JPH11197877A - Flux cored wire for hard build-up welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow the member to have superior toughness and wear resistance by applying a flux cored wire to the working part of the member that receives heavy impact and that requires wear resistance. SOLUTION: This flux cored wire is one with flux packed inside the outer skin of an iron-based metal. In this case, the ratio of the components in the entire wire is designed to be as follows, by weight: 0.5<C<=1.5%, 0.6-2.1% Si, 0.6-1.8% Mn, 2.5-7.5% Cr, 0.1<=W<1.5%, 0.1<=V<1.5%, 1.0-8.0% Mo, and 0.2<B<=0.8%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flux cored wire for hardfacing welding, and more particularly to a mantle liner or a cone cable liner of a cone crusher used for crushing rocks and the like, and a jaw plate of a jaw crusher. The present invention relates to a flux-cored wire for hardfacing welding, which is capable of imparting excellent toughness and abrasion resistance to a member subjected to heavy impact and requiring wear resistance by applying the same to an action portion of the member. .

[0002]

2. Description of the Related Art The hardfacing welding method is widely used as a measure for improving the wear resistance of various parts such as iron and steel making facilities and civil engineering construction machines, or as a means for repairing worn parts. Above all, like the shovel tip of construction machines such as crushers and power shovels represented by cone crushers and jaw crushers,
When modifying parts where high levels of wear resistance and impact resistance are required, a method is often used in which a strong steel material is used for the body and a high hardness metal is overlaid on the parts where wear resistance is required. Is done.

[0003] As a welding material used for such hardfacing welding, a coated arc welding rod has been widely used in the past. However, recently, from the viewpoints of higher welding performance, labor saving, and higher performance, shielded welding rods have been used. An automatic or semi-automatic welding method using carbon dioxide as a gas has been adopted. The main welding materials used for automatic or semi-automatic welding are solid wires and flux-cored wires.However, in the method using solid wires, the wire components themselves must be made of a high-hardness metal material. Processing is extremely difficult, and it is very difficult to form a thin wire.

On the other hand, in the case of a flux-cored wire, for example, a steel material having good drawability such as mild steel is used as a hoop material, and various alloying elements are contained in a powdery state in the hoop material, thereby forming a weld overlay metal. Can be easily adjusted, and a wire that gives a hard build-up weld metal under excellent drawability can be manufactured with high productivity. Moreover, if necessary, the welding workability can be improved by including a slag forming agent, a deoxidizing agent, an arc stabilizer, etc. in the contained flux component.
Recommended as the preferred hardfacing welding method. An example of such a flux-cored wire is disclosed in, for example,
No. 4,1693 (high-Cr flux-cored wire) and the like, and JIS Z 3326 defines the chemical components of the deposited metal using various flux-cored wires.

[0005] Among the hardfacing welding materials used for the above applications, typical ones are martensitic and high Cr.
Although it is an iron-based build-up welding material, the martensite-based build-up welding material does not contain high-hardness carbide inside the deposited metal, so it is generally compared to the case of using a high-Cr iron-based welding material. The wear resistance of the hardfacing weld metal is insufficient, and it is difficult to obtain a satisfactory wear life. On the other hand, high-Cr iron-based welding consumables contain a considerable amount of high-hardness carbide, etc., and are therefore superior to martensite-based welding consumables, particularly in terms of wear resistance to severe earth and sand wear. In exchange, there is a tendency for the weld metal to have poor elongation and toughness and tend to crack, and the hardfacing part may become chipped or peeled during use, making it unusable. There is also a fear of inviting. It is considered that such chipping or peeling is mainly caused by insufficient cracking resistance of the high Cr iron-based overlay welding metal.

That is, the cracks generated in the hardfacing welded portion are developed by the stress applied to the wear part during operation, and eventually, the build-up deposited metal is dropped or peeled, thereby shortening the service life. Therefore, for wear members that are particularly exposed to severe impact, improvement of crack resistance is strongly desired as a precondition for ensuring wear resistance.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to have high hardness, excellent wear resistance, and excellent crack resistance. It is an object of the present invention to provide a flux-cored wire for hardfacing welding, which gives a build-up deposited metal having the following characteristics.

[0008]

The flux-cored wire for hardfacing welding according to the present invention, which can solve the above-mentioned problems, is a flux for hardfacing welding in which a flux is filled in an iron-based metal sheath. In a cored wire, the ratio of the total wire amount to C: more than 0.5% and 1.5% or less, Si: 0.6 to 2.1%, Mn: 0.6 to 1.8%, Cr : 2.5 to 7.5%, W: 0.1% to less than 1.5%, V: 0.1% to less than 1.5%, Mo: 1.0 to 8.0%, B: 0 It is characterized by being more than 0.2% and 0.8% or less.

Among the elements contained in the flux-cored wire, Mo is particularly important, and its content is more preferably 2.0% or more, further preferably 3.0% or more, and most preferably 4.0%. It is super.

In the above flux-cored wire,
The flux component to be filled in the metal shell may be composed of only each of the above-described elements constituting the weld metal by being fused and integrated with the metal shell by overlay welding, but in addition to those elements, In order to improve welding workability,
It is also effective to fill the metal outer shell with components that are not incorporated into the deposited metal component, such as an arc stabilizer, a slag forming agent, and a gas generating agent.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present inventors have made an effort to improve the problems pointed out in the prior art as described above, and in particular, to influence the hardness and crack resistance of a weld metal welded by hardfacing. Factors to be exerted have been studied in terms of the chemical composition of the deposited metal. As a result, it has been found that the formation of carbides is effective in improving the hardness of the deposited metal, but extremely deteriorates the crack resistance.

However, if the generation of carbides is controlled in order to increase the crack resistance, the hardness of the deposited metal decreases, and satisfactory wear resistance cannot be obtained. Therefore, studies were repeated to find a weld metal component that can increase the hardness of the weld metal and also improve the crack resistance. As a result, each content of Cr, W, V, Mo, and B in the deposited metal, in particular, Mo
And the content of B are appropriately controlled, and the weld metal structure is formed as a composite structure composed of martensite and boride in steel, thereby increasing the hardness of the weld metal and miniaturizing the weld metal structure to improve crack resistance. It was also found that a surface-hardened member having much better wear resistance than conventional materials could be obtained.

Accordingly, the present invention provides a flux-cored wire capable of reliably providing a hardfacing weld metal having such an appropriate and fine metal structure.

Hereinafter, the reason why the chemical composition of the flux-cored wire for hardfacing welding in the present invention is determined will be described in detail.

C: more than 0.5% and 1.5% or less C is a main element that forms a martensitic steel by forming a solid solution in a matrix mainly composed of Fe, and has a C content of 0.5% in the wire. In the following, the amount of C dissolved in Fe inside the weld metal formed by the hardfacing tends to be insufficient and the matrix becomes insufficient in hardness, and even if high hardness boride is generated around the matrix as described later. The hardness of the deposited metal as a whole cannot be sufficiently increased. On the other hand, when the C content is 1.
If it exceeds 5%, part of the Fe matrix of the deposited metal remains as austenite without becoming martensite. Because austenite has low hardness, it not only lowers the hardness of the entire weld metal, but also has a coefficient of thermal expansion that is significantly different from that of martensite or boride. It will be easier. In view of the advantages and disadvantages of C, the lower limit of the C content is more preferably 0.55% or more, still more preferably 0.7% or more.
A more preferred upper limit of the amount is 1.3% or less.

The preferred C content in the build-up deposited metal is about 0.2 to 0.9%. However, since C is partially burned and consumed during welding, the yield during welding is taken into consideration. The C content in the wire is set in the above range, which is slightly larger than the above.

Si: 0.6 to 2.1% Si has a deoxidizing effect and contributes to cleaning of the deposited metal. In order to effectively exhibit such an effect, the content should be 0.6% or more, more preferably 0.7% or more. However, if it is too much, the amount of Si solid solution in the Fe matrix increases, and the toughness decreases. Since the crack resistance has an adverse effect, it must be suppressed to 2.1% or less, more preferably 2.0% or less. The preferable Si content in the build-up deposited metal is about 0.6 to 1.9%. However, Si acts as a deoxidizing agent or a slag forming agent at the time of welding to become SiO ₂ and partly consumed. Therefore, in consideration of the consumption, the amount of Si in the wire is specified in the slightly larger range.

Mn: 0.6 to 1.8% An element which has a deoxidizing effect and contributes to the cleaning of the deposited metal similarly to the above-mentioned Si, and 0.6% or more is required to exert its effect effectively. , More preferably 0.8% or more. However, if it is too much, austenite is liable to be formed in the deposited metal and adversely affects hardness and crack resistance. More preferably 1.6
% Or less. The preferred content of the Mn in the build-up deposited metal is about 0.6 to 1.6%,
Mn also acts as a deoxidizing agent or a slag forming agent during welding to form MnO ₂ and partially consume it. Therefore, the amount of Mn in the wire is specified in a slightly larger range as described above in consideration of the consumed amount. doing.

Cr: 2.5 to 7.5% Cr is an important element that combines with B to form borides and contributes to increasing the hardness of the deposited metal. It should be contained at least 2.5%, more preferably at least 3.0%. On the other hand, if the Cr content is too large, high temperature cracking is likely to occur when the deposited metal solidifies, so it must be suppressed to 7.5% or less, more preferably 6.8% or less. It should be noted that there is almost no oxidation consumption of Cr during overlay welding, and most of the Cr is taken into the overlay weld metal.

W: 0.1% or more and less than 1.5% W also combines with B to form a boride, thereby contributing to an increase in the hardness of the deposited metal, and also provides elongation to the deposited metal to suppress shrinkage cracking and to withstand resistance. It also has the effect of increasing cracking. In order to exert such effects effectively, 0.1% or more, more preferably 0.2%
%, More preferably 0.4% or more. However, if the content is too large, the crack resistance tends to be rather deteriorated. Therefore, 1.5% or less, more preferably 1.% or more. It should be kept below 45%, more preferably below 1.3%. In addition, there is almost no oxidation consumption of W during overlay welding, and almost all of it is taken into the overlay weld metal.

V: 0.1% or more and less than 1.5% V also combines with B to form a boride, thereby contributing to increase the hardness of the deposited metal, and also to prevent hot cracking when the deposited metal solidifies. Works effectively. Such an effect can be effectively exhibited by containing 0.1% or more, more preferably 0.2% or more, and still more preferably 0.3% or more. It should be kept below 1.5%, more preferably below 1.4%, even more preferably below 1.2%, most preferably below 1.0%.
In addition, there is almost no oxidation consumption of V during the overlay welding, and most of the V is taken into the overlay welding metal.

Mo: 1.0 to 8.0% Mo is a main element that combines with B to form a boride and contributes to increase the hardness of the deposited metal, and also contributes to the formation of the boride. Mo also exerts an effect of forming a solid solution in the Fe matrix to enhance the hardenability of the deposited metal. In order to effectively exhibit these effects, the content must be 1.0% or more. A more preferred Mo content is 2.0% or more, still more preferably 3.0% or more, and most preferably 4.0% or more.
Although it is more than 0%, if it becomes too large, the toughness of the deposited metal tends to be reduced and the crack resistance tends to be impaired.
It must be kept at 8.0% or less, more preferably at 7.0% or less. It should be noted that there is almost no oxidation consumption of Mo during overlay welding, and most of the Mo is taken into the overlay weld metal.

B: more than 0.2% and 0.8% or less B is an element indispensable for boride formation,
If the content is not more than 0.2%, a sufficient amount of boride will not be formed in the deposited metal, not only a satisfactory hardness will not be obtained, but also the metal structure will be coarse and sufficient crack resistance will be obtained. Is also difficult to obtain. However, if the content is too large, it causes grain boundary embrittlement and lowers the toughness of the deposited metal, which adversely affects the cracking resistance. Therefore, 0.8% or less, more preferably 0.7% or less. , More preferably 0.6% or less. In addition, there is almost no oxidation consumption of B during the overlay welding, and most of the B is taken into the overlay welding metal.

The constituent elements constituting the flux-cored wire of the present invention are as described above, and the remaining components are substantially Fe
And other elements such as P, S, N, O, etc. or other elements may be mixed therein, but these elements are also allowed as long as they are inevitable impurity amounts. Further, in the flux-cored wire, the flux component to be filled into the metal sheath is a component which does not affect the chemical component of the deposited metal to be deposited (that is, is not taken into the deposited metal), and It is also effective to include an appropriate amount of a component having an effect of improving welding workability, such as a slag forming agent, an arc stabilizer, and a gas generating agent. However, since these components are components that are not substantially mixed into the deposited metal, their contents are not taken into account when setting the chemical components of the flux-cored wire.

Next, the reason why by specifying the above chemical components, it is possible to obtain a deposited metal having high hardness and improved crack resistance will be described.

First, B has the property of easily segregating at the matrix grain boundaries and forming borides by combining with Cr, Mo, W, V and the like. Borides generated by the reaction with these elements are formed in a network along the matrix grain boundaries in the deposited metal, exhibiting the characteristic of suppressing the growth of the matrix grains and refining the crystal grains. Increases the toughness of metal and improves crack resistance. Moreover, the generated boride has a high hardness and contributes to an increase in the hardness of the deposited metal.

On the other hand, it has been confirmed that Cr, Mo, W and V also easily react with C. However, when B is present in the system, most of them become borides, so that the amount of carbides generated in the deposited metal is increased. Is extremely small. As a result, most of C contained in the deposited metal forms a solid solution in the Fe matrix, which contributes to the formation of Fe into martensite. In general, it is known that martensite increases in hardness as the amount of C solid solution in Fe increases, and when C in the deposited metal is not used for forming carbides and most of the solid solution forms in the matrix. As a result, the hardness of the matrix composed of martensite increases, and the hardness of the entire deposited metal increases.

The effect of making the formation of carbides difficult is not limited to increasing the hardness of martensite. That is, since carbides are extremely brittle, the formation of carbides reduces the toughness of the deposited metal and adversely affects the cracking resistance. However, as described above, the content of B, Cr, Mo, W, V, etc. is reduced. In the adjusted component system, it is considered that the amount of carbide inside the deposited metal is extremely small, and this also has a favorable effect on the improvement of crack resistance.

As described above, the effect of adding B is not only to increase the hardness of the deposited metal due to the formation of borides and increase the matrix hardness, but also to reduce the size of crystal grains and suppress the cracking of the deposited metal by suppressing the formation of brittle carbides. It also contributes to the improvement of the weldability, and together with these effects, it has a remarkable effect on increasing the hardness of the deposited metal and improving the crack resistance.

As described above, it is important to make the matrix martensite in order to increase the hardness of the deposited metal. In order to stably transform the matrix into martensite, it is effective to improve the hardenability of the deposited metal, and Mo has a significant effect on the improvement of the hardenability. In addition, Mo generates boride as described above and contributes to the improvement of the hardness of the deposited metal.
Is positioned as a very important element. In order to improve the quenchability of Mo and effectively exhibit the combined effect of boride generation, the Mo content in the flux-cored wire is 1.0% or more, more preferably 2.%.
It should be 0% or more, more preferably 3.0% or more, and most preferably more than 4.0%. When the Mo content is less than 1.0%, most of Mo is consumed as boride. , Since Mo dissolved in the matrix cannot substantially exist,
The effect of increasing the hardenability of the deposited metal is not effectively exhibited,
This causes a decrease in the matrix hardness and, consequently, a decrease in the hardness of the deposited metal. The effect of Mo saturates at about 4 to 5%, and when the Mo content exceeds 8.0% excessively, the toughness of the deposited metal decreases, and satisfactory crack resistance cannot be secured.

The chemical components of the wire defined in the present invention are:
Adjustment is made according to the metal shell and the flux components filled therein. Normally, mild steel or Cr steel is used as the metal sheath, and the elements that are lacking in the skin metal are filled into the inside as flux components, so that the chemical composition of the flux-cored wire as a whole falls within the range described above. do it. Therefore, it goes without saying that the outer shell component is not limited, but in view of the drawability at the time of producing a flux-cored wire, it is preferable to use a material excellent in the drawability as the metal sheath material, Elements that increase the hardness of the metal shell, such as Si, C, B,
Mo, W, and the like are desirably filled as flux components as much as possible in the metal outer cover to adjust the components.

In addition, among the above-mentioned elements used for adjusting the components by filling the inside of the metal sheath, C, Si, Mn, B, Cr,
W, V, Mo, etc. may be supplied as respective metal powders, or may be supplied as an alloy with Fe or the like.

The cross-sectional shape and size of the flux-cored wire, the flux filling rate, and the like are not particularly limited, and may be arbitrarily determined in consideration of the welding method to be used and the overlay welding position.

The hardfacing welding method or welding conditions using the flux-cored wire of the present invention are not limited at all.
In addition to the most common carbon dioxide gas arc welding method, gas arc welding method (MIG welding, MAG welding, TIG welding, etc.) mixed with inert gas such as Ar as shielding gas, submerged arc welding method, self-shielded arc welding method And the like are non-limiting examples.

The type of the base material on which the hardfacing welded metal layer is formed is not particularly limited as long as it is a material having strength and toughness that can withstand stress during use as a support layer of the hardfacing overlay. However, steel materials such as mild steel and low alloy steel are most practical in consideration of strength characteristics, adhesion to the deposited metal layer, cost, and the like.

As described above, the deposited metal welded by overlay welding using the flux-cored wire of the present invention has high hardness and excellent crack resistance, and when applied to a portion that is subjected to heavy impact. But it demonstrates outstanding toughness and wear resistance,
In particular, the present invention can be widely applied to a crusher, a crusher, and the like, specifically, a cone crusher, a jaw crusher, a roller mill, an impact crusher, and the like. In fields other than crushing and crushing, for example, raw material transport parts of ironworks, various handling parts provided in raw material storage facilities such as iron ore, various wear-resistant parts such as rolling rolls, and construction machine parts such as power shovels. Can be widely used for mining machinery parts used for mining, mining, coal and the like.

[0037]

EXAMPLES Next, examples of the present invention will be described. However, the present invention is not limited by the following examples, and the present invention should be practiced with appropriate modifications within a range that can be adapted to the gist of the preceding and the following. Of course, these are also possible, and all of them are included in the technical scope of the present invention.

Example 1 Flux-cored wires having the chemical components shown in Table 1 below were produced by using mild steel as the metal sheath material and adjusting the components of the filling flux and the filling amount. The filling rate of the flux is 15 to 35%, and the wire diameter is 1.2 to 1.6 mm.
(Diameter).

Using each of the obtained flux-cored wires, a mild steel base material (thickness 50 mm × width 150 mm × length 2)
As shown in FIG. 1 (1 represents a base material and 2 represents a deposited metal), a hardfacing weld was formed on the surface of the (00 mm) surface to form a deposited metal layer. The build-up welding conditions were as follows. (Welding conditions) Welding current: 200 A, welding speed: 35 cm / min, welding voltage: 33 V, shielding gas: 100% CO ₂ , wire protrusion length: 20 mm, preheating / interpass temperature: 200 to
350 ° C overlay metal thickness: 10mm (three layers)

For each of the overlay welding materials obtained, the weld metal components were examined, and the hardness (Vickers hardness under a load of 30 kgf) and the state of cracks (color check of the surface of the weld metal) were examined. Were obtained.

Further, the same flux-cored wire and welding conditions as those described above were employed, and a wear resistance evaluation test apparatus schematically shown in FIG. 2 [in the figure, 3 is an upper mold base material (mild steel), 4 is a lower mold base material ( Mild steel), 5 is a hardfacing deposited metal layer, 6 is a crushed stone, 7 is an upper material chute, 8 is a lower material chute, 9 is a load detector (load cell), 10 is an actuator, and 11 is tempered glass. In this case, a hardfacing welded metal layer 5 is formed on each of the working surfaces of the upper mold base 3 and the lower mold base 4, each test material is mounted on a test apparatus, and the chart rock is continuously fed from the upper raw material chute. The sample was charged and crushed under the following conditions, the weight of the test material before and after the test was measured, and the wear resistance was examined by weight reduction (total of four test materials). Since the weight loss of the test material is expected to be affected by the weight (input amount) of the rock subjected to crushing, the specific wear amount (weight loss of test material / weight of crushed rock) was evaluated. Table 2 shows the results. (Crushing conditions) Crushing raw material: Chert rock, input size 2-5 mm, outlet size: 2.5 ± 1 mm Frequency at crushing: 2 Hz Average crushing load: 5 kN Number of repetitions: about 8,000

[0042]

[Table 1]

[0043]

[Table 2]

From Tables 1 and 2, the following can be considered. No. Nos. 11 to 18 are examples satisfying all the requirements of the present invention.
It is more than 00, and no crack is recognized on both the surface and the inside of the deposited metal. However, the hardness of the deposited metal is affected by the amount of Mo added, and even within the range specified in the present invention, the hardness tends to increase as the amount of Mo increases. However, the tendency is almost saturated when the Mo amount exceeds 4%.

In contrast to these examples, 1 to 10
Is a comparative example lacking any of the requirements specified in the present invention, and has a problem in either hardness or crack resistance as described below.

No. 1: The hardness of the deposited metal was low due to the insufficient amount of C in the wire, and the deposited metal was hot cracked because it did not contain V.

No. 2: Low temperature cracking occurred in the deposited metal due to too much Mn, and a large amount of Mn and Cr
Since the amount is insufficient, the hardness of the deposited metal is low and the wear resistance is poor.

No. 3: There is no problem in the hardness and crack resistance of the deposited metal, but blow holes are generated in the deposited metal due to insufficient amounts of Si and Mn. No. 4: Since the Mo content is insufficient, the hardness of the deposited metal is insufficient.

No. 5: The cracking resistance was reduced due to excessive amounts of W and B, and cracking occurred. No. 6: Hot cracking has occurred due to too much Cr content, and hardness is low and cold cracking has occurred due to insufficient B content.

No. 7: Hardness was low due to insufficient W content, and cracking resistance was poor due to too much Si content, causing low temperature cracking. No. 8: Since the C content is too large, the hardness is low and low-temperature cracking is also observed. No. 9: The cracking resistance was lowered due to too much Mo content, and low-temperature cracking occurred. No. 10: The cracking resistance was reduced due to too much V content, and the deposited metal was cracked at low temperature.

No. Nos. 11 to 18 (Example) and
Comparing 1 to 10 (Comparative Examples) as a whole, it can be seen that the specific wear amount of the deposited metal is much better in the former case and has excellent wear resistance. That is, in the comparative example in which even one of the above-mentioned prescribed requirements defined in the present invention is not obtained, the surface hardness of the obtained deposited metal is low, or defects such as cracks and blow holes occur in the surface layer or inside of the deposited metal layer. The specific wear amount is increased due to chipping or peeling from the defective portion. For the hardness and wear resistance of the deposited metal,
The o content dependency is recognized, and the higher the Mo content, the higher the hardness and the better the abrasion resistance. However, it can be confirmed that the tendency is almost saturated when the Mo content is about 4%.

[0052]

The present invention is constituted as described above, and among the elements contained in the flux-cored wire, C, B, and
By specifying the content of Cr, Mo, W, V, etc., the meat has high hardness, excellent crack resistance, and excellent wear resistance even when exposed to crushing / crushing conditions subjected to heavy impact. It is possible to obtain a flux-cored wire for build-up welding that gives a build-up weld metal.

[Brief description of the drawings]

FIG. 1 is a sketch showing a hardfacing welding method adopted in an experiment.

FIG. 2 is a schematic sectional explanatory view showing a rock crushing test method for evaluating the wear resistance of a hardfacing welded metal layer formed using a flux-cored wire.

[Explanation of symbols]

 Reference Signs List 1 base material (base material) 2 weld metal 3 upper die base material (mild steel) 4 lower die base material (mild steel) 5 hardfacing deposited metal layer 6 crushed stone 7 upper raw material chute 8 lower raw material chute 9 load detector ( Load cell) 10 Actuator 11 Tempered glass

Claims (3)

[Claims] 1. A flux-cored wire for hardfacing welding in which a flux is filled in an iron-based metal sheath, wherein a ratio of C: more than 0.5% to 1.5% (mass) in the total amount of the wire. %; The same applies hereinafter), Si: 0.6 to 2.1%, Mn: 0.6 to 1.8%, Cr: 2.5 to 7.5%, W: 0.1% or more Less than 1.5%, V: 0.1% or more and less than 1.5%, Mo: 1.0-8.0%, B: more than 0.2% and 0.8% or less. Flux-cored wire for hardfacing welding. 2. The flux-cored wire for hardfacing welding according to claim 1, wherein the Mo content is more than 4.0% and not more than 8.0%. 3. A flux for hardfacing welding, characterized in that the flux contains at least one of an arc stabilizer, a slag forming agent and a gas generating agent as a flux component in addition to the components of claim 1 or 2. Cored wire.