JP2006098085A - Texture prediction method of build-up layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a texture prediction method of a build-up layer capable of predicting the texture of the build-up layer simply and accurately without performing building-up actually. <P>SOLUTION: This texture prediction method of the build-up layer formed by fusing and solidifying a material for build-up generating a two-liquid phase separation reaction by being fused has a constitution including a fusing process for fusing the material for build-up at a higher temperature than a dispersion phase crystallization temperature at which a dispersion phase dispersed in a matrix is crystallized, a quenching solidifying process for quenching and solidifying the fused material for build-up, and a texture observation process for observing the texture of the material for build-up solidified after being fused. Hereby, the texture of the build-up layer is predicted without performing building-up based on the observed texture. In addition, the two-liquid phase separation temperature and the dispersion phase crystallization temperature of the material for build-up are specified, and the texture of the build-up layer is predicted without performing building-up based on the difference between the two-liquid phase separation temperature and the dispersion phase crystallization temperature. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a buildup layer structure prediction method for predicting a buildup layer structure formed by melting and solidifying a buildup material.

Aluminum-based materials are lightweight and are used in various fields such as automobiles. In a member molded from an aluminum-based material, in order to improve mechanical characteristics and the like of a predetermined part, a build-up process for forming a build-up layer in the part is performed. For example, an intake valve or an exhaust valve repeatedly contacts a valve seat of a cylinder head of an automobile engine at a high temperature. For this reason, a built-up layer made of a copper alloy having high thermal conductivity and excellent heat resistance and wear resistance is formed on the valve seat. The build-up layer is formed by irradiating the build-up material with a laser beam serving as a heat source to melt and solidify the build-up material (see, for example, Patent Documents 1 and 2).
JP-A-5-50273 JP 2001-105177 A

  For example, various characteristics such as heat resistance and wear resistance are required for a built-up layer formed on a valve seat of a cylinder head of an automobile engine. Therefore, as described in Patent Documents 1 and 2, normally, an alloy powder composed of a plurality of components is used for the build-up material so as to satisfy desired characteristics. In this case, the build-up material changes the constituent component, for example, changes the addition amount of one component from the viewpoint of wear resistance, and changes the addition amount of another component from the viewpoint of cladding properties. Designed to let you. The designed overlay material is evaluated by actually overlaying.

  As described above, conventionally, each time a single build-up material is designed, it has been necessary to perform a series of operations of manufacturing the build-up material powder, build-up test, and evaluating. For this reason, development of the overlay material requires a lot of time and cost, and this has become a big problem as the composition of the overlay material increases.

  For the evaluation of the build-up material, it is effective to observe the structure of the formed build-up layer. That is, mechanical properties such as wear resistance are predicted from the structure of the overlay layer. Therefore, if it is possible to know in advance how the structure of the built-up layer changes in response to changes in the composition of the built-up material, it is possible to evaluate the built-up material without actually performing the build-up. It becomes. However, no method has yet been found that can predict changes in the structure of the overlay layer from changes in the components of the overlay material.

  The present invention has been made in view of such a situation, and provides an overlay layer structure prediction method capable of easily and accurately predicting an overlay layer structure without actually overlaying. This is the issue.

  The present inventor has earnestly studied to obtain the relationship between the change of components and the structure of the built-up layer for the material of the two-liquid phase separation system that melts and causes a two-liquid phase separation reaction among the built-up materials. Repeated. As a result, the inventors have invented two types of methods capable of predicting the structure of the overlay layer from the change in the components of the overlay material.

  That is, the first method for predicting the structure of the build-up layer according to the present invention is a method for predicting the structure of the build-up layer formed by melting and solidifying a build-up material that melts and causes a two-liquid phase separation reaction, A melting process in which the build-up material is melted at a temperature higher than the dispersion phase crystallization temperature at which the dispersed phase dispersed in the matrix crystallizes, a rapid solidification process in which the melted build-up material is rapidly solidified, and a build-up solidified after melting. A structure observation step of observing the structure of the material, and based on the observed structure, the structure of the build-up layer is predicted without being built up.

  The first method for predicting a structure of a build-up layer according to the present invention targets a build-up material of a two-liquid phase separation system that melts and causes a two-liquid phase separation reaction. This build-up material is a monotectic material, and in a molten state, it separates into two liquid phases within a certain temperature range. Here, the two-liquid phase includes a matrix component and a dispersed phase component dispersed in the matrix. Further, at a temperature higher than the upper limit of the temperature range, the matrix component and the dispersed phase component are melted to form a one-liquid phase state.

FIG. 1 shows an example of a phase diagram of a monotectic alloy. The state diagram shown in FIG. 1 is a conceptual diagram when it is assumed that the monotectic alloy is a binary system of components A and B. As shown in FIG. 1, the alloy of composition X is a melt in a single liquid phase at a temperature exceeding temperature T1. When the temperature is gradually lowered from this state, a melt having an L ₂₂ concentration appears as a new phase from the temperature T1, and a two-liquid phase state (L ₁ + L ₂ ) is obtained. In the present specification, this temperature T1 is referred to as a two-liquid phase separation temperature. T1 is one of transformation points. As the temperature decreases, the old melt concentration changes along the L ₁₂ -L _1M line, and the melt concentration of the new phase changes along the L ₂₂ -L _2M line. At temperature T2, the melt concentration of the new phase becomes L _2M , where the L _2M concentration melt generates β crystals and L _1M melt due to the twin crystal reaction. In the present specification, this temperature T2 is referred to as a dispersed phase crystallization temperature. T2 is also one of transformation points. When the monotectic reaction ends and the L _2M concentration melt disappears, the β crystal continues to crystallize as the temperature decreases, and the concentration of the remaining melt changes along the L _1M -L _1E line (L ₁ + β). When the temperature reaches T _E , an α-phase and a β-phase are formed by the eutectic reaction (α + β).

For example, when the number of nuclei of the L ₂ phase generated at the temperature T1 is small and the specific gravity difference between the two liquid phases (L ₁ phase, L ₂ phase) is large, holding at a temperature between T1 and T2 for a long time, The two liquid phases separate up and down by gravity. Therefore, if the cooling is performed from the temperature T1 to the temperature T2 at an appropriate cooling rate, the L ₂ phase is dispersed in the L ₁ phase. In this case, the size of the L ₂ phase varies depending on the cooling rate from T1 to T2. The L ₂ phase is separated into β crystals (solid phase) and L _1M melt (liquid phase) at a temperature T2. When the temperature T _E is reached at a relatively high cooling rate, the L ₂ phase particles are considered to be dispersed in the matrix as “particles in which β crystals are dispersed”. Hereinafter, in the present specification, the “particles in which β crystals are dispersed” are referred to as “dispersed particles”. In addition, here, the explanation was made on the assumption that the monotectic alloy is a binary alloy, but a multi-component alloy that is a practical alloy can be considered in the same way.

  In the melting step of the first cladding layer structure prediction method of the present invention, the temperature higher than the temperature at which the dispersed phase starts to crystallize from the two-liquid phase state (dispersed phase crystallization temperature) as the temperature decreases, in other words The overlay material is melted at a temperature at which the dispersed phase is completely melted. In the next rapid solidification process, the melted build-up material is rapidly cooled and solidified from its melting temperature. By rapid cooling, it is possible to obtain a structure that directly reflects the state at the time of melting. That is, it is possible to obtain a structure that is equivalent to an actual overlay layer or that can be inferred by comparison. In the next structure observation step, the structure of the build-up material that has undergone the above two steps is observed.

  The build-up material melted in the melting process and solidified in the rapid solidification process has a structure in which dispersed particles are dispersed in a matrix. The structure of the build-up material solidified after melting (hereinafter referred to as “material structure” as appropriate) varies depending on the melting temperature and the components of the build-up material. Specifically, the size of the dispersed particles and the volume ratio of the dispersed particles in the matrix vary depending on the melting temperature and components of the build-up material. The present inventor has found that the change in the material structure and the change in the structure of the built-up layer actually built up show the same tendency.

  Therefore, if the various overlaying materials having different components are melted and solidified by the first method for predicting the structure of the overlaying layer of the present invention, and each of the tissues is observed, the overlaying with respect to the change of the component is caused by the change in the structure. The organization of the stratum can be predicted. As a result, the build-up material can be evaluated without actually building up, and the optimum composition of the build-up material having a desired structure can be easily determined.

  The second method for predicting the structure of a build-up layer according to the present invention is a method for predicting the structure of a build-up layer formed by melting and solidifying a build-up material that melts and causes a two-liquid phase separation reaction. Identify the two-liquid phase separation temperature of the material and the dispersed phase crystallization temperature at which the dispersed phase dispersed in the matrix crystallizes, and based on the difference between the two-liquid phase separation temperature and the dispersed phase crystallization temperature, It is characterized by predicting the structure of the overlay layer without overlaying.

  In the second method for predicting the structure of the built-up layer of the present invention, as in the first method for predicting the structure of the built-up layer, the build-up material of the two-liquid phase separation system is targeted. Here, the two-liquid phase separation temperature is a temperature at which the liquid material is separated from one liquid phase into two liquid phases, and corresponds to T1 in FIG. The difference between the two-liquid phase separation temperature and the dispersed phase crystallization temperature indicates the temperature range in which the two liquid phases coexist, and varies depending on the components of the build-up material. The present inventor has found that this temperature difference is related to the structure of the built-up layer that is actually built up. That is, the change in the difference between the two-liquid phase separation temperature and the dispersed phase crystallization temperature and the change in the size of the dispersed particles in the structure of the built-up layer actually built up show the same tendency. I found out.

  Therefore, if the difference between the two-liquid phase separation temperature and the disperse phase crystallization temperature is determined for various overlay materials having different components by the structure prediction method of the second overlay layer of the present invention, It is possible to predict the structure of the built-up layer with respect to changes in the components. As a result, the build-up material can be evaluated without actually building up, and the optimum composition of the build-up material having a desired structure can be easily determined.

  According to the first method for predicting the structure of the overlay layer of the present invention, various overlay materials having different components are melted and solidified, and each structure is observed. The organization can be predicted. Moreover, if the difference between the two-liquid phase separation temperature and the disperse phase crystallization temperature is obtained with respect to various overlaying materials having different components by the structure prediction method of the second overlaying layer of the present invention, It is possible to predict the structure of the built-up layer with respect to changes in the components. As described above, according to the structure prediction method of the two overlay layers of the present invention, the overlay material can be evaluated without actually overlaying, and the optimum composition of the overlay material having a desired structure can be evaluated. Can be easily determined.

  Hereinafter, the structure prediction method of the two overlaying layers of the present invention will be described in detail. In the two methods for predicting the structure of the overlay layer of the present invention, both are intended for the overlay material that melts and causes a two-liquid phase separation reaction. Therefore, first, the target overlay material will be described, and then each method will be described. Note that the two methods for predicting the structure of the overlaying layer of the present invention are not limited to the following embodiments, and modifications and improvements that can be made by those skilled in the art are made without departing from the scope of the present invention. It can be implemented in various forms.

<Material for meat>
The build-up material which is the target of the structure prediction method of the two build-up layers of the present invention is not particularly limited as long as it is a material that melts and causes a two-liquid phase separation reaction. For example, a copper alloy, an aluminum alloy, an iron alloy, a nickel alloy, a cobalt alloy, and the like can be given. The component of the build-up material may be appropriately selected according to the material of the base material forming the build-up layer and the characteristics required for the build-up layer. For example, when a built-up layer is formed on a valve seat of an aluminum alloy cylinder head, the built-up layer is required to have high heat resistance and wear resistance. In this case, a copper alloy is suitable as the build-up material. Examples of the copper alloy include copper (Cu) -nickel (Ni) -silicon (Si) -molybdenum (Mo) -iron (Fe), Cu-Ni-cobalt (Co) -Fe-Mo-Si, Cu In addition to the -Fe-B system, improved alloys obtained by adding new elements to these may be used. As the build-up material, an alloy powder used for actual build-up can be used. However, in consideration of cost and the like, it is desirable to weigh a pure metal, a master alloy, etc. of a size suitable for melting so as to obtain a target composition to obtain a build-up material. Moreover, you may use the metal powder material which weighed and adjusted so that it might become the target composition by compacting.

<Structure prediction method of first overlay layer: Rapid solidification method>
The first method for predicting a structure of a built-up layer according to the present invention includes a melting step, a rapid solidification step, and a structure observing step. Based on the observed structure, the structure of the built-up layer without being built up Predict. Hereinafter, each process etc. are demonstrated in order.

(1) Melting step This step is a step of melting the above-described build-up material at a temperature higher than the dispersed phase crystallization temperature at which the dispersed phase dispersed in the matrix is crystallized. That is, in this step, the build-up material is housed in a melting crucible or the like and heated to a temperature higher than the dispersed phase crystallization temperature in a heating furnace. Then, the overlay material is completely melted. As the heating furnace, a high-frequency heating furnace, a Tamman furnace, or the like may be used. Further, in order to suppress oxidation of the build-up material, it is desirable to melt in an inert gas atmosphere such as argon gas or a vacuum atmosphere. The temperature at which the build-up material is melted (melting temperature) may be higher than the disperse phase crystallization temperature, but preferably about the temperature at which the build-up material is heated during actual build-up processing. For example, when a copper alloy is built up by irradiating laser light, the copper alloy is considered to be heated to a temperature of about 1800 ° C., depending on the laser output. Therefore, when this copper alloy is used as a build-up material, it may be melted at about 1800 ° C.

(2) Rapid solidification process This process is a process of rapidly solidifying the build-up material melted in the previous melting process. In this step, the material is rapidly cooled from the temperature at which the build-up material is melted in the previous melting step (melting temperature = cooling start temperature). The cooling rate in this step is desirably the same as the cooling rate at the time of actual build-up from the viewpoint of obtaining a structure equivalent to or compared with an actual build-up layer. Specifically, it is desirable to set it at 50 ° C./second or more. More preferably, it is 100 ° C./second or more and 1000 ° C./second or less. The cooling method is not particularly limited. For example, a normal mold casting method, a method of casting a mold by sucking a part of a molten build-up material, a splat cool with a droplet sandwiched between molds, and the like can be mentioned.

(3) Structure observation process This process is a process of observing the structure of the build-up material that has solidified after melting through the previous two processes. The observation of the structure may be in accordance with a normal method for observing the alloy structure, and the cross section of the solidified build-up material may be observed with an optical microscope or the like. In the observation of the tissue, the state of the dispersed particles, that is, the size and shape of the dispersed particles, the area ratio in the observation visual field, etc. may be mainly measured. Among these, the size of the dispersed particles has a great influence on the friction characteristics of the built-up layer. Therefore, it is desirable to measure the size of the dispersed particles in the tissue observation. Specifically, the maximum diameter of the dispersed particles may be measured. Here, the “maximum diameter of the dispersed particles” means the maximum length when the dispersed particles are sandwiched between two parallel lines.

  (4) The structure observed in the structure observation step differs depending on the melting temperature of the overlay material and the difference in components. For example, when attention is paid to the size of the dispersed particles, the maximum diameter of the dispersed particles changes depending on the melting temperature of the build-up material and the difference in components. In the same tendency as this change, the dispersed particles in the structure of the actually built-up overlay layer also change. Therefore, for example, the change in the size of dispersed particles in the structure of the actually built-up layer may be predicted from the change in the maximum diameter of the dispersed phase due to the difference in the components of the building-up material.

<Structure prediction method of second overlay layer: Transformation point identification method>
The structure prediction method of the second build-up layer of the present invention specifies a two-liquid phase separation temperature, which is two transformation points of the build-up material, and a dispersed phase crystallization temperature, Based on the difference from the disperse phase crystallization temperature, the structure of the build-up layer is predicted without build-up.

  Examples of methods for measuring the two-liquid phase separation temperature and the dispersed phase crystallization temperature include the following two methods. One is a method of performing a thermal analysis in a process in which heating is stopped and cooling is performed after the build-up material is melted in a one-liquid phase state. As described above, the molten state of the build-up material of the two-liquid phase separation system changes from the one-liquid phase state to the two-liquid phase state with the temperature being lowered, with the two-liquid phase separation temperature as a boundary. When the molten state changes, energy accompanying the state change is released. Therefore, after melting to become a one-liquid phase state, slowly cooling and measuring the change in temperature of the cooling process over time (thermal analysis), the temperature that changes from one liquid phase to two liquid phases depends on the energy released. The cooling rate becomes slow. That is, the slope of the thermal analysis curve indicating the change over time in the build-up material temperature becomes gentle. Similarly, when the dispersed phase is crystallized, energy accompanying the change of state (solidification heat accompanying crystallization) is released. The binary alloy shown in FIG. 1 will be described. At the temperature (T2) at which the dispersed phase crystallizes, the degree of freedom becomes 0 due to the phase rule, and the temperature is kept constant until the β crystal is completely crystallized. It is. In this method, the temperature at which the slope of the thermal analysis curve changes is used as information for specifying the two-liquid phase separation temperature and the dispersed phase crystallization temperature in order from the high temperature side.

  The other is a method of observing a structure obtained by melting a build-up material at various temperatures and rapidly cooling from each temperature. By melting and rapidly cooling the overlay material, it is possible to suppress the appearance of other phases and obtain a structure that reflects the state at the time of melting as much as possible. Therefore, in this method, by observing the structure obtained for each melted temperature, it is judged whether the temperature is a one-liquid phase state, a two-liquid phase state, or a dispersed phase crystallization state, and the two-liquid phase separation temperature And information for specifying the dispersed phase crystallization temperature.

  As will be shown in later examples, the difference between the two-liquid phase separation temperature and the dispersed phase crystallization temperature varies depending on the components of the build-up material. On the other hand, the structure of the actually built-up layer also varies depending on the components of the built-up material. For example, when the difference between the two-liquid phase separation temperature and the dispersed phase crystallization temperature is reduced with the change in the content of a certain component, the size of dispersed particles in the built-up layer structure is also reduced. Thus, the change in the difference between the two-liquid phase separation temperature and the dispersed phase crystallization temperature and the change in the size of the dispersed particles in the build-up layer structure show the same tendency. Therefore, it is only necessary to obtain the difference between the two-liquid phase separation temperature and the disperse phase crystallization temperature for various build-up materials having different components, and predict the structure of the build-up layer with respect to the change of the component from the temperature difference change.

  Based on the above-mentioned embodiment, the structure prediction method of the two build-up layers of the present invention was carried out, and compared with the structure of the build-up layer that was actually built up. Hereinafter, it demonstrates in order.

(1) Microstructure observation by the first overlay layer structure prediction method (rapid solidification method) Cu-Ni-Si-Mo-Fe copper alloys were used as the overlay material. In this copper alloy, the composition of Cu-12.5% Ni-2.3% Si-8.5% Mo-9% Fe (unit: mass%, the same applies hereinafter) was used as the basic composition.

First, 70 g of a melting raw material weighed so as to have the above basic composition was melted at 1500 ° C., 1600 ° C., 1700 ° C., and 1800 ° C. in a high-frequency melting furnace. The dissolution atmosphere was an argon gas atmosphere. Next, the molten metal at each temperature was suction cast into a SUS316 pipe having an outer diameter of 6 mm and a thickness of 2 mm. The cooling rate at this time was about 100 ° C./second at a high temperature.
Further, a composition in which only the amount of Ni was increased with respect to the basic composition (Cu-20.5% Ni-2.3% Si-8.5% Mo-9% Fe) was measured to have the same composition. The raw material was melted at each temperature in the same manner as described above, and then rapidly cooled.

  In FIG. 2, the optical micrograph of the alloy structure of both compositions is shown for every melting temperature. The alloy having any composition has a structure in which hard particles (silicides of Fe and Mo), which are dispersed particles, are dispersed in a Cu-based matrix. From FIG. 2, it can be seen that with the same composition, the lower the melting temperature, the larger the size of the hard particles. It is considered that the two-liquid phase separation proceeds as the melting temperature is lower. That is, since the molten state at each temperature is different, a difference occurs in the structure depending on the melting temperature. In addition, at the same melting temperature, the size of the hard particles decreases as the amount of Ni increases. In other words, it can be seen that the structure becomes finer as the amount of Ni increases.

  Moreover, about the composition which increased the quantity of Ni, Si, Mo, and Fe with respect to the said basic composition, after melt | dissolving the melt | dissolution raw material measured so that it might become the same composition at 1800 degreeC, about 100 degreeC / second cooling rate Then, each tissue was observed. These results are summarized in (4) below.

(2) Temperature measurement by the second cladding layer structure prediction method (transformation point identification method) Similar to the above (1), Cu-Ni-Si-Mo-Fe-based copper alloys are targeted, and Cu-12. The composition of 5% Ni-2.3% Si-8.5% Mo-9% Fe was taken as the basic composition. The dissolved raw material weighed to have this basic composition, and each dissolved raw material weighed to have a composition in which the amounts of Ni, Si, Mo, and Fe were changed with respect to the same composition were 1800 ° C. (one-liquid phase state) And then cooled at a cooling rate of about 2 to 6 ° C./second. Thermal analysis of this cooling process was performed, and for each, a two-liquid phase separation temperature and a dispersed phase crystallization temperature were specified.

  FIGS. 3A to 3D show changes in the two-liquid phase separation temperature (T1) and the dispersed phase crystallization temperature (T2) with respect to changes in each component. As shown in FIGS. 3A, 3B, and 3D, the difference between ΔT1 and T2 (ΔT = T1−T2) became smaller as the amounts of Ni, Si, and Fe increased. On the other hand, as shown in FIG.3 (c), (DELTA) T became large with the increase in Mo amount.

(3) Structure of build-up layer with respect to changes in components Alloy powder (Cu-12.5% Ni-2.3% Si-8.5% Mo-9) of the basic composition used in (1) and (2) above % Fe) was used to actually build up the surface of the base material made of an Al—Si (aluminum-silicon) alloy to form a built-up layer. Overlaying was performed under the conditions of a laser output of 3.5 kW and a feed rate of 900 mm / min by a known method using laser light. And the cross-sectional structure | tissue of the formed overlay was observed, and the maximum diameter of the hard particle which is a dispersion particle was measured. The “maximum diameter of hard particles” is the maximum length when the hard particles are sandwiched between two parallel lines. In this case, the maximum diameter of the hard particles was 0.9 mm.

  In addition, each alloy powder in which the amounts of Ni, Si, Mo, and Fe were changed with respect to the basic composition was used, and the overlay was formed on the surface of the base material in the same manner as described above. And the cross-sectional structure | tissue of each formed overlaying layer was observed, and the maximum diameter of the hard particle | grains which are dispersion | distribution particles was measured. FIG. 4 shows changes in the maximum diameter of the hard particles with respect to changes in each component.

  As shown in FIG. 4, the maximum diameter of the hard particles decreased as the amount of Ni or Si increased. Further, when the Ni content was increased to 18% and the Fe content was increased, the maximum diameter of the hard particles was reduced. From this, it can be seen that the hard particles are refined with increasing amounts of Ni, Si, and Fe. On the other hand, as the amount of Mo increased, the maximum diameter of the hard particles increased.

(4) Comparison between the results obtained by the above two methods and the actual structure of the overlay layer The maximum diameter (D ′) of the hard particles in each structure having different components was measured by the structure observation in (1) above. (Melting temperature 1800 ° C.). Moreover, the difference (ΔT) between the two-liquid phase separation temperature (T1) and the dispersed phase crystallization temperature (T2) was calculated for each component by the temperature measurement in (2) above. Table 1 shows D ′, ΔT, and the maximum diameter (D) of the hard particles of the actual built-up layer measured in (3) above with respect to the alloy components.

まず、Ｎｉに着目した場合、Ｎｉ量が増加すると、Ｄ’は小さくなる。同様に、ΔＴも小さくなる。この傾向は、実際の肉盛層の組織における硬質粒子の最大径Ｄの傾向と一致する。また、Ｓｉ、Ｆｅに関しても同様のことがいえる。次に、Ｍｏ量に着目した場合、Ｍｏ量が増加すると、Ｄ’は大きくなる。同様に、ΔＴも大きくなる。この傾向も、実際の肉盛層の組織における硬質粒子の最大径Ｄの傾向と一致する。このように、成分の変化に対する硬質粒子の最大径Ｄ’の変化から、あるいは、ΔＴの変化から、実際に肉盛りした肉盛層の組織における硬質粒子の大きさの変化を予測することができる。

First, when focusing on Ni, D ′ decreases as the amount of Ni increases. Similarly, ΔT also decreases. This tendency coincides with the tendency of the maximum diameter D of the hard particles in the actual structure of the overlay layer. The same applies to Si and Fe. Next, when focusing on the Mo amount, D ′ increases as the Mo amount increases. Similarly, ΔT also increases. This tendency also coincides with the tendency of the maximum diameter D of the hard particles in the actual structure of the overlay layer. As described above, it is possible to predict the change in the size of the hard particles in the actually built-up layer structure from the change in the maximum diameter D ′ of the hard particles with respect to the change in the component or from the change in ΔT. .

  In addition, a separate wear test was conducted to examine the relationship between the maximum diameter of the hard particles and the frictional wear amount of the built-up layer. FIG. 5 shows a schematic diagram of the wear test apparatus. As shown in FIG. 5, the friction test apparatus 1 includes a holder 5, a valve material 3, and a high frequency heating coil 4. The valve material 3 is made of SUE50 and has a cylindrical shape. The valve material 3 is rotatable around the axis. The high frequency heating coil 4 is wound around the valve material 3. The high frequency heating coil 4 heats the valve material 3. The holder 5 has a cylindrical shape. The holder 5 is disposed to face the valve member 3 in the axial direction. A concave portion is formed on the end surface of the holder 5 on the valve material 3 side. The holder 5 is movable toward the valve material 3 side. The short-axis columnar test piece 2 is disposed in the concave portion of the holder 5. A built-up layer 20 is formed on the surface of the test piece 2. The friction test was performed by moving the holder 5 in the direction of the valve material 3 and sliding the built-up layer 20 on the surface of the valve material 3. The conditions for the friction test were air, no lubrication, a heating temperature of 600 ° C., a surface pressure of 1.96 MPa, and a rotational speed of 0.3 m / s. And the abrasion loss of the build-up layer 20 after making it slide-contact for 30 minutes was measured.

  FIG. 6 shows the relationship between the maximum diameter of the hard particles and the frictional wear amount of the built-up layer. FIG. 6 shows that the larger the maximum diameter of the hard particles, the smaller the amount of wear and the higher the wear resistance of the built-up layer. Thus, the mechanical characteristics of the build-up layer change depending on the size of the hard particles. Therefore, predicting the structure of the overlay layer, specifically, the size of the dispersed particles, makes it possible to predict the mechanical properties of the overlay layer and is useful in designing the overlay material.

It is an example of the phase diagram of a monotectic alloy. It is an optical micrograph which shows the structure | tissue for each melting temperature of two types of alloys from which Ni amount differs. It is a graph which shows the change of the two liquid phase separation temperature (T1) with respect to the component change of an alloy powder, and a dispersed phase crystallization temperature (T2), (a) is Ni amount, (b) is Si amount, (c) is Mo. The amount, (d) shows the Fe amount. It is a graph which shows the change of the maximum diameter of a hard particle with respect to the component change of an alloy powder. It is the schematic of an abrasion test apparatus. It is a graph which shows the relationship between the maximum diameter of a hard particle, and the amount of frictional wear of a build-up layer.

Explanation of symbols

1: Wear test device 2: Test piece 20: Overlay layer 3: Valve material 4: High-frequency heating coil 5: Holder

Claims (6)

A method for predicting the structure of a built-up layer formed by melting and solidifying a built-up material that melts and causes a two-liquid phase separation reaction,
A melting step of melting the build-up material at a temperature higher than a dispersed phase crystallization temperature at which a dispersed phase dispersed in a matrix crystallizes;
A rapid solidification process for rapidly solidifying the melted material,
A structure observation process for observing the structure of the build-up material solidified after melting;
Including
A method for predicting a structure of a built-up layer, wherein the structure of the built-up layer is predicted based on the observed structure without being built up.   The method for predicting a structure of a built-up layer according to claim 1, wherein the build-up material is made of a copper alloy.   The method for predicting a structure of a built-up layer according to claim 1, wherein in the rapid solidification step, the build-up material is rapidly solidified at a cooling rate of 50 ° C / second or more. A method for predicting the structure of a built-up layer formed by melting and solidifying a built-up material that melts and causes a two-liquid phase separation reaction,
Identify the two-liquid phase separation temperature of the build-up material and the dispersed phase crystallization temperature at which the dispersed phase dispersed in the matrix crystallizes,
A method for predicting a structure of a built-up layer, which predicts the structure of the built-up layer without building up based on a difference between the two-liquid phase separation temperature and the dispersed phase crystallization temperature.   The method for predicting a structure of a built-up layer according to claim 4, wherein the build-up material is made of a copper alloy.   5. The build-up layer according to claim 4, wherein the two-liquid phase separation temperature and the dispersed phase crystallization temperature are specified by thermal analysis in a cooling process after the build-up material is melted to be in a one-liquid phase state. Organization prediction method.

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