JP5446290B2 - Manufacturing method for machine structural parts - Google Patents

Description

  The present invention relates to a machine structural component capable of effectively increasing the overall rigidity by a simple method and a manufacturing method thereof.

  Steel materials such as steel for machine structural use can be obtained at a lower cost than other alloys, and the strength, toughness, etc. can be obtained by adding alloys, heat treatment such as quenching and tempering, and surface hardening treatment such as carburizing and nitriding. The mechanical properties of can be greatly improved. However, even if these mechanical characteristics are improved, the rigidity is hardly changed, so a technique for increasing the rigidity has been strongly demanded.

  In recent years, a material called high-rigidity steel has been developed to meet the above demand. Since this steel has a higher Young's modulus than ordinary steel, it is possible to achieve high rigidity. Moreover, since it is steel, it can aim at the improvement of the mechanical characteristic by heat processing etc. similarly to normal steel. As such high-rigidity steel, for example, steel disclosed in Patent Document 1 is disclosed.

  In Patent Document 1, a boric acid containing 4A group element, 5A group element, 6A group element and Fe and / or a composite thereof is dispersed in a matrix made of iron or an iron alloy in a predetermined amount. Rigid steel is described. This high-rigidity steel is obtained by increasing the Young's modulus while utilizing the excellent properties of steel by dispersing a high-rigidity boride in the matrix phase of the steel.

JP 2004-218069 A

However, the high-rigidity steel described in Patent Document 1 can be mass-produced in comparison with the sintering method described later by manufacturing a relatively large steel ingot using a melting method, but TiB ₂ Since the boride of high hardness such as is dispersed, the workability is very poor and it is very difficult to manufacture a component having a complicated shape. In addition to the melting method, it is also possible to manufacture using a sintering method, but in this case, it is possible to greatly improve the Young's modulus, but it is difficult to mass-produce compared to the melting method. Problems arise.
For these reasons, there is a demand for a machine structural component and a method for manufacturing the same that can effectively achieve high rigidity by a relatively easy method.

  The present invention has been made in view of such conventional problems, and is intended to provide a machine structural component capable of effectively increasing the overall rigidity by a simple method and a manufacturing method thereof. .

In the present invention, an excellent machine structural part is manufactured by supplying a material for overlay welding to the surface of the substrate and welding it to form the overlay weld, and then removing the substrate and performing the overlay welding. It consists only of parts,
The build-up weld includes a boride containing one or more elements selected from a group 4A element, a group 5A element, a group 6A element, and Fe in a matrix phase made of pure iron or an iron alloy, and / or a composite thereof. is a machine structural part, characterized in that made of a high rigidity steel product was allowed to 10% to 70% dispersion by volume.

The present invention , which is a method of manufacturing the machine structural component , prepares a base material,
1 is selected from a group 4A element, a group 5A element, a group 6A element and Fe in a matrix phase made of pure iron or an iron alloy by supplying and welding a raw material for overlay welding to the surface of the substrate. Forming a built-up weld made of high-rigidity steel in which boride containing elements of more than seeds and / or composites thereof is dispersed by 10 to 70% by volume,
Then, in the manufacturing method for a machine structural part, characterized in that only the overlay weld part to remove the substrate (claim 1).

  The machine structural component is configured by only the remaining welded portion after removing the base material after forming the welded portion on the surface of the base material by overlay welding. And this build-up welding part consists of high rigidity steel which disperse | distributed boride or / and its composite_body | complex with the volume ratio of the said specific range. That is, the mechanical structural component is constituted by a high rigidity steel having a high Young's modulus as a whole by a simple method. As a result, it is possible to easily and effectively increase the rigidity of the entire component and improve the mechanical characteristics of the entire component.

  Moreover, the said build-up welding part is formed by supplying and welding the said raw material for build-up welding to the surface of the said base material. That is, the material for overlay welding is formed by melting and solidifying by welding. Therefore, at the time of welding, the material for build-up welding can be rapidly solidified to finely disperse the borides and / or composites thereof contributing to high rigidity. Thereby, an intensity | strength characteristic can also be improved.

  Thus, according to the present invention, it is possible to provide a machine structural component and a method for manufacturing the same that can effectively increase the overall rigidity by a simple method.

Explanatory drawing which shows the components for mechanical structures (test material) comprised only by the overlay welding part in an Example.

  In the present invention, the boride to be dispersed in the build-up weld constituting the mechanical structural part is limited to elements other than Fe, such as 4A group, 5A group, and 6A group. This is because, as is well known, these borides have a high Young's modulus and are suitable for increasing the Young's modulus.

Moreover, the volume fraction of the boride and / or the composite thereof dispersed in the build-up weld is set to 10 to 70%.
If the volume ratio is less than 10%, the effect of increasing the rigidity may not be sufficiently obtained. On the other hand, if it exceeds 70%, welding may be difficult. Further, after welding, there is a possibility that the processing becomes difficult.

  In addition, if the volume fraction of the said boride and / or its composite is 10 to 70%, the said build-up welding part will be regardless of the composition of the matrix phase which consists of a pure iron or an iron alloy, and is highly rigid build-up. A weld can be obtained. However, since the elements forming the boride such as Ti and / or the composite thereof are easily bonded to carbon, it is desirable that the amount of carbon contained in the matrix phase is small.

Moreover, the said build-up weld part is a mass%, contains Ti: 4.2-40.0%, B: 1.8-18.0%, and is the said boride or / and its composite_body | complex. Of these, 50% or more by volume is preferably TiB ₂ ( claim 2 ).
Here, TiB ₂ is characterized by a high Young's modulus and a low density among borides. Further, by adding a raw material containing Ti and B at the time of solidification, it can be easily produced as a stable boride. Therefore, considering the Young's modulus improvement effect and manufacturability, it is greatly superior to the case where other borides are used, so among the borides to be dispersed or / and their composites, It is preferable that 50% or more is TiB ₂ . On the other hand, when the volume ratio is less than 50%, the Young's modulus improvement effect may be reduced.

Moreover, in order to make the volume fraction of TiB ₂ contained in the boride or / and the composite thereof 50% or more, it is preferable to appropriately adjust the amount of Ti and B to be added, and the range of Ti is It is preferable that the content is 4.2 to 40.0% and B is 1.8 to 18.0%. In addition, in order to suppress the formation of borides other than TiB ₂ , it is necessary to balance the addition amounts of Ti and B, and in particular, B is not excessively added compared to the addition amount of Ti. Is preferred. That is, it is preferable that the compounding ratio of Ti and B is close to 1: 2 in terms of the number of atoms (Ti / B = 2.215 in terms of mass ratio). Thereby, the ratio of TiB ₂ can be increased.

It is preferable that the material for overlay welding used in the manufacturing method is composed of a powder material that can become the high-rigidity steel by welding or a material obtained by solidifying the powder material into a predetermined shape ( Claim 3 ).
In this case, the uniformity of the material for overlay welding can be sufficiently ensured, so that the quality of the overlay weld made of high-rigidity steel obtained by welding is stabilized, that is, Young's modulus. Can be reduced.
Moreover, the component adjustment of the said build-up welding part becomes easy by using what mixed 1 or multiple types of powder as said raw material for build-up welding. Further, the manufacturing cost can be greatly reduced as compared with the conventional melting method.

When using a powder raw material as the build-up welding raw material, it is preferable to mix so that the powder is as uniform as possible. Care should be taken when mixing is not sufficient and uneven, as post-weld performance may be uneven depending on location.
Moreover, there is no restriction | limiting in particular as a mixing method of a powder raw material, A V-type mixer, a ball mill, a vibration mill, etc. can be used.

When a raw material obtained by solidifying a powder raw material into a predetermined shape as the above-described overlay welding raw material, for example, a welding rod obtained by compacting and sintering a powder raw material into a rod shape, is processed into a target size and shape by rolling, drawing, etc. It is preferable to do.
In addition, when sintering a powder raw material and producing a welding rod, in a sintering process, it is necessary to suppress the production | generation of the oxide by atmospheric gas and raw material powder reacting during sintering. Moreover, even if an oxide is generated, it is necessary to suppress the generation amount to a level that causes a problem in use.

As said powder raw material, the atomized powder adjusted to the target component and the mixed powder which mixed the boride raw material and the other raw material besides that can be used.
As the boride raw material, it is possible to use a commercially available powder that has already become a boride, a mixed powder of a powder containing 4A group element, 5A group element, 6A group element (ferroalloy powder or the like) and ferroboron powder, or the like. it can. These produce borides or their composites by the reaction that takes place during solidification during welding.
As raw materials other than the boride raw material, powder ferroalloy powder containing a group 4A element, a group 5A element, and a group 6A element, or a powder composed of a component close to the final target component (for example, mainly Fe-Cr). If so, stainless steel powder) or metal powder such as pure iron can be used.

Moreover, it is preferable that the particle size of the said powder raw material is 20-300 micrometers.
When the particle size of the powder raw material is less than 20 μm, the powder raw material may be clogged or scattered in the powder supply path at the time of welding, and welding workability may be extremely reduced. On the other hand, when it exceeds 300 μm, there is a risk of causing poor melting at the time of welding or coarsening of the boride in the build-up weld. Therefore, when a large powder raw material is used, it is necessary to pulverize it with various pulverizers such as a ball mill, a vibration mill, an attritor, etc. to adjust to a desired particle size.

Further, the welding, the powder plasma welding, powder laser welding, TIG welding, is preferably carried out using any of the methods of arc welding (claim 4).
For example, when a powder raw material is used as the material for overlay welding, it is preferable to use powder plasma welding or powder laser welding. Moreover, when using the welding rod which compacted or sintered the powder raw material as the said material for overlay welding, it is preferable to carry out using TIG welding or arc welding. Thereby, overlay welding can be performed easily.

The welding method may be appropriately selected depending on the shape and size of the part to be finally obtained.
Moreover, it is preferable to set it as the welding method and welding conditions which can prevent the contact with air | atmosphere and the production | generation of an oxide at the time of welding. In addition, the welding conditions (for example, current, welding speed, etc.) vary depending on the above-described overlay welding raw material and welding technique to be used, and it is preferable to select conditions that do not cause defects (such as poor melting).

The preheating at the time of welding is not particularly limited, but is preferably about 300 to 500 ° C. in order to improve the weldability.
Moreover, the post-heating at the time of welding is important for preventing the generation of defects after welding, and it is preferable to gradually cool after reheating to about 400 to 500 ° C. However, if the component performance changes due to post-heating, it is necessary to lower the post-heating temperature or to remove residual stress by peening. In addition, there is no problem even if the post-heating is omitted for parts that are heated to a temperature equal to or higher than the transformation point by tempering after welding.

Moreover, as a method of removing the said base material from the said build-up welding part formed by build-up welding, methods, such as a wire cut, the cutting process by a grindstone, a band saw, and a grinding process, can be used.
Moreover, after removing the said base material, you may perform processes, such as cutting, so that it may become a desired shape with respect to the said build-up welding part. In addition, when processing such as cutting is not required, such processing may not be performed.

  The mechanical structural component can be applied to, for example, a diaphragm for an acoustic speaker, a jig for a test evaluation facility, an automobile component such as a push rod or a connecting rod. It is particularly suitable for parts that are relatively small and require high rigidity.

A machine structural component and a manufacturing method thereof according to an embodiment of the present invention will be described.
In this example, as shown in Table 1, 16 kinds of welding materials (welding materials a to p) as raw materials for build-up welding were prepared, and test materials (examples) as examples in the machine structural parts of the present invention were prepared. Examples E1 to E14) and test materials as comparative examples (Comparative Examples C1 and C2) were prepared, and tests for evaluating Young's modulus, weldability, and workability were performed.

Specifically, first, as shown in FIG. 1A, overlay welding was performed on the surface 20 of the base material 2 under various conditions using various welding materials to form the overlay weld 11.
Then, as shown in FIG.1 (b), the base material 2 is removed from the build-up welding part 11 by wire cutting, and the test material 1 of the machine structural component comprised only by the build-up welding part 11 (Example E1) To E14, Comparative Examples C1 and C2).

In this example, SKD61 equivalent (Fe-5% Cr) of 15 × 100 × 130 mm was used as the base material.
Moreover, as a material of the welding material, titanium diboride (TiB ₂ ) having a particle diameter of 40 to 70 μm, ferroboron (Fe-20% B) having a particle diameter of 50 to 150 μm, ferrotitanium (Fe—) having a particle diameter of 50 to 150 μm. 40% Ti), titanium (Ti) with a particle size of 40-100 μm, iron base material (Fe-3% Cr-0.4% Mo) with a particle size of 50-150 μm, boron with a particle size of 1.0-1.5 μm Tantalum fluoride (TaB ₂ ), ferrochromium (Fe-70% Cr) having a particle size of 50 to 150 μm, ferromolybdenum (Fe-70% Mo) having a particle size of 50 to 150 μm, ferroniobium (Fe-70%) having a particle size of 50 to 150 μm Nb) and a mixed powder obtained by mixing ferrovanadium (Fe-80% V) powder having a particle diameter of 50 to 150 μm so that the volume fraction of boride in the built-up welded portion has a predetermined value.

Moreover, as a form of the welding material, the above-mentioned mixed powder or a welding rod formed by compacting this powder into a rod shape and sintering it was used.
As a welding method, powder plasma welding was used. The welding conditions are: welding current: 180 A, plasma gas: 3 L / min, shield gas: 15 L / min, carrier gas: 5 L / min, supply amount: 25 g / min, welding speed: 80 mm / min, weaving width: 12 mm, pass Number: 10 passes, preheating: none, afterheating: none.

Next, it shows in Table 1 about the characteristic of the overlay welding part formed by overlay welding using various welding materials (welding material ap).
The type of boride was determined using an EPMA analyzer.
The volume ratio of the boride was determined by the procedure of measuring the area ratio (= volume ratio) using an image analysis device for a field of view with an arbitrarily selected area of 1 mm ² in the overlay weld. In the table, those in which the volume fraction of the boride is out of the range (10 to 70%) of the present invention are shown as x marks.
The ratio of TiB _{2 to} the boride and its composite was determined by measuring the area ratio (= volume ratio) of particles that could be determined to be TiB ₂ by color tone discrimination with an image analyzer.

Next, each test and its evaluation were performed on the test materials shown in Table 1 (Examples E1 to E14, Comparative Examples C1 and C2).
The Young's modulus was measured by a composite vibrator method using a crystal resonator by cutting a 10 × 10 × 10 mm cubic test piece from the specimen. The resonance frequency of the crystal resonator was 110.25 KHz. The measurement direction is the thickness direction of the build-up weld (the direction perpendicular to the surface of the removed base material). And when the Young's modulus improvement effect with respect to the Young's modulus of a general steel is determined to be 10% or less and the Young's modulus is 230 GPa or less, the standard was not satisfied.

The weldability satisfies the standard if there is no melting failure or continuous blowhole of 30 μm or more in the specimen.
For the workability, a cutting test using an end mill was performed on the specimen, and the criterion was satisfied if the amount of blade wear was a predetermined amount (0.3 mm) or less.

  And as shown in Table 1, about evaluation of Young's modulus, what did not meet a standard was shown as x mark. In addition, regarding the evaluation of weldability and workability, those that sufficiently satisfy the standard are indicated by ◎, those that satisfy the standard are indicated by ○, and those that do not satisfy the standard are indicated by ×.

Next, the effect in the test material (Examples E1-E14) as an Example of this invention is demonstrated compared with the test material (Comparative Examples C1 and C2) as a comparative example.
As can be seen from the results in Table 2, Examples E1 to E14 of the present invention are made of high-rigidity steel in which borides and / or composites thereof are dispersed at a volume ratio (10 to 70%) in the above specific range. It is comprised only by the overlay welding part. Therefore, the Young's modulus shows a high value. And Young's modulus, weldability, and workability all satisfy the standards.

On the other hand, Comparative Example C1 did not satisfy the criteria for Young's modulus because the volume fraction of boride in the overlay weld was low. That is, the effect of the present invention to increase the rigidity of the entire part could not be obtained sufficiently.
In addition, Comparative Example C2 has a high Young's modulus because of the high volume fraction of boride in the weld overlay, but did not satisfy the standards for weldability and workability.

  Thus, the machine structural component of the present invention removes the base material after forming the build-up welded portion on the surface of the base material by build-up welding, whereby the boride or / and the composite thereof are identified as described above. It can comprise only the build-up welding part which consists of high-rigidity steel disperse | distributed with the volume ratio of the range. That is, the whole can be made of high-rigidity steel having a high Young's modulus by a simple method. Thereby, the high rigidity of the whole component can be achieved easily and effectively. Moreover, sufficient characteristics such as weldability and workability can be secured.

DESCRIPTION OF SYMBOLS 1 Machine structural component 11 Overlay welding part 2 Base material 20 Surface

Claims (4)

  Prepare the substrate,
  1 is selected from a group 4A element, a group 5A element, a group 6A element and Fe in a matrix phase made of pure iron or an iron alloy by supplying and welding a raw material for overlay welding to the surface of the substrate. Forming a built-up weld made of high-rigidity steel in which boride containing elements of more than seeds and / or composites thereof is dispersed by 10 to 70% by volume,
  Then, the said base material is removed and it is only the said overlay welding part, The manufacturing method of the components for machine structures characterized by the above-mentioned.   In Claim 1, the said build-up weld part contains Ti: 4.2-40.0%, B: 1.8-18.0% by the mass%, and the said boride or / and its The composite is TiB ₂ Occupies 50% or more by volume ratio, a method for manufacturing a machine structural component.   3. The machine structural component according to claim 1, wherein the material for overlay welding is made of a powder material that can be made into the high-rigidity steel by welding or a material obtained by solidifying the powder material into a predetermined shape. Production method.   The method for manufacturing a machine structural component according to any one of claims 1 to 3, wherein the welding uses any one of powder plasma welding, powder laser welding, TIG welding, and arc welding. .

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