JPS6233094A - Flux cored wire for welding - Google Patents

Abstract

PURPOSE:To improve the toughness of a weld zone, impact characteristic and welding workability by incorporating C, Si, Mn and TiO2 into a wire at a prescribed ratio each by the total weight of the wire and specifying the content of N. CONSTITUTION:The flux cored wire for gas shielded arc welding is composed, by the total weight of the wire, of <=0.20wt% C, 0.30-1.50wt% Si, 0.50-3.00wt% Mn and 2.50-8.50wt% TiO2. The content of N is specified to <=0.02wt%. The welding workability is thereby improved and the toughness and impact characteristic are improved.

Description

[Detailed Description of the Invention] 1. The present invention relates to a flux-cored wire for gas-shielded arc welding, which improves the toughness of the welded part, improves the impact characteristics, and also improves the welding workability. The present invention relates to a flux-cored wire for welding.

! Welding flux-cored wire, which has traditionally been used for Cot gas arc welding, has recently become popular because semi-automatic and automatic welding is easily possible.

Tuxed wire is made by winding a metal tube made of extruded tube or electric resistance welding tube onto a spool, placing the spool on a vibrating table, and filling the end with flux powder while vibrating the metal tube, or by winding the metal tube into a long shape. It is manufactured by sequentially bending the metal strip in the width direction and joining both ends by welding, brazing, etc. to form a metal tube, and filling the inside of the metal tube with flux powder during the formation of the metal tube. When the welding flag-cored wire obtained in this way is used for gas arc welding, especially semi-automatic welding and automatic welding, melting, refining, deoxidation, and solidification are performed in a small volume in which welding is limited to a very short time of several seconds. Therefore, the wire itself is required to have various properties such as good welding workability, slab formability, and arc stability, and these properties are achieved by adjusting the composition of the flux powder contained in the metal tube. It is something.

The flux component of conventional black-cored wire for welding is C-: 0.20w based on the total weight of the wire.
t% or less, Si: 0.30-1.50v 7%, M
n: 0.50-3.00wt%, Ti○2: 2.50
~8.5 (ht%) is known,
It has been put into practical use.

However, when welding is carried out using such conventional welding flux-cored wire,
There are problems in that the toughness of the welded part is insufficient, the impact properties are poor, and the standards of classification societies etc. may not be met, and welding workability is also not good. Ta.

the purpose The present invention solves the conventional problems as described above.

It is an object of the present invention to provide a flux-cored wire for welding that can improve the toughness of a welded part and improve impact characteristics, and at the same time improve welding workability.

Aoi! As a result of various studies to achieve the above object, the inventors of the present invention found that during welding, N contained in the wire sheath, welding flux, and voids in the flux is brought into the weld metal. The inventors discovered that this is a factor that deteriorates the welding process and also deteriorates welding workability, leading to the completion of the present invention.

That is, in the present invention, C: 0.2 with respect to the total weight of the wire.
0wt% or less, Si: 0.30-1.50wt
%, Mn: 0.50-3.00wt%, Tie,
: A flux-cored wire for gas shielded arc welding containing 2.50 to 50 wt% of B, characterized in that the N content is 0.020 wt% or less based on the total weight of the wire, and further , based on the total weight of the wire, Ti: 0.30 wt% or less, B:
0.010wt% or less, Ni: 3.00wt% or less, Cr: 2.00wt% or less, Mo: 1.00
wt% or less, AQ: 1.0wt% or less, Mg: 0
．． 5wt% or less, Nb: 0.5wt% or less, Ta
: 0.50 wt% or less of one or more selected from the group, and/or B i : Q, 02
0wt% or less, Pb: 0.020wt% or less, S
b: 0.20wt% or less, TQ: 0.02
0wt% or less, Al2O,: 1.0wt% or less, Zr
O,: 2.5 wt% or less, SiO2: 1.0 wt% or less, MgO: 0.5 wt% or less, NatO: 0.6
wt% or less, KiO: 1. Qwt% or less, F:
It contains one or more selected from the group below 0.5wt%.

As described above, the key point of the present invention is to keep the N content to 0.020 wt% or less based on the total weight of the wire, and by using the wire according to the present invention, mild steel, high tensile steel, low alloy steel, etc. When welding, even if the base metal to be welded contains N as an impurity, since the N content of the wire itself is kept low, the overall amount of N in the weld metal is low, and the classification society It has toughness that satisfies standards such as

The reason why the composition of the welding black-cored wire of the present invention is set in the above composition range is as follows.

C: 0.20% or less C is a necessary element to improve the strength of the weld metal, but if added in large amounts, the toughness will decrease, so Q, 20wt
% or less 6 Si: 0.30 to 1.50% Si has a deoxidizing effect, so it increases the cleanliness of the steel and improves the mechanical properties of the welded part. However, 0.30wt
If it is less than %, this effect will be small and
Since blowholes are likely to occur, the content was set at 0.30 wt% or more. In addition, if the amount of St is too large, the hardness of the welded part will increase and the mechanical properties will deteriorate, so the amount of St is set at 1.50 wt% or less.

Mn: 0.5 (1-3,00wt, %Mn has deoxidizing and desulfurizing effects, which increases the cleanliness of steel and improves the mechanical properties of the weld. However, O,SO%1
If it is less than 1%, this effect is small and
0.50wt as blowholes are more likely to occur.
% or more.

Furthermore, if Mn is too large, the hardness of the welded part increases, the viscosity of the molten metal increases, and the shape of the weld bead deteriorates, so the Mn content was set at 3.00 wt% or less.

TiO: 2.50 to 8.50 wt% Ti○2 acts as a slag forming agent, and when added in an appropriate amount, slag covers the entire circumference of the bead and improves the mechanical properties of the weld. However, if the amount of TiO2 is too small, the amount of slag formed will be small and will not cover the entire circumference of the bead.
That's all. In addition, if the amount of Tie is too large, the amount of slag formed will increase, the viscosity of the slag caught in the weld metal will increase, the surface of the bead will no longer be covered uniformly, and the removability of the slag will decrease. 8.
．． The content was set to 50 wt% or less.

N: 0.020 tst% or less As mentioned above, N is a component that has a significant negative effect on the toughness and impact resistance of the weld metal, and also has a negative effect on welding workability, so the content was set at 0.020 wt% or less.

Ti: 0.30wt% or less, B: 0. O1O%
Ij% or less, Nb: 0.5wt% or less, T a: 0
．． 50wt% or less, Al: 1.0wt% or less, M g
: 0.5wt% or less, Ni: 3.00i+t%
Below, Cr: 2.00wt% or less, Mo: 1
．． 00 wt% or less, each of the above components makes the crystal grains of the weld metal finer and contributes to improving the mechanical strength. Of these, Ti
,B.

Nb, Ta, AQ, and Mg act as deoxidizers to improve the cleanliness of the welded area. Further, Ni, Cr, and Mo are additives for improving the strength of the weld metal. These components depend on the amount of the components in the base material, but if they exceed a predetermined amount, their effects will become saturated.

B i: 0.020wt%e or less, Pb:
0.020wt% or less, Sb: 0.20wt% or less, TQ: 0.020wt% or less, AQ,
O@: 1.0wt% or less, ZrO2: 2.5w
t% or less, SiO2: 1.0wt% or less, MgO:
0.5wt% or less, Na2O: 0.6wt% or less, K
tO: 1.0 wt% or less, F: 0.5% or less. Each of the above components is effective in improving welding workability. Among these, Bi, Pb, and Sb.

TQ improves the peelability of slag, Afl2O, ZrO, Sin, MgO adjusts the viscosity of slag and diversifies welding work postures, and Na, ○, and 20. F stabilizes the arc and contributes to improving welding workability. However, when the amount of each component exceeds the above range, the effect of each component contributing to welding workability is lost.

In the present invention, it goes without saying that an appropriate coating material may be formed on the wire surface within the above-mentioned composition ranges.

Examples are shown below.

Example 1 Blacks component is C: 0.0 with respect to the total weight of the wire
8wt%, Si: 0.80wt%, Mn: 2
．． 50iit%, TiO2: 6.00wt%,
Using flux-cored welding wires of 1 and 2+u++φ with various N contents, multi-layer welding was performed on a 20 mm thick 5S-41 plate having a groove shape as shown in Fig. 1 under the following welding conditions. Impact test pieces were taken from the positions shown in FIG. 1 and tested for absorbed energy (vEo).

[Welding conditions]

Welding current 280A arc voltage
30V Welding speed 40cm/win Shielding gas CO: 20Q/min Wire protrusion length
25IIIIII The results are shown in FIG. As is clear from Fig. 2, the absorbed energy increases as the N content increases.

When the value of energy (v E o) decreases and the N content in the total weight of the wire exceeds 0.020 wt%, vE.

It can be seen that the value is less than 5.5, which deviates from the ship classification standard.

Example 2 Welding flux-cored wires (1, 2 mmφ) according to the present invention having wire compositions (wt%) shown in Table 1 and welding flux-cored wires (1, 2 mφ) for comparison
Welding workability and the value of absorbed energy (v E o) when welding was conducted using the welding method (mφ) were investigated.

Welding workability is evaluated by comprehensively considering slag formation, peelability, welding work posture, arc stability, bead appearance, etc. Good is 0 degrees, poor is X, and in between The value is shown in the table as Δ. The absorbed energy was measured using a base material having the same groove shape as in Example 1, welding under the same welding conditions, and collecting impact test pieces in the same manner, and the results are shown in the table.

Table 1 (a) Table 1 ω) Table 1 (c) Table 1 (d) From Table 1 above, the welding franked wire according to the example of the present invention has good welding workability and Although the absorbed energy (vEo) satisfies the ship classification standard, it is clear that the comparative examples are inferior to the inventive examples when welding workability and absorbed energy are comprehensively judged.

Effects As described above, the present invention provides a flux-cored wire for welding, which contains C, Si, Mn, and TiO2 in predetermined amounts based on the total weight of the wire, and has a N content of 0.020 wt% or less. and further thereto, Tin B,
At least one or two or more selected from the group of Ni* Cr, Mat Al, Mgt Nb, and Ta,
and/or Bi, Pb, Sb, Tff.

Al2O,,ZrO,,5in2. MgO, Na2O.

Since it is a flux-cored wire for welding that contains at least one kind or two or more kinds selected from the group of K2O and F, it has good welding workability, improved toughness, and impact properties that fully satisfy the ship classification standards. It has the effect of increasing the value to

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a welding state in an example of the present invention and showing the sampling position of an impact test piece. FIG. 2 is a diagram showing the relationship between the N content in the total weight of the wire and the absorbed energy (v E o).

Claims (1)

[Claims] 1. C: 0.20 wt% or less, S based on the total weight of the wire
i: 0.30-1.50wt%, Mn: 0.50-3.
In a flux-cored wire for gas shielded arc welding containing 00wt% and TiO_2: 2.50 to 8.50wt%, the N content is 0.02% based on the total weight of the wire.
A flux-cored wire for welding characterized by having a content of 0 wt% or less. 2. Ti: 0.30wt% or less based on the total weight of the wire,
B: 0.010 wt% or less, Ni: 3.00 wt% or less, Cr: 2.00 wt% or less, Mo: 1.00 wt% or less, Al: 1.0 wt% or less, Mg: 0.5 wt% or less,
The flux-cored wire for welding according to claim 1, which contains one or more selected from the group of Nb: 0.5 wt% or less and Ta: 0.5 wt% or less. 3. Based on the total weight of the wire, Bi: 0.020wt% or less, Pb: 0.020wt% or less, Sb: 0.020wt
%, Tl: 0.020wt% or less, Al_2O_3:1
．． 0 wt% or less, ZrO_2: 2.5 wt% or less, Si
O_2: 1.0wt% or less, MgO: 0.5wt% or less, Na_2O: 0.6wt% or less, K_2O: 1.0w
Claim 1 containing any one or more selected from the group of t% or less, F: 0.5wt% or less
The flux-cored wire for welding according to item 1 or 2.