JPH02268994A - Submerged arc welding wire and flux for corrosion resistant refractory steel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a steel with excellent corrosion resistance and fire resistance (hereinafter referred to as corrosion-resistant fire-resistant steel) used for architecture, civil engineering, marine structures, etc. in the marine environment. related to welding materials. More specifically, in addition to obtaining a weld metal that is resistant to corrosion in an environment near the coast including the sea (hereinafter referred to as a beach area) or a seawater splash zone (hereinafter simply referred to as a splash zone) and has excellent high temperature resistance, This invention relates to a submerged arc welding wire and flux with good welding workability.

[Prior Art] Conventionally, among various steel structures used in the fields of architecture, civil engineering, and marine structures, the surfaces of steel members of buildings, offices, and residences, which are closely connected to daily life, have been known to be exposed to heat in the event of a fire. Fireproof coating is applied to prevent temperatures from exceeding 350°C.

This is because the yield strength decreases to 60 to 70 tons at room temperature at about 350°C, which may cause the building to collapse.

Incidentally, recently, fire-resistant steel is being developed that can ensure a yield strength of 70 or higher at a higher temperature of 600° C. than at room temperature, and can be uncoated or lightly coated, thereby reducing construction costs. Furthermore, non-conventional steel materials with added weather resistance are also being considered.

In this case, it is important to have excellent corrosion resistance, especially for steel structures in coastal areas and splash zones where the influence of salt is large.

However, there is no conventional submerged arc welding material used for corrosion-resistant fire-resistant steel having such characteristics. For this reason, even if a structure is made of corrosion-resistant fire-resistant steel, if it is constructed using conventional submerged arc welding materials, the welded part must be welded with slag wool, as in the case of conventional steel, in order to prevent thermal damage in the event of a fire. It is necessary to carefully apply fireproof coatings such as spraying using rock wool, glass wool, etc. as a base material, spreading felt material, and covering with fireproof mortar, resulting in high construction costs. In addition, corrosion occurs due to the influence of salt, and the service life is significantly shortened, so it is necessary to increase the thickness of the steel plate in advance, and to apply strict anti-corrosion measures such as painting, which increases construction costs.

By the way, from the viewpoint of high-temperature properties, there are submerged arc welding materials for CrMO steel, and examples of welding wires containing a large amount of Cr are disclosed in JP-A-53-95146, for example. JP-A-59-4994 discloses a flux with a specific basicity intended for use in combination with a high Cr-containing wire.

On the other hand, in Japanese Patent Publication No. 60-48279, Cu-Cr
- Examples of wires and fluxes for submerged arc welding of highly weathering steel plates to obtain Ni-based weld metals are disclosed.

[Problems to be Solved by the Invention] In the well-known welding material for highly weathering steel sheets that obtains a Cu-Cr-Ni based weld metal component, there are three problems in improving high-temperature properties.

In addition, although it exhibits sufficient weather resistance in inland natural environments, there is an important problem in that it has poor corrosion resistance in coastal areas and splash zones.

On the other hand, although welding materials for Cr-Mo steel have good high-temperature properties, there is a problem in improving corrosion resistance.

Further, the toughness of the weld metal is ensured by performing SR after welding, and the toughness as welded is very poor. Therefore, it cannot be used for architectural purposes.

Furthermore, the wire for Crt-MolI4 is very expensive because it contains a large amount of alloy components, and there is a drawback that there is no cost advantage in omitting the fireproof coating.

It should be noted that the conventional flux for Cr-Mo steel has poor high-temperature properties when combined with the conventional unshu wire used in building structures.

The purpose of the present invention is to create a weld metal that maintains sufficient weather resistance in inland natural environments, is resistant to corrosion in marine environments, has excellent high-temperature properties at 600°C, and has good impact toughness as welded. It is an object of the present invention to provide a corrosion-resistant, refractory unshu submerged arc welding wire and flux that have good welding workability.

[Means for Solving the Problems] The present invention overcomes the above-mentioned problems and achieves the objects,
Weight t, C: 0.01-0.15%, Si:
0.5'4 or less, Mn: 0.4-2.5'! ,
P: 0.05% or less, Cu: 0.1-0.6%
, Ni: 0.4H or less, Mo: 0.06-0
．． 80%, Nb: 0.003-0.030%, the remainder consists of Fe and inevitable impurities, 0I
IO+20Nb) :0. The present invention is a corrosion-resistant refractory unshu submerged arc welding wire characterized by a resistance of +5 to 1.25.

Further, in the present invention, the weight t is 5i02: 5-35*
, MgO: 5-35$, CaO: 5-25%, F
BI~g*, P: 0.1% or less, Cu: 0.1~
0.8%;, Ni: 0.6! Below ji, Mo: 0
．． 1~! , 0%; , Nb: 0.01-0. +4
11; (Mo+10Nb): 0.3-2
．． This is a corrosion-resistant, refractory, unshu submerged arc welding flux characterized by a zero corrosion resistance.

[Function] In order to obtain corrosion-resistant and refractory submerged arc welding wire and flux, the inventors first investigated existing welding materials and found that the yield strength of the weld metal at 600°C satisfies 70 zero or more at room temperature. It was concluded that the materials used were difficult to put into practical use.

That is, wire or flux that can provide the necessary high-temperature proof strength has large amounts of expensive alloying elements added to it, increasing the cost of welding materials, which offsets the construction cost reduction effect achieved by reducing the fireproof coating.

Furthermore, unlike Gr-Mo steel, which is originally used at high temperatures,
Welded metals containing large amounts of alloying elements, which are used in building structures that are intended for use at room temperature, have too high a strength, resulting in problems with their cracking resistance, and their as-welded toughness is extremely poor. It was also revealed.

On the other hand, as a result of studying weld metal components that can obtain excellent high-temperature properties and, at the same time, excellent corrosion resistance in coastal areas and splash zones, we found that the content of Cr, which is a component that improves high-temperature properties and weather resistance in inland natural environments. found that the corrosion resistance was extremely poor. Therefore, as a result of further detailed examination of the components, the wire and flux of the present invention were obtained.

The component elements and their addition M in the present invention will be explained below.

First, the welding wire has sufficient high-temperature resistance with the combined addition of Mo and fine fiNb, does not substantially contain Cr, and is suitable for use in coastal areas and splash zones by adding Cu and regulating C and Ni. It is characterized by suppressing the occurrence of corrosion caused by salt.

Mo and Nb form fine carbonitrides, and Mo increases high-temperature yield strength through solid solution strengthening, but it is difficult to obtain a 70% yield strength at 600°C by adding MO or Nb alone. In other words, the minimum amount of each component that produces a composite effect is 0.06! lk, Nb is 0
, 003. On the other hand, if the amounts of Mo and Nb are too large, the strength at room temperature becomes too high and the toughness deteriorates, so the upper limit of the content of Mo and Nb is 0.8 each.
0%, 0.030'! Is it necessary to do so?

Furthermore, even if Mo and Nb are each within the above specified values, if the total amount of these components is too small, the target high temperature proof strength cannot be obtained. Moreover, even if the content is excessive, the toughness of the weld metal may deteriorate, so it is necessary to limit the content of Mo and Nb in the wire. In other words, it was found that in the wire, Nb has an effect equivalent to about 20 times the addition amount of MO;
By setting it in this range, it is possible to obtain adequate room temperature strength and good toughness while obtaining sufficient high temperature yield strength of the weld metal. Note that the addition of Mo and Nb also contributes to improving weather resistance in inland natural environments.

Next, in order to improve corrosion resistance, it is necessary to contain CIJ in a range of 0.1 to 0.6*. When Cu is less than 0.1, corrosion occurs, and when Gu exceeds 0.6, the toughness of the weld metal deteriorates.

Although it is better to have a small content of C in terms of corrosion resistance, it is necessary to ensure room temperature strength and to exhibit the effect of adding Mo and Nb, and for that purpose, 0.01!
Ii is the lower limit. In addition, if it exceeds 0.15%, hot cracking susceptibility increases and toughness deteriorates.
The upper limit of C is 0.15%.

Regarding Si, it can be added to the weld metal from the welding flux to be combined, and there is no particular lower limit specified for the welding wire. However, 0. If the Si content exceeds 0.5%, the toughness of the weld metal decreases, so the content of Si must be 0.5* or less.

Mn is an essential element for ensuring strength and toughness, and it is necessary to contain 0.4 or more. On the other hand, 2.5t
If it exceeds Mn, the susceptibility to hot cracking increases and the toughness deteriorates, so the upper limit of Mn is set to 2.5t.

Although it is desirable to include P from the viewpoint of corrosion resistance, it increases hot cracking susceptibility and is also a component that particularly deteriorates the toughness of weld metal, so only an upper limit is specified.
．． Limited to 05'4 or less.

Finally, Ni is preferable for adding weather resistance in inland natural environments, but it is a component that should not be added in large amounts for corrosion resistance in coastal areas and splash zones. Therefore, only the upper limit of Ni was specified, and the content was set to 0.40% or less, which is a content that does not significantly deteriorate the corrosion resistance.

The components of the wire of the present invention are as described above, with the remainder consisting of Fe and unavoidable impurities.

Next, the flux of the present invention will be explained in detail.

As with the above-mentioned wire, it is important to first add Mo and Nb in flux as well.

This combined addition provides a weld metal with sufficient high-temperature yield strength, and the addition of Mo or Nb alone is insufficient. In order to obtain this combined effect, MO should be at least 1% O, and Nb should be 0.1% or more, based on the total weight of the flux. More than anti-static is necessary. Furthermore, if Mo and Nb are in excess, the room temperature strength becomes too high and the toughness deteriorates, so Mo needs to be 190* or less and Nb needs to be 0.14 or less.

Further, even if Mo and Nb are each within the above specified values, if the total of these components is too small, the target high temperature proof strength cannot be obtained. Furthermore, even if the content is excessive, the toughness of the weld metal may deteriorate, so it is necessary to limit the total content of No and Nb. In other words, it was found that Nb has an effect equivalent to about 10 times the addition amount of Mo in the flux, and by setting Mo + 10Nb in the range of 0.3 to 2.0, sufficient high-temperature proof strength of the weld metal can be achieved. It is possible to obtain appropriate room-temperature strength and good toughness. As in the case of the wire described above, the addition of Mo and Nb also contributes to improved weather resistance in inland natural environments.

To add MO or Nb to the flux, metal powder or a compound containing these elements, such as oxide or nitride, is used. Note that the numerical values specified above indicate values converted to MO or Nb.

In order to improve corrosion resistance, which is another property aimed at by the flux of the present invention, substantially no C is contained.
The same is true for wires.

It is necessary to contain 0.1% or more of Cu to improve corrosion resistance. However, since the toughness of the weld metal deteriorates, the upper limit of Cu is set to 0.8 t.

Addition of P is also effective in improving corrosion resistance, but it is also a component that not only increases the sensitivity of the weld metal to high-temperature sidewalls, but also particularly deteriorates the toughness of the weld metal. Therefore, P specifies only the upper limit and is 0
．． Limit to 1% or less.

Although Ni is preferable for adding weather resistance in inland natural environments, it is a component that should not be added in large amounts for corrosion resistance in coastal areas and splash zones. Therefore, only the upper limit of Ni was specified, and the content was set to 0.6 or less, which is a content that does not significantly deteriorate the corrosion resistance.

Next, Sin is a component necessary for adjusting the viscosity of the slag and obtaining a good bead appearance. When Sin is less than 5, the viscosity is too low, resulting in rough bead waveforms and non-uniform bead widths. On the other hand, when Sin exceeds 35, the amount of oxygen in the weld metal increases and the toughness decreases.

SjO is added as an ore or a composite containing Sin, such as silica sand, wollastonite, chamotte, zircon sand, and olivine sand.

Furthermore, MgO is a necessary component to enable highly efficient welding using a large current due to its effect of increasing the slag melting point. To obtain this effect of MgO, a minimum of 5t is required, and if it is less than 5%, the bead waveform becomes rough. On the other hand, M
If more than 35 t of gO is added, uneven bead toes and pock marks will occur. MgO is added as an ore or composite containing MgO, such as magnesia clinker and olivine.

Further, CaO is an effective component for obtaining good toughness of weld metal, and a minimum content of 5 is required. However, CaO is 2
If it exceeds 5%, the melting point of the slag becomes too high and pock marks occur. CaO is added by carbonate lime, wollastonite, etc.

Finally, as an essential component, F is necessary to reduce the amount of oxygen in the weld metal and obtain good toughness, and addition of 1 or more is effective. On the other hand, if more than 8 F is added, the melting point of the slag becomes high and pock marks occur.

Addition of F to the flux includes CaF, AlF2.
Mgl'2.8aF2. Metal fluorides such as Na, , ^fLF, etc. are used as raw materials.

The specific components in the flux of the present invention have been described above, but in addition to the above-mentioned components, the flux of the present invention can also contain ordinary flux components as appropriate.

First, MnO and An, 03 are added as components for adjusting the fluidity of the slag. However, MnO is 15
Exceeding the slag will deteriorate the slag removability, and 82゜03 is 2.
(If it exceeds n, the slag melting point becomes too high and undercuts tend to occur. For MnO, use manganese silicate, manganese carbonate, manganese dioxide, manganese slag, etc., and for A12o3, use an ore or synthetic material such as alumina or chamotte.

Next, Tin2 and B203 can be added as appropriate for the purpose of improving the toughness of the weld metal. Rutile, titanium slag, etc. are used for TiO2, and borax, colemanite, etc. are used for B203.

Other carbonates such as BaC0, Na2 (:0., Fe,
A.R.

Metals such as Ti, Ca, Mg, Mn, Si, and V can also be added as appropriate.

The flux of the present invention is produced by granulating each raw material using a suitable fixing agent such as water glass, alumina sol, silica sol, etc., and drying or firing at a high temperature.

[Example] Example: 1 First, wires (wire diameter: 4.8 mrlJφ) having 19 different compositions of l1l-1119 shown in Table 1 were produced. Among these, W1 to WIO are wires of the present invention, Wll to 1f19
is a comparative example. Next, a corrosion-resistant fire-resistant steel having the chemical composition shown in Table 2 was prepared with a groove shape (L, = 25 mm) shown in Fig. 1.
, θ1=20°, d=]6m+n), the third
Multilayer welding was carried out under the welding conditions shown in the table.

The slacks combined with these wires are 5i
02=40%, Mn0=20*, Ca0=2
5%. TiO□=l;.

It is a melting type flux (particle size 20 to D mesh) with a composition of F=5%;

After welding is completed under the above conditions, the position shown in Fig. 2 (e = 7
A tensile test piece and a Charpy impact test piece were taken from +nl11) and subjected to a mechanical test.

The 6 most important factors when evaluating the mechanical performance of weld metal
The yield strength at 00℃ is 33k, which is the minimum yield point at room temperature of 5M50 steel specified by 2MA of JrSG3106.
The goal was to secure 70% or more of gf/m+n2. In other words, it was determined that a yield strength of 23 kgf/mm2 or more is applicable for the weld metal at 600°C.

Also, from the surface of the steel plate after welding, the thickness is 3+nm, the width is 50mg+ in the direction of the weld line, and the length is 15mm so that the welded part is in the center.
A plate-shaped corrosion test piece of 0m11 was taken and JISZ237
A corrosion test of the welded portion was conducted according to the salt spray test method specified in Section 1. Regarding the evaluation of corrosion resistance, cases where no pitting corrosion occurred and the rusted area ratio was 50 or less were judged to be good. The corrosion test conditions were as follows:
4% NaCl aqueous solution per 80co+2, 2.0mM
/hr for 48 hours.

Table 4 shows the results of these tests. As is clear from these results, the weld metal made from the wire of the present invention has good room-temperature strength and high-temperature yield strength, and also has a high impact value and good corrosion resistance, whereas the comparative wire lacks high-temperature yield strength. Some of them have excessive tensile strength or low impact value at room temperature, and some have poor corrosion resistance, so they are not satisfactory as corrosion-resistant and fire-resistant tires.

F Example: 2 Next, bond fluxes having 14 compositions of Fl to F]4 shown in Table 5 were prepared. Of these, F1
~F6 is the inventive flux, and F7~P14 are comparative examples. These fluxes are produced by first blending and mixing the flux raw materials, then granulating them using water glass as a binding agent.
Firing was carried out at 400°C for 2 hours, and the temperature was 12 to 100.
The grains were sized into mesh.

The test method was to use corrosion-resistant fire-resistant steel with the chemical composition shown in Table 2.
The groove shape shown in Fig. 3 (t2 = 32 mm, θ2 = 70
°, θ3=60', a=1211110. b=
7o+m, c=13mm), one-pass welding was performed for each layer under the two-electrode welding conditions shown in Table 6.

The wire combined with these fluxes is W15 shown in Table 1, and this wire is Mn-based, which is used in conventional welding of structural steel.

After welding was completed under the conditions shown in Table F, a tensile test row and a Charpy impact gamma test piece were taken from the position shown in FIG. 4, and a mechanical test was conducted. In addition, the bead appearance was also inspected, and the results are shown in Table 7. In addition, as in the case of wire, it was determined that a yield strength of 23 kgf/mm2 or more of weld metal at 600° C. can be applied to the flux.

Also, from the surface of the steel plate after welding, the thickness is 3n+m, the width is 50+nm in the direction of the welding line, and the length is 15mm so that the welded part is in the center.
A plate-shaped corrosion test piece of 0n+m was taken and JrSZ237
Corrosion tests were conducted on the welds according to the salt spray test method specified in Section 1, and the results are shown in Table 7. Corrosion resistance was evaluated as good if pitting corrosion did not occur and the rusted area ratio was 50% or less. The corrosion test conditions were as follows: 4! j; 80% Naf4 aqueous solution
C[112] was sprayed at a rate of 2.0 mM/hr for 48 hours.

As is clear from the results shown in Table 7, all of the fluxes of the present invention have good high-temperature yield strength and normal-temperature strength, high impact values, good corrosion resistance, and no problems with bead appearance.

On the other hand, some comparison fluxes lack high-temperature yield strength, have excessive tensile strength at room temperature, have low impact values, and have inferior corrosion resistance. It is not satisfactory as a fireproof construction flux.

[Effects of the Invention] As described above, the wire and flux of the present invention can provide a weld metal with good high-temperature strength characteristics, impact toughness, and corrosion resistance, and also have good welding workability, so they can be used for corrosion-resistant fire-resistant steel. When applied to welded parts of structures, it is possible to significantly reduce construction costs related to corrosion-resistant and fire-resistant construction.

[Brief explanation of drawings]

1 and 3 are front views showing the welding groove shape used in the example, and FIGS. 2 and 4 are front sectional views showing the test piece sampling position.

Claims (1)

[Claims] 1. In weight%, C: 0.01 to 0.15%, Si: 0.5% or less, Mn: 0.4 to 2.5%, P: 0.05% or less, Contains Cu: 0.1 to 0.6%, Ni: 0.40% or less, Mo: 0.06 to 0.80%, Nb: 0.003 to 0.030%, and the balance is Fe.
and unavoidable impurities, and (Mo+20Nb): 0.15 to 1.25. A submerged arc welding wire for corrosion-resistant fire-resistant steel. 2. In weight%, SiO_2: 5-35%, MgO: 5-35%, CaO: 5-25%, F: 1-8%, P: 0.1% or less, Cu: 0.1-0. 8%, Ni: 0.6% or less, Mo: 0.1 to 1.0%, Nb: 0.01 to 0.14%, and (Mo+10Nb): 0.3 to 2.0. A submerged arc welding flux for corrosion-resistant fire-resistant steel.