KR20090045252A - Iron-based corrosion resistant wear resistant alloy and deposit welding material for obtaining the alloy - Google Patents

Abstract

Compared to 304 stainless steel, high chromium cast iron, and high carbon-high chromium cast iron-based materials, the present invention is superior in corrosion resistance and wear resistance, and moreover, high carbon-high chromium carbide precipitated iron-based abrasion resistant alloys are hardly obtained. High-performance, low-cost, low-C-high-Si-high Cr-B-Nb-based iron-based corrosion-resistant alloy having corrosion resistance and superior abrasion resistance to these metals, and hardly causing brittle peeling peculiar to high Si-containing steel To provide. The alloy is C: 0.5 to 2.0% by weight, Si: 2.5 to 4.5%, Mn: 0 to 10% or less, Cr: 15 to 31%, Ni: 0 to 16%, Cu: 7% or less, Mo 10% or less, B: 0.5 to 3.5%, 0 ≦ Nb + V ≦ 8%, and (Si × B) ≦ 2014 / Cr ² + 0.083Cr + 1.05 in the range of 15% ≦ Cr <27%. Satisfies 1.25% ≦ (Si × B) ≦ 6.0% in the range of 27% ≦ Cr ≦ 31%, and (Si × B) ≧ 570 / Cr ² − in the range of 15% ≦ Cr <20% It satisfies 0.066Cr + 1.145 and satisfies (Si × B) ≧ 1.25 in the range of 20% ≦ Cr ≦ 31%.

Corrosion and wear resistant alloys, brazing welded materials, 304 stainless steel, high chrome cast iron

Description

Iron-based corrosion resistant wear resistant alloys and obtaining welding alloys {Iron-based corrosion resistant wear resistant alloy and deposit welding material for obtaining the alloy}

The present invention is an iron-based alloy of a low carbon-high silicon-boron-niobium-high chromium cast steel having excellent corrosion resistance and abrasion resistance, more specifically, 304 stainless steel or high chrome cast iron, high carbon-high chrome cast iron system Compared to the material, the corrosion resistance and abrasion resistance is overwhelmingly excellent. Furthermore, the high carbon-high chromium carbide precipitated iron-based abrasion resistant alloy has high corrosion resistance which is hardly obtained, and has higher wear resistance than these metals and high Si-containing steel. The present invention relates to a high-performance, low-cost, iron-based corrosion resistant alloy in which unique brittle peeling is unlikely to occur, and a deposition welding material for obtaining the alloy.

Recently, waste incineration plants, car shredder fluidized bed incinerators, waste oils, waste liquid incinerators, etc. have been constructed and operated. High-chromium cast iron is used for the heat-resistant wear-resistant part of this apparatus, and SCH13 heat-resistant cast steel etc. is used for the apparatus which receives high temperature thermal oxidation. However, after some time of operation, their components and devices are worn, damaged, and corroded by treatment or heat, and their life countermeasures are required.

As a countermeasure to increase the lifespan of these devices and members, growth repair welding of wear parts is mainly used, and as the welding material, a high carbon-high chromium cast iron-based welding material which is an iron-based alloy is mainly used. The reason is that it is an inexpensive iron-based alloy and is excellent in wear resistance and high temperature oxidation resistance. However, these furnaces and peripheral devices are exposed to corrosive combustion gases at high temperatures or acid dew point corrosion occurring at the time of shutdown, and can be coped with only high temperature oxidation resistance and abrasion resistance. This is a phenomenon.

In other words, if the high carbon-high chromium cast iron-based welding material has excellent wear resistance and does not have excellent corrosion resistance, the life of these various devices cannot be extended. In particular, corrosion resistance requires corrosion resistance by chlorine gas, hydrochloric acid, sulfuric acid, dilute sulfuric acid, and the like.

Regarding these usage environments where corrosion resistance, oxidation resistance, and high temperature wear resistance are required, the cobalt-based alloy stellite is considerably superior to the iron-based growth material, and application as a growth material is considered. However, this alloy is considerably expensive compared to the iron base alloy, and cannot balance the cost effect. For this reason, the development of the iron-group upbring welding material which has the equivalent performance at low cost is calculated | required (nonpatent literature 1).

[Non-Patent Document 1] 14th Practical Welding Lecture Text "Basic and Application of Surface Treatment Technology" (1) The Eastern Society of the Welding Society June 23-24, 1988

In addition to this, the use of expensive alloys having rare-value metal elements such as nickel and cobalt as simple disposable wear materials is considerably unnecessary when judged from the direction of international resource saving. The inventors of the present invention have always thought that they should be used effectively for high value-added endurance materials or resource-recoverable applications, and inexpensive iron-resistant wear alloys should be used for disposable applications such as wear materials.

As iron-based wear-resistant alloys, high-carbon-high chromium cast iron-based growth materials have been frequently used at present, but the corrosion resistance is extremely low compared to cobalt and nickel-based alloys. I could not say that. Representative composition of the high-carbon-high chromium cast iron-based welding material mainly used conventionally is "C: 3 to 6%, Cr: 16 to 36%, Mo: 0 to 3%, Fe: the rest".

However, alloys belonging to this are considerably superior in abrasion resistance, and despite the iron-based alloy, they are excellent in high temperature oxidation resistance at one end by high chromium content, and are widely used in high temperature wear applications of 600 ° C and 600 ° C or higher. As one of the representative examples, there is an alloy having a chemical component described below. `` C: 5.2%, Cr: 32%, Si: 0.6%, Mn: 0.7%, Fe: Rest ''

This iron-based abrasion-resistant welded growth metal shows excellent abrasion resistance, and when expressed by a wear coefficient, SS400 mild steel is set to 100 to abrasion test value of 5.0 to 10, and shows about 10 to 20 times wear resistance of mild steel. However, since it is too high carbon content, corrosion resistance is not enough.

Therefore, the present inventors are equivalent to or at least equivalent to the wear resistance of the high carbon-high chromium cast iron-based weldable growth alloy, and are similar to the corrosion resistance of the cobalt alloys of Stellite Nos. 1 and 6, As for corrosion media, the development of low-cost iron-based alloys with equivalent or higher corrosion resistance was planned. As a nickel-based alloy and an alloy having excellent abrasion resistance, a colloidal No. 6 alloy is famous. Its wear coefficient WR is 5 and slightly superior to WR = 8 of Stellite No. 1, but in terms of sulfuric acid corrosiveness is inferior to that of Stellite alloys. When it surpassed this, it judged that it surpassed nickel group. Standard compositions of stellite No. 1 and No. 6 are as follows.

[Standard Chemical Composition of Stellite No. 1 of Cobalt Group Alloys]

`` C: 2.1%, Si: 0.8%, Mn: 0.4%, Cr: 32.0%, Fe: 2.0%, W: 12.0, Ni: 1.7, Mo: 0.1, Co: Rest ''

[Standard Chemical Composition of Stellite No. 6 of Cobalt Group Alloys]

`` C: 1.2%, Si: 0.8%, Mn: 0.5%, Cr: 27%, Ni: 2.7%, W: 4.5%, Fe: 2.5%, Mo: 0.1%, Co: Rest ''

In view of the alloying elements contained in these cobalt-based alloys, cobalt, tungsten, and the like are contained in a large amount, and are composed of very expensive elements. Therefore, since the cobalt-based alloy is a very expensive alloy, it is extremely difficult to meet the cost-effectiveness in terms of cost in the case of a device with a very large growth area.

For this reason, it is considered that the use of this alloy is limited only to the use that can exert a lot of effects by the growth of an extremely limited portion. Various valve sheets, for example, the tip of the needle valve, the pump rod, the pump sleeve, the cam shaft and the like. Stellite No. 1 and No. 6 alloys are heat-resistant, corrosion-resistant, and wear-resistant alloys that require three factors at the same time, particularly suitable for use at 600 ° C or higher, and are world-renowned alloys. However, it is a phenomenon that it is continuously used for the development of the apparatus which requires corrosion resistance and abrasion resistance also about the use below 600 degreeC.

Even in applications below 600 ° C, the use of alloys containing expensive rare elements in simple wear members is antisocial and expensive in view of the waste of global resources and the depletion of future resources, as described above. The element should be applied for more meaningful value added uses and for recoverable use.

Therefore, the present inventor proposes a high wear resistance "growth welding material and clad material", which is a low-cost iron-based alloy and exhibits high temperature oxidation resistance of 600 ° C or higher and excellent high temperature oxidation resistance as one means of solving and advancing this problem even slightly. The patent was acquired (patent document 1). The patented alloy is grown in an apparatus requiring high temperature wear resistance, oxidation resistance, and corrosion resistance for applications of 600 ° C. or higher, thereby giving superior performance to Stellite No. 1 and achieving significant cost reduction.

Patent Document 1: Patent No. 3343576

Representative applications include rotary kiln lift lifters used at ambient temperatures of 800-900 ° C., clean car cooler shoot liners used at 900-1000 ° C., copper resource recovery clean car glides of 900 ° C. or higher. River, 800 ℃ clean car conveying bucket, fluidized bed boiler tube, air blowing nozzle twisting, etc., and a lot of practical results on the growth of these, greatly reducing the cost of longer life Contribute to. Representative component compositions and performances of this patent-grown alloy are shown below.

[FREA-METAL chemical composition (wt%) of No.55 alloy]

Welding metal composition "C: 1.3%, Si: 4.5%, Ni: 3.7%, Mn: 3.6%, Cr: 36%, Fe: remainder"

Base material: SUS310S 9mmt

Hardness: HV977

Wear factor: 4.2

The first-layer Cr analysis value: 35%

Microstructure: * 400 times (photograph No. 1 in FIG. 2)

In addition, the test piece No. 55 which performed the bending process (bending radius 290 mmR) which made the hardened metal inside is shown by photograph No. 2 in FIG. In addition, alloy No. is employ | adopted in the composition comparison test mentioned later (refer FIG. 1).

The biggest feature of this patent alloy is that high Si is contained in a high chromium iron base alloy of more than 30%. Si is considerably cheaper than elements such as expensive V, W, Mo, Co, and Ni which give high temperature abrasion resistance and heat resistance. However, the biggest drawback of high Si containing steels is that they make the alloy considerably softer, and because of this drawback, a large amount of addition to the iron-based abrasion-hardening metals is still undermined. Nevertheless, the present inventors pay attention to the properties of promoting the formation of the low cost elements, high temperature oxidation resistance, and chromium carbide, which are present on the earth, which are characteristic of Si. High content, ie 3.0-7.0% was added.

In addition, although high Si containing steel called silica is already manufactured, this metal is an alloy developed for the intermetallic wear application, and the precipitation amount of the carbide which gives abrasion resistance as much as one hundredth of carbon content is extremely There was little and it was an alloy which cannot tolerate practical use in severe high temperature reduction wear applications like the said patent alloy (patent document 2).

Patent Document 2: Japanese Patent Application Laid-Open No. 54-81115

The weld metal of the high Si-containing steel has a property of exfoliation of a cut surface on a surface layer surface, and there is a risk of scattering into a cut shape when the bending process is performed. When pressed harder, the weld metal breaks so as to fall off from the base metal. Looking at the bending test piece No. 55 of the said wear-resistant alloy, the typical peeling state can be recognized. Therefore, the patented alloy was mainly used in the form of a welding rod or welded growth wire multiplied by the opportunity of bending.

Although the above-mentioned patent alloy was developed by the addition of high Si, its use is a high temperature wear application of 600 ° C. or higher, and imparts high temperature oxidation resistance equivalent to SUS310S despite iron-based alloys, and acicular chromium carbide which is difficult to drop off at high temperature. By depositing a large amount, high temperature wear resistance and high temperature hardness were remarkably improved. In particular, the alloy has a high ductility compared to room temperature at a high temperature of 600 to 1000 ° C., so that the softness is improved, and Si is dissolved in a large amount of matrix in the deposited metal, thereby improving the high temperature oxidation resistance of the matrix. It contributed to the thing and made it possible to endure the high temperature of 1000 degreeC.

In particular, the condition "Cr% ≥-1.6Si% + 37Cr%", which is the basis for constituting the above-described patented alloy, is based on Cr and Si, which promotes a large amount of precipitation of acicular chromium carbides necessary for securing excellent wear resistance at 600 ° C or higher. It is a two-element correlation. If this correlation is satisfied, the precipitation of acicular chromium carbide (Cr ₇ C ₃ ) cannot be obtained, resulting in a decrease in high temperature wear resistance.

Normally, as the metal's permeability, wear is easily promoted because the hardness of the metal matrix is extremely softened at a high temperature range of over 600 ° C to 1000 ° C, but acicular carbides are entangled in the entire surface of the matrix like fibers of a knitted fabric. Since it is incorporated in the thickness direction, selective abrasion of the soft matrix is prevented, and high temperature abrasion is prevented by extracting a large amount of high hardness acicular carbide, which is the basis of the patent alloy technology. From the structure of this alloy, it is possible to recognize the precipitation of excellent acicular carbide (photo No. 1 in Fig. 2).

However, the excellent properties at high temperatures, on the contrary, are disadvantages that have a high vulnerability at the normal temperature, and are very poor in bending workability, and can only be applied to straight items when a wear resistant steel sheet made of the above-described patent alloy is produced. In the case of an article having a curvature, it was unavoidably carried out by a welding wire or a hand welding rod, and manufacturing cost always became expensive.

As described above, although the patented alloy has a performance comparable to that of the stellite alloy, its maximum drawback is high Si content, so that peeling is likely to occur in the form of slices on the surface layer of the weld metal, and particularly a large area is obtained. Eggplant makes the production of wear resistant steel sheets difficult. In addition, in the welding welding between clad steels formed of the same alloy, when the metal is pulled by the welding stress, peeling occurs in the hardened metal, and welding welding is very difficult.

Problems to be Solved by the Invention

The object of the present invention is to improve brittleness, which is a drawback of high Si-containing steels, to maintain overwhelming corrosion resistance compared to high chromium cast iron based alloys and 304 stainless steels. Low carbon-high chromium-high Si which has the same or better performance than No. 6 and is equal to or higher than the high carbon-high chromium cast iron-based growth alloy or stellite No. 1 and No. 6 in terms of wear resistance. It provides an iron-based corrosion-resistant wear-resistant alloy of boron-niobium cast steel, and a growth welding material for obtaining the alloy.

BRIEF DESCRIPTION OF THE DRAWINGS The figure which shows the influence of Si * B amount and Cr amount on bending workability.

2 is a photograph of alloy evaluation, photograph 1 is a micrograph showing a needle-like structure of a conventional alloy, and photograph 2 is a photograph of a sample cross section showing bending fracture of a conventional alloy.

Fig. 3 is a photomicrograph showing the structure of the alloy No. 10-C of the present invention, and the picture 2 is a picture after the bending cracking test.

4 is a micrograph showing the structure of the alloy No. 5 of the present invention.

Means to solve the problem

In order to achieve the above object, the present inventors combines a large amount of Cr with a small amount of Si, Mo, Cu, Ni, and the like to improve the sulfuric acid resistance, which is a weak point of the iron-based alloy, and has already developed a Worthite alloy ( C <0.07%, Cr 20%, Ni 25%, Si 3.5%, Mo 3%, Cu 2%) as one model to find an alloy having excellent hydrochloric acid resistance, and is an expensive cobalt-based alloy of stellite No. The development of low-cost iron-based alloys with the same or more corrosion resistance and wear resistance than 1 and No. 6 was planned.

Worthite alloys are used in sulfuric acid corrosion applications in chemical plants and petroleum-fired boilers, Cr-Ni-Si-Mo-Cu stainless steels developed by Worthington Pum of the United States. Although the Worthite alloy was used as one model from the viewpoint of sulfuric acid corrosion resistance, a problem with this alloy was that the alloy contained a large amount of Ni, which is contrary to the intention of the present inventors. It was a great departure from the point of view of. Worthte alloys are used as corrosion-resistant structural materials that require strength to the last, for example, stainless steel cast steel pumps and the like. Therefore, although it is important that the metal itself has toughness, it is embrittled because it is high Si content, and it is assumed that it is designed in high Ni content in order to improve the embrittlement. Naturally, although high Ni content is mainly aimed at improving the corrosion resistance, it has a low hardness and is poor in wear resistance as the wear-resistant cured metal material, and is an iron-based alloy which cannot be used as the wear-resistant alloy planned by the present inventors.

Since the growth alloy developed by the present inventors has the basic principle of satisfying corrosion resistance and wear resistance at the same time, stainless steel is often used for the base metal. For this reason, since this inventor can expect to pick up Ni content in the welding metal from the stainless steel of a base metal, etc., Ni content added to a welding material is 13% at the beginning, and resource saving is aimed at. It was. That is, the Ni addition amount of the developed alloy is usually 5% or less, and only 13% at most is added. On the other hand, about Si is as follows.

(1) About embrittlement of high Si-containing steel

There is a high silicon steel sheet as a high Si-containing steel of iron-based metals. An example of the component is shown below.

`` C: 0.12%, Si: 4.12%, Mn: 0.07%, P: 0.07%, S: 0.005%, Fe: Rest ''

Silicon steel sheet is mainly used for the core of a transformer or a motor. When the Si content is increased, the magnetism becomes stronger, and it is preferable. However, when 5% or more of Si is added, the steel is receded, and when it is added more than that, the rolling operation becomes difficult, making the thin plate difficult. Si has the property of softening steel simply by adding it to carbon steel. Moreover, since the equivalent Si is added to the high chromium alloy containing a large amount of Cr, the embrittlement tendency of Si itself and the soft and hard chromium carbide precipitated by the high chromium alloy synergistically promote the embrittlement of the alloy. It is quite difficult to give ductility to the alloy.

(2) Effect of C on the embrittlement, corrosion resistance and abrasion resistance of high Si containing steel

First, the carbon content can be considered as one of the important component elements in improving the ductility of the weld metal, that is, not causing peeling, and improving the corrosion resistance. The high carbon-high chromium cast iron-based welding fusing material has a considerably high carbon content and is included in the cast iron range containing 4.5 to 6.0%. As a result, a large amount of soft chromium carbide was precipitated, and the Cr content contained in the matrix was reduced to extremely reduce the corrosion resistance. That is, the biggest cause of the poor corrosion resistance of various high carbon-high chromium cast iron welding welding materials is to contain a large amount of carbon in order to obtain abrasion resistance, a carbide forming element having a high affinity with carbon, chromium, tungsten, vanadium, It is a point that abrasion resistance is ensured by combining carbon with titanium, niobium, and the like and depositing a large amount of hard carbide in the metal matrix.

It is said that chromium carbide has high hardness of HV1650 to 2100, niobium carbide to HV2400, titanium carbide to HV2800, vanadium carbide to HV2800, and tungsten carbide to HV2400 to 3000. The high chromium cast iron alloy has excellent wear resistance by the precipitation of these carbides, while the corrosion resistance of the weld metal is extremely deteriorated because of its high carbon content.

Generally, from the iron-carbon binary state diagram, the carbon content is about 2.0 to 2.1% and less than that is cast steel, and when it exceeds more, it is called cast iron. In addition, since it was judged that the cast steel of 2.0% or less than the carbon-containing cast iron exceeding 2.0% was superior in terms of mechanical properties, particularly the toughness of the metal matrix, the developed welded alloy had a carbon content of the first layer weld metal of 2% or less. Designed. Naturally, it was assumed that low carbon content also contributes to the improvement of corrosion resistance.

When the carbon content of the welding material is 3.0% or less, it is determined that the amount of carbide precipitates to form a pore, and when the first layer is grown on mild steel, the first layer is subjected to penetration of mild steel. The deposited metal did not show sufficient carbide precipitation and resulted in a considerable drop in wear resistance. For example, even if the carbon content is added to the welding material by 3.0%, when one layer is grown in mild steel or stainless steel base material, the carbon content in the weld metal varies depending on the penetration depth into the base metal, but is 1.8% to 2.1. The range of% (precipitation depth of about 30% to 40%). This content becomes around 2.0% of the carbon content divided into cast steel and cast iron. Usually, the amount of carbon contained in the high carbon-high chromium cast iron-based welding material is required to be at least 4.5% or more, and the state of over-vacuum that precipitates sufficient carbides even under the influence of dilution of mild steel from the first layer. It is important to keep it. That is, even if it receives 30% of penetration, it is necessary for the carbon content of the 1st layer weld metal to be about 3% or more, and to become a super vacancy.

From this, the upper limit of the carbon content of the 1st layer weld metal of a developed alloy made 2.0% or less which is content which distinguishes cast steel and cast iron into one target. As another reason, the carbon content of the alloy of Stellite No. 1 of the cobalt-based alloy is C: 2.0%, and the corrosion resistance performance criterion of the developed welding material is equal to or greater than that of Stellite No. 1. Since the target was set, the carbon content was determined to be about the same amount.

Table 1 shows a comparison of wear resistance by the difference in carbon content. Alloys No. 41 and No. 42 are mentioned because they are not included in the range of developed alloy components because they are high Si-containing steel and do not contain Nb and B, but the wear resistance comparison due to the difference in the amount of carbon is good.

TABLE 1

Effect of carbon content on wear resistance (% by weight)

The No. 41 alloy and the No. 42 alloy were produced by adjusting to almost the same chemical component except for carbon content. The wear resistance of the No.42 alloy having a high carbon content was about 2.5 times better than that of No.41. Since the carbon content of the No.42 alloy is high, the amount of precipitation of chromium carbide is large, and the wear resistance is improved.

Although carbon content is one of the factors which have a big bad influence on corrosion resistance, if carbon content is reduced in order to improve corrosion resistance, the precipitation amount of carbide will decrease and abrasion resistance will fall remarkably. Therefore, the present inventors fixed a component composition of high carbon-high chromium cast iron which precipitates a large amount of carbides by high carbon content and secures abrasion resistance. In other words, even if the amount of carbon added is 0.5% ≦ C ≦ 2.0 to 2.5%, it has been aimed to develop an alloy capable of securing excellent wear resistance and securing excellent corrosion resistance and excellent toughness. Regarding the welding growth material, various heterogeneous growth methods exist, and since the penetration depths are different and the base material dilution ratios are different, the maximum amount of C is 2.5% or less.

(3) Effect of Cr on the Brittleness and Wear Resistance of High Si-Containing Steels

Cr is the alloying element that most affects the embrittlement of high Si-containing steels. The chromium content of the deposited metal of the first layer actually grown using a welding material having a chromium addition amount of up to 45% is about 25% to 50% of the base metal when the base material is mild steel or sten steel, so it is about 23 To 34%. When the amount of chromium added is 25%, it is about 15 to 19%. When the base material of SUS304-316 is used, if the welding material of Cr 35% was used, the chromium content of the welding metal of a 1st layer will be about 26 to 31%. Although the penetration depth differs depending on the welding method, the Cr content of the 1st layer weld metal on average is selected in the range of roughly "15% <= Cr <= 31%.

When the maximum addition amount is 45%, the base material dilution rate is 50% or used in the case of the water-sealed bar exceeding this, and if the base material is mild steel, the chromium content of the first layer weld metal is about 23%, and falls within the above range. do. In particular, in the case of the wear-resistant steel sheet, it is formed by one layer growth, and the thickness of the weld metal is about 4 to 6 mm. Regarding the embrittlement of the weld metal obtained from the weld growth material or the wear resistant steel sheet, the behavior of the first weld metal is considered to be the most important. Therefore, it was necessary to formulate the range of the chromium content of the 1st layer weld metal. The reason for this is that chromium is the most contained element in the development alloy compared to other alloying elements, and furthermore, since it has a great influence on the embrittlement of the deposited metal, the grasp of the influence of other small amount addition alloys is within the specified range of this element. Judgment is very important in behavior.

In addition, since the above-mentioned patent alloy needs to deposit a large amount of acicular chromium carbides in order to give excellent high temperature wear resistance at 600 degreeC or more, the two-element correlation formula of Cr and Si "Cr≥-1.6Si + 37 (weight%) It was very important to satisfy. When the Cr content is 32% or more and the Si content is 3% or more, a large amount of acicular chromium carbide precipitates to cause significant embrittlement and peeling occurs on the hardened metal surface. No.2).

With respect to this patented alloy, the developed alloy is not an alloy mainly focused on high temperature wear resistance, but an alloy developed mainly for securing ductility and improving corrosion resistance of high Si-containing steel, which is vulnerable to iron-based alloys. Therefore, since it is not necessary to satisfy the condition of Cr≥-1.6Si% + 37Cr% for securing wear resistance at high temperature, it is possible to reduce the addition amount of silicon and chromium to soften the weld metal, compared with the former. When the amount of Si added is decreased, the amount of precipitated chromium carbide decreases, so that the ductility is recovered, but the wear resistance decreases remarkably.

This phenomenon has been demonstrated in the experiments described below. The toughness and abrasion resistance of the alloy in the case where the amount of Cr added which had the most impact on the wear resistance was reduced from 36% to about 20 to 25% by using the patented alloy as the base alloy was examined. Investigation of toughness produced the wear resistant steel plate which welded the test alloy on 5 mm thickness 1 layer on thickness 9mmt x width 100mm x length 400mm with the SUS310S base material, and determined the toughness by the bending test of 200R and 290R. In this bending test, it was judged that toughness was not possible when some of the weld metal was peeled off or lacked. The wear coefficient WR was based on the wear coefficient WR = 15 or less which Stellite No. 6 has, and needed what was superior to this. Table 2 shows the alloy composition and Table 3 shows the results of the investigation.

TABLE 2

FREA-METAL modified alloy (added weight%)

TABLE 3

Test result

In spite of the high Si addition amount, the flexural performance was passed (o) for all alloys because of the low Cr content, it is assumed that the precipitated amount of acicular chromium carbide was small and contributed to the flexural ductility. Degraded.

This test proved that Cr, ie, chromium carbide, had the greatest effect on toughness (flexibility) and wear resistance. As for wear resistance, two kinds of alloys of No. 58 and No. 70 barely passed. The wear resistance of WR is high even when Nb is added in an amount of 20% (containing about 21%) of Cr in alloy No.58 and 25% (containing about 25%) of Cr in alloy No. 70. The minimum value of 14-15 was shown, and it turned out that it is impossible to adjust abrasion resistance by addition of Nb alone.

(4) Effect of B addition on wear resistance and ductility of high Si steel

The FREA-METAL alloy (No. 55) in which Cr and Si content were large, and a large amount of soft acicular chromium carbide was precipitated in the matrix was easily peeled off by bending (photo No. 2 in Fig. 2). Si itself cannot improve the properties of softening steel. However, as for the developed alloy, it has been found that the precipitation amount of the chromium carbide most affects the softening of the alloy. However, this tends to cause the chromium carbide to be needle-shaped as the Si content increases. It was thought to have promoted embrittlement and to be one of the major factors that lowered the wear resistance by causing cracking or peeling.

In order to improve the bending ductility, it is important to reduce the amount of large crystals of soft acicular chromium carbide. By reducing the amount of acicular carbide, the wear resistance is lowered, so as to compensate for this, a highly hardened finely refined compound having a spherical shape, island shape, reticular shape and irregular shape, which is dispersed and crystallized, is refined. It was thought that the method of preventing the brittleness of the weld metal and improving the wear resistance was the best means.

Niobium is a means of improving wear resistance without promoting brittleness of high Si steel, and having a highly hard boride which does not adversely affect corrosion resistance, or affinity with carbon, and crystallized spheroidized carbide. The coexistence with carbides aimed at improving wear resistance. At the same time, it was expected that the effects of these two elements could not be tolerated in embrittlement such as peeling or dropping off of the surface metal, which is the biggest drawback of the high Si-containing steel, and acted in a direction of suppressing embrittlement.

Wear resistance can be improved by adding boron in the chromium content of the weld metal in a range of 15% ≦ Cr ≦ 31%. However, in addition of boron alone, for example, 0.5% addition contributes to improvement in wear resistance. In addition, the addition of 4.0% significantly hardened the weld metal and caused numerous cracks in the direction perpendicular to the weld beads. By addition of B alone, the range of addition amount was narrow, and it was very difficult to judge the soft state of the weld metal. The wear resistance of the low B-containing steels and the high B-containing steels were compared. Although the high B-containing steels exhibited excellent wear resistance, significant embrittlement occurred. The effect of the addition amount of boron on the wear resistance and bending workability is shown in Table 4.

TABLE 4

Effect of Boron Addition on Wear Resistance and Flexibility

Cr: Content (1st layer weld metal)

In addition, the high silicon content, which is the biggest feature of the developed alloy, is a very effective factor against high temperature oxidation resistance, sulfuric acid corrosion resistance, hydrochloric acid corrosion resistance and organic acid corrosion resistance, but when it is added 3.5% or more to an iron-based alloy, it has a very soft property. In spite of its excellent performance, it was not used much for iron welding welding materials. Increasing the amount of Si added to the high Cr steels makes it easier to needle the chromium carbides, resulting in a tendency to soften the weld metal. When 5% alone is added, surface peeling occurs on the weld metal and decreases to 2.5%. Wear resistance is significantly worse. Therefore, the addition amount of Si which is the center of a development alloy at least 2.5% and at most 4.5%-5.5% is essential, and it was an absolute condition to remove embrittlement within this addition range.

Si also had a narrow range of addition, as in B, and it was very difficult to evaluate the ductility and wear resistance of the weld metal in the single addition. Therefore, the necessity of the product (weight%) of SixB arises as a method to consider, including the influence of both B and Si. Although B gave very high hardness due to the extraction of boride, it was thought that the type, shape, size and amount of boride affect the ductility of steel. In particular, when the size is significantly smaller than the size of the acicular chromium carbide, it is assumed that the factor that physically promotes fracture in bending processing is greatly reduced. Moreover, when the hardness of the microborides is considerably hard, it was expected to improve the wear resistance of the deposited metal.

Therefore, the No.10-C alloy showing excellent results in sulfuric acid resistant and hydrochloric acid corrosion was extracted, and the carbides and borides crystallized in the alloys were identified by SEM-EDX analyzer. As the crystallized product, three kinds of borides were identified: Cr ₇ C ₃ chromium carbide (about HV2100), Cr ₂ B (about HV1400), Mo ₂ FeB ₂ (about HV2400), and NbB (about HV2250). All of them occupied 30% of the total weld metal. The crystals had the shape of Cr ₇ C _{3 in} the form of petals or resins, the NbB of borides being indefinite, Cr ₂ B in the form of plates, and the Mo ₂ FeB ₂ in the form of reticulates (photo 1 in FIG. 3). Reference).

Since the carbon content of the No. 10-C alloy was about 0.7% to 0.8%, only Cr ₇ C ₃ was crystallized out of the carbide, and Nb did not form niobium carbide. However, niobium boride (NbB) was crystallized and given a high hardness comparable to niobium carbide. Therefore, in the case where the carbon content is multiplied, it has been found that Nb forms a boride and contributes to the improvement of wear resistance. The reason why the wear resistance was excellent also in the low carbon content was found to be in the crystallization of these borides.

When carbon content increases, niobium carbide is also crystallized at the same time, and it is thought that it contributes to the improvement of abrasion resistance further. By coexistence of B and Nb, it succeeded in improving abrasion resistance by the outstanding hardness, without reducing bending ductility. It is assumed that the alloy is embrittled in the shape of various boride crystals, and there is chromium boride (Cr ₂ B). This is a plate-like structure in shape, but is concerned because it is similar in shape to fine acicular chromium carbide (see photo 1 in FIG. 3). In fact, in the bending test, the No. 10-C alloy can be bent easily, and no surface layer peeling occurs by this (see photo 2 in FIG. 3). It was due to the difference of crystallization amount with acicular chromium carbide, or did not affect bending workability very much. The hardness of the borides is cited in the Metal Chemical Heat Treatment Handbook <Author = Crab, Wae, and Borsenoke>.

(5) Correlation of Si × B and Cr Content

The correlation of the product of Si * B addition amount and Cr content can be considered as a correlation with the precipitation amount of acicular chromium carbide which promotes brittleness most. When Cr content is small, the precipitation amount of Cr carbide will naturally decrease and embrittlement tendency will decrease, whereas abrasion resistance will fall drastically. Increasing the amount of Si alone greatly increases the tendency of embrittlement of metal due to the characteristic tendency of embrittlement of Si and the ability of needle chromium carbide to cope with it. Therefore, co-adding with B improves ductility and wear resistance to some extent. It was examined whether the composition range was expanded.

In the case of the low Cr content, the product of Si × B was set higher than 7.5, and in the case of high Cr, the product of Si × B was set from 1.55 to 6.4 to investigate the alloy composition range satisfying both the ductility and wear resistance of the alloy. . The investigation results are shown in Tables 5 and 6.

TABLE 5

Si x B alloy (wt%)

TABLE 6

Test result

Although the upper limit of Si × B is 7.5, the wear resistance can be secured, but if it is added further, the flexural ductility cannot be secured, and the lower limit of Si × B is 6.4, the flexural ductility can be ensured, but the wear resistance is not satisfied below this. As a result, the width of the upper and lower adjustment ranges was considerably narrow, so that the wear resistance was excellent at an upper limit of 6.1 and a lower limit of 12.4 with respect to the wear coefficient. The alloy composition range satisfying excellent ductility and abrasion resistance at the same time was quite narrow and could only be obtained in a limited range. As a result, it was difficult to obtain a wide alloy composition range satisfying both ductility and wear resistance simultaneously only by the correlation of the product of Si × B and Cr.

(6) effect of adding Nb

In particular, at the lower limit of Si × B, the flexural ductility was significantly improved, but it was found that the wear resistance significantly decreased. Although B and Nb are not so effective in single addition, it was supposed that they contribute significantly to the improvement of abrasion resistance at a lower limit by adding these together. It was thought that this makes it possible to greatly expand the alloy composition range that satisfies both ductility and wear resistance.

Si x B of the No. 35 alloy was 1 and 8, but the wear coefficient WR = 9.3 was secured by adding Nb = 4.0% and AL = 2.0%. The alloy No. 33 had Si × B = 3.5 and a wear coefficient WR = 5.9 was obtained by addition of Nb = 4.0%. Since the lowest reference value of the wear coefficient WR indicating wear resistance is 15, it is possible to greatly expand the alloy composition range which is sufficiently within the reference value and simultaneously satisfies ductility and wear resistance by coexistence of Nb and B.

In the product of Si × B, Nb is present as a third effective element for improving wear resistance, and a wide range of addition amount including 0 to 8.0% and no addition can be selected, and the wear resistance can be easily adjusted. It was expected to be able. It is well known that Nb is an element that spheroidally refines carbide, and there is little risk of softening the metal, and since niobium carbide <about HV2400> and niobide <about HV2250> give high hardness, wear resistance can be improved. there was.

For example, in the case where the graphite shape of gray cast iron is acicular graphite, the casting is softened, so that the graphite is spheroidized by adding Mg and Ca to form spheroidal graphite cast iron. The addition of Mg and Ca also brought about effects on carbides. When the carbon content of the alloy is considerably low, such as 0.5%, crystallization of carbides is drastically reduced, but niobium boride (NbB) and chromium boride (Cr ₂ B) are dispersed and crystallized by boron addition to contribute to improvement of wear resistance.

As described above, both B and Nb form microcrystals that prevent embrittlement of the alloys of the present invention, thereby replacing soft needle-like chromium carbides with both, thereby enabling ductility recovery of steel, and significantly improving wear resistance by high hardness. I could make it. Although already proved by experiment, although the effect of adding Nb alone cannot acquire sufficient wear resistance, it was possible to aim at the improvement of abrasion resistance by the coexistence addition effect with B.

The essential condition of the developed alloy is the absolute condition of the product of Si x B and the coexistence of Nb in the correlation with the Cr content, and it is quite sufficient to secure a wide range of alloy compositions sufficiently satisfying the ductility and wear resistance even if any of them are omitted. It is difficult.

By properly combining three elements of Si, B, and Nb, it is significant that the brittleness, which is conventionally the biggest drawback of high Si-containing steel, can be alleviated. The effective use of Si which gives oxidation resistance was made possible. As a result, Co and Ni can consider the effective use of Si as a substitute for expensive rare-value alloy elements, and can provide excellent corrosion resistance against hydrochloric acid and chlorine gas corrosion. The effective use of hydrochloric acid and sulfuric acid in pyrolysis equipment and fluidized bed furnaces has been expanded.

As a method for evaluating the rolling of the alloy, it was assumed that the bending test was the simplest and most accurate, and the ductility was evaluated by bending. Flexural performance and wear resistance were summarized from the correlation of the product of chromium content and Si x B. As a result, even when the bending test is performed at a constant curvature, the marginal tendency that no delamination or fracture occurs in the weld metal is low when the Cr content is low, and the product of Si × B becomes an expensive value, and when the chromium content is high, the product of Si × B is It tends to be a low value. The method of evaluating the bending processing performance by the product of Si × B extended the evaluation range significantly than the method of evaluating with B or Si alone, which helped to determine the performance more accurately.

(7) Evaluation of ductility and wear resistance by bending processing of wear resistant steel sheet

When the Si content is contained, for example, the highest 4.5%, a large amount of acicular carbide is precipitated with a chromium content of about 30% or more from the equation of Cr% ≥-1.6Si% + 37.In the case of Si = 4%, Cr is about 31%. Since it became%, the range of chromium content in a 1st layer welding metal was made into "15% <= Cr <= 31%. And the appropriate component range of the main influence element for obtaining the weld metal which is excellent in bending workability, ie ductility, was specified as follows.

15% ≤ Cr ≤ 31% (content of the first layer weld metal)

0.5% ≤C≤2.0% (addition amount)

2.5% ≤Si≤4.5% (addition amount)

0≤Nb + V≤8.0% (addition amount)

0.5% ≤B≤3.5% (addition amount)

The appropriate range of SixB in which this component affects bending workability within a specific range was determined. The product of Si and B which gives the weld metal which is excellent in bending workability without embrittling a matrix was the range of "1.25 <Si * B <= 11.5." As a general tendency, when the Cr content is low, the value of Si x B is high, and when the Cr content is high, the value of Si x B is low. In particular, when the value of Si × B decreases, wear resistance tends to decrease, and Nb is added for the purpose of supplementing the wear resistance.

As the value of Si x B increases, the weld metal tends to embrittle, and therefore the bending work performance deteriorates, and in order to increase the bending work performance, it is necessary to lower the value of Si x B. When the value of Si × B is low, the ductility of the weld metal increases, bending performance is improved, but on the contrary, abrasion resistance decreases, so that Nb is added within a range of 0 ≦ Nb + V ≦ 8% to adjust the wear resistance. For example, when the value is high as 4.0 ≦ Si × B ≦ 11.5%, the amount of Nb added is within 0.5 to 4%. When the value of 4.0 ≧ Si × B ≧ 1.25% is low, the amount of Nb added is 4 Abrasion resistance was improved by increasing the ratio to 8%.

The developed alloy is intended to improve corrosion resistance. When the chromium content of the first layer deposited metal is 15 to 18%, carbon and chromium are bonded to the grain boundary by welding heat to form Cr ₂₃ C ₆ carbide. Precipitation due to grain boundary and the lack of Cr required for corrosion resistance caused the risk of grain boundary corrosion. By adding 0.5% or more of Nb, Nb having a stronger affinity with carbon than Cr bonds with carbon and has an effect of suppressing precipitation of Cr ₂₃ C ₆ .

The addition purpose of Ti≤1.0% or less is also for the same effect as Nb. However, Ti has an extremely high affinity with oxygen, and it is determined that the amount of loss in the high temperature oxidation reaction in the metal is higher than that of Nb.

The method of evaluating the bending performance of the weld metal is to produce a clad steel sheet which is grown on the whole surface of weld metal of 5 to 6mm by one layer growth on a steel plate having dimensions of 9mm thickness × 100mm width × 400mm length of SS400, SUS304, SUS310S. The bending process was carried out by the press with hardened metal inside. The target Stellite No. 1 alloy was grown in two layers of 5 mm thickness on SS400 by gas welding. The length of the test piece was about 200 mm.

The bending curvature is about 200 R, and the bending process has no effect on the hardened metal at all, and the sound bending performance is obtained. The flexural ductility was evaluated as a case where ▲ occurred and a case where a large number of surface layer peeling or agglomerate deficiency occurred on the surface of the hardened metal and the toughness was insufficient. The results are shown in FIG.

In FIG. 1, this ductility relationship was shown, with SixB as the vertical axis and Cr content of the first layer weld metal as the horizontal axis. The upper curve shows the breaking limit line of the surface layer peeling or dropping which occurs in the weld metal when the clad steel sheet is bent at a curvature of 200 R. The upper curve shows that breakage is easily broken by bending. The underline shows a limit line in which the low stress wear coefficient WR of the deposited metal maintains 15, and below this, the wear coefficient increases and the wear resistance significantly deteriorates.

In the proper component range surrounded by upper and lower limit lines, the bending workability of the wear-resistant steel sheet constituted by single layer growth is R-bending to a radius of 200 mm in curvature, and there are many alloys that can bend to a very small curvature of less than that. It was. The bending workability was as good as or higher than that of sterite No. 1, and the bending workability equivalent to or higher than that of the high carbon-high chromium cast iron alloy used in the wear-resistant steel sheet was obtained. Alloys capable of micro-R bending to this extent with high Si-containing steels could not exist in the past.

The next important property is the improvement in wear resistance at room temperature. As described above, the carbon content, which is the most important factor in the improvement of wear resistance, has been drastically lowered than that of the high chromium cast iron-based alloy. Therefore, bending performance and corrosion resistance have been improved, but wear resistance is reduced, thereby ensuring wear resistance. Became important.

The evaluation method of evaluation of abrasion resistance was performed using the circulation belt grinder polishing test machine. The wear coefficients of various alloys were calculated based on the ratio of the wear volume of the alloy to be compared with the wear volume of SS400 on the basis of mild steel SS40O.

The target of wear resistance of the developed alloy was abrasion resistance in the case of gas welding the Stellite No. 1 alloy, and the wear coefficient thereof was WR = 8. The growth method of the stellite alloy is usually gas welded in the case of the growth of small items, but the growth of parts having a large area is grown by the arc welding method. Compared with gas welding, welding efficiency is higher, the growth technique is easier than gas welding, and the recent welding skill is familiar with arc welding. However, the biggest drawback of arc welding is the deep penetration of the base material, which leads to abrasion resistance. It is greatly reduced.

The wear coefficient at the time of growing Stellite No. 1 by the TIG method is 54, and wear resistance equivalent to that of the gas method cannot be obtained unless two or three layers are grown. In addition, since the wear coefficient of the high chromium cast iron is 14 to 17.5, and the wear coefficient of the high carbon-high chromium cast iron welding rod is in the range of 14 to 10, the target value is the wear coefficient WR = 8 of the stellite No. 1 gas welding. In addition, as a minimum target value, it was set as the abrasion coefficient 14 of stellite No.6. The appropriate range of the wear coefficient WR of the developed alloy was 1 ≦ WR ≦ 15.

(8) Evaluation of Flexural Machining Performance and Wear Resistance of Overhead Welding Materials

Bending performance performance and wear resistance evaluation of a welding material are basically suited to the correlation of Si * B obtained with a wear resistant steel plate, and Cr. The difference between the wear resistant steel sheet and the cast steel is that the dilution rate due to the base material is different and bending processing is not necessary. Therefore, a larger amount of alloying is allowed as compared with the case of producing a wear resistant steel sheet.

Although it is the component addition range in a welding material, since the welding growth method, a kind of base material, and a penetration depth also differ significantly, it is necessary to correct the component obtained by the clad steel plate. For example, a penetration rate of about 50% is expected in the construction of hand welding rods, about 35% in MIG welding, about 45% in TIG welding, about 35% in flux-cored wires, and 30 in the sub-magidized arc method. To 60% is predicted. In general, since it is easy to be affected by a very deep penetration, the amount of addition needs to be added in a large amount compared with the case of manufacturing a clad steel sheet. Therefore, the penetration depth in the case of clad steel sheet is assumed to be in the range of about 25 to 35%.

In the case of the raised welding material, the difference in comparison with the clad steel sheet is that the necessity of bending processing is considerably multiplied. Originally, since the surface of the article having the shape is raised, there is no need for bending. However, in the case of wet welding, the layers are overlapped with the first and second layers, so that the increase in the number of layers decreases the influence of the base material dilution, which is similar to the design component. However, in general, there are many two-layer growths, and a thickness of about 3 mm in the first layer and a thickness of 5 to 6 mm in the second layer are generally obtained. If the number of more layers is welded, the amount of the welding material used increases and the number of growing steps increases, which is expensive and is usually a method in which two-layer growth is generally performed.

Examining each alloy component added to the welding material, the carbon content is 0.5% ≤C≤2.5%, the chromium content is 15% ≤Cr≤45%, 0≤Ni≤13%, 0≤Mn≤10%, It is 0 <= Nb + V <= 8%, Cu: 7% or less, Mo: 10% or less, and even if it is influenced by a penetration, the performance can be ensured within a sufficient range.

B, which greatly influences the bending performance, was set at 0.5% to 4.5% and Si at 2.5% to 5.5%. In particular, the maximum amount of Si that affects the bending performance could be 1.5% less than in Patent No. 3343576. That is, since the present alloy is not an alloy developed for use in high temperature applications at 600 ° C or higher, precipitation of acicular carbide is not necessary, and the amount of Si added directly related to the deposition of acicular carbide can be reduced.

By appropriate combination of the four elements of Cr, Si, B, and Nb, the bending performance (ductility) at room temperature, the targeted wear resistance, and the corrosion resistance of the alloy developed at this time were secured.

Table 7 compares the hardness and wear resistance of representative various alloys. SS400, SUS310S stainless steel, high chromium cast iron, sulfuric acid resistant steel sheet are cut out from the material, and Stellite Nos. 1 and 6 are grown 5 mm by two-layer gas welding, and GL and UF are two layers by non-gas arc method. 5mm was raised.

The alloy of the wear-resistant steel sheet was grown to a thickness of about 5 mm in one layer by the sub-majid arc method. The materials for the raised product were SS400, SUS304, and SUS310S stainless steel, and a thickness of 9 mm was adopted.

TABLE 7

Comparison table of hardness and wear resistance of representative alloys

The present invention has been completed based on these findings. The iron-based corrosion-resistant abrasion-resistant welding material includes, by weight, C: 0.5 to 2.5%, Si: 2.5 to 5.5%, Mn: 0 to 10%, and Cr: 15. % To 45%, Ni: 0 to 13%, Cu: 7% or less, Mo: 10% or less, B: 0.5% to 4.5%, 0 ≦ Nb + V ≦ 8%, the balance being iron and unavoidable impurities Is made of.

In addition to these components, one or two or more of Ti: 1.0% or less, AL: 3% or less, rare earth metals: 5% or less, and N: 0.2% or less may be included.

Specifically, the welding material is a coated arc welding rod, a flux cored composite wire, a metal powder, or a casting rod.

In addition, the iron-based corrosion-resistant wear-resistant alloy of the present invention, C: 0.5 to 2.0%, Si: 2.5 to 4.5%, Mn: 0 to 10% or less, Cr: 15 to 31%, Ni: 0 to 16%, Cu: 7% or less, Mo: 10% or less, B: 0.5 to 3.5%, 0 ≦ Nb + V ≦ 8%, and (Si × B) ≦ 2014 / in a range of 15% ≦ Cr <27% It satisfies Cr ² + 0.083Cr + 1.05, satisfies 1.25% ≦ (Si × B) ≦ 6.0% in the range of 27% ≦ Cr ≦ 31%, and in the range of 15% ≦ Cr <20% (Si × B) Low carbon-high silicon-high chromium-boron-niobium-based iron group satisfying ≥570 / Cr ² -0.066Cr + 1.145 and satisfying (Si x B) ≥1.25 in the range of 20% ≤Cr≤31% It is a corrosion resistant wear resistant alloy.

In addition to these components, one or two or more of Ti: 1.0% or less, AL: 3% or less, rare earth metals: 0.5% or less, and N: 0.2% or less may be included.

Specifically, the iron-based corrosion-resistant alloy is a raised weld metal or cast steel, and both exhibit wear resistance and corrosion resistance that are comparable to or exceed those of the cobalt-based alloys of stellite Nos. 1 and 6, respectively.

The role of each element which comprises this invention material and this invention alloy is as follows.

C: 0.5 to 2.5% (material), 0.5 to 2.0% (alloy)

If the amount of C is 0.5% or less, the amount of precipitation of chromium carbide which contributes to wear resistance decreases. When the amount of C exceeds 3% (Cr, Fe), ₇ C ₃ type carbide precipitates as a granulated needle-like carbide, which affects the peeling and embrittlement of the grown metal and deteriorates the bending workability. In the case of a wear-resistant steel sheet, since bending workability is required, the carbon content contained in the weld metal is preferably 2% or less. 2% or less is a transition point from cast iron to cast steel, which is judged from the iron-carbon state diagram, because cast steel is more ductile than cast iron. In the wet welding, the penetration into the base metal is affected, and even when 2.5% of C is added to the alloying material, the carbon content of the first layer deposited metal is reduced to about 1.5 to 1.9% when the base metal is diluted 25%. Therefore, the maximum amount of carbon added to the alloy is preferably 2,5% or less.

In addition, the amount of carbon contained in the deposited metal affects corrosion resistance, and the amount of carbon contained in the deposited metal does not affect the corrosion of the 10% hydrochloric acid solution in the range of 0.5% to 3.0%, but the amount added in the 10% sulfuric acid solution is 2.0%. If abnormal, corrosion resistance rapidly decreases. In the range of 0.5% to 1.5%, no change is recognized for the corrosion loss, but changes rapidly at 2.0% or more.

Particularly preferred amount of carbon is preferably 0.5% or more for the lower limit, 2.0% or less for the upper limit in consideration of sulfuric acid corrosion resistance, and at most 2.5% or less considering the influence of the penetration depth of the heterogeneous welding method.

Si: 2.5 to 5.5 (material), 2.5% to 4.5% (alloy)

Si has a function of preventing the oxidation of steel. Oxidation resistance increases at 2.5% or more, and the addition of 5% or more alone effectively inhibits oxidation in the temperature range up to 1100 ° C. From the viewpoint of corrosion resistance, Si is effective in corrosion resistance of hydrochloric acid and sulfuric acid, and its value is exhibited in the presence of Cr, Mo, and Cu.

However, high Si tends to be easily peeled off from the surface when the steel is vulnerable and a large amount is added, and in particular, the minimum amount is 2.5% because it adversely affects the bending workability of the wear-resistant steel sheet. If it is less than that, the wear resistance and the oxidation resistance are lowered and the hydrochloric acid corrosion is adversely affected.

If the Si exceeds 4.5%, the steel becomes considerably weakened, causing deterioration of the ductility of the steel, and the exfoliation of the slices occurs on the surface of the surface while being grown. In addition, since this adversely affects the bending workability, this is the upper limit of the maximum amount added. In addition, when Si is 4.5% or more and Cr content is 30% or more, a large amount of acicular chromium carbide precipitates and is withdrawn. In particular, the Si addition amount is preferably 2.5% or more for the lower limit and 5.5% or less for the upper limit in consideration of the influence of the penetration depth by the heterogeneous welding method, and particularly preferably 4.5% or less for the upper limit.

When the Cr content is increased to increase the Si content, the hardened metal does not fall proportionally. Therefore, the Si content is as low as possible within the required range of 2.5%? Si? 4.5% to prevent embrittlement. As the amount of Si decreases, the wear resistance decreases, so that the wear resistance is restored because the decrease in coexistence of B, Nb, V, and the like decreases. In this case, the form of boride, niobium, and vanadium carbide is spherical, and it is important to physically increase the fracture toughness of the alloy like spherical graphite of dark tile cast iron, which is the best means of securing the ductility of high Si steel.

Cr: 15% to 45% (material), 15 to 31% (alloy)

Generally speaking, Cr is extremely effective for suppressing oxidation of steel and contributes to improvement of high temperature oxidation resistance. Cr combines with carbon to precipitate various chromium carbides, giving high hardness to improve the wear resistance of steel. However, in order to improve abrasion resistance, it is necessary to form chromium carbide in combination with Cr, and therefore it is necessary to add a large amount of carbon. However, when the amount of carbon added is 3% or less, the deposited metal of the first layer has a carbon content of about 2% due to the dilution of the base material, so that precipitation of sufficient carbides cannot be expected and wear resistance is deteriorated, while corrosion resistance is improved. It became. Due to the improvement in the corrosion resistance of the iron-based alloy of the present invention, the precipitation of a large amount of carbide is suppressed and remains in the matrix.

The amount of Cr was increased to improve the corrosion resistance, and the improvement of the wear resistance was performed by addition of B, Nb, and Si, which did not adversely affect the corrosion resistance, and the amount of C added was suppressed to 2.5% or less. In the alloy of the present invention, providing ductility of high Si-containing steel is one of the main purposes of the claims of the present patent, and the Cr content has a great influence on the ductility of high Si steel. The correlation between the Cr content and the product of Si and B has already been described in detail.

Since the welding growth is grown on the heterogeneous base metal, it is subjected to dilution from the base metal. In this invention, the chromium content of the 1st layer weld metal obtained by dilution of a base material was made into 15% minimum and 31% maximum. Therefore, since the dilution rate by a base metal differs in the various growth methods, the minimum addition rate was made into 15%, and the maximum addition rate was made into 45%.

If the Cr content is higher than 25%, it is easy to precipitate soft acicular carbides in combination with Si, and in the case of alloys which require ductility due to impact abrasion, the low Cr containing steel is difficult to precipitate. For example 15% chromium steel is required. Especially preferable Cr values are 15% or more with respect to a minimum and 31% or less with respect to an upper limit.

Mn: 0 to 10% (material, alloy)

Mn and Ni promote austenitization and increase its stability. The austenite forming capacity of Mn is approximately half of Ni. This Mn has the effect of stabilizing the workability of over welds. Since the alloy of the present invention has a high Si content as a basic composition, ferrite is contained. In order to maintain the austenite structure, Ni is added as a substitute for Ni because it is expensive. Especially preferable Mn addition amount is 0% to an upper limit of 8% or less.

Ni: 0 to 13% (material), 0 to 16% (alloy)

As is well known in the alloy of the present invention, the addition of high Ni is not preferable from the viewpoint of the consumption of the rare value alloy, and O% is preferable. Therefore, it cannot be added only when the addition is necessary in corrosion resistance and bending ductility. When the Cr content is 23.5% or more and less than 31%, when the Ni content is increased by 3 to 6%, the tendency to be flexible or the surface layer peeling of the weld metal disappears, and the effect of improving the Si × B value by three points was recognized. . The use of the alloy of the present invention has many waste incineration relations, and is effective in terms of corrosion resistance of chlorine gas and high content is preferable. The high temperature also has the effect of preventing carburization, and in applications subject to thermal shock, the effect of preventing the passivation of the passivation film of Cr is prevented. Therefore, when the use temperature is high, the Ni content is preferably high.

The alloy structure of the present invention is basically easy to form a mixed structure of ferrite + austenite, and it is possible to convert the structure into an austenite structure by the combined addition of Mn and Ni. For example, in case of hardening growth on heavy-bonded austenitic stainless steel, if the temperature change of this device is severe and thermal shock is applied, if the hardening metal contains a large amount of ferrite, the difference in the coefficient of linear expansion with that of the austenitic stainless steel As a result, a stress may be generated in the weld fusion wire and a risk of peeling may occur. In such a case, by adding Ni, it is possible to change the hardened metal into an austenite single structure and to adjust it to the base material and the same structure. For this purpose, the maximum addition amount of Ni is preferably 13% or less. If it is insufficient, it can be adjusted by adding Mn.

Nb + V: 0% or more, 8% or less (material, alloy)

Nb has the effect of spherical refinement of carbides, and can withstand tissues that are difficult to physically break or embrittle in tissue composition. As described above, the effect is the same as the graphite shape which affects the ductility of gray cast iron and dark tile cast iron. The effect on the carbide shape is an effect such as Ca and Mg to spheroidize graphite. In addition, niobium carbide itself has a hardness of about HV2400, which is quite hard. In the case of low carbon, for example, in a region where C = 0.7% and NbC (niob carbide) is not determined, highly hard NbB (niobide boride, Hv2250) is instead determined and there is an effect of preventing a decrease in wear resistance.

On the other hand, V forms a fine carbide, and its forming ability is located between Cr and Mo, and the high temperature wear resistance is improved by improving the temper resistance by this carbide reaction and the secondary hardening by the temper. It also improves resistance to softening deformation due to temperature rise and breaking due to heat checking.

In the correlation between Cr content and Si x B, at high Si x B values such that peeling dropout occurs in the weld metal, that is, in the limit state in which flexural ductility cannot be obtained, these elements must be added. There is no. By adding, the embrittlement of further weld metal is accelerated | stimulated. In view of preventing grain boundary corrosion of 15% of low chromium-containing steel, addition of at least Nb + V ≧ 0.5% is preferred. Therefore, the addition amount is 0% or more, Preferably it is 0.5% or more. However, even if it adds 8% or more in total, since the effect is saturated and there exists a danger of embrittlement of a growth metal, the maximum addition amount was made into 8% in total.

B: 0.5% to 4.5% (material), 0.5% to 3.5% (alloy)

The shape of the boride crystallized in the alloy component range of the present invention may be crystallized into a shape which is difficult to promote embrittlement of the alloy. For example, Mo ₂ FeB ₂ is a mesh, NbB is a negative phase, Cr ₂ B Is a plate. Each micro hardness is HV2400, HV2250, HV1400 and is fairly hard. Cr ₂ B is crystallized in plate form, but larger crystals are also shown compared to acicular chromium carbides, but they are small in number, most of them are short and discontinuous, and problematic in shape, but physically soften the matrix as long as they are not continuously crystallized. There is little risk to do it. As evidence of this, the hardened metal was considerably healthy even in the 200R bending process, and even small piece peeling did not occur. In order to obtain these effects, the minimum addition amount of B is from 0.5% to the maximum addition amount to 3.5%, and considering the penetration depth of the heterogeneous welding method, the maximum addition amount is 4.5% or less as the welding material.

Ti: 1.0% or less (material, alloy)

Titanium carbides also result in significantly higher hardness, but titanium makes weldability difficult and the bead surface is not smooth. Therefore, in order to prevent grain boundary corrosion in 15% low chromium steel as in Nb, the addition is at most 1%.

Rare earth metals such as Al: 3% or less, N: 0.2%, Ce and Y: one or two or more kinds (materials, alloys) of 0.5% or less in total

Since the alloy of the present invention may be used from a high temperature to a high temperature of 600 ° C or higher, there is a need to provide high temperature oxidation resistance. These can be selectively added mainly to improve high temperature oxidation resistance. For example, the oxidation resistance at a high temperature is improved, and in particular, when sulfur gas is present in the use atmosphere, the effect is exerted. In this case, it is better to reduce the amount of Ni and increase the amount of Al. If Al exceeds 3%, an alumina film is formed on the grown metal, and slugs are likely to be interposed, which impairs welding workability. In order to acquire a stable effect, 0.5% or more and 3% or less are preferable.

Mo: 10% or less (material, alloy)

Mo exerts a remarkable effect by coexisting with Cr, Cu, and Si in sulfuric acid corrosion resistance or hydrochloric acid corrosion of the alloy of the present invention, and is equivalent to or higher than Stellite Nos. 1 and 6 in cobalt-based alloys. Indicates. However, Mo currently becomes a considerably expensive alloy, and if the addition amount is increased too much, the manufacturing cost of the alloy of the present invention greatly increases, so the minimum addition amount is 0%, and the maximum addition amount is 10%. In particular, the sulfuric acid corrosion exceeded the corrosion resistance of the stellite by the addition of 8%, and therefore the maximum addition amount was made 10% or less, and the particularly preferable maximum addition amount was made 8% because it was excessively added even further.

Cu: 7% or less (material, alloy)

Cu improves sulfuric acid resistance and hydrochloric acid resistance. In a waste incinerator, acid dew point liquids such as sulfuric acid and hydrochloric acid, which are highly corrosive, are produced when the combustion is stopped. However, Mo alone is not very effective, and complex addition with Cu is effective. Moreover, according to the composite addition, microstructure becomes fine, it becomes easy to precipitate fine acicular carbide in the state containing high Cr and high Si, and high temperature wear resistance improves.

Regarding the base metal, regardless of its kind, for example, mild steel, weather resistant steel sheet, sulfuric acid resistant steel, seawater resistant steel, various stainless steel, Mn-Cr austenite steel, nickel alloy steel, chromium alloy steel, etc. Although weldable steel can be used, it is preferable to contain 9 to 35% of Cr and 0 to 25% of Ni from the point of suppressing dilution, and ensuring corrosion resistance and high temperature oxidation resistance.

Effects of the Invention

Although the iron-based corrosion-resistant metal of the present invention is an inexpensive iron-based alloy, it can withstand sulfuric acid and hydrochloric acid corrosion as an alternative metal of expensive cobalt-based alloys and nickel-based alloys, and moreover, wear resistance is equivalent to or better than these alloys. It is an innovative alloy that can be used as various welding materials, wear resistant steel sheets, and cast steels.

In the global view, the rare value alloys such as expensive cobalt and nickel are consumed enormously as alloys of welding fostering materials for simple abrasion prevention of production equipment, and they are abandoned without being lost, dispersed and consumed all over the world. to be. In the future, unnecessarily wasting these rare value alloys will result in depletion of the loss of children, and at the present time, effective utilization of rare alloys and resource recovery efficiency should be planned. Therefore, the present inventors have continued to study that inexpensive silicon has a huge reserve on the earth in terms of resource utilization, and has been incorporating low-cost silicon from 26 years ago and adding it as a welding utilization material.

At that time, the alloy addition amount was developed in the SLCE alloy of C 5.2%, Si 12.3%, Cr 20% (wear coefficient WR = 7, average hardness HV730) to prepare a wear-resistant steel sheet. He has delivered a large number of copper refining plants, paper companies, and cement plants, and has exported to Sweden's paper mills. This alloy was resistant to hydrochloric acid corrosion and sulfuric acid corrosion, and obtained its own evaluation, but it was a very soft alloy lacking workability such as bending work.

When Si is added to the metal as an alloy, especially inexpensive iron-based alloys cause weakening of Si, and it is quite difficult to supply for use as a welding material. In particular, there existed the characteristic which produces numerous cracks in the thickness direction of a weld metal. Due to its weakness, the exfoliated peeling of the raised metal occurred from the surface layer surface, or if the content increased, the dropping occurred from the base metal in a lump form. In addition, in the case of a wear-resistant steel sheet, peeling and dropping occurred only by pressing with a press or the like in the distortion elimination work, and use was limited except for a limited use. When used as a welding growth wire or a welding rod, peeling and dropping occurred in the hardened growth metal only when the growth product was slightly impacted.

After many years of research, the present inventor has succeeded in overcoming the vulnerability by abandoning the addition of Si alone and coexisting with elements such as B, Nb, and V and reaching the present application. The method hardly prevents Si from softening iron-based alloys, but when Si is increased, it is possible to observe the property of agglomerating chromium carbides of high chromium steel, to suppress the deposition of acicular chromium carbides, and to compensate for the decrease. Niobium carbide, spheroidal refining, net or irregular, and boron to precipitate a plate-like boride are added. This suppresses embrittlement and improves wear resistance. In particular, Nb was an alloying element which is considerably effective as an adjusting alloy of wear resistance by expanding the adjusting range of wear resistance.

Best Mode for Carrying Out the Invention

EMBODIMENT OF THE INVENTION Embodiment of this invention is described below.

The composition of the weld metal of the various wear-resistant steel sheets produced in order to obtain the correlation of Si * B and Cr is shown to Tables 8-10.

TABLE 8

Addition Chemical Composition of Weld Metal of Wear Resistant Steel Sheet

TABLE 9

TABLE 10

The bending workability of these wear resistant steel sheets was investigated. The amount of Cr contained in the first layer weld metal is calculated by setting the base material dilution rate to 25%. As described above, the method for evaluating the bending performance of the weld metal is to raise the entire surface of the weld metal of 5 to 6 mm in one layer on a steel sheet having dimensions of 9 mm thickness x 100 mm width x 400 mm length of SS400, SUS304, and SUS310S. One clad steel sheet was manufactured, and the bending process was performed by the press with hardened metal inside. The target Stellite No. 1 alloy was grown in two layers of 5 mm thickness on SS400 by gas welding. The length of the test piece was about 200 mm.

Bending process curvature is about 200R, and sound bending performance is obtained without affecting hardened metal at all by bending work, and, in the case of no defect situation, surface surface peeling and slight deficiency of several places are on the surface of hardened metal The flexural ductility was evaluated as a case where ▲ occurred, a case where a large number of surface layer peeling or agglomerate deficiency occurred on the surface of the hardened metal and the toughness was insufficient. The results are described below.

TABLE 11

Effect of Si × B on the Flexural Machining Performance of Wear-resistant Steel Sheets

The amount of Cr contained in the weld metal for the first layer (the base material dilution rate is 25%, not the addition amount).

TABLE 12

TABLE 13

TABLE 14

TABLE 15

(1) Correlation of Si × B and Cr

1 is shown collectively. Although the amount of carbon added was significantly reduced from 0.5 to 2.0%, within the appropriate range of correlation between the product of Si × B and Cr content, No. 2, No. 6, No. 10-C, No. 15, No.16, 16-C, No.23, No.26, No.32, No.32-1, No.33, No.34, No.38, No.66, No.67, No.68, No. 72 and alloys have a large number of alloys having a wear coefficient of 3 to 6 and capable of securing abrasion resistance at least about twice that of Stellite No. 1 and No. 6.

In addition, even when compared with high carbon-high chromium cast iron-grown alloy GL (WR = 6), it is remarkable that more wear resistance is obtained, and in the present development, UF (WR = 2) of iron-based high temperature wear-resistant welded growth alloy has the best wear resistance. Although recognized worldwide as an alloy, No. 66 and No. 38 were able to secure wear resistance comparable to this.

As a tendency, the upper limit curve was lowered from about 15% to about 27% of Cr content by about 11.5 to 6, and saturated to about 6 between Cr = 27% and 31%. When Si * B exceeds this limit, bending performance will fall remarkably, peeling and falling off to the weld metal itself generate | occur | produce, and it shows that ductility falls extremely.

The higher the Si x B value, the higher the wear resistance. On the contrary, the lower the Si x B value, the better the bending performance, but the lower the wear resistance. Nb was added to improve wear resistance.

(2) Effects of Nb Addition

Regarding the No. 6 alloy having a 19% Cr content, Si × B = 6.5 and an Nb addition amount of 0.5% yielded a wear coefficient WR = 5.6, while Si × B = 2.6 for a No.62 alloy having the same Cr amount. Abrasion coefficient = 6.5 was obtained with 6.0% of Nb addition amount, and almost the same wear resistance was obtained. If Si x B is a low value of 2.6, the wear coefficient is reduced to about 9 to 15, but by adding 6% Nb, the wear coefficient can recover to 6.5.

Nb has clearly demonstrated the ability to improve wear resistance. When the value of Si × B was in the range of 1.25 to 4.5, the wear coefficient WR tended to be considerably worsened to 8 to 15 regardless of the Cr content, but the bending performance was reversed. In order to improve abrasion resistance within the range, it can be improved by adding or subtracting the amount of Nb added between 4 and 8%. When the product of Si × B is 4.5 or more and 11.5 or less, the amount of Nb is adjusted in the range of 0.5 to 4%, and when the product of Si × B is reduced to about 14.5 or less, the amount of 4 to 8% Selecting can improve abrasion resistance without reducing bending ductility.

Although the flexural ductility of alloy No. 10 is ●, since the product of Si * B is high as 8.6, when it falls to about 7, it becomes possible to change into (circle). Alloy No. 17 can also improve 으로 to o when the amount of Nb added is reduced from 4% to 1 to 2%. It was found that good bending ductility and excellent wear resistance were obtained by adjusting the amount of Nb added or adjusting Si x B within the range surrounded by the upper and lower limit curves.

(3) Effect of V as Substituent of Nb

Usually, since V is effective as a spherical carbide forming element equivalent to Nb, the effect of V was investigated. In order to investigate the difference in the effects on the wear resistance of Nb and V, a comparison between the Nb alloy group and the V alloy group was attempted. The Nb-added alloy group is shown in Table 16, and the V-added alloy group is shown in Table 17.

TABLE 16

Nb addition alloy (Cr is 1st layer content)

TABLE 17

V additive alloy group (Cr is the first layer content)

The base materials were SS400, Si × B = 4.3, and the amounts of C, Cr, and Si were the same, and Nb = 3% and V = 2%, both of No.7 of the Nb alloy and No.50 of the V alloy. The wear coefficient WR was 11.0 in the Nb alloy and 7.4 in the V alloy, and the V addition side was slightly superior in wear resistance.

No. 9 of the Nb alloy and No. 49 of the V alloy were compared. The amount of alloy addition is the same, and the base material SS400 is also the same. At the same amount of addition, Nb = 4% and V = 4%, resulting in a difference between the wear coefficient of the former WR = 11.0 and the latter WR = 19.0.

In the case of Si x B = 4.3, V had more abrasion resistance than Nb even though the amount of V added was slightly smaller than that of Nb. In the case of Si × B = 1.8, the Nb side overwhelmingly improved wear resistance at the same amount of addition.

Judging from the comparative tests, it was found that the addition of Nb was effective when the Si x B = 1.8 was low, and the addition amount of V was smaller than Nb when the Si x B = 4.3 was high, which was effective in improving wear resistance. V also contributed to the improvement of wear resistance like Nb. Regarding the flexural ductility, the amount of V added was limited up to 8% as Nb without any problem. Moreover, coexistence addition of Nb and V is also conceivable, and the sum total addition amount of both is 8% or less.

(3) Influence of base material on wear resistance

When the Cr content is approximately 25% or more and less than 31%, the SUS310S base material was used a lot, but when the content of 25% or less was increased by using a base material of mild steel and 304 stainless steel in combination, the difference in abrasion resistance due to the difference between the base materials was concerned. It is because the numerical value of the wear coefficient WR which shows abrasion resistance mixed and compared the numerical value obtained from the stainless steel base material and the mild steel base material. Originally, it was necessary to test with the same base material, but since the chromium content of the weld metal had to be varied from 15% to 31%, it was used to adjust the chromium content of the weld metal by infiltration of the base material. I could not help it.

Table 18 shows the effect of the type of base material on the wear resistance. In the alloy No. 6 and alloy No. 19, the base material was SS400 for the former and SUS310S for the latter with the same component addition amount. Similarly, alloys No. 7 and No. 20 had SS400 for the former, SUS310S for the latter, and SS400 for the latter, and 310S for the latter.

TABLE 18

Effect of parent material on wear resistance

The factors affected by the difference of the base materials were hardness values, which had little effect on the wear resistance. The difference in these wear coefficients was not a problem since it is included in the claims. Therefore, even if the wear coefficients of SS400 and SUS310S were regarded as the same, it could be judged that there was no problem.

(4) Relationship between Ni content and flexural ductility

Table 19 shows the relationship between the Ni content of the weld metal and the bending workability.

TABLE 19

Relationship between nickel content and bending workability of weld metal

SS400 and SUS304 stainless steel base materials were used in the Cr content of about 23 to 24%, and SUS31OS stainless steel was used when the Cr content was 25% or more. When the SS400 mild steel base material is used, the Ni content ranges from about 0.0 to 10%, about 2.0 to 12% for the SUS304 base material, and about 5.0 to 16% for the SUS310S base material.

When the Cr content is greater than or equal to 23.5% and less than 31%, an increase in Ni content of about 3 to 6% tends to improve the flexural ductility by about 3 points with the Si x B value, but alloys in which cracking occurs are also mixed. In the range enclosed by this area, the combination of various elements must be carefully investigated and the alloy must be carefully constructed. In the case where the Cr content is 23,5% or less, even if the Ni content is 7 to 8%, the weld metal breaks, and the Ni addition is broken and there is no effect of preventing the breakage.

(5) Correlation between Si × B and Cr content

1) Upper limit curve where peeling or dropping of hardened metal occurs

15% ≤Cr≤27%

Si × B≤2014 / Cr ² + O.083Cr + 1.05 (1)

27% ≤Cr≤31%

1.25% ≤Si × B≤6.0% (2)

2) lower limit curve for the wear-resistant WR of the hardened metal to maintain the lowest 15;

15% ≤Cr≤20.0%

Si × B = 570 / Cr ² -0.066Cr + 1.145 (3)

20.0% ≤Cr≤31%

Si × B≥1.25 (4)

3) When the Ni content of the deposited metal increases by 3 to 6%, the upper limit curve for peeling and dropping is parallelized by moving the equation (1) upward by Si x B = 3 points in the range of 23.5% ≤Cr≤31, O%. In this case, the range where cracking is unlikely to occur is increased.

(6) Corrosion Resistance Evaluation of Overgrown Welding Material

The corrosion resistance of the alloy of the present invention was developed with the goal of Worthite alloy as already described. The chemical component is as follows. C <0.07%, Cr 20%, Ni 25%, Si 3.5%, Mo 3.0%, Cu 2.0%

In addition, there is DIN8556 E20.25.5LCuR26 as a welding material. The typical chemical component is as follows. C 0.025%, Mn 2%, Si 0.4%, Cr 21%, Ni 25%, Mo 5%, Cu 1.8%, Nb 0.1%, N 0.08%

Both alloys have high Ni content and are corrosion resistant structural materials and cannot be used as wear resistant metals. In the latter case, although it is a welding material, Si = 0.4% is low and since carbon content is extremely small, it cannot be used as a wear-resistant metal. Therefore, the inventors made carbon content required as a wear-resistant metal to 0.5% or more and 2.0% or less. Moreover, since Si containing was the subject of this development alloy, the range was made into 2.5% ≤ Si ≤ 5.5%. In addition, Nb and V of the carbide forming element were added to improve abrasion resistance, and B, which forms a boride having high hardness, was co-added.

The alloys were designed so as not to deteriorate the corrosion resistance maintained by the two types of alloys while changing the two types of corrosion resistant alloys into wear resistant alloys. DIN8556 welding rods are used for joining phosphoric acid, sulfuric acid, acetic acid, salt, and seawater plants and for corrosion-resistant materials on mild steel or low-alloy steels, but not for wear-resistant materials, but for mechanical structural members.

Invented alloys superior to the corrosion resistance of Stellite No. 1 and Stellite No. 6 alloys within the range of the flexural ductility and wear resistance. The corrosion resistance comparison test of these alloys was done. The corrosion test measures the loss of corrosion when immersed in 10% aqueous sulfuric acid solution, 5% ferric chloride solution, 10% hydrochloric acid solution, and 48% caustic soda solution for 480 hours at room temperature. It was.

SS400 mild steel, SUS310S, SUS304 stainless steel, high chromium cast iron, and sulfuric acid resistant steel were cut out from the sheet material to obtain a test piece. Everything else was a growth material, 5 mm thickness was grown on SUS310S, and the test piece was created. The growth test piece is the loss of corrosion including the base material SUS310S, and the collection of the hardened metal itself and the disclosure in the corrosion test are not comparable because some alloys have many cracks, and the base material is assumed to contain the base material. Corrosion test of

The test piece had a dimension of 50 × 50 mm and a thickness of 9 mm. The thickness of the hardened metal was about 5 mm, and the base metal surface was cut based on the hardened metal surface to secure a thickness of 9 mm. The total surface area of the test piece was 68 cm 2. Although the indication of the corrosion loss per unit area was considered, since the SUS310S dissimilar metal of the base metal was included, the total corrosion loss measurement was displayed as it is and compared.

The reason why SUS31OS was chosen for the base metal is to transfer a large amount of chromium to the weld metal by penetration from the base metal. Thereby, adjustment of the addition amount of Cr of the weld metal was easy to be performed. In SUS304, the amount of chromium contained was less than 18%, and SUS31OS containing 25% made it easier to obtain a larger amount of chromium from the base metal. This is because the corrosion resistance is excellent. The Cr content of the single-layer grown weld metal is equal to or greater than that of the additive components by picking up Cr from the SUS310S base metal under the influence of penetration. The base metal penetration rate was 25%.

In the correlation between Si x B and the Cr content of the first layer weld metal, an alloy within the enclosed range was appropriately selected and subjected to a corrosion test. The alloy which was subjected to the corrosion test was surrounded by ○ from the outside and considered easy to recognize. SUS310 and 310S heat-resistant stainless steel base materials are selected when used in a high temperature region of 800 ° C or higher, but SUS304 and 316 stainless steel are mainly used as the plate material selected as a heat-resistant material from around room temperature to 800 ° C. Therefore, the Cr content contained in the 1st layer welding metal judged from the addition amount of chromium is assumed to be about 23 to 30% of range. In the case of a Cr content of less than that, mild steel or stented steel is selected and diluted in a base material, and chromium content falls in many cases. When corrosion resistance is required, at least the base metal is made of stainless steel, and 304, 316, 310S steel is mainly used. Therefore, although the corrosion test was mainly performed in the range of about 23-30% of Cr content, 16% chromium steel was also investigated because irradiation of some low chromium steel is also needed.

In the case of alloy No. 5 having a low Cr content of 16%, alloys No. 10 and 17 have a high Cr content of 27% and 30% Cr, and alloys No. 16, 14, and 39 have a C content. Is changed to 2%, 3%, 5.4% and contains no Mo, 10% Ni for No.22 alloy, 8% Mn for No.28 alloy, 8% Mo for No.29 alloy, 30% No.30 alloy A value close to the upper limit of the addition amount of each alloy component such as Ni, Mn, Mo, and Cu in the alloy of the present invention was selected by 6% of silver Cu, and the difference in corrosion was examined. The findings are summarized in Tables 20-22.

TABLE 20

Various Alloy Chemical Compositions for Corrosion Resistance Comparison

TABLE 21

Corrosion resistance test results of various alloys

Table 22

10% aqueous hydrochloric acid solution, 48% aqueous sodium hydroxide solution

In the corrosion test, since all of SUS310S was used as the base material, the Cr content was increased by picking up Cr from the base material. For example, alloy No.10 had a Cr content of 20% in the flexural ductility test of the graph, but increased to Cr = 27% in the corrosion test piece. Naturally, Cr and Ni are taken out of the SUS310S base material, and the Cr and Ni contents of the weld metal increase. Corrosion test numbers were taken from the English Corrosion C indicating corrosion, followed by a C number. Therefore, all alloys related to the corrosion test are related to the C alloy.

(7) About 10% sulfuric acid corrosion (about C alloy)

No. 5, No. 22, No. 28, No. 29 and No. 30 alloys were compared with Stellite No. 1 and No. 6 by comparison of the corrosion loss after immersion in 10% sulfuric acid solution for 480 hours. The wear coefficient WR, which shows abrasion resistance, which exhibited a very good corrosion resistance, was 8 to 10, showing abrasion resistance equivalent to Stellite No. 1. The alloys No. 10 and No. 17 exhibited the same corrosion resistance as that of the stellite, but the wear resistance showed the highest wear resistance among the patented alloys, and the wear coefficient WR was 3.3.

It is surprising that these iron-based alloys showed significantly better results than the cobalt-based alloys of stellite alloys for 10% sulfuric acid corrosion. Therefore, to confirm the reliability, 40% sulfuric acid solution having a highly corrosive concentration was selected. The loss of corrosion in the case of immersing the test piece continuously for 4 hours by heating the solution in the range of 50 to 70 degrees was compared. Since it is difficult to perform the corrosion test for 480 hours again, since it was a simple confirmation test, it performed as a short time acceleration test. The results are shown in Table 23.

TABLE 23

40% sulfuric acid solution -50 ~ 70 ℃ accelerated corrosion test result (test time; 4H)

Also in the accelerated test, sulfuric acid corrosion resistance equivalent to or greater than Stellite No. 1 and No. 6 was shown. In particular, the No. 5 alloy was considerably superior, and the No. 30 alloy was slightly inferior to the stellite, but there was no significant difference, and it could be judged to be equivalent.

Next, the influence of carbon content on sulfuric acid corrosion resistance was investigated. The investigation results are shown in Tables 24 and 25.

TABLE 24

Effect of Carbon Content on Sulfur Dioxide

TABLE 25

480 hours immersion test comparison

In the range of 0.5% ≦ C ≦ 3.0%, when correlated with corrosion resistance, sulfuric acid corrosion was easily affected by carbon content, and when 2% or more, sulfuric acid corrosion resistance tended to be lowered. It was determined that boron did not affect sulfuric acid corrosion. Therefore, 2% or less of carbon should be used for sulfuric acid corrosion.

It was thought that sulfuric acid corrosion was not possible with iron-based wear-resistant metals in the past, but it is superior to Stellite No. 1 and No. 6 containing 50 to 65% of expensive cobalt, which is a corrosion-resistant wear-resistant material. Iron-based alloys equal to or greater than .1 were invented. In terms of global consumption, the use of a sterile alloy containing a large amount of rare cobalt for simple abrasion use and for use in a resource that cannot be recovered is a waste of effective resources. Should be used.

(8) About hydrochloric acid corrosion

With respect to hydrochloric acid corrosion, alloy No. 29, alloy No. 10 and alloy No. 30 are superior to the stellite alloy, but in the 10% hydrochloric acid solution corrosion test, the alloy No. 10 is made of stellite No. 1, No. 6 It is important to use No.10 alloy for superior hydrochloric acid corrosion resistance.

The effect of carbon content on hydrochloric acid corrosion was investigated. Regarding hydrochloric acid corrosion, only the alloy No. 17 showed about 10 times the corrosion loss compared to other alloys, but there was no significant difference with respect to other alloys, and the influence of carbon content of the deposited metal was not seen. Stellite No. 1 tends to be more resistant to hydrochloric acid corrosion than No. 6 whose carbon content is multiply, and hydrochloric acid corrosion is not affected by the amount of carbon added as sulfuric acid corrosion.

Expensive Mo addition is required to obtain corrosion resistance against stellite. However, the recent price increase of the alloy price of Mo caused a huge impact on the cost of the alloy, which can not help to halve the low-cost merit of the iron alloy. Therefore, the present inventors did not seek corrosion resistance as much as stellite, but simultaneously invented an alloy having significantly superior corrosion resistance compared to the same iron-based alloys. This is No. 16 and No. 14.

Compared with high chrome cast iron produced by casting, No.16 alloy exhibits about 54 times corrosion resistance for 10% sulfuric acid corrosion, 72 times for 5% ferric chloride, and 94 times corrosion resistance for 10% hydrochloric acid solution. It was. Alloy No. 14 showed almost the same tendency. Compared with the conventional high carbon-high chromium cast iron-based welding alloy GL, which is a conventional iron-based alloy, the No. 16 alloy has excellent corrosion resistance of about 19 times in 10% sulfuric acid solution and about 23 times in 5% ferric chloride solution. Compared with the high chromium cast iron alloy used in the present invention, it has been shown to have considerably superior corrosion resistance and that the iron-based alloy is sufficiently applicable to the corrosion-resistant wear application.

Example

Next, an Example is disclosed and the effect of this invention is made clear by comparing with a comparative example. In recent years, the price of oil has soared along with the cost of coal imports, and Japan, a resource-heavy country, is in trouble with fuel spikes. In particular, coal-fired power plants, steel mills, and cement plants that use huge amounts of coal reduce the use of expensive, high-quality coal, and the use of mixed coal with low-cost coarse coal is increasing. Among the coarse coal, there is coal with a high sulfur content, and if it is deposited in the stock yard, the moisture increases due to rain, and the sulfur content contained in the coal reacts with water to form dilute sulfuric acid.

As an example, in the process of introducing coal to the mill, there is a trough conveyor, but a wear resistant steel sheet in which a high carbon-high chromium cast iron-based alloy has been grown because its bottom plate liner is conventionally worn. Its chemical composition was the previously described GL alloy. After mixing coal containing a large amount of sulfur, a long life is given because of simple wear, but the life is shortened to only 2.5 months due to the corrosion of dilute sulfuric acid. When this development alloy was applied to the bottom liner, corrosion wear did not occur at all even after one year, and it is still used.

In order to prove the fragility of the high Si containing steel, the bead photograph after the above-mentioned bending process was taken. As a representative example, the No. 55 alloy exhibited a weakness, which is a defect of high Si content, and the bead surface pressed by the press caused peeling over the entire surface. However, No.10-C alloy which is the alloy of this invention shows the soundness in the bending process of 200R.

Regarding the precipitation amount of chromium carbide due to the difference in chromium content, the microstructures of No. 5 (Cr = 16%) of low chromium-containing steel and No. 10-C (Cr = 27%) of high chromium-containing steel were compared. As shown in the photograph 1 of FIG. 3 and FIG. 4, crystallization of plate-like coarse chromium boride (Cr ₂ B) is shown in 10-C of a high chromium alloy, and it is not seen in the No. 5 alloy. Therefore, low chromium steel may be used for applications subject to medium impact wear, and high chromium steel may be employed for wear applications subjected to light shock.

Claims (7)

By weight% C: 0.5-2.5%, Si: 2.5-5.5%, Mn: 0-10% or less, Cr: 15% -45%, Ni: 0-13%, Cu: 7% or less, Mo: 10% Or less, B: 0.5% to 4.5%, 0 ≦ Nb + V ≦ 8%, and the balance consisting of iron and unavoidable impurities. The iron-based corrosion resistant wear-resistant welding material according to claim 1, further comprising one or two or more of Ti: 1.0% or less, Al: 3% or less, rare earth metals: 0.5% or less in total, and N: 0.2% or less. . 3. The iron corrosion resistant wear-resistant welding material according to claim 1 or 2, which is a receiving rod, a flux cored composite wire, a metal powder, or a casting rod. By weight% C: 0.5-2.0%, Si: 2.5-4.5%, Mn: 0-10% or less, Cr: 15-31%, Ni: 0-16%, Cu: 7% or less, Mo: 10% or less , B: 0.5 to 3.5%, 0 ≦ Nb + V ≦ 8%, satisfying (Si × B) ≦ 2014 / Cr ² + 0.083Cr + 1.05 in the range of 15% ≦ Cr <27%, 27 1.25% ≤ (SixB) ≤6.0% in the range of% ≤Cr≤31%, and (SixB) ≥570 / Cr ² -0.066Cr + 1.145 in the range of 15% ≤Cr <20% The low-carbon-high-silicon-high chromium-boron-niobium-based iron-based corrosion-resistant alloy that satisfies and satisfies (Si x B)> 1.25 in a range of 20% ≤Cr≤31%. The iron-based corrosion-resistant alloy according to claim 4, further comprising one or two or more of Ti: 1.0% or less, Al: 3% or less, rare earth metals: 0.5% or less in total, and N: 0.2% or less. The iron-based corrosion-resistant alloy according to claim 4 or 5, wherein the abrasion resistance and the corrosion resistance are comparable to or better than those of Stellite Nos. 1 and 6, which are cobalt-based alloys. The iron-based corrosion resistant wear resistant alloy according to claim 4 or 5, which is a raised weld metal or cast steel.

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