JPS591514B2 - Ni-based coated arc welding rod - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a Ni-base coated arc welding rod, and more particularly to a Ni-base coated arc welding rod that has excellent tensile properties and bending performance of weld metal.

Ni-based coated arc welding rods are applicable to Ni and high-Ni alloys, which have excellent corrosion resistance, oxidation resistance, heat resistance, and low-temperature toughness. The range of applications is expanding, including welding of %Ni steel, welding of dissimilar materials such as stainless steel and high-nickel and low-alloy ferrite steel, and overlay welding.

On the other hand, by industry, it is expected that the demand for Ni-base coated arc welding rods will continue to expand, as they are widely used in petrochemical, textile, nuclear power, chemical machinery, and low-temperature storage tank fields.

Ni-based coated arc welding rods can be broadly classified into Inconel type (Ni
-Nb for -C, -Nb-Mo' for Ni-C), bus alloy system (Ni-Mo, Ni-Mo-Cr), monel system (N
It can be classified as i-Cu) and Ni-based, but both are Ni-based.
The content is 60% or more.

However, in welding materials containing 60% or more of Ni, it is known that a trace amount of hydrogen contained in the weld metal has an adverse effect on its mechanical properties, and the smaller the amount, the less the adverse effect.

Therefore, in Ni-base coated arc welding rods, the moisture content of the coating material, which is the main hydrogen source for the weld metal, is strictly controlled, and in practical terms, it is usually about 0.10%. However, in order to control the moisture content in the coating material to 0.10%, it is necessary to carefully select the raw materials used, and in particular, hydrated minerals that are blended for the purpose of improving paintability cannot be used. However, even with welding rods in which the moisture content of the coating material is strictly controlled at 0.10%, side bending test of weld metal during welding of thick plates due to the recent increase in container size.
In experiments, microcracks occur along the grain boundaries of columnar crystals in the weld metal before plastic deformation occurs during 180-degree bending. Also,
In high heat input welding such as vertical welding, the columnar crystals of the weld metal grow coarsely, and the coarse crystal grains are sensitively affected by minute amounts of hydrogen, resulting in significant deterioration of mechanical properties. However, it is practically difficult to reduce the water content of the coating below this level, and we conducted research to see if there is a way to prevent deterioration of mechanical properties even if hydrogen is contained in the weld metal. . As a result, the deterioration of mechanical properties does not depend only on the amount of hydrogen, but also on the amount of oxygen, and reducing the amount of oxygen has a large effect on preventing deterioration of mechanical properties, and furthermore, adding a small amount of B New findings have been obtained indicating that the effect of suppressing the deterioration of mechanical properties due to hydrogen and oxygen is significantly large. The present invention was made based on the above new knowledge, and it is capable of sufficiently withstanding plastic deformation of 180 degree bending even in a single severe side bending test of welded metal of a thick plate, and is capable of high heat input welding. At the same time, it is no longer necessary to reduce the water content of the coating to the conventional level, which makes it possible to incorporate water-containing minerals such as talc and mica, which greatly improves coating properties and reduces the cost. This made it possible to provide welding rods.

That is, in the present invention, the core wire contains 60% or more of Ni, the oxygen content in the core wire is controlled to 0.02% or less, and 20 to 60% of metal carbonate is added to the total weight of the coating material. Furthermore, the total water content in the coating material is controlled to 0.5% or less, and one or both of the core wire or the coating material contains B, Al, Tl, and Si.
The amount of B is calculated as the effective amount of B shown below and is 0.001 to 0.01%, Al,
An N1-based coated arc welding rod characterized in that the total content of one or more of Ti and Si is 1 to 7% by weight of the core wire, or the above coating further contains 5% or less of hydrated minerals. It is a combination.

Effective B amount (to) = 0.5 x {B amount in core wire (to)} + 0
．． 15X {Amount of B in B alloy in coating material} +005
×{Amount % of B in B compound in coating material} The present invention will be described in detail below.

First, in the present invention, the amount of oxygen in the core wire is controlled, and B, Al, and Tl are added to one or both of the core wire and the coating material.
The most important point is that it contains one or more types of ,Sl, and this makes it possible to provide a welded part with good mechanical properties. That is, while keeping the amount of oxygen in the core wire low, Al, Ti, and S as deoxidizing elements
By containing one or more types of i, the amount of oxygen in the weld metal can be reduced and deterioration of mechanical properties can be suppressed.

Furthermore, by containing a small amount of B, it prevents the embrittlement of the weld metal, especially at the grain boundaries, caused by oxygen and hydrogen, and can also be used in weld metal of thick plates or weld metal with coarse grains due to high heat input welding. It is possible to obtain sound mechanical properties even in Next, the reasons for limiting each component will be explained. First, the mechanical properties of the weld metal obtained by combining the welding rod of the present invention with the base metal at low temperatures, room temperature, and high temperatures,
There is not much difference whether the alloying elements and deoxidizers necessary to ensure corrosion resistance etc. are added to the core wire or to the coating material.

However, in order to obtain a good weld metal with little segregation, at least most of the main component Ni is added to the core wire, and the metals added to the coating material are added to the core wire using the N1 base line for the purpose. The amount should be limited to the amount necessary to obtain the desired weld metal component. Therefore, in the present invention, in order for the weld metal to have Inconel-based, Hastelloy-based, Monel-based, and nickel-based components, the core wire must contain 6070 or more Ni. In addition, one type or two or more types of alloying elements such as Cr, MO, CuTiNb, etc. can be appropriately used in the core wire depending on each of the Inconel type, Hastelloy type, Monel type, and Nickel type.

Next, regulating the amount of oxygen in the core wire is a basic requirement of the present invention, and the amount of oxygen in the weld metal is proportional to the amount of oxygen in the core wire, and as the amount of oxygen in the weld metal increases, mechanical However, if the amount of oxygen in the core wire exceeds 0.02%, the amount of oxygen in the weld metal will increase and the mechanical properties will deteriorate significantly.

Therefore, the amount of oxygen in the core wire is limited to 0.02% or less. In addition, regarding the components of the coating material, by blending metal carbonate, the slag is given high basicity and P and S in the weld metal are reduced, and the hydrogen partial pressure is reduced by the CO2 gas produced by decomposition. The purpose is to improve the durability of the drop weld metal, and the amount of metal carbonate added must be 20% or more based on the total weight of the coating material. However, if it exceeds 6070, the fluidity of the slag deteriorates and a good bead shape cannot be obtained. Therefore, it is limited to 20-60%. The metal carbonates mentioned here include, for example, lime carbonate, barium carbonate, magnesium carbonate, manganese carbonate,
Refers to lithium carbonate or composite additives thereof. In addition, the moisture content of the coating material is controlled to reduce hydrogen in the weld metal and improve the microfracture resistance of the final solidified part, and the total moisture content of the coating material is kept below 0.5%. When controlled, the microcrack resistance of the final solidified portion is significantly improved due to the synergistic effect with the addition of B and deoxidizer elements such as Al, Ti, and Si.

However, if it exceeds 0.5%, the micro-cracking resistance deteriorates, so it is limited to 0.5% or less. Furthermore, in the present invention, one of the main requirements is to add an appropriate amount of B to one or both of the core wire and the coating material, which is highly effective in preventing deterioration of mechanical properties due to hydrogen and oxygen. but,
If the effective B amount is less than 0.001%, there is almost no effect;
If it exceeds 0.01%, high temperature cracks are likely to occur.

Therefore, the effective B amount is limited to 0.001 to 0.0170. As mentioned above, B can be added to either or both of the core wire and the coating material, but the effect of preventing deterioration of mechanical properties is controlled by the amount of B in the weld metal.
This is called the "effective amount of B," and when calculated using the following formula, a value that closely approximates the amount of B in the weld metal is obtained. Therefore, in the present invention, the following formula is used as the formula for calculating the effective amount of B. be. Effective amount of B (to) = 0.5 x {Amount of B in the core wire (to)} + 015 x {Amount of B in the B alloy in the coating (to)
}+0.05X {Amount of B in B compound in coating material (total)}
However, B alloy means an alloy of B and other metals such as Fe-B, SlB, etc., and B compound refers to Na2B4O7, Mn
B4O7・8H20, Li2B407・5H20 etc.
oxide, or KBF4, NaBF4, LiBF4
, MnBF4, BN, and other B compounds.

In addition, one of the main requirements of the present invention is to add one or more of Al, Tl, and Sl to one or both of the core wire and the coating material. The deoxidation reaction in the molten pool prevents moisture in the coating material and oxygen in the atmosphere from migrating into the weld metal, and prevents deterioration of mechanical properties due to an increase in the amount of oxygen in the weld metal. Effects can be obtained with one or more of Ti and Si, and these elements can be added to either or both of the core wire and coating material, but Al, Ti
If the total content of one or more of Al, Ti, and Si is less than 1%, there is almost no effect, and if it exceeds 7%, high-temperature cracking is likely to occur. The total amount is limited to 1 to 7% in terms of core wire weight ratio.
The desirable range of is 0.2 to 5% in terms of cord weight ratio, and 0.
．． If it is less than 2%, there is little effect, and if it exceeds 5%, high temperature cracks are likely to occur. Further, a desirable range of Ti is 0.2 to 5% by weight of the core wire, and if it is less than 0.2%, it has little effect, and if it exceeds 5%, high temperature cracks are likely to occur. Further, the desirable range of Si is 4% or less in terms of core wire weight ratio, and if it exceeds 4%, high temperature cracks are likely to occur. Furthermore, in the present invention, a hydrous mineral can be further blended into the coating material.

The purpose of these additions is to improve the coating properties of the coating, but 5% or less of the total weight of the coating is sufficient.
Even if it is added in excess of 5%, the effect will not be so great. Therefore, it is limited to 5% or less. Note that the hydrated minerals mentioned here refer to talc, mica, and the like. As described above, in the present invention, the amount of oxygen in the core wire is controlled, and B(!:.Al, Ti
It is clear that the greatest requirement is to take advantage of the synergistic effect of including the deoxidizer elements of , Sl, and that this improves the mechanical properties and microfracture resistance of the weld metal.

Here, referring to an example of the method for manufacturing welding rods, N
l Prepare the base wire and coating powder, mix the coating powder with water glass (sodium silicate aqueous solution, potassium silicate aqueous solution, etc.), coat the core wire, and dry and bake at about 400'C for about 1 hour. do.

Hereinafter, the effects of the present invention will be described in more detail based on Examples.

Example Table 1 shows the chemical composition of the sample core.

In the table, G indicates an O content outside the scope of the present invention. The core wire size is 4.01 in diameter! , the length was 350 pieces. Table 2 shows the compositions of welding rods made from these combinations of core wires and coating materials. The total water content of the coating material was measured using ASTM A316-64T. Table 3 shows the chemical composition of the weld metal of these welding rods. Table 4 shows the results of the tensile test of the weld metal. The welding method is JIS Z3224, and the welding conditions are: rod diameter 4.0 m, welding position downward, welding current 130 m.
~150A (AC), welding heat input is 10,000 to 15,000 J/(
1-JMoV! It is. Similarly, Table 4 shows the joint tensile test results when 9% Ni steel (25 mmt) was welded using some of the welding rods shown in Table 2. In addition, the welding conditions are: rod diameter is 4.0 m7!11 Welding posture is vertical position, welding current is 110 to 130 A (AC), welding heat input is 19,000 to 35,000 J/ClrL, The groove shape used was
The bead lamination procedure is as shown in Figure 2, and the joint tensile test piece is in accordance with JIS Z3l2l.

Similarly, Table 4 shows ASTMA-533 steel (75
The results of a side bending test of a welded part in which the main welding was performed using the same welding rod as that used for battering welding (mmt) are shown. The welding conditions for buttering welding of the groove surface and main welding of the joint are that the rod diameter is 5.01! , welding position is downward position, welding current is 150 to 170A (DC reverse polarity)
, welding heat input is 11,000 to 17,000 J/CI! It is L,
The groove shape is shown in FIG. 3, and the lamination procedure is shown in FIG. 4.

Here, the hatched areas in the figure indicate battering locations.
Similarly, Table 4 shows the results of a C-type jig restraint butt welding test using SM41B (25 mm thick). The test method was JIS Z3l55, and the welding conditions were: rod diameter was 4.0 m, welding position was downward, welding current was 140 A (AC), welding speed was 18 α/cm, and the groove shape was as shown in Figure 5. That's right. As is clear from these results, the welding rods of the present invention 1, 2, 4, 6, 7, 9, 10
,11,13,14161718202123
? 9?
Ra tsu tsu 25262
829313335ra tsu
La ) !
9 Is Kura 3639414244 and Ni 45 good? tsu
) ) It is clear that good results can be obtained.

[Brief explanation of drawings]

FIGS. 1, 3, and 5 are diagrams showing the groove shapes used in the example, and FIGS. 2 and 4 are diagrams showing the bead lamination procedure in the example.

Claims (1)

[Scope of Claims] 1. The core wire contains 60% or more of Ni, the amount of oxygen in the core wire is controlled to 0.02% or less, and 20 to 60% of metal carbonate is added to the total weight of the coating material. salt, the total water content in the coating is controlled to 0.5% or less, and one or both of the core wire or the coating contains B and one or more of Al, Ti, and Si. The amount of B is calculated as the effective amount of B shown below and is 0.001 to 0.01%, Al, Ti, Si
The total amount of one or more types is 1 to 7% by weight ratio of the core wire.
A Ni-based coated arc welding rod. Effective B amount (%) = 0.5 × {B amount in core wire (%)} + 0
．． 15 x {B amount (%) in B alloy in coating material} + 0.0
5 x {Amount % of B in B compound in coating material} 2 Core wire is 60
% or more of Ni, and the amount of oxygen in the core wire is 0.02% or more.
% or less, containing 20 to 60% of metal carbonate and 5% or less of hydrated minerals based on the total weight of the coating material, and further controlling the total water content in the coating material to 0.5% or less, and B and one of Al, Ti, and Si in one or both of the core wire and coating material.
Contains one or more species, and the amount of B is the effective B as shown below.
Calculated as amount, 0.001-0.01%, Al, Ti
, the total amount of one or more types of Si is 1 in terms of core weight ratio.
7% Ni-based coated arc welding rod. Effective B amount (%) = 0.5 × {B amount in core wire (%)} + 0
．． 15 x {B amount (%) in B alloy in coating material} + 0.0
5× {Amount of B in B compound in coating material (%)}