JP6936755B2 - Hardened Overlaid Gas Shield Arc Fluxed Wire for Welding - Google Patents

Description

The present invention is a flux-filled wire for gas shielded arc welding applied to hard overlay welding of track rollers, mill hammers, excavator car claws, etc., which has good welding workability and no opening defects on the bead surface. In particular, the present invention relates to a hardened overlay gas shielded arc welding flux-containing wire capable of obtaining a weld metal having sufficient Vickers hardness even when no heat treatment is performed after welding (as it is welded).

There are various factors in structural wear. The causes of the wear are metal-to-metal wear due to contact between metals, earth and sand wear caused by earth and sand, slag, etc., corrosive wear in which part or the entire surface is thinned due to a corrosive environment, and repeated impacts. There are various forms such as impact wear. Therefore, it is necessary to select a welding material corresponding to the form of wear of the structure. Among them, hardened overlay welding is known as a method of forming an overlay metal having excellent abrasion resistance at a portion where abrasion resistance is required of various industrial machines represented by construction machinery and power generation equipment.

If the form of wear is intermetal wear, the hardness of the overlaid weld metal can be handled at the 450 Hv level. On the other hand, in the case of earth and sand wear, the hardness of the overlaid weld metal is often required to be 500 Hv or more. In particular, when the hardness of the overlaid weld metal is 600 Hv or more, the yield changes depending on the method of adding the raw material applied to the flux to be filled in the flux-cored wire for shielded metal arc welding and the flux-cored wire for gas shielded arc welding, so that the yield is stable. It becomes difficult to secure the hardness of the welded part.

In hard build-up welding by gas shield arc welding, for example, as shown in the disclosed technology of Patent Document 1, as a shield gas in order to reduce the amount of fume generation and slag generation, to obtain a flat bead shape and a small penetration depth. A hardened build-up MIG arc welded wire using pure Ar gas is disclosed. However, the technique disclosed in Patent Document 1 has a problem that welding workability is poor, such as a large amount of spatter generated and a poor bead shape. In addition to this, in the technique disclosed in Patent Document 1, in order to obtain a weld metal having a Vickers hardness of 550 Hv or more, the amount of Cr, V, and W, which have high raw material costs, is increased, so that the manufacturing cost becomes high. There was a point.

Further, Patent Document 2 discloses a flux-cored wire for gas shielded arc welding in which the Vickers hardness of the weld metal portion is stable and 800 Hv or more can be obtained. However, in the technique disclosed in Patent Document 2, a large amount of difficult-to-draw raw materials such as Mo, W, V, and Co are added. For this reason, there is a problem that the thickness of the outer skin of the flux-cored wire is liable to fluctuate, and the wire is broken frequently in the wire drawing process, so that the wire diameter cannot be made smaller than 3.2 mm.

Japanese Unexamined Patent Publication No. 2011-104624 Japanese Unexamined Patent Publication No. 61-7090

Therefore, the present invention has been devised in view of the above-mentioned problems, and is in a state in which welding workability is good, there are no opening defects on the bead surface, and heat treatment is not particularly performed after welding. It is an object of the present invention to provide a flux-containing wire for hardened overlay gas shielded arc welding, which can obtain a weld metal having a Vickers hardness of 550 Hv or more even (as welded).

The gist of the present invention is that in a wire containing a flux for hardened overlay gas shielded arc welding in which a steel outer skin is filled with flux, the total mass of the steel outer skin and the flux is C: 0. 2 to 0.8%, Si: 0.2 to 0.8%, Mn: 2 to 5%, Mo: 1 to 6%, Cr: 4 to 8%, Al: 0.1 to 1.0%, mg: 0.1 to 1.0%, further containing, by mass% with respect to total mass of the wire, in the flux, the total of TiO ₂ converted value of Ti oxides: 1-6%, of SiO ₂ converted value of Si oxide Total: 0.1 to 1.0%, total _{of one or more Na 2} O conversion values and K ₂ O conversion values of Na compound and K compound: 0.01 to 0.30%, of fluorine compound Total F conversion value: Contains 0.01 to 1.0%, and the balance is characterized by containing Fe content of steel outer skin, iron powder in flux, Fe content of iron alloy powder, and unavoidable impurities. Hardened overlay gas shield Arc welded flux-filled wire.

According to the flux-welded wire for hardened overlay gas shielded arc welding to which the present invention is applied, welding workability is good and welding workability is good on the bead surface when performing hardened overlay welding of track rollers, mill hammers, excavator car claws, etc. Provided is a flux-containing wire for hardened overlay gas shielded arc welding, which can obtain a weld metal having a Vickers hardness of 550 Hv or more even when there is no opening defect and no heat treatment is performed after welding (as it is welded). be able to.

The present inventors have provided a hardened overlay gas shielded arc welding flux-filled wire with stable arc, low spatter generation, good slag encapsulation and slag peeling properties, and on pits, blow holes and bead surfaces. Various studies were conducted to obtain a weld metal having a Vickers hardness of 550 Hv or more even when a bead shape without opening defects was obtained and no heat treatment was performed after welding (as welded).

As a result, it was found that stable hardness of the weld metal can be obtained by adjusting the amounts of C and Cr in the flux-cored wire to appropriate amounts and further adding Mo. It was also found that the defect resistance is improved by using appropriate amounts of Si and Mn and adding appropriate amounts of Al and Mg.

Regarding welding workability, by adjusting the appropriate amounts of Ti oxide, Si oxide, Na compound, K compound and fluorine compound in the flux-cored wire, the arc is stable and the amount of spatter generated is small, and the slag encapsulation property is improved. It was found that the slag peelability and the bead shape were improved.

Hereinafter, the reasons for limiting the composition of each component of the flux-cored wire for cured overlay gas shielded arc welding to which the present invention is applied will be described. The content of each component composition is expressed in% by mass with respect to the total mass of the wire, and when the mass% is expressed, it is simply expressed as%.

[Total of steel outer skin and flux C: 0.2-0.8%]
C is an important element for enhancing the hardenability of the weld metal, and has the effect of forming carbides between Cr and Mo to increase the hardness of the weld metal. If C is less than 0.2%, the target hardness of the weld metal cannot be obtained. On the other hand, when C exceeds 0.8%, the weld metal becomes too hard and the ductility is lowered, and opening defects are likely to occur on the bead surface. Therefore, the total of the steel outer skin and the flux is set to 0.2 to 0.8%. In addition to the components contained in the steel outer skin, C can be added from metal powder from flux, alloy powder, and the like.

[Total of steel outer skin and flux Si: 0.2-0.8%]
Si is added as an antacid. It also has the effect of improving arc stability and bead shape. If Si is less than 0.2%, the arc is unstable and blow holes and pits are likely to occur. On the other hand, if Si exceeds 0.8%, it segregates at the grain boundaries as an oxide, the ductility of the weld metal is lowered, and opening defects are likely to occur on the bead surface. Therefore, the total of the steel outer skin and the flux is set to 0.2 to 0.8%. In addition to the components contained in the steel outer skin, Si can be added from alloy powders such as metal Si, Fe-Si, and Fe-Si-Mn from flux.

[Mn: 2-5% in total of steel outer skin and flux]
Mn is added as a deoxidizer in the same manner as Si. It also has the effect of reducing segregation of low melting point compounds and improving crack resistance. If Mn is less than 2%, opening defects are likely to occur on the bead surface, and blow holes and pits are likely to occur. On the other hand, if Mn exceeds 5%, the bead shape tends to be convex, resulting in a defect. Therefore, the total Mn of the steel outer skin and the flux is set to 2 to 5%. In addition to the components contained in the steel outer skin, Mn can be added from alloy powders such as metal Mn, Fe-Mn, and Fe-Si-Mn from flux.

[Mo: 1 to 6% in total of steel outer skin and flux]
Mo has the effect of promoting the formation of Cr carbides and increasing the hardness of the weld metal. If Mo is less than 1%, the target hardness of the weld metal cannot be obtained. On the other hand, if Mo exceeds 6%, disconnection is likely to occur in the wire drawing process. Therefore, the total Mo of the steel outer skin and the flux is 1 to 6%. In addition to the components contained in the steel outer skin, Mo can be added from alloy powders such as metal Mo and Fe-Mo from flux.

[Cr: 4-8% in total of steel outer skin and flux]
Cr is an important element for forming carbides and ensuring the hardness of the weld metal. If Cr is less than 4%, the target hardness of the weld metal cannot be obtained. On the other hand, when Cr exceeds 8%, the weld metal becomes too hard and the ductility is lowered, and opening defects are likely to occur on the bead surface. Therefore, the total Cr of the steel outer skin and the flux is set to 4 to 8%. In addition to the components contained in the steel outer skin, Cr can be added from alloy powders such as metal Cr, Fe-Cr, and chromium carbide from flux.

[Total of steel outer skin and flux Al: 0.1 to 1.0%]
Al acts as a strong deoxidizer and has the effect of adjusting the viscosity of the molten slag to improve the bead shape. If Al is less than 0.1%, deoxidation is insufficient and pits and blow holes are likely to occur. On the other hand, when Al exceeds 1.0%, the viscosity of the slag becomes high and the bead shape tends to be convex. Therefore, Al is 0.1 to 1.0% in total in the steel outer skin and the flux. In addition to the components contained in the steel outer skin, Al can be added from alloy powders such as metal Al, Fe-Al, and Mg-Al from flux.

[Mg: 0.1 to 1.0% in total of steel outer skin and flux]
Mg acts as a strong antacid like Al. If Mg is less than 0.1%, deoxidation is insufficient and blow holes and pits are likely to occur. On the other hand, if Mg exceeds 1.0%, the arc becomes unstable and the amount of spatter generated increases. Therefore, the total of the steel outer skin and the flux is set to 0.1 to 1.0%. In addition to the components contained in the steel outer skin, Mg can be added from alloy powders such as metal Mg, Fe-Mg, and Al-Mg from flux.

_{[Total of TiO 2} conversion values of Ti oxide in flux: 1 to 6%]
The Ti oxide has the effect of improving the stability of the arc. It is also added for the purpose of improving the bead shape. _{If the total of the TiO 2} conversion values of the Ti oxide is less than 1%, the arc is unstable, the amount of spatter generated increases, and the bead shape also deteriorates. On the other hand, _{if the total of the TiO 2} conversion values of the Ti oxide exceeds 6%, the amount of slag becomes excessive and the slag peelability and the bead shape deteriorate. _{Therefore, the total TiO 2} conversion value of the Ti oxide in the flux is 1 to 6%. The Ti oxide can be added from rutile from flux, titanium oxide, titanium slag and the like.

_{[Total SiO 2} conversion value of Si oxide in flux: 0.1 to 1.0%]
The Si oxide has the effect of adjusting the viscosity of the slag to improve the bead shape. If the total value of the Si oxides in _{terms of SiO 2} is less than 0.1%, the viscosity of the slag becomes low, the slag encapsulation property deteriorates, and the bead shape becomes poor. On the other hand, _{if the total SiO 2} conversion value of the Si oxide exceeds 1.0%, the amount of slag becomes excessive and the slag peelability and the bead shape deteriorate. Therefore, the total value of Si oxides in the flux in _{terms of SiO 2} is 0.1 to 1.0%. Si oxides can be added from silica sand, feldspar, etc. from the flux.

_{[Total of one or more Na 2} O conversion values and K ₂ O conversion values of Na compound and K compound in the flux: 0.01 to 0.30%]
The Na compound and the K compound have the effect of increasing the stability and concentration of the arc and reducing the amount of spatter generated. _{If the total of one or more of the Na 2} O conversion value and the K ₂ O conversion value of the Na compound and the K compound is less than 0.01%, the arc is unstable and the amount of spatter generated increases. On the other hand, if the _{sum of one or more of the Na 2} O conversion value and the K ₂ O conversion value of the Na compound and the K compound exceeds 0.30%, the arc concentration is too strong and the amount of spatter generated is rather large. More. Therefore, the total of one or more of _{the Na 2} O conversion value and the K ₂ O conversion value of the Na compound and the K compound in the flux is 0.01 to 0.30%. The Na compound and K compound in the flux can be added from sodium fluoride, sodium titanate, potassium silicate, sodium silicate and the like.

[Total F conversion value of fluorine compounds in flux: 0.01 to 1.0%]
The fluorine compound has an effect of improving the detachability of droplets and reducing the amount of spatter generated. If the total F conversion value of the fluorine compounds is less than 0.01%, the detachment of droplets becomes unstable, so that the arc itself becomes unstable and the amount of spatter generated increases. On the other hand, when the total F conversion value of the fluoride exceeds 1.0%, the melting point of the slag is lowered and the bead shape becomes non-uniform. Therefore, the total F conversion value of the fluorine compounds in the flux is set to 0.01 to 1.0%. The fluorine compound in the flux can be added from sodium fluoride, potassium siliceous fluoride, potassium fluoride fluoride, cryolite, aluminum fluoride, fluorite and the like.

The flux-cored wire for hardened overlay gas shielded arc welding of the present invention has a steel outer skin U-shaped, filled with flux, and has a predetermined wire diameter (1.0 to 1.6 mm) by wire drawing a hole die or a roller die. ) Is reduced in diameter. The flux filling rate is preferably 15 to 30% from the viewpoint of productivity and welding workability. The types of wires can be roughly divided into seamless wires in which the seams of the molded steel outer skin are welded and wires having seams without welding the seams of the steel outer skin. In the present invention, the cross-sectional structure is defined. It is not particularly limited, and any wire can be adopted.

Further, the rest of the flux-containing wire for hardened overlay gas shield arc welding to which the present invention is applied includes Fe content of the steel outer skin, iron powder of the flux, Fe-Si, Fe-Mn, Fe-Al, Fe-Mg, etc. Fe content and unavoidable impurities of iron alloy powders such as Fe-Mo, Fe-Cr, and Fe-V. The unavoidable impurities are not particularly specified, but from the viewpoint of high temperature crack resistance, P is preferably 0.015% or less and S is preferably 0.015% or less.

Further, the shield gas at the time of welding is carbon dioxide gas, and the flow rate of the shield gas is preferably 20 to 35 liters / minute in order to prevent defects and nitrogen from the atmosphere.

Hereinafter, examples of a flux-cored wire for hardened overlay gas shielded arc welding to which the present invention is applied will be specifically described.

First, various prototypes of flux-cored wires shown in Table 1 were made using JIS G3141 SPCC strip steel for the steel outer skin. The wire diameter was 1.6 mm and the flux filling rate was 17 to 25%.

Productivity is evaluated by filling a U-shaped steel outer skin with blended, mixed / agitated, and dried flux, and then dies a round wire wire (wire diameter 3.2 mm) up to 1.6 mm. And the presence or absence of disconnection when wire drawing was performed with a cassette roller die was evaluated.

Welding workability was evaluated using the SM490A steel sheet shown in Table 2 in accordance with JIS Z3114, and under the welding conditions shown in Table 3, a 4-layer underlay welding test was performed in a downward welding posture, and during welding. The arc stability, the amount of spatter generated, the slag encapsulation property, the slag peeling property, and the bead shape were investigated.

After the welding was completed, the bead surface was subjected to a penetrant inspection according to JIS Z2343-1 to investigate the presence or absence of cracks (opening defects). In addition, for the evaluation of blow holes and pits, the test piece after welding was subjected to an X-ray transmission test according to JIS Z3106, and the presence or absence of blow holes and pits was investigated.

The hardness of the weld metal was measured by measuring the Vickers hardness of the test plate after welding defect evaluation in accordance with JIS Z3114 and JIS Z2244, and the average of 10 points was 550 to 700 Hv. These results are summarized in Table 4.

Wire Nos. In Tables 1 and 4. 1-No. 10 is an example of the present invention, wire No. 11-No. 18 is a comparative example. Wire No. which is an example of the present invention. 1-No. _{10 is the total of the TiO 2} conversion values of C, Si, Mn, Mo, Cr, Al, Mg, and Ti oxides of the flux-filled wire, the total of the SiO ₂ conversion values of the Si oxide, and the Na of the Na compound and the K compound. one or the sum of two or more ₂ O conversion value and K ₂ O converted value, the sum of the F converted value of the fluorine compound is proper, disconnection does not occur during manufacture of the flux cored wire, arc in overlay welding Is stable, the amount of spatter generated is small, the slag encapsulation property, slag peelability and bead shape are good, there are no opening defects or blow holes on the bead surface, and the hardness of the weld metal is good, which is an extremely satisfactory result. Met.

In the comparative example, the wire No. In No. 11, since C was small, the hardness of the weld metal was low. In addition, since the amount of Si is small, the arc becomes unstable and blow holes and pits are generated. Further, since the amount of Mn is large, the bead shape becomes convex and becomes defective, and the total F conversion value of the fluorine compound is small, so that the amount of spatter generated is large.

Wire No. In No. 12, since C was abundant, the hardness of the weld metal was high, and opening defects were also generated on the bead surface. In addition, _{since the total TiO 2} conversion value of the Ti oxide was small, the arc was unstable, the amount of spatter generated was large, and the bead shape was also bad. Further, since the amount of Al is small, blow holes and pits are generated. Wire No. In No. 13, _{since the total of the TIO 2} conversion values of the Ti oxide was large, the slag peelability was deteriorated and the bead shape was also poor. In addition, since the amount of Mg was large, the arc was unstable and the amount of spatter generated was large. Further, since the amount of Cr is large, the hardness of the weld metal is high, and opening defects are generated on the bead surface.

Wire No. In No. 14, _{since the value of Si oxide in terms of SiO 2} was small, the slag encapsulation property was poor and the bead shape was also poor. Further, since the amount of Cr was small, the hardness of the weld metal was low. Furthermore, since there is a large amount of Si, opening defects occur on the bead surface.

Wire No. In No. 15, _{since the value of Si oxide in terms of SiO 2} was large, the slag peelability was deteriorated and the bead shape was also poor. Further, since the amount of Mn is small, opening defects are generated on the bead surface, and blow holes and pits are also generated.

Wire No. _{In No. 16, since the sum of one or more of the Na 2} O conversion value and the K ₂ O conversion value of the Na compound and the K compound was small, the arc was unstable and the amount of spatter generated was large. Moreover, since there was a large amount of Al, the bead shape was convex. Further, since the amount of Mo was small, the hardness of the weld metal was low.

Wire No. _{In No. 17, the total amount of one or more of the Na 2} O conversion value and the K ₂ O conversion value of the Na compound and the K compound was large, so that the amount of spatter generated was large. Moreover, since the total F of the F conversion values of the fluorine compounds was large, the bead shape was bad. Further, since the amount of Mg is small, blow holes and pits are generated.

Wire No. Since the number 18 had a large amount of Mo, the wire was broken before reaching the target wire diameter in the wire drawing process, so the production was discontinued.

Claims (1)

In a hardened overlaid gas shield arc welding flux-cored wire in which a steel outer skin is filled with flux, the total of the steel outer skin and the flux is the mass% of the total weight of the wire.
C: 0.2-0.8%,
Si: 0.2-0.8%,
Mn: 2-5%,
Mo: 1-6%,
Cr: 4-8%,
Al: 0.1 to 1.0%,
Mg: 0.1 to 1.0%, and in mass% of the total weight of the wire, in the flux,
_{Total TiO 2} conversion value of Ti oxide: 1-6%,
_{Total SiO 2} conversion value of Si oxide: 0.1 to 1.0%,
_{Na 2} O conversion value of Na compound and K compound and _{one or more total of K 2} O conversion value: 0.01 to 0.30%,
Total F conversion value of fluorine compound: Contains 0.01-1.0%,
A flux-containing wire for hardened overlay gas shielded arc welding, characterized in that the balance is composed of Fe content of a steel outer skin, iron powder in a flux, Fe content of iron alloy powder, and unavoidable impurities.