KR20050066141A - Flux cored wire for overlaying of roll and method for overlaying of roll using thereof - Google Patents

Abstract

The present invention does not fall after the impact toughness of the weld metal even after stress welding heat treatment, and in combination with the sintered flux for the welding workability of the roll growth flux cored wire and its welding method will be.

The flux cored wire for roll growth of the present invention is made of metal powder, ferroalloy or deoxidizing agent in the hollow portion of the tubular outer cover made of steel base steel, and Cr, Ni, Mo, Al, Mg, Si satisfying a specific equation. , A flux of Mn, residual Fe and unavoidable impurities is filled in a specific range based on the total weight of the wire, and the welding welding wire is used in combination with a sintered flux having a specific range of basicity. There is this.

Description

Flux cored wire for roll growth and growth welding method using same {FLUX CORED WIRE FOR OVERLAYING OF ROLL AND METHOD FOR OVERLAYING OF ROLL USING THEREOF}

The present invention does not drop the impact toughness of the weld metal even after stress welding heat treatment, combined with the sintered flux in the basic range of 1.20 to 1.50, welding operations such as slag peeling, bead appearance and arc stability during welding construction The present invention relates to a flux cored wire for excellent roll growth and a growth welding method performed with the sintered flux using the same.

Industrial rolls always have the potential for partial wear or accidental damage, in which case even undamaged good parts are wasted by replacing the rolls with new ones or by uniformly polishing the entire roll surface to the depth of the partial wear or damage. As a result, there is a problem that the raw unit of the roll made of expensive material rises and the roll management cost increases.

In order to reduce the rising cost of the roll as described above, the wear part or the damaged part of the roll may be fostered and reused, but the welding wire used for the roll fusing welding may be used for MIG welding. As a small diameter stainless wire is mainly used, there is a problem that the welding speed is too slow. In order to increase the welding speed, it is possible to increase the diameter and automatically weld the wire, but it is not economical because the price of the welding stainless wire is too expensive.

And the most important problem in roll surface welding is to control the metallographic characteristics of the welding weld similar to the roll material, because it is difficult to control the composition of the welding metal and the metallurgical characteristics according to the stainless steel wire. The problem is that it cannot be used unless it is a special case.

Accordingly, the present inventors can apply to automatic submerged arc welding, which has a compositional range similar to that of the known components of the roll and has a high welding speed, in performing the growth welding of the roll surface, thereby improving welding workability. Not only that, but also a suitable welding welding wire and a growth welding method thereof have been disclosed in Korean Patent No. 343751.

However, the product disclosed in the patent focuses only on the high hardness value of the weld metal (Vickers hardness of 250 or more), and mentions the low temperature impact toughness value through stress relief heat treatment to prevent cracking after multi-layer welding. In addition, in view of the histological properties (high hardness and low elongation) of martensite, there is a problem that low-temperature impact toughness is formed.

Therefore, even after stress welding heat treatment, the impact toughness value of the deposited metal does not drop and the slag peeling, bead appearance, and arc stability are all reduced when combined with sintered flux with basicity within the range of 1.20 ~ 1.50. It is an object of the present invention to provide a flux cored wire for excellent roll growth and a welding method thereof.

According to the first aspect of the present invention,

In the flux cored wire for surface growth of a roll filled with flux in a steel shell,

With respect to 100 wt% of the total flux composed of metal powder, ferroalloy, or deoxidizer in the hollow portion of the tubular shell made of steel base steel, the composition is Cr 10.0-25.0 wt%, Ni 4.0-8.0 wt%, Mo 1.0 It is characterized in that the flux of Al, Mg, Si, and Mn satisfying the following Equation (1) to 5.0 wt% and the remaining amount of Fe and unavoidable impurities is filled in an amount of 10 to 40 wt% based on the total weight of the wire. A flux cored wire for roll growth is provided.

According to the second aspect of the present invention,

In fostering the surface of the roll by automatic welding,

A flux cored wire for roll growth according to the first aspect;

The basicity defined by the following formula (2) is defined by CaO, MgO, K ₂ O, FeO, MnO, which are basic oxides, and SiO ₂ , which is an acidic oxide, and TiO ₂ , Al ₂ O ₃ , and ZrO ₂ , which are amphoteric oxides. Provided is a method for surface growth welding of a roll, which is carried out by submerged arc welding using a sintered flux adjusted to 1.50.

The reason for limiting the content of each component constituting the flux is as follows.

The Cr component is added using metal powders such as metal chromium powder, ferrochrome, chromium nitride, chromium carbide, and ferroalloy. The Cr component is a carbide generating element and is a ferrite generating element in metallography. Cr is a component that is closely related to the hardness, strength increase and abrasion resistance, heat resistance and oxidation resistance of the roll surface welding, and if the content is less than 10.0 wt%, the predetermined strength cannot be obtained during stress removal heat treatment after the welding. In case of exceeding 25.0%, fine cracks are generated on the surface of the beads after continuous fusing welding, and deterioration of slag peelability and uneven appearance of the beads after welding occur. Therefore, it is recommended to use the content of 10.0 ~ 25.0wt%.

The Ni component is an austenite forming element, and is a component that improves low temperature toughness and uses Me-Ni, which is a metal powder, as a component that contributes to the improvement of corrosion resistance of the welded portion. If the content is less than 4.0wt%, not only the impact toughness is not secured after the welding-stress removal heat treatment, but the elongation is lowered. If the content exceeds 8.0wt%, the tensile strength of the weld is high, causing high temperature cracking of the weld. The content is preferably used 4.0 to 8.0wt%.

Mo component uses Fe-Mo, an alloy iron, as an element to improve strength and corrosion resistance after stress relief heat treatment. If the content is less than 1.0wt%, it causes a decrease in strength after the stress relief heat treatment, and if the content exceeds 5.0wt%, the impact toughness is lowered, so the content is preferably 1.0 to 5.0wt%.

Al has a strong deoxidizer function, which reduces the oxygen and nitrogen concentration in the deposited metal, and also provides a function to enhance slag peelability and bead appearance after welding. However, Al is not preferable because it lowers the toughness of the deposited metal. As the raw material, a metal alloy such as Mg-Al, Me-Al, Fe-Al, metal powder or ferroalloy is used.

Mg also acts as an arc stabilizer as well as the function of deoxidizer, but when added excessively, high melting point slag may be generated, leading to deterioration of slag fluidity. As the raw material, Mg-Al may be used as the metal alloy, Me-Mg may be used as the metal powder, or the like.

Si and Mn are components that control the strength and elongation of the weld metal and have a deoxidation function during welding. Ferro silicon (Fe-Si), ferro manganese (Fe-Mn), metal manganese (Me-Mn) etc. can be used as the raw material.

Furthermore, the reason for placing the condition range of Equation 1 is as follows.

In the order of strong deoxidation function in the smelting process of iron oxide (FeO) in the weld metal melted at high temperature, Al, Mg, Si, Mn in order. In this order, slag and deposited metal are produced through the deoxidation function of molten iron oxide, and these elements form a close correlation with the behavior of molten iron. When it exceeds 0.35wt%, due to excessive slag formation, the work performance degradation such as slag peeling, arc instability, etc. is caused in the welding workability, so the range of the above formula is preferably 0.10 to 0.35.

As a welding method using the fusing welding wire of the present invention configured as described above, various methods are possible, but the most preferred method is submerged arc welding, in which the basicity is 1.20 to 1.50 in particular. Combination with the sintered flux, which promotes the formation of carbides in the growth metal of the welding weld, prevents precipitation of non-metallic inclusions and improves crack resistance.

The formula for calculating the basicity described above is as follows.

[Equation 2]

When the basicity calculated by the above equation is 1.20 or less, the amount of dissolved oxygen remaining in the deposited metal is increased to cause toughness deterioration due to the excess oxygen in the deposited metal. Since the appearance of the other weld metal becomes poor, it is preferable that the basicity range is within 1.20 to 1.50.

In addition, the smooth supply of wire is essential for welding construction, and in order to maintain the wire feeding property, the lubricant is applied to the surface of the wire by applying a lubricant such as a solid or a liquid to solve the problem. As a lubricant, the amount of organic carbon which is 500 ° C. or lower at a melting temperature is limited to 0.005 to 0.015% by weight relative to the weight of the measurement sample.

If the range of the organic carbon attached to the wire surface is less than 0.005wt% of the weight of the measurement sample, it causes anxiety and bead non-uniformity of the arc due to the unstable supply of the wire during welding, and if it exceeds 0.015wt% during welding It is not preferable to generate fine defects on the bead surface due to gas generation.

Details of the technical configuration and specific welding characteristics of the welding for welding the roll-forming flux cored wire and the sintered flux of the present invention composed of the above components and contents will be clearly understood through the embodiments with reference to the drawings. .

(Example)

Example 1: Fabrication and growth welding of flux cored wire for roll growth

The growth welding flux cored wire used in the embodiment of the present invention was manufactured with a wire diameter of 1.6 mm, and a welding specimen was manufactured by performing multi-layer welding as shown in FIG. 1 by combining the automatic welding flux.

The multi-layer growth welding conditions are as shown in Table 1 below, and examples of the components of the fluxes performed in the present invention are shown in Table 2 below, and are performed together with the growth welding flux cored wires produced by the present invention. An example of the composition and basicity of the automatic sintered flux are shown in Table 3 below.

Welding current Welding voltage Welding speed Interlayer temperature Floor 280A 32 V 25 CPM 200 ℃ 4th floor, 9 pass

% Flux Composition to Wire Weight Sintered flux base C Cr Ni Mo Si Mn Mg Al Fe Example 1 1.0 12.8 4.3 1.1 0.1 0.9 0.2 0.2 Balance 0.32 1.40 Example 2 1.2 13.8 4.3 1.1 0.2 0.8 0.2 0.2 Balance 0.32 1.42 Example 3 0.8 16.4 4.5 1.1 0.2 0.9 0.2 0.2 Balance 0.31 1.40 Example 4 1.0 19.7 4.5 1.1 0.2 1.0 0.2 0.2 Balance 0.25 1.40 Example 5 0.8 24.6 4.5 1.1 0.3 1.0 0.3 0.3 Balance 0.33 1.44 Example 6 1.0 10.2 6.0 5.0 0.1 0.8 0.2 0.2 Balance 0.34 1.50 Example 7 1.0 16.5 4.8 1.1 0.2 1.0 0.2 0.2 Balance 0.25 1.43 Comparative Example 1 1.0 19.7 5.5 1.3 0.4 0.5 0.5 0.2 Balance 0.56 2.00 Comparative Example 2 0.8 32.8 9.1 2.1 0.2 0.9 0.2 0.2 Balance 0.22 1.43 Comparative Example 3 1.0 14.8 10.0 3.5 0.3 0.4 0.4 0.2 Balance 0.59 1.35

ingredient ZrO ₂ FeO TiO ₂ CaO K ₂ O MnO SiO ₂ MgO Al ₂ O ₃ basicity 0.17 2.23 0.96 11.2 0.32 4.8 18 28 22.3 1.44

Thereafter, as shown in the graph of FIG. Was carried out. At this time, the tensile specimen and impact specimen specifications were taken according to the international standard prescribed in AWS B4.0 STANDARD METHODS FOR MECHANICAL TESTING OF WELD, and the results are shown in Table 4 below.

Tensile Strength (N / mm ² ) Impact value (J) (shock temperature -10 ℃) Welding workability Bead appearance Slag peelability Arc stability Example 1 968 38 o o o Example 2 980 35 o o o Example 3 985 36 o o o Example 4 970 30 o o o Example 5 985 32 o o o Example 6 968 34 o o o Example 7 986 34 o o o Comparative Example 1 960 10 x o o Comparative Example 2 990 5 x x x Comparative Example 3 990 28 x x x

As shown in Tables 2 and 4, Examples 1 to 3 satisfying the scope of the present invention can be confirmed that the impact value is excellent at 35J or more at the impact temperature of -10 ℃ and the appearance of the bead, slag welding during the welding process It turns out that peelability, arc stability, etc. are also excellent.

Furthermore, Examples 4 to 7 satisfying the scope of the present invention was confirmed that the tensile strength, impact value and welding workability is good.

On the contrary, in the case of Comparative Examples 1 and 3, the weldability was found to be inferior to 0.35, which is the range of Equation 1. Tensile strength was high, but impact value dropped rapidly and welding workability such as bead appearance, slag peelability, arc stability, etc. was remarkably decreased.

Example 2: Appropriate Organic Carbon Content of Solid Lubricant

Calcium stearate (main component) was applied to the surface of the wire corresponding to Example 1 in Table 2 in the Examples as a solid lubricant, and then the same process as in the above Example was repeated.

The amount of organic carbon attached to the wire was measured using a model name RC-412 as a surface analysis device. The instrument can measure carbon, hydrogen, and water content in a multi-layered phase by selectively using nitrogen or oxygen as a carrier gas. When nitrogen gas is used, CO ₂ and H ₂ O can be measured in a non-oxidizing atmosphere. When oxygen gas is used in an oxidizing atmosphere, C in the sample is converted into CO ₂ and measured.

The welding workability according to the amount of organic carbon measured by the above equipment was evaluated, and the results are shown in Table 5 below with good o, poor x and the middle thereof as Δ.

Welding workability Organic Carbon (wt%) Bead appearance Slag peelability Arc stability 0.003 x △ x 0.005 o o o 0.015 o o o 0.020 x o △

As shown in Table 5, when the organic carbon is less than 0.005wt% of the weight of the measurement sample, it causes anxiety of the arc and bead nonuniformity due to unstable wire feeding during welding, and in the case of more than 0.015wt%, gas generation during welding Since fine defects are generated on the bead surface, the amount of organic carbon combusted at the melting temperature of 500 ° C. or less is preferably in the range of 0.005 to 0.015 wt%.

As described above, when the weld welding is performed by combining the roll cored flux cored wire and the sintered flux having a basicity of 1.21 to 1.50 according to the present invention, unlike the conventional method, the strength of the weld metal by stress relief heat treatment after the weld welding is different. And low temperature impact toughness, it is a roller surface growth welding material for alloy steel, especially Cr-Mo steel, which is widely used in steel mills.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side view of a multi-layer growth welding performed with a wire produced by the present invention on a metal plate surface.

Figure 2 is a graph showing the conditions for heat treatment of the specimen after performing the multi-layer growth welding as shown in Figure 1 with the wire produced by the present invention.

Claims (3)

In the flux cored wire for surface growth of a roll filled with flux in a steel shell, With respect to 100 wt% of the total flux composed of metal powder, ferroalloy or deoxidizer in the hollow portion of the tubular outer cover made of steel base steel, the composition is Cr: 10.0 to 25.0 wt%, Ni: 4.0 to 8.0 wt%, Mo: 1.0 to 5.0 wt%, and the flux of Al, Mg, Si, and Mn satisfying the following Equation 1 and the remaining amount of Fe and unavoidable impurities is filled so that 10 to 40 wt% based on the total weight of the wire. Flux cored wire for roll growth, characterized in that [Equation 1] In fostering the surface of the roll by automatic welding, A flux cored wire for roll growth according to claim 1; The basicity defined by the following formula (2) is defined by CaO, MgO, K ₂ O, FeO, MnO, which are basic oxides, and SiO ₂ , which is an acidic oxide, and TiO ₂ , Al ₂ O ₃ , and ZrO ₂ , which are amphoteric oxides. A surface growth welding method for a roll, characterized in that it is carried out by submerged arc welding using a sintered flux adjusted to 1.50. [Equation 2] The organic carbon content according to claim 2, wherein the organic carbon is attached to the surface of the wire when the solid lubricant is applied to the flux-cored wire for growing the roll, and burns at a melting temperature of 500 ° C. or less, in a range of 0.005 to 0.015 wt% based on the weight of the sample. Surface growth welding method of the roll, characterized in that to satisfy.