition of 0.01% or more has the effect of increasing strength. Since an excessive addition causes an increase in normal temperature strength and hardness, the upper limit is 0.50%.
And However, in order to prevent further deterioration of toughness,
It is preferably set to not more than 05%.

The above-mentioned elements may be added to one or both of the outer coat and the flux. The above is the means for reducing the amount of angular deformation that occurs during welding, but the present inventors have found that the penetration at the time of welding is shallower, the finished bead shape after welding is improved, and the efficiency is further improved. We also considered the improvement of the welding speed. As a result, the use of iron powder can improve the bead shape after welding. Furthermore, the amount of spatter generated during welding can be reduced and the deposition rate can be significantly improved. In the present invention, based on the above characteristics, the content rate of each component is determined as follows.

Iron powder: 4.0 to 12.0% Iron powder must be added in an amount of 4.0% or more in order to sufficiently achieve the effect of improving the welding efficiency, which is the characteristic of the metal powder-based flux-cored wire. If it is less than 4.0%, the welding speed of the wire becomes slow and the welding efficiency is lowered. On the other hand, if it exceeds 12.0%, other components in the flux, such as a slag forming agent,
Absolute amounts of deoxidizing agents, alloying agents, etc. are insufficient to deteriorate the bead shape, and a predetermined strength cannot be obtained. Therefore, iron powder
It is set to a range of 4.0 to 12.0%.

Arc stabilizer: 0.05 to 1.1% In the wire of the present invention containing iron powder as a main component, addition is essential in order to stabilize the arc and reduce the amount of spatter generated. If the amount of the arc stabilizer is less than 0.05%, the effect as the arc stabilizer cannot be obtained. On the other hand, when the content exceeds 1.1%, the arc length becomes extremely long, which hinders the droplet transfer property, resulting in frequent spattering. Therefore, the arc stabilizer is 0.05
˜1.1% range. The arc stabilizer mentioned here includes alkali metals such as Li, Na and K, and compounds thereof.

Slag-forming agent: 0.3 to 3.5% The slag-forming agent must be added in order to improve the bead shape within a range that does not lower the deposition rate. 0.3
If less than%, no bead shape improving effect is observed and 3.5
If it exceeds 0.1%, the amount of slag increases, defects such as slag entrainment occur, and welding efficiency decreases. Therefore, the slag forming agent excluding the arc stabilizer is 0.3 to 3.5%. As the slag forming agent, TiO ₂ , SiO ₂ , ZrO ₂ ,
Oxides such as Al ₂ O ₃ , MnO, and MgO, CaF ₂ , B
Fluorides such as aF ₂ , MgF ₂ and LiF and CaCO
Carbonates such as ₃ , BaCO ₃ can be used.

Although the above are the essential components, it is desirable that the flux filling rate of the wire according to the present invention is 8 to 20%. The reason for this is that if the filling rate exceeds 20%, disconnection troubles frequently occur during wire drawing and productivity deteriorates, and if it is less than 8%, the stability of the arc is impaired. There is no restriction on the cross-sectional shape of the wire, and when the wire has a small diameter of 2 mm or less, it is generally a relatively simple cylindrical shape. Further, it is also effective to subject the surface of the seamless wire to a plating treatment such as Cu.

[0032]

EXAMPLES Table 1 shows the chemical composition of the steel shell used for the wire of this example. Table 2, Table 3, Table 4, and Table 5 show the flux compositions of the wire of the present invention used in Examples and the comparative wire, and (1)
The Ar ₃ point (T) calculated by the formula is shown. The wire diameter is 1.2 mm in each case. As the steel plate, a JIS G3106 SM400B material was used. This steel sheet was subjected to one-pass welding on both sides under the welding conditions shown in Table 6 in order to manufacture a T-shaped fillet welding test body shown in FIG. In the figure, reference numerals 1 and 2 denote a base metal to be fillet welded, 3 denotes a restraint portion (2 places), and 4 (4 places) a tack welded portion.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

[Table 4]

[0037]

[Table 5]

[0038]

[Table 6]

After welding, after measuring the amount of angular deformation δ,
The longitudinal section of the weld metal was observed and the presence or absence of cracks in the weld metal and the bead shape were determined. As a comprehensive evaluation, the values of w and d shown in FIG. 3 are used as the magnitude of the angular deformation amount δ (3).
The value of δ calculated by the formula is less than 1.2 × 10 ^-2 radian and no occurrence of cracks is observed, and the bead shape,
Those with excellent appearance were passed, and others were rejected. δ = 0.5 sin ⁻¹ (2d / w) ···· (3)

Table 7 shows the test results. As is clear from Table 7, all the welded joints made of the wire according to the present invention have a small amount of angular deformation, no occurrence of cracks, and good bead shape and appearance. On the other hand, the comparative wire No. 21,2
No. 2 is the case where the parameter T is 620 or more or the element group that increases the high temperature strength is not added, and No. As shown in 22, even if the value of T is 533, the angular deformation becomes large. No. In Nos. 23, 25, 26, 27, and 28, since the hardenable elements were high, the weld metal hardened and cracks occurred. N
o. In No. 24, since the arc stabilizer was not added, the droplet transferability was poor, and spatter frequently occurred during welding. N
o. In Nos. 29 and 30, the amount of iron powder added was too small or too large to be outside the range of the present invention, and the bead appearance and shape after welding were poor. In addition, the T value exceeds 620, the amount of angular deformation is large, and the test fails.

[0041]

[Table 7]

Although SM400B material was used in this experiment, the effect of reducing the amount of angular deformation of the wire is not lost even if the type of steel sheet is changed because the base material is diluted.
Further, even if the shield gas composition is changed to Ar—CO ₂ mixed gas and used, in the case of the wire according to the present invention, good performance can be obtained in the angular deformation amount without affecting the performance.

[0043]

Although the welded joint is an essential technical element in the production of steel structures, the prevention of welding deformation and its correction technology are often obtained empirically. Recently, welding deformation reduction technology has been demanded from the viewpoint of streamlining the design of steel structures and aesthetics, etc., and at the same time, supplies welding materials with less deformation that occurs due to lack of skilled welders and automation of welding process. It was desired to do. According to the present invention, the welding deformation is reduced in the automatic and semi-automatic welding processes without deteriorating the various characteristics of the joint portion, and the work for correcting the deformation can be omitted within a range where there is no economical problem. It is possible to achieve the remarkable effect.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the transformation temperature and the amount of angular deformation.

FIG. 2 is a diagram showing an outline of a T-shaped fillet welded joint.

FIG. 3 is a diagram illustrating the definition of an angular deformation amount δ.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiro Kojima 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation Corporate Technology Development Division

Claims (3)

[Claims] 1. A steel shell with iron powder based on the total weight of the wire;
4.0-12.0%, arc stabilizer; 0.05-1.1
%, Slag forming agent other than arc stabilizer; 0.3 to 3.5
% Of the total wire weight, wherein C is 0.03 to 0.09% Si and 0.2 to 1.0% Mn. 0.3 to 3.0% Ni; 0.2 to 5.0% contained, and further Cu; 0.1 to 1.5% Cr; 0.1 to 3.0% Mo; 0.1 % To 2.0% V; 0.1 to 0.7% Nb; 0.01 to 0.05%, and 1% by weight or more of each element in the wire. Accordingly, the parameter T determined by the following formula (1) is less than 620. T = 630.0-476.5C + 56.0Si-19.7Mn-16.3Cu-26.6Ni-4.9Cr + 38.1Mo + 124.8V + 136.3Ti-19.1Nb + 198.4Al + 3315.0B ... (1 ) 2. A steel shell with iron powder based on the total weight of the wire;
4.0-12.0%, arc stabilizer; 0.05-1.1
%, Slag forming agent other than arc stabilizer; 0.3 to 3.5
% Of the total wire weight, which is a mag-weld flux-cored wire filled with a metal powder-based flux containing C: 0.03 to 0.15% Si; 0.2 to 1.0% Mn 0.3-3.0% is contained, Cu; 0.1-1.5% Cr; 0.1-3.0% Mo; 0.1-2.0% V; 0.1 .About.0.7% Nb; 0.01 to 0.50% of any one kind or two or more kinds, and a parameter T determined by the following formula (1) by the weight% of each element occupying in the wire. Is less than 620, and a mag-weld flux-cored wire with little welding deformation. T = 630.0-476.5C + 56.0Si-19.7Mn-16.3Cu-26.6Ni-4.9Cr + 38.1Mo + 124.8V + 136.3Ti-19.1Nb + 198.4Al + 3315.0B ... (1 ) 3. The mag-weld flux-cored wire with less welding deformation according to claim 2, further containing Ni: 0.2 to 5.0% with respect to the total weight of the wire.