JPH073389A - Metal band saw barrel material and metal band saw excellent in fatigue life property - Google Patents

Abstract

PURPOSE:To provide a metal band saw barrel material and a metal band saw having a high fatigue life. CONSTITUTION:This metal band saw barrel material excellent in fatigue life properties is a one contg., by weight, 0.25 to 0.60% C, <=0.6% Si, <=1.2% Mn, 0.4 to 1.00% Ni, 4.5 to 6.5% Cr, one or two kinds of Mo and W by 0.5 to 3.0% as Mo+1/2W, 0.03 to 0.50% V, 0.03 to 0.20% Al and 0.015 to 0.040% N, preferably contg. <=0.30% of one or >=two kinds among Nb, Ti and Zr, and the balance Fe with impurities, and this metal band saw is a one characterized by joining the same barrel material with a blade material constituted of high speed steel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal band saw composed of a body made of high speed tool steel and joined in parallel with the blade, and more particularly to a metal band saw body having improved fatigue life. Is.

[0002]

2. Description of the Related Art Metal band saws use a high-speed tool steel blade material and an inexpensive low-grade steel body material by electron beam welding to save the cost of expensive high-speed tool steel. After that, heat treatment according to the high speed steel of the blade material, for example, about 11
Quenching at 60 to 1220 ° C and tempering at 540 to 580 ° C are performed. Conventional body material is S50C or AISI
6150 was used, but when these body materials were heat treated under the same quenching and tempering conditions as high-speed tool steel, the toughness of the body material decreased due to the quenching temperature being too high, and the tempering temperature was also high. Since it is too much, the hardness is lowered, sufficient tensile strength is not obtained, and the fatigue strength is also lowered, so that there is a problem that the body part is broken.

In order to solve this problem, the inventors of the present invention have investigated a material capable of ensuring a sufficient hardness even under the same heat treatment condition as that of the high speed steel, and have published Japanese Patent Publication Nos. 54-5366 and 55-32778. No. 4, Japanese Patent Publication No. 61-2202, Japanese Patent Laid-Open No. 2-115353, and other new alloys have been developed and put to practical use.

[0004]

The metal band saw is
In general, a blade material and a body material are endlessly welded and driven by two wheels provided in a band saw machine to cut a non-cutting material horizontally fixed between the wheels, mainly a steel material. In the metal band saw, tension is applied between the wheels so that the steel material does not have a bend, and at the same time, the metal band saw receives repeated bending stress along the wheels during driving. Further, the wheel is inclined with respect to the horizontal, and the metal band saw is loaded with a twist corresponding to the inclination of the wheel. Therefore, while driving the metal band saw,
Subjected to tensile stress and bending and torsional stress.

In the metal band saw as described above,
Recently, cutting conditions have become more severe due to the increase in difficult-to-cut materials such as super heat resistant steel and stainless steel and the improvement of cutting efficiency, and even higher performance and longer life materials are required for body materials. Has been. Further, in order to reduce the cutting cost, the metal band saw machine has been automated and operated unmanned, which requires a stable and long-life body material. An object of the present invention is to provide a metal band saw body and a metal band saw that can obtain a stable and high fatigue life even if heat treatment is performed simultaneously with the high speed steel as a blade material.

[0006]

The present inventor has recognized that Al (aluminum), which reduces the fatigue life of a metal band saw body and is not preferable, exists in a specific steel such as N (nitrogen) present in the steel. It has been found that the effect of suppressing the growth of crystal grains during the heat treatment and increasing the fatigue life becomes remarkable by combining with the above) to form aluminum nitride, and reached the present invention.

That is, in the present invention, C: 0.25 by weight%
~ 0.60%, Si: 0.6% or less, Mn: 1.2% or less, Ni: 0.4 to 1.0%, Cr: 4.5 to 6.5.
%, 1 type or 2 types of Mo and W at Mo + 1 / 2W.
5 to 3.0%, V: 0.03 to 0.50%, Al: 0.
03 to 0.20%, N: 0.015 to 0.040%, preferably one or more of Nb, Ti and Zr, 0.30% or less, and the balance Fe and impurities. It is a metal band saw body with excellent fatigue life characteristics. In the metal band saw in which the metal band saw body is joined in parallel with the blade material made of high-speed tool steel and subjected to heat treatment, the crystal grains of the body forming the metal band saw have an ASTM grain size number of 6.
It becomes finer than No. 5 and has a high fatigue life.

[0008]

As described above, one of the greatest features of the present invention is that Al is combined with N existing in steel to form aluminum nitride, which suppresses the growth of crystal grains during heat treatment and enhances the fatigue life. Especially. Since the basic composition of steel also greatly influences the fatigue life, the effect of increasing the fatigue life by suppressing the growth of crystal grains due to the formation of aluminum nitride is not clearly shown only by specifying the amounts of Al and N. . Therefore, it is necessary to specify the other constituents to have a high fatigue life and to add Al and N. The reasons for the components specified in the present invention will be described below.

First, the reasons for limiting the elements for preventing the coarsening of the crystal grains of the body material by quenching of high speed tool steel will be described. Al combines with N in steel to form aluminum nitride. Aluminum nitride does not form a solid solution in the matrix even at a high temperature such as quenching of high speed steel, and prevents coarsening of crystal grains. Al is not effective unless it is 0.03% or more, and when it is excessive, a large amount of nonmetallic inclusions are formed, and when the blade material and the body material are joined by electron beam welding, the inclusions of Al float in a beat shape. Therefore, the upper limit was made 0.20%.

N is an essential component for forming a nitride and preventing coarsening of crystal grains. In order to secure the amount of the nitride enough to prevent the coarsening of the crystal grains, N is 0.
015% or more is required, and if it is too large, a pinhole is formed in the bead of welding, so the upper limit was made 0.04%.

Nb, Ti and Zr are nitride forming elements like Al. However, these elements are strong carbide-forming elements, and since carbide partially forms a solid solution during heating during quenching of high-speed steel, it does not have the effect of preventing crystal grain coarsening as much as nitride. Therefore, it is necessary to add it together with Al. Excessive addition causes a tendency for the fatigue strength to decrease due to an increase in the amount of carbide, so the upper limit was made 0.30%. These elements are less effective unless 0.05% or more of one element or a combination of two or more elements, so the content is preferably 0.05% or more.

Next, the reasons for defining the elements that ensure the basic characteristics of the body of the present invention will be described. C is an essential element for ensuring the strength and toughness of the body material. Cr, M
It combines with carbide forming elements such as o, W, and V to precipitate fine carbides during tempering, thereby increasing tempering softening resistance. The amount of C must be determined in balance with the amount of carbide-forming elements, and 0.25% or more is required to obtain Hv of 450 or more by tempering. Since an excessive amount of C reduces toughness, the upper limit is 0.60. %.

[0013] Cr not only enhances the hardenability of the body material, but also C
In order to increase the fatigue life, it is necessary to be 4.5% or more in order to increase the softening resistance of temper and increase the toughness. However, when Cr carbides are excessive, the softening resistance is decreased, and therefore, the balance of other carbide forming elements is 6.5% or less, preferably 5.
It is limited to 5% or less. Ni forms a solid solution in the matrix and contributes to the improvement of toughness. Further, even if fatigue cracks occur, the cracks propagate slowly and are elements that prevent brittle fracture, and are essential elements for increasing the fatigue life. To obtain this effect, 0.40% or more is required, and an excessive amount has the adverse effect of insufficient heat treatment hardness, so 1.0% was made the upper limit.

Mo and W are elements effective for toughness and wear resistance, and at the same time are secondary hardening elements. In order to obtain temper hardness, it is necessary to add one or two of Mo and W. is there. However, since these carbides easily aggregate, if they are excessive, the toughness is lowered. This gives Mo equivalent (=
It is effective to add 0.5 to 3.0% of Mo + 1 / 2W). V is an element that precipitates as a primary carbide during solidification and is effective for refining crystal grains. Further, since carbide is hard, it contributes to wear resistance. 0.03% to obtain these effects
The above is necessary. However, the excess of VC carbides increases the probability of becoming the starting point of fatigue crack generation, so the upper limit was made 0.50%.

Mn is added to steel as a deoxidizing agent. M
If n is contained excessively, cold workability is impaired, so the upper limit was made 1.2%. Si, like Mn, is added as a deoxidizer. An excess of Si tends to increase non-metallic inclusions and impair fatigue strength, so the upper limit is 0.6%.
And

[0016]

EXAMPLES The present invention will be described below based on examples.
Table 1 shows the chemical composition of the present invention steel and the comparative steel. Steel ingots of these components were manufactured by melting in an electric furnace, and the steel ingots were processed by hot rolling and cold rolling to a thickness of 1 mm and subjected to a reliability test. As the accuracy test, heat treatment hardness, grain size and tensile fatigue test were performed. The heat treatment of the test material is the same as the normal heat treatment of the high-speed steel SKH59, which is a typical blade material, and the quenching temperature is 1200 ° C and the tempering temperature is 560 ° C.
After that, the measurement was performed. For the tensile fatigue test, a tensile test piece with a notch having a depth of 1 mm and a radius of 2 mm shown in FIG. 1 was used. The finish of the notch was JIS 3S precision finish. As the stress loading condition, a partial oscillating tensile load having a minimum tensile stress of 295 N / mm ² and a maximum tensile stress of 980 N / mm ² was used, and the stress cycle was 10 Hz.

[0017]

[Table 1]

The results of these tests are shown in Table 2. As shown in Table 2, Comparative Steels 1 to 4 in which the amounts of Al and N are small and the effect of refining the crystal grains due to the formation of aluminum nitride is small, the grain size number of ASTM is smaller than 5.2 and the grains are coarse grains. I understand. Along with this, it can be seen that the comparative steels 1 to 4 have significantly shorter fatigue lives than the inventive steels 8 to 18. Further, in Comparative Steels 5 to 7 in which the amounts of Ni, V and Cr are smaller than those of the steels of the present invention, the grain refinement effect due to the formation of aluminum nitride is exhibited, but the Ni, V or Cr amounts are not appropriate, so the fatigue life Is shorter than the steel of the present invention.

[0019]

[Table 2]

As shown in Table 2, in the steel of the present invention, grain refinement by Al and N and optimization of other alloy components
It has a high fatigue life of 7 × 10 ⁴ times or more. Also,
It can be seen that the invention steels 15 to 18 in which Nb, Ti, and Zr are added together to the invention steel have extremely high fatigue life of 11 × 10 ⁴ times or more.

[0021]

According to the present invention, as the metal band saw body material, fine crystal grains and long fatigue life can be obtained even if the heat treatment is performed under the same conditions as the high speed steel as the blade material. Therefore, the metal band saw of the present invention not only reduces the cost of cutting the material, but also has high reliability against automatic unmanned operation and can be used with peace of mind.

[Brief description of drawings]

FIG. 1 is a diagram of a test piece used for a tensile fatigue test of a test steel.

Claims (4)

[Claims] 1. C: 0.25 to 0.60% by weight, S
i: 0.6% or less, Mn: 1.2% or less, Ni: 0.4
˜1.0%, Cr: 4.5 to 6.5%, 0.5 or 3.0% of Mo + 1 / 2W with one or two kinds of Mo and W, V:
0.03 to 0.50%, Al: 0.03 to 0.20%,
N: 0.015 to 0.040%, balance Fe and impurities, and a metal band saw body having excellent fatigue life characteristics. 2. C: 0.25 to 0.60% by weight, S
i: 0.6% or less, Mn: 1.2% or less, Ni: 0.4
˜1.0%, Cr: 4.5 to 6.5%, 0.5 or 3.0% of Mo + 1 / 2W with one or two kinds of Mo and W, V:
0.03 to 0.50%, Al: 0.03 to 0.20%,
N: 0.015 to 0.040%, Nb, Ti and Zr
A metal band saw body having excellent fatigue life characteristics, characterized in that it comprises one or more of 0.30% or less and the balance Fe and impurities. 3. A blade material made of high-speed tool steel and a body material joined in parallel with the blade material, the body material having a C: 0.25-
0.60%, Si: 0.6% or less, Mn: 1.2% or less, Ni: 0.4 to 1.0%, Cr: 4.5 to 6.5.
%, 1 type or 2 types of Mo and W at Mo + 1 / 2W.
5 to 3.0%, V: 0.03 to 0.50%, Al: 0.
03-0.20%, N: 0.015-0.040%, chemical composition consisting of balance Fe and impurities, and crystal grain size is finer than 6.5 in grain size number, fatigue life Metal band saw with excellent characteristics. 4. A blade material made of high-speed tool steel and a body material joined in parallel with the blade material, the body material having a C: 0.25-
0.60%, Si: 0.6% or less, Mn: 1.2% or less, Ni: 0.4 to 1.0%, Cr: 4.5 to 6.5.
%, 1 type or 2 types of Mo and W at Mo + 1 / 2W.
5 to 3.0%, V: 0.03 to 0.50%, Al: 0.
03-0.20%, N: 0.015-0.040%, N
0.30% of one or more of b, Ti and Zr
Hereinafter, a metal band saw having excellent fatigue life characteristics, characterized in that the chemical composition and the grain size of the balance Fe and impurities are finer than 6.5 in terms of grain size number.