JPH10176247A - Iron base silicon-manganese alloy or iron base silicon-manganese-nickel alloy good in grindability and alloy powder thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an easily grindable and mass-producible iron base S-Mn or iron base Si-Mn-Ni alloy and to produce the alloy powder thereof. SOLUTION: This alloy and alloy powder have a compsn. contg., by weight, 0.40 to 1.20% C, 5.0 to 12.0% Si and 19.0 to 42.0% Mn or <=30% N, and the balance Fe, also satisfying Si >=11.89-2.92C-0.077Mn, moreover having >=550 Vickers hardness (Hv), and in which the area ratio of dendrite in the structure is regulated to <=50%. Furthermore, in a condition in which they have this componental compsn., Si<=8.3C+0.14Mn is also satisfied, and moreover, <=1.10 relative permeability (μ) is satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an iron-based Si--Mn alloy or an iron-based Si--Mn--Ni alloy having particularly excellent pulverizability, and an alloy powder thereof.

[0002]

2. Description of the Related Art Conventionally, ferromanganese, ferrosilicon and silicomanganese, which are mainly used as deoxidation, desulfurization, slag-making and alloying components additives in steel production, are known as J
IS standard (G2301, G2302, G2304-19
86), the alloy components are high [Mn ≧ 73%, (Mn + Si) ≧ 74%, for example]
And the carbon content is extremely high (for example, FMnM
2: C ≦ 2.0%, SiMn0: C ≦ 1.5%). Then, these alloyed irons are to be supplied as alloy powders or granules according to the prescribed particle size for the purpose of use. In other words, these ferro-alloys have a characteristic feature that they are supplied in large quantities and in the form of powder and granules, as shown in the production method for lots in JIS. And a high carbon content, so that a powdery shape can be easily obtained after cooling after melting.

On the other hand, in recent years, with the diversification of steel products, the necessity of powdered ferromagnetic iron having a smaller amount of alloys such as Si and Mn and a lower carbon content than conventional JIS standards has been increasing. ing. For example, the flux of a flux-cored wire for arc welding applied to welding of a steel structure contains various powder raw materials such as a slag forming agent, a deoxidizing agent, an alloying agent, and iron powder depending on the purpose. Contains powdered ferromanganese, ferrosilicon, silicomanganese, iron powder and the like in a total amount of several tens%. The segregation of the components generated from the mixed flux may adversely affect the welding quality when welding steel.

[0004] Therefore, there is a strong demand for a method in which a single alloy iron powder having the same components as those prepared by blending the above several kinds of powder raw materials and having the same components is used in advance and used in a flux. However, generally, when Si, Mn and carbon in ferroalloys are reduced, their ductility and toughness gradually improve, and it becomes difficult to obtain a medium-granular product with ordinary production equipment. In addition, when component adjustment for improving this is performed, it becomes easy to take on magnetism, and a flux mixed with ferromagnetic alloyed iron powder is used, for example, as shown in the proposal of Japanese Patent Publication No. 4-72640. When forming a flux-cored wire by continuously forming a strip, filling with flux, and seam welding, depending on the manufacturing conditions, segregation of components, poor fusion of the seam, etc. may occur, resulting in flux-cored wire. This may adversely affect the production yield of the wire and the welding quality when welding steel.

[0005] Furthermore, the flux of a flux-cored wire for arc welding applied to the welding of steel structures such as high-strength steel and low-temperature steel, for example, contains Si, Mn, Ni, iron powder and the like at the same time. Is common. As these raw materials, in addition to simple raw materials (Si powder, Mn powder and Ni powder), the above-mentioned powdery ferrosilicon, ferromanganese,
Silicomanganese, ferronickel and the like are mainly used. These alloy components, Si, Mn, and Ni, are components that mutually act strongly on the quality of the weld. Therefore, the flux in which the raw materials are blended and mixed does not have a component segregation that is likely to occur due to a component variation for each raw material lot and a particle size difference for each raw material type. It is preferred that it is. For this purpose, a single iron alloy powder of iron-based Si-Mn containing Ni is required.

[0006]

Therefore, iron-based Si--Mn alloy powder or iron-based S
In producing the i-Mn-Ni alloy powder, it is necessary that the powder can be easily pulverized in the production process in order to mass-produce the powder. As an alloy powder having a high iron content, Japanese Patent Publication No. 4-62838,
No. 594 discloses Fe-Mn-based alloy powders, but they have the disadvantage that the pulverizability is extremely poor in conventional mechanical pulverization. Conventionally, these powders are iron alloys and are easily used. Iron-based Si that can be mass-produced by grinding
Actually, there is no -Mn alloy powder or iron-based Si-Mn-Ni alloy powder. In addition, the fact that the alloy powder is non-magnetic can further expand various uses.

[0007] The present invention relates to an iron-based Si-Mn alloy or an iron-based Si-M alloy as described above, which does not exist at present and which can be easily pulverized and mass-produced.
An n-Ni alloy and its powder are provided. The gist of the invention is as follows: (1) By weight%, C: 0.40 to 1.20%, Si:
5.0-12.0%, Mn: 19.0-42.0%, the balance being Fe, and Si ≧ 11.8-9-2.
92C-0.077Mn, Vickers hardness (Hv) ≧ 550, dendrite area ratio of structure ≦ 5
0-% iron-based Si-
Mn alloy.

(2) C: 0.40 to 1.20 by weight%
%, Si: 5.0 to 12.0%, Mn: 19.0 to 4
2.0%, the balance being Fe and Si ≧ 1
1.89-2.92C-0.077Mn and Si ≦
8.3C + 0.14Mn, Vickers hardness (Hv) ≧ 550, dendrite area ratio of structure ≦ 5
An iron-based Si-Mn alloy having good pulverizability, wherein 0% and relative magnetic permeability (μ) ≦ 1.10.

(3) The iron-based Si-Mn alloy according to the above (1) or (2), wherein P: 0.10 to 0.40% is contained. (4) The iron-based Si-Mn alloy powder according to the above (1) to (3), wherein the particle diameter is 212 µm or less. (5) The iron-based Si-Mn- having good pulverizability according to any one of the above (1) to (3), which contains 30% or less of Ni.
Ni alloy. (6) The iron-based Si-Mn-Ni alloy powder according to (5), wherein the particle size is 212 µm or less.

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing the relationship between the Vickers hardness (Hv) of the iron alloy slab according to the present invention and the area ratio (%) of the dendrite phase when observed with an optical microscope. From FIG. 1, it can be seen that the grindability of this kind of ferroalloys has a strong correlation between the hardness (Hv) of the slab and the dendrite area ratio (%), and the dendrite area ratio is set to 50% or less and the hardness (Hv) is set to 550 or more. This confirms that the pulverizability becomes easy.

FIG. 2 is a graph showing the relationship between the chemical composition of the cast slab and the magnetism of the Si-Mn alloy iron according to the present invention.
The vertical axis represents the value (%) of the ferromagnetic component contained in the slab measured by a ferrite meter, and the value of the horizontal axis, A / F (hereinafter referred to as austenite index), is shown in FIG. Is the value determined by the C, Si and Mn contents of
The meaning to the right (the larger the value) is, the stronger the austenitizing tendency is. From this Figure 2,
As the austenite index increases, the amount of ferrite exhibiting magnetism decreases almost linearly, and even when variations are considered,
When the austenite index becomes 2.40 to 2.80, the amount of ferrite almost disappears, and it is confirmed that the ferrite is demagnetized.

Next, the reasons for the regulation of the components in the present invention will be explained from the viewpoint of pulverizability and demagnetization. First, Vickers hardness (Hv) of slab, which has an important effect on grindability
The relationship between and the chemical components was determined by a series of tests and could be expressed by a relational expression. This equation is shown below. Hv = 380C + 130Si + 10Mn + [P] -10
76 However, each component is% by weight, [P] = 80 (P ≧ 0.10
%) And [P] = 0 (P <0.10%)

From the result of FIG. 1 that the crushability is improved when the Vickers hardness (Hv) is about 550 or more,
C, in order to obtain an iron-based Si-Mn alloy having good grindability,
The combination of Si, Mn and P contents is determined by the above equation. From this equation, the effect of C, Si, and Mn on the hardness (Hv) increases in the order of Mn <Si <C. However, considering the range of each component claimed in the present invention, practically, It can be seen that the influence of Si (coefficient = 130) is the strongest.

Therefore, for example, even when the content of Si is 5%, which is the lower limit of the claims, the values of C, Mn and P necessary for securing the Vickers hardness (Hv) of this ferromagnetic iron to 550 or more are experimentally determined. Asked by. The example is shown in Table 1 as No.
1 and No. 2. In No. 1, the pulverizability was insufficient because the content of Si was too low at 4%. However, from the data of No. 2, C and Mn were respectively determined to be almost the upper limit values (C: 1.20) of the present invention.
%, Mn: 42.0%), and if about 0.15% of P is added, good pulverizability can be obtained even with about 5% of Si, and this value is almost at the lower limit. It became clear that there was. When the content of Si is increased to 5% or more, the necessary contents of C, Mn, and P may be small, but when this value exceeds about 12%, the pulverizability is good, but nonmagnetic properties can be secured. It becomes difficult. Therefore, the range of Si amount is set to 5.0 to 1
2.0%.

Next, the effect of C will be described. N in Table 1
Examples are shown in o3, No4 and No5. No3, No4
From the results of the above, when Si is about 7% and Mn is about 24%, C
If the content is 1% or more, good pulverizability can be obtained. Also,
From the result of No. 5, when C is about 0.4%, it is necessary to increase Si and Mn in order to secure stable grindability. The upper limit of C is 1.20.
%, The effect on grindability and non-magnetism hardly changes. Therefore, the range of the C amount is set to 0.40 to 1.20.
%.

Regarding Mn, Vickers hardness (Hv)
The effect on grindability is not as strong as that of C or Si because of its small contribution (coefficient of the previous formula: 10) to the alloy, but in order to keep this ferromagnetic alloy in a nonmagnetic stable austenite phase, At least about 19% is necessary, and as described above, when Si having a strong ferrite forming ability is about 12%, Mn is required to be 40% or more. So M
The range of n amount was 19.0 to 42.0%.

[0017]

[Table 1]

It has also been found for the first time that the addition of a small amount of P to the ferroalloy of the present invention is extremely effective in increasing the hardness (Hv), ie, improving the grindability. Based on other examples, P is 0.1%
With the above addition, the Vickers hardness (Hv) increases by about 80. However, if added in an excessively large amount, there is a risk of embrittlement of the material of a steel product using the alloy powder of the present invention. Therefore, the range in the present invention is set to 0.10 to 0.40%.

The reasons for limiting the components of C, Si, Mn and P which affect the crushability of the iron-based Si-Mn alloy of the present invention have been described above. By selecting and setting Hv ≧ 550, the alloyed iron of the present invention can always ensure good pulverizability. The formula for calculating the hardness (Hv) is as follows: Hv = 380 C + 130 Si + 10 Mn + [P] −1076 (1) Conditions for Obtaining Good Grindability .89-2.92C-0.077Mn (2) is obtained. When the content of P is less than 0.10%, Si ≧ 12.51-2.92C-0.077Mn
In order to obtain the hardness (Hv) ≧ 550,
It suffices that the content of Si is increased by about 0.6% as compared with the equation (2).

Next, FIG. 1 shows that the smaller the dendrite area ratio, the better the pulverizability. The reason for this will be described. FIG. 3 shows an optical micrograph of the solidified structure of the slab. FIG. 3A shows a dendrite area ratio of 24%,
Hardness (Hv) is a structure of 682, and its grindability is good. On the other hand, FIG. 3B is a structure of a dendrite area ratio of 73% and hardness (Hv) of 347, and its grindability is poor. .
3 (a) and 3 (b), the dendrite is large in FIG. 3 (b), and the electron micrograph of the fracture surface has many irregularities, and in comparison, FIG. 3 (a) is smooth. Both fracture surfaces have the characteristic of cleavage fracture surface, but when a crack generated between dendrite structures by external force progresses,
When the tip of a crack collides with a dendrite structure having a different metallurgical property, extra fracture energy is required to further break and advance the dendrite structure as compared with a case where the dendrite structure is small, and therefore, the dendrite area ratio is reduced. Reducing the amount has the effect of improving the crushability in addition to the hardness.

Next, the relationship between non-magnetism and components will be described. In FIG. 2, it was revealed that when the A / F (austenite index) becomes 2.80 or 2.40 or more, the ferromagnetic alloy is almost completely demagnetized. When the relationship straight line between F and α is obtained, they become as shown in equations (3) and (4) in FIG. 2, respectively. In each case, if the condition of non-magnetism (α ≦ 0) is included, the expressions (3) and (4) are as follows.
From formula (3), [133-47.4 (30C + 0.5Mn) /1.5Si] ≦ 0 (3 ′) From formula (4), [114-47.4 (30C + 0.5Mn) /1.5Si] ≦ 0 ... (4 '), and when this is arranged, the expression (3') is Si≤7.1C + 0.12Mn (A / F≥2.80) (4 ') The expression is Si≤8.3C + 0.14Mn (A / F ≧ 2.40) (5) is obtained, and the amounts of C, Si, Mn and the relationship between them for the non-magnetic ferromagnetic iron of the present invention are expressed by this relational expression. It will be regulated. In many tests, it was confirmed that A / F ≧ 2.40 [formula (5)] was practically sufficient for demagnetization.

Further, when C and Mn are largely changed using the above-mentioned equations (2) and (5), good grindability (Hv ≧ 550) and non-magnetism (A / F ≧ 2.40) are obtained. ) Are calculated as shown in Table 2. From Table 2, for each C and Mn content, if the Si content (12.0% or less) in the thick frame is selected according to the purpose, good pulverizability and demagnetization can be obtained. I understand. As is apparent from Table 2, the present invention is characterized in that Si plays an extremely important role in both pulverizability and demagnetization.

As described above, the basic components of the iron-based Si-Mn alloy powder of the present invention, such as C, Si, Mn, and the reason for the limitation when a small amount of P is added thereto, have been described. As other components, Al: 1.0% or less;
When Ti: 2.0% or less is contained in each range,
This has the effect of slightly improving grindability. Other B, Mo, C
r, V, Nb, and the like can be contained in a range that does not impair the grindability and demagnetization.

[0024]

[Table 2]

The reason why the relative magnetic permeability (μ) of the iron-based Si—Mn alloy powder is set to 1.10 or less is that the value of the relative magnetic permeability (μ) of 1.10 is a critical value having a property of slightly magnetizing. Considering, for example, the application when used as a flux raw material in a flux-cored wire for welding, if the relative permeability (μ) is 1.10 or less, welding is also performed during seam welding in the flux-cored wire manufacturing process. Since no defects are generated, the ferrite amount of the cast slab, which was measured to obtain a measure of demagnetization this time, shows that the relative magnetic permeability (μ) 1.10 is just 1 in ferrite amount. ~ 2% (A / F
≧ 2.40). This fact made the relative magnetic permeability (μ) of the alloy powder less than 1.10.

The iron-based Si—Mn alloy powder has a particle size of 21%.
The reason why the particle size is set to 2 μm or less is that, for example, considering the use when used as a flux raw material in welding wires and the like, if the powder has a particle size of 212 μm or less, the yield in the wire manufacturing process is improved. Further, since there are advantages such as prevention of segregation of flux components and reduction in variation in welding performance, the particle size is set to 212 μm or less.

Next, the pulverizability and magnetism when the iron-based Si-Mn alloy of the present invention contained Ni was investigated. As a result, it was confirmed that good crushability and substantial non-magnetism can be ensured in the range of 30% or less of Ni. The crushability and the demagnetization are improved as the Ni content is increased, but the effect of increasing the Vickers hardness (Hv) of the slab is slightly smaller than that of Mn. Has an effect equivalent to that of Mn.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail based on embodiments. (Example 1) A molten raw material blended so as to have predetermined components was melted using a high-frequency induction heating furnace (melting amount: 2 kg) and cast into a mold to obtain a slab having a thickness of 10 to 25 mm.
This slab was roughly pulverized with a hammer, and the pulverizability was evaluated with a ring mill pulverizer having the shape shown in FIG. FIG. 4A is a plan view of the ring mill pulverizer taken along the line BB ′ of FIG. 4B, and FIG.
FIG. 4A is a cross-sectional view taken along the line AA ′ of FIG. 4A, in which an inner ring 2 is inserted into an outer cylinder 1 integrated with a bottom member 3, and horizontal vibration is applied to the bottom member 3 under predetermined conditions. When given, inner ring 2
Moves, and the slab inserted between the outer cylinder 1 and the inner ring 2 is crushed by impact. The crushability was evaluated by using a slab (average size of 10 to 20 mm) roughly crushed by the ring mill crusher.
Lump), put about 100g, amplitude 100mm, frequency 18
After giving an impact at 00 times / minute for 60 seconds, the particle size is 212 μm
When the following ratio was 90% or more, the evaluation symbol was ◎ (extremely good), when it was 50% or more, was と し た (good), and when it was less than 50%, it was △ (insufficient). The test results are shown in Table 1,
This is as described for the limited ranges of the Si and C contents. In Table 1, No. 1 is a comparative example, and No.
In Examples 2 to 5, good pulverizability was obtained in the examples of the present invention.

Example 2 A small amount of dissolution (2 kg) was carried out in the same manner as in Example 1. Table 3 shows the chemical compositions of the alloy powders and the results of investigations on the cast pieces (hardness, dendrite area ratio, ferrite content, and grindability). No1 in the table
-12 and No18, No19 and No21 all have excellent pulverizability. No2, No4, No
5, No7, No8, No11, No12 and No21 have almost no ferrite content and are substantially non-magnetic iron-based Si-
It turns out that Mn alloy powder was obtained. No1
Nos. 1 and 12 are cases where Ti and Al were added in small amounts, respectively. On the other hand, comparative materials No13 to No17 and N
O20 has insufficient pulverizability, and all have Vickers hardness (Hv) <550 and dendrite area ratio> 50%. Nos. 18 to 21 in the table show the effect of adding P on the hardness (Hv) and the dendrite area ratio, and No. 18 and No. 19 in which other components hardly change.
Also, comparing No. 20 and No. 21, it can be seen that the addition effect is remarkable.

[0030]

[Table 3]

Example 3 Table 4 shows the chemical composition, magnetism, and other characteristic values of the alloy powder obtained by dissolving a small amount in the same manner as in Example 1. No. 1 to No. 4 of the present invention each have an austenite index of 2.40 or more and a ferrite content of 0.14% or less, exhibiting (good) non-magnetism,
Also, the pulverizability is good. On the other hand, Comparative Examples No. 5, No. 6, and No. 7 have low austenite indices of 1.44, 1.75, and 2.14, respectively, and have strong magnetism due to precipitation of a large amount of ferrite phase. I understand. In this case, it can be seen that there is an abnormal relationship between the hardness (Hv) and the grindability.

[0032]

[Table 4]

Example 4 High-frequency induction heating furnace (melting amount 2)
(50 kg), the effect of the present invention was further confirmed by a large amount of dissolution. Dissolve and cast raw materials, thickness 20-50m
m was obtained. The cast slab was coarsely pulverized by a jaw crusher and further finely pulverized by a rod mill, and then an alloy powder was produced through an integrated process of sieving with a particle size of 212 μm. Table 5 shows the chemical composition, particle size composition, relative permeability (μ) measured by a vibrating sample magnetometer, Vickers hardness (Hv), dendrite area ratio (%), and ferrite measured on a slab. The ferrite content (%) is indicated by a meter. As a result, as shown in Table 5, Examples Nos. 1, 2, and 3, which fall within the scope of the present invention, all have sufficient pulverizability in a conventional mechanical pulverization method, and also have a relative magnetic permeability (μ). It was confirmed that the result of the above-mentioned small amount dissolution was reproduced even in a small and large amount dissolution.

[0034]

[Table 5]

(Example 5) High frequency induction heating furnace (capacity 25
0 kg) to produce an alloy powder containing Ni in the same manner as in Example 4. Table 6 shows the chemical composition, particle size composition and relative permeability (μ) of the obtained alloy powder, Vickers hardness (Hv) measured on a slab, and dendrite area ratio (%).
And ferrite content (%). As a result, in Example No. 1 containing Ni. Each of Examples 1 to 7 can be easily pulverized by a mechanical pulverization method. 1 to
No. 5 is substantially non-magnetic when the relative magnetic permeability (μ) is 1.10 or less. In addition, in Example No. In 5, the particle size is 212.
Although 9% of coarse-grained portions were generated, the total amount could be reduced to 212 μm or less by re-grinding with the same rod mill.

[0036]

[Table 6]

[0037]

As described above, according to the present invention, a non-magnetic iron-based Si-Mn alloy powder or an iron-based Si-Mn-Ni alloy powder having a large iron component content can be produced in an extremely Good pulverizability and easy mass production became possible.

[Brief description of the drawings]

FIG. 1 shows a Vickers hardness (H) of an iron alloy slab according to the present invention.
FIG. 4 is a diagram showing the relationship between v) and the area ratio (%) of the dendrite phase when observed with an optical microscope.

FIG. 2 is a diagram showing a result of obtaining a relationship between a chemical composition of a cast slab and magnetism in a Si—Mn alloy iron including the present invention.

FIG. 3 is a view showing an optical microscope photograph of a solidified structure of a cast slab.

FIG. 4 is a schematic view showing a ring mill pulverizer used for pulverizability evaluation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer cylinder 2 Inner cylinder ring 3 Bottom member 4 Top lid 5 Cast piece

Continued on the front page (72) Inventor Masao Kamada 3-5-4 Tsukiji, Chuo-ku, Tokyo Nippon Steel Welding Industry Co., Ltd. (72) Inventor Hitoshi Nishimura 3-5-4 Tsukiji, Chuo-ku, Tokyo Nippon Steel Inside Welding Industry Co., Ltd. (72) Inventor Kuniki Suzuki 8-4 Nihonbashi Koami-cho, Chuo-ku, Tokyo Inside Japan Heavy Chemical Industry Co., Ltd. (72) Inventor Toshishi Kikuchi 8-4-2 Nihonbashi Koami-cho, Chuo-ku, Tokyo No. Japan Heavy Chemical Industry Co., Ltd.

Claims (6)

[Claims] 1. The composition contains, by weight%, C: 0.40 to 1.20%, Si: 5.0 to 12.0%, and Mn: 19.0 to 42.0%, the balance being Fe, and , Si ≧ 11.89−2.92
C-0.077Mn, Vickers hardness (Hv) ≧ 550, dendritic area ratio of the structure ≦ 50%
Iron-based Si-Mn having good pulverizability, characterized by being
alloy. 2. The composition according to claim 1, comprising 0.40 to 1.20% of C, 5.0 to 12.0% of Si, and 19.0 to 42.0% of Mn, with the balance being Fe. , Si ≧ 11.89−2.92
C-0.077Mn and Si ≦ 8.3C + 0.14M
n, and Vickers hardness (Hv) ≧ 55
0, an iron-based Si-Mn alloy having good pulverizability, characterized by satisfying a dendrite area ratio of the structure ≦ 50% and a relative magnetic permeability (μ) ≦ 1.10. 3. The iron-based Si—Mn alloy having good pulverizability according to claim 1, wherein the content of P is 0.10 to 0.40%. 4. The iron-based Si—Mn alloy powder according to claim 1, wherein the particle size is 212 μm or less. 5. The iron-based Si—Mn having good pulverizability according to claim 1, which contains 30% or less of Ni.
-Ni alloy. 6. The iron-based Si—Mn—Ni alloy powder according to claim 5, having a particle size of 212 μm or less.