JPS60158998A - Bonded flux for submerged arc welding - Google Patents

Abstract

PURPOSE:To provide a titled flux which is hardly pulvesizable and maintains good air permeability and welding operability for a long period by preparing a flux which has a specific grain size distribution and bulk density and of which the particle strength by a prescribed measuring method is a specific value or below. CONSTITUTION:A flux consisting of 30-60wt% particles larger than >=840mu grain size and <=20wt% particles smaller than 210mu grain size and having 1.1- 1.8g/cm<2> bulk density and <=10 particle strength C is prepd. The strength C is the value obtd. from C=B-A by putting 50g the flux of which the constituting ratio (wt%) smaller than 210mu is A together with 9 pieces of steel balls having 8mm. diameter into a cylindrical vessel sized 40mm. inside diameter and 300mm. length and rotating the vessel for 60min at a speed of 30 revolutions/min around the line centering at the point of 150mm. in the axial line direction from the centers at both ends of the vessel, running through said points and intersecting orthogonally with the axis of the cylinder, then measuring the constituting ratio (wt%) B of the particles smaller than 210mu.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to pound flux used in submerged arc welding, and in particular, it is resistant to pulverization even after repeated use, has appropriate air permeability, and produces good welding. This relates to a flux that can maintain its workability for a long time.

Prior Art Submerged arc welding fluxes are generally divided into melt flux and pound flux. Among these, pound flux is used by granulating the blended raw materials using a binder such as water glass, firing at a temperature of about 300 to 600°C, and sizing. Therefore, it is possible to add iron powder, alloying elements, deoxidizing agents, gas generating agents, etc. to the flux, and there is an advantage that the performance of the weld metal can be adjusted relatively easily.

However, the individual particles of Pond Flux are merely physically bonded to each particle of the blended raw materials via a binder, and are susceptible to heat and impact and easily pulverize. For this reason, when the flux after completion of welding is collected by suction by a collection machine and used repeatedly, the flux becomes powdered and the amount of dust increases, as shown in FIG. 1st
The figure shows a case in which the cycle of welding and suction recovery using a flux recovery machine was repeated five times using ordinary iron powder-containing flux used for single-sided welding with a composition of symbol I in Table 2 and a grain size of 12 x 100 mesh. It shows the change in particle size distribution of 840 g11 or more and 840 μm to 210 g1 after 5 cycles compared to the initial flux.
It can be seen that the composition ratio of particles with a particle diameter of 210 pm or less increases accordingly. In this way,
When the flux becomes powder and the dust content increases, the air permeability of the flux is impaired and pock marks occur on the bead surface.

Conventionally, in order to prevent the above-mentioned defects, studies have been made on the composition of the flux, such as increasing the concentration of the binder or increasing the firing temperature.

For example, JP-A-51-52!1153 discloses a method in which clay minerals are contained in flux, granulated with an alkaline aqueous solution, and fired in an atmosphere containing carbon dioxide gas.

Furthermore, Japanese Patent Laid-Open No. 1111491/1983 proposes a method of mixing Portland cement into flux in order to improve the collapse resistance of flux.

Purpose of the Invention The present invention provides a flux that is less likely to powder even after repeated use and maintains good air permeability and welding workability over a long period of time by optimally maintaining the physical properties of the flux. be.

That is, in the particle size structure of the flux, (1) by increasing the proportion of particles with large diameters compared to conventional ones, particle strength can be increased, and at the same time, appropriate air permeability can be maintained even if the flux is powdered to some extent.

(2) By maintaining the bulk density within an appropriate range, the degree of pulverization of particles can be reduced, and appropriate air permeability can be obtained while maintaining a good bead shape.

(3) By regulating particle strength, the present invention was completed based on the discovery that proper air permeability can be achieved even during repeated use and pock marks can be prevented.

Structure and operation of the invention, namely 1 The present invention is characterized in that particles having a larger particle size than 840 #11 account for 30 to 60 percent, and particles smaller than 210 lubricant account for 20 percent or less, and further have a bulk density. is 1
．． 1-1.8 g/crri', and further has a particle strength C of 10 or less as measured by the measurement method described below.

The present invention will be explained in detail below.

First, it is necessary for the flux that particles with a particle size larger than 840 Pm account for 30 to 80% by weight, and particles with a particle size smaller than 210 Bm account for 20% by weight or less. This is to ensure proper air permeability in the flux. If the composition ratio of particles with a particle size larger than SAO4m is less than 30% by weight, it will not be possible to maintain proper air permeability during repeated use, causing pockmarks. occurs.

If it exceeds 60% by weight, the fire resistance of the flux will be excessive, resulting in irregular repeats or undercuts. Furthermore, if the proportion of particles with a particle size smaller than 210 gm exceeds 20%, air permeability deteriorates and pock marks occur during repeated use.

Furthermore, even in the flux having the above particle size structure, it is necessary to set the bulk density to Cl-1,θg/crrf. In other words, the bulk density is necessary to reduce powdering of the flux and to ensure proper air permeability, and is 1.1 g.
If it is less than 1.8g/cm'', it will become powdery after repeated use and the breathability will deteriorate, and if it exceeds 1.8g/cm', the bead will be pressed down too strongly by the flux and the bead will become disordered and the breathability will deteriorate. , pockmarks occur.

Furthermore, it is necessary that the particle strength C measured by the particle strength measuring method described below is 10 or less.

That is, if it exceeds 10, even if the particle size composition and bulk density are appropriate, the flux will become powdered to a large extent and ribbon marks with poor air permeability will occur.

The particle strength in the present invention is 210 p-w, and the flux 5 which has been measured in advance with respect to the composition ratio A of smaller particles (wt%) is 210 p-w.
0g with 8 iron balls with a diameter of 8cm and an inner diameter of 40cm and a length of 3
Place it in a 00mar cylindrical container, pass through the center at a point 150mm in the axial direction from the center of both ends of the container,
After rotating for 80 minutes at a rotation speed of 30 rpm around a line perpendicular to the cylinder axis, the composition ratio of particles smaller than 210 pm was measured at 8% by weight, and the value C calculated by C = B - A was calculated. Let it be particle strength.

In quantitatively evaluating the particle strength of flux, this measurement method uses a flux with the same particle size structure as that used for actual welding as a test flux, in order to be closer to the actual powdering tendency. It is something.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 2 A flux having the composition shown in Table 2 was granulated with water glass,
380℃ for 1 hour in case of process, 530℃ in case of II.
The mixture was fired for 1 hour to produce 11 types of flux shown in Table 1. In Table 1, fluxes Fl-F5 correspond to examples of the present invention, and fluxes F6 to Fil are comparative examples. That is, FB, FB, and F'll are comparative examples in which the particle size structure is outside the appropriate range, FB is the bulk density, FIO is the particle strength, and F7 is the comparative example in which the bulk density and particle strength are respectively outside the appropriate range. .

Using the above flux, welding is first performed, and the flux with good welding workability is collected with a collection machine, and then 4
The material was collected by suction using a recovery machine, and welding was performed after recovery was performed five times in total.

The welding conditions in this case are as shown in Table 3, 1.5%
Using Mn (JIS Z33115AW31 applicable) wire, 0.14% C10, 28% Si, 1.37% Mn
(Equivalent to 32 [1 in NX standard)] Flat plate bead welding was performed on a steel plate. Workability was evaluated based on the presence or absence of pockmarks, the presence or absence of undercuts, and the appearance of the bead surface.

Table 4 shows the results, and while excellent welding workability is obtained in all cases of the present invention, all of Comparative Examples F6 to Fil have drawbacks. That is, F.B.
and Fil, defects occurred during welding with new flux without a welding-recovery cycle,
In both FB and FIO, pock marks occurred during welding with flux after 5 times of collection, which was not preferable.

Table 1

[Brief explanation of the drawing]

FIG. 1 is a graph showing an example of a change in particle size distribution when a normal iron powder-containing flux is used and the welding-flux recovery process is repeated five times. Patent Applicant: Takigi Nippon Steel Co., Ltd. Agent, Patent Attorney: Masaru Inoue, First Diagram: C゛) Sashiko ~z1 (4μ Electric Small I) Foam Preliminary Procedures Amendment February 29, 1980, Commissioner of the Patent Office: Wakasugi Kazuo 1, Indication of the case Patent Application No. 11820 of 1982, 2 Name of the invention: Pond flux for submerged arc welding 3, Relationship with the person making the amendment Patent applicant address: 2-chome Otemachi, Chiyoda-ku, Tokyo No. 6 No. 3 Name
(665) Nippon Steel Corporation Representative Takeshi 1) Yutaka 4, Agent 103 Address 2-2-1-6 Nihonbashi, Chuo-ku, Tokyo Contents of amendment (1) Specification page 10 Table 1 The bulk density of Fluffx NoF8 is r1.83g/cm''J, rl, 86g/
Correct it as crn'J. (2) Amend page 11 as shown in the attached sheet. Agent Patent Attorney Masao Inoue

Claims (1)

[Claims] 30 to 60% by weight of particles having a particle size larger than 840 g In and 20% by weight particles having a particle size smaller than 2107zm.
% by weight or less, and has a bulk density of 1.1 to 1.8 g/
cm' and the particle strength C measured by the following method:
Pound slacks for submerged arc welding, characterized in that: is 10 or less. [Measurement method of particle strength] 50 g of flux whose composition ratio (weight %) of particles smaller than 210 lm is A is placed in a cylindrical container with an inner diameter of 40 mm and a length of 300 mm, along with 8 iron balls with a diameter of 8 mm. Centering on a point 150 +++ m in the axial direction from the center of both ends of the container, passing through that point and perpendicular to the cylindrical axis, 3
After rotating for 60 minutes at a rotation speed of 0 revolutions/minute, 210
measuring the constituent proportion (wt%) B of particles smaller than m,
Let the value C calculated by the following formula be the particle strength. C=B-A