JPS61259895A - Production of flux cored wire for welding - Google Patents

Abstract

PURPOSE:To prevent the variance of welding quality by subjecting partly or fully the metallic powder of flux raw material to a surface oxidation treatment then mixing the same with the other flux raw materials and using such mixture. CONSTITUTION:The metallic or ferro alloy powder of the flux raw material such as metallic manganese or ferromanganese is partly or fully subjected to the surface oxidation treatment. More specifically the metallic or ferro alloy powder is subjected to a heating treatment for 0.5-10 hours at >=500 deg.C. A prescribed oxide film is formed on the surface of the metallic powder or ferro alloy powder in this stage. The flux raw material subjected to the surface oxidation treatment is mixed with the other flux raw material such as silica or alumina and the flux cored wire is formed. The deterioration of the properties of the flux during the pelletazing stage and after packing is prevented by the above-mentioned method, by which the variance of the quality in the weld zone is prevented.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a method for manufacturing a flux-cored wire for welding, and particularly to a method for advantageously manufacturing a flux-cored wire that can provide stable weld quality. .

(Prior art) In recent years, in the field of arc welding, welding flux-cored wire (composite welding wire) with built-in flux has replaced conventional manual welding or solid wire.
That is, flux-cored wires, which have a predetermined flux contained within a tubular metal sheath, have come to be widely used in order to improve the efficiency and save labor of welding work.

Carbon steel or low-alloy steel is generally used as the outer sheath of this flux-cored wire for welding, and the flux housed in the tubular body composed of such an outer sheath is titania-based or lime-based. , lime titania type, etc., but in any of the fluxes, ferromanganese (F e -Mn) and metallic manganese (Mn) are used for deoxidizing or adding alloys.

Ferrosilicon (Fe-3i), Ferromolybdenum (
Metal powders such as Fe-Mo) and/or ferroalloy powders are used as a component of the flux raw material.

(Problem to be solved) However, such metal powders and ferroalloy powders are generally made into fine particles in order to effectively fill them into the outer shell, and therefore have a significantly large surface area. During storage or during the granulation process, such altered metal powders and alloyed iron powders are used as flux raw materials together with new, unaltered powders to form the outer shell. When filled into the flux-cored wire, the altered metal powder or iron alloy powder may become unevenly distributed in the longitudinal direction of the resulting flux-cored wire. In addition, when welding flux containing such metal powder or alloyed iron powder is filled into the outer skin and then heated for the purpose of removing moisture from the flux, the surface of the metal powder or alloyed iron powder may be It may also be oxidized and altered.

By the way, the oxidation and deterioration of metal powders and alloyed iron powders in these cases is not simply surface oxidation, but is caused by moisture on the oxidized surface, as the surface of the powder or granule is often subjected to oxidation when it is wet with moisture. This may reduce the deoxidizing performance of the flux, or
The alloy yield is reduced and the quality of the weld is adversely affected. Moreover, such uneven distribution of metal powder and alloyed iron powder in the longitudinal direction of the wire also causes variations in the quality of the welded part.

(Solution Means) The present invention has been made in view of the above circumstances, and is characterized by a flux-cored wire for welding in which flux is encapsulated in a predetermined metal sheath. During production, surface oxidation treatment is applied to some or all of the metal powder and/or alloyed iron powder that is the raw material constituting the flux, and the mixture is mixed with other flux raw materials and used as the flux. It's because I did it.

That is, in the present invention, some or all of the metal powder or alloy iron powder used as a flux raw material is handled in a state in which the surface is oxidized in advance to form an oxide film on the surface of the powder. After mixing it with other flux raw materials to form the desired flux, the wire is manufactured by incorporating it into a predetermined metal sheath so that it can be encapsulated in the sheath. The presence of such an oxide film on the surface prevents deterioration of the metal powder or iron alloy powder during storage or during the flux granulation process, as well as deterioration during the heating and drying process after filling. This could have been prevented.

Incidentally, the surface oxidation treatment in the present invention is generally performed on ferromanganese, metallic manganese, or ferrosilicon in an oxidizing atmosphere such as air.

Approximately 50% of metal powder such as ferromolybdenum or ferroalloy powder
This is carried out by heat treatment at a temperature of 0° C. or higher for about 0.5 to 10 hours. It goes without saying that it is desirable that the oxidizing atmosphere used in this surface oxidation treatment be a dry atmosphere from which moisture is removed as much as possible. In addition, through such surface oxidation treatment, a certain oxide film is formed on the surface of the metal powder or alloyed iron powder, but such an oxide film does not have much effect on the quality of the weld. It's not what it brings.

The thus obtained metal powder or iron alloy powder, the surface of which has been partially or completely oxidized, can be used as a raw material for other fluxes,
For example, it is mixed with TiO□ (rutile), zircon, silica, alumina, charcoal, etc. in a predetermined ratio and used as a desired flux.

In order to form a flux-cored wire for welding using such a flux, it is preferable to granulate the flux (mixture) and then granulate it in the same way as in the conventional case. In order to obtain a welding wire of the desired small diameter, a method was adopted in which the welding wire was filled with water and then drawn. In addition, in such a welding wire, the end connecting portions such as the abutting portions, overlapping portions, or folded portions of the tubular outer skins may be joined by welding, brazing, etc. as necessary, and If necessary, a predetermined metal coating such as copper plating is applied to the surface of the outer sheath, thereby completing the intended welding flux-cored wire.

(Effects of the Invention) As is clear from the above description, the present invention provides surface oxidation treatment for some or all of the metal powder and/or alloy iron powder used as the flux raw material when producing a flux-cored wire for welding. This prevents deterioration in quality during storage or during the flux granulation process, and effectively prevents deterioration in quality during the heating and drying process after filling into the outer shell. In order to ensure good quality of welded parts,
This makes it possible to effectively suppress variations in quality of welded parts, and this is where the great industrial significance of the present invention lies.

(Examples) Examples of the present invention are shown below in order to clarify the present invention more specifically, but the present invention is to be interpreted as being limited only to what is described in such Examples. It goes without saying that this is not the intention. In addition,
Percentages in the examples are based on weight unless otherwise specified.

When manufacturing the intended flux-cored wire for welding using a flux with the following composition, the flux raw materials Fe-Mn, Fe-3i and Fe-Mo are subjected to a prescribed surface oxidation treatment, The combinations shown in Table 1 were used. Incidentally, the surface oxidation treatment of each flux raw material was carried out by heating each powder at a temperature of 1000''C for 1 hour in dry air.

Rutile (Ti(h)...45 Zircon (ZrO, 5iO2)...1010Fe-...
20 Fe-3i =10 Fe-Mo ・ ・ ・ ・ ・
3 Feldspar...10 Fluorite...2 Fe-Mn with or without surface oxidation treatment made of this flux composition.

A flux (mixture) containing Fe-3i and Fe-Mo was dried at 350°C for 5 hours and filled into an electric resistance welded tube (outer skin) made of mild steel.
．． Various desired flux-cored wires were obtained by drawing the wires to 2fiφ.

Using the various flux-cored wires obtained, arc welding was performed under the following welding conditions, and the impact characteristics (vEo) of the welded part (welded metal) and the amount of diffusible hydrogen contained therein were evaluated. The results are also shown in Table 1 below.

Search m (1) Welding current: 300A Arc voltage: 32V Welding speed: 30 tons, 7CO, flow rate
-・-2ON/,,nAs is clear from the results in Table 1, the iron alloy powder 1 constituting the flux raw material according to the present invention, namely Fe-Mn, Fe-3i, F
It has been found that by using e-Mo that has been subjected to surface oxidation treatment, the impact properties (VEO) of the weld zone are improved and the amount of diffusible hydrogen is also reduced.

Claims (1)

[Claims] In manufacturing a flux-cored wire for welding in which flux is encapsulated in a predetermined metal sheath, surface oxidation is applied to some or all of the metal powder and/or alloyed iron powder that is the raw material constituting the flux. Processed,
A method for producing a flux-cored wire for welding, characterized in that the flux is mixed with other flux raw materials and used as the flux.