JP2010007179A - METHOD FOR MANUFACTURING Zn-Sn-Mg-BASED ALLOY - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a Zn-Sn-Mg-based alloy which is hardly disconnected. <P>SOLUTION: The molten metal obtained by melting the raw material containing >1 to <80 mass% Sn, >0.01 and <5 mass% Mg, and the balance Zn is solidified, and the molten metal under solidification is cooled down to ≤50°C at a cooling rate of ≥20°C/sec from the eutectic temperature of the Zn-Sn-Mg-based alloy. For the purpose of cooling, the cooling water is preferably sprayed to the molten metal under solidification. Heat treatment is executed after the cooling, and thereby the elongation can be further improved. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a Zn—Sn—Mg alloy, and more particularly, to a method for producing a Zn—Sn—Mg alloy suitable for producing a Zn—Sn—Mg alloy wire that can be used as an alloy wire for thermal spraying. .

  In order to prevent corrosion of iron materials such as iron pipes and iron plates, a film is formed on the surface of the iron material by thermal spraying. Here, thermal spraying is a surface treatment in which a coating material is heated and dissolved to form fine particles, and the coating material formed into fine particles is solidified and deposited on the surface of the coating target to form a film on the surface of the coating target. It is a kind of. For example, a thermal spray alloy wire such as a zinc alloy or an aluminum alloy is used as a coating material. Various methods for casting a thermal spray alloy wire such as a zinc alloy or an aluminum alloy have been proposed (for example, Patent Documents 1 to 3). The following three production methods are mainly known.

  The known first manufacturing method is a method of manufacturing an alloy wire having a predetermined wire diameter by performing a melting step, a casting step, an extrusion step, and a wire drawing step in this order. Specifically, the manufacturing method includes a melting step of melting a plurality of materials prepared with predetermined alloy components to obtain a molten metal, a casting step of casting a molten metal in a mold to form a billet, and extruding a billet to obtain a predetermined amount. An extrusion process for processing the alloy wire having a cross-sectional shape; and a wire drawing step for drawing the alloy wire having a predetermined cross-sectional shape to process it into an alloy wire having a predetermined wire diameter.

  In the first manufacturing method, a forging process may be performed between the extrusion process and the wire drawing process as necessary. In this forging process, after the extrusion process, an alloy wire having a predetermined cross-sectional shape is forged into a small diameter alloy wire. In the wire drawing step, the alloy wire having a small diameter obtained in the forging step is drawn and processed into an alloy wire having a predetermined wire diameter.

  The second known manufacturing method is a method of manufacturing an alloy wire having a predetermined wire diameter by performing a melting step, a casting step, a forging step, and a wire drawing step in this order. That is, the extrusion process is omitted as compared with the first manufacturing method.

  A known third manufacturing method is a method of manufacturing an alloy wire having a predetermined wire diameter by performing a melting step, a continuous casting step, and a wire drawing step in this order. Specifically, the manufacturing method includes a melting step of melting a plurality of materials prepared with a predetermined alloy component to obtain a molten metal, and an alloy having a predetermined cross-sectional shape by pouring the molten metal into a groove formed on the outer periphery of the casting wheel. A continuous casting process for forming a wire, and a wire drawing process for drawing an alloy wire having a predetermined cross-sectional shape to form an alloy wire having a predetermined wire diameter. Similarly, in this third manufacturing method, a forging process may be performed between the continuous casting process and the wire drawing process as necessary.

Japanese Patent Laid-Open No. 11-181562 JP 2002-12932 A JP 2007-21484 A

  However, in any of the above manufacturing methods, the diameter of the alloy wire is reduced at the time of processing. Therefore, if the material of the alloy wire does not have strength or ductility, it may be disconnected. For this reason, heat treatment or the like may be performed depending on the material of the alloy wire. In particular, with respect to a Zn—Sn—Mg alloy wire, if the amount of Sn is small, the wire becomes slightly brittle and the workability deteriorates. For this reason, it may break in the wire drawing process.

  Then, this invention is made | formed in view of the said problem, and it aims at providing the manufacturing method of a Zn-Sn-Mg type alloy which is hard to be disconnected in a wire-drawing process.

  In order to achieve the above object, the Zn-Sn-Mg based alloy production method of the present invention has Sn exceeding 1% by mass and less than 80% by mass, Mg exceeding 0.01% by mass and 5% by mass. %, And the molten material obtained by melting the remaining Zn is solidified, and the molten metal being solidified is changed from the eutectic temperature of the Zn-Sn-Mg alloy to 20 ° C / second or more. It cools to 50 degrees C or less with the cooling rate of.

According to the method for producing a Zn—Sn—Mg alloy of the present invention, it is preferable to spray cooling water on the molten metal being solidified.
Moreover, according to the manufacturing method of the Zn-Sn-Mg alloy of this invention, it is suitable to heat-process after cooling.

  Furthermore, according to the method for producing a Zn—Sn—Mg alloy of the present invention, it is preferable to perform heat treatment at 100 ° C. or higher.

  According to the present invention, since the molten metal being solidified is rapidly cooled from the eutectic temperature of the Zn—Sn—Mg alloy to 50 ° C. or less at a cooling rate of 20 ° C./second or more, the zinc crystal can be refined. And the mechanical properties of the alloy can be improved. As a result, the ductility of the alloy is improved, and a Zn—Sn—Mg alloy that is difficult to break in the wire drawing process can be made.

  According to the present invention, the ductility of the alloy can be further improved by performing a heat treatment after cooling.

It is a figure which shows the manufacturing apparatus used for the manufacturing method of the alloy of this invention. It is a figure which shows the method of the bending test based on this invention. It is a figure which shows the result of having observed the structure | tissue of the test piece manufactured on the conditions without water cooling with the optical microscope. It is a figure which shows the result of having observed the structure | tissue of the test piece manufactured on the conditions with water cooling with the optical microscope. It is a graph which shows the measurement result of heat processing temperature and its time, and the elongation of a test piece. It is a figure which shows the result of having observed the structure | tissue of the test piece manufactured on the conditions without heat processing with the optical microscope. It is a figure which shows the result of having observed the structure | tissue of the test piece manufactured on the conditions with heat processing with the optical microscope.

  As described above, the production method of the present invention is a material in which Sn exceeds 1% by mass and less than 80% by mass, Mg exceeds 0.01% by mass and less than 5% by mass, and Zn is the balance. From the eutectic temperature of the Zn-Sn-Mg alloy to 50 ° C. or less at a cooling rate of 20 ° C./second or more while solidifying the melt obtained by melting Cooling. If it carries out like this, a zinc crystal can be refined | miniaturized and the mechanical property of an alloy material can be improved. This makes it possible to make a Zn—Sn—Mg alloy wire that is difficult to break in the wire drawing step.

  In the production method of the present invention, the material has Sn exceeding 1% by mass and less than 80% by mass, Mg exceeding 0.01% by mass and less than 5% by mass, and the balance being Zn. The alloy obtained by the production method of the present invention is particularly suitable as an alloy material for forming a thermal spray coating on the surface of an iron material. When a coating is formed by thermal spraying using a wire made of this material, It can be suitably used when a coating is formed by thermal spraying using a wire made of a material and Zn wire. By carrying out like this, anticorrosion performance can be improved compared with the sprayed coating using only Zn. The anticorrosion performance can be equal to or higher than that of Zn-15Al (Zn is 85 mass%, Al is 15 mass%).

  When a coating is formed by thermal spraying using an alloy wire made of this material, or when a coating is formed by thermal spraying using a wire made of this material and Zn wire, the resulting thermal spray coating has an Sn content of 1% by mass. And less than 50% by mass, Mg is more than 0.01% by mass and less than 5% by mass, and the balance is Zn. More specifically, when a coating is formed by thermal spraying using a wire made of this material and Zn wire, Sn exceeds 1% by mass and less than 80% by mass, and Mg exceeds 0.01% by mass. And by thermal spraying using a wire made of a material that is less than 5% by mass and the balance being Zn, and Zn wire, Sn is more than 1% by mass and less than 50% by mass, and Mg is 0.01% by mass And less than 5% by mass, and a sprayed coating with the balance being Zn is formed.

  In the obtained sprayed coating, when the Sn content is 1% by mass or less, or when the Mg content is 0.01% by mass or less, the substantial anticorrosion performance by adding these is The improvement effect cannot be obtained. On the other hand, when the Sn content is 50% by mass or more, or when the Mg content is 5% by mass or more, the effect of improving the substantial anticorrosion performance by adding these is obtained. I can't.

  When the alloy obtained by the production method of the present invention is used as a wire, if the Sn content in the alloy is less than 60% by mass, the effect of improving ductility when cooling or heat treatment is performed according to the present invention is more remarkable. When the Sn content is less than 45% by mass, the effect becomes even more remarkable.

When a Zn—Sn—Mg alloy sprayed coating having such a composition is formed on the surface of an iron material, there is an advantage that white rust is unlikely to occur, the wire is easy to produce, and there are no sanitary problems.
Details of the production method of the present invention will be described. FIG. 1 shows a configuration of a manufacturing apparatus for carrying out a method of manufacturing a wire using a Zn—Sn—Mg alloy. In this apparatus, a continuous casting machine 101 and a winder 102 are provided. In the continuous casting machine 101, a groove 112 having a U-shaped cross section is formed on the outer periphery of a rotary casting wheel 111. A crucible 115 is disposed above the casting wheel 111. The crucible 115 can store the molten metal 103 of Zn—Sn—Mg-based alloy in the crucible 115 and has a hot water outlet 116 formed at the bottom thereof. A spray nozzle 113 is provided in the vicinity of the crucible 115, and the spray nozzle 113 is provided with an outlet 114 for spraying cooling water.

  In manufacturing, the molten metal 103 is supplied from the crucible 115 to the portion of the groove 112 positioned at the top of the casting wheel 111 while slowly rotating the casting wheel 111. Then, the molten metal 103 starts to solidify when heat is taken away by the casting wheel 111. Immediately thereafter, cooling water is sprayed from the spray nozzle 113 toward the molten metal 104 in the groove 12 that is solidifying.

  Thereby, the molten metal 104 being solidified is rapidly cooled, and the alloy wire 105 is manufactured. Since this alloy wire 105 is formed by rapid cooling of the molten metal 104 during solidification, the crystal becomes fine, and therefore the ductility can be improved. The obtained alloy wire 105 is wound up by the winder 102.

  The rapid cooling by spraying the cooling water from the spray nozzle 113 toward the molten metal 104 being solidified is preferably performed immediately after the molten metal 103 is poured into the groove 102 as much as possible. In order to achieve the improvement of ductility by refining the crystal, the cooling condition is that the eutectic temperature of the Zn-Sn-Mg alloy is 198 ° C or higher to 50 ° C or lower at a cooling rate of 20 ° C / second or higher. It is necessary to adopt.

  As long as the above cooling conditions can be adopted, the cooling method may be air cooling with cold air, or cooling using other fluid, in addition to the above-described water cooling.

  The alloy wire 105 wound up by the winder 102 is then subjected to a wire drawing process.

  According to the present invention, it is preferred to heat treat the cooled alloy. The ductility can be further improved by heat treatment. For example, it is preferable to heat-treat the alloy wire that has been rapidly cooled as described above before the wire drawing step after winding or before winding.

  As the heat treatment condition, a temperature condition of 100 to 200 ° C. is preferable. In particular, 130 to 170 ° C. is effective. For example, ductility can be improved by performing heat treatment at 100 ° C. for 60 minutes or more. Alternatively, the ductility can be similarly improved by performing a heat treatment for 30 minutes or more at 130 ° C. or higher.

[Example 1]
Using the apparatus shown in FIG. 1, an alloy wire 105 having a diameter of 10 mm in which the crystal became fine and the ductility was improved under the conditions described later was obtained. The alloy wire 105 was processed into an alloy wire having a diameter of 1.6 mm by a wire drawing machine (not shown).

  Specifically, in the above-described production method, the cooling water was sprayed at different times. More specifically, as shown in Table 1, Test Specimen 1 to Specimen 4 were manufactured by changing the timing of spraying the cooling water (hereinafter referred to as “water cooling timing”).

  That is, Zn, Sn, and Mg were melted at 450 ° C., and these melted materials were prepared so that Sn was 30% by mass, Mg was 0.3% by mass, and Zn was the balance to obtain a molten metal. . The water cooling timing was changed based on the timing at which the molten metal 103 discharged from the outlet 116 of the crucible 115 shown in FIG. 1 reached the groove 102 (hereinafter referred to as “arrival timing”). Specifically, the position of the spray nozzle 113 shown in FIG. 1 was adjusted along the direction of rotation of the casting wheel 111 so that the required water cooling timing was reached.

  About the obtained test piece 1-test piece 4, the tensile test was done and the tensile strength and elongation were measured. Further, a bending test was performed to measure the load and the break angle. Further, the Vickers hardness Hv was measured. The average value of the results of six measurements was taken as the measurement result.

  The bending test was performed according to JIS Z2248 “Metal material bending test method”. Specifically, as shown in FIG. 2, a test piece 150 having a diameter of 1.6 mm and having a horizontal axis is placed on a pair of supports 161 and 162 having a diameter of 10 mm and spaced apart in the horizontal direction. I placed it. A load 170 was applied to the test piece 150 in the vertical direction between the support 161 and the support 162 by a pressing member 163 having a semicircular shape with a radius of 5 mm at the tip end.

  As a result, the test piece 150 was deformed into a V shape as shown in FIG. When the test piece 150 breaks due to deformation, the bending angle θ generated by the intersection of the extension line of the portion 151 in contact with one support 161 and the extension line of the portion 152 in contact with the other support 162 in the test piece 150 is It was measured. The bending angle θ is an angle when the load 170 is applied, and is not an angle after the load is removed. At this time, the presence or absence of tears, scratches and other defects in the outer portion of the curved portion 153 of the test piece 150 was investigated.

(Test piece 1)
An alloy wire manufactured under conditions without water cooling was designated as test piece 1. The test piece 1 was broken when the tensile strength was 125 N / mm ² , the elongation was 1%, the load when the bending test was performed was 20 N, and the bending angle θ was 40 degrees. The Vickers hardness Hv was 26.

  The evaluation results for the test piece 1 are shown in Table 1.

(Test piece 2)
An alloy wire manufactured under conditions with water cooling was designated as test piece 2. The water cooling timing was 30 seconds after the arrival timing at which the molten metal 103 shown in FIG. In cooling, normal temperature cooling water was continuously sprayed for 5 to 10 seconds. The temperature of the molten metal 104 before water cooling was 200 to 250 ° C., and the temperature of the wire 105 after water cooling was 20 to 40 ° C. The test piece 2 was fractured when the tensile strength was 154 N / mm ² , the elongation was 10%, the load during the bending test was 25 N, and the bending angle θ was 150 degrees. The Vickers hardness Hv was 35.
The evaluation results for the test piece 2 are shown in Table 1.

(Test piece 3)
An alloy wire manufactured under conditions with water cooling was designated as test piece 3. The water cooling timing was 15 seconds after the above arrival timing. In cooling, normal temperature cooling water was continuously sprayed for 5 to 10 seconds. The temperature of the molten metal 104 before water cooling was 250 to 300 ° C., and the temperature of the wire 105 after water cooling was 30 to 50 ° C. This test piece 3 had a tensile strength of 150 N / mm ² and an elongation of 14%. As a result of the bending test, even when the load was 25 N and the bending angle was 180 degrees, it did not break. The Vickers hardness Hv was 35.
The evaluation results for the test piece 3 are shown in Table 1.

(Test piece 4)
An alloy wire manufactured under conditions with water cooling was used as a test piece 4. The water cooling timing was 5 seconds after the arrival timing. In cooling, normal temperature cooling water was continuously sprayed for 5 to 10 seconds. The temperature of the molten metal 104 before water cooling was 300 to 350 ° C., and the temperature of the wire 105 after water cooling was 30 to 50 ° C. This test piece 4 had a tensile strength of 155 N / mm ² and an elongation of 16%. As a result of the bending test, even when the load was 25 N and the bending angle was 180 degrees, it did not break. The Vickers hardness Hv was 35.
The evaluation results for the test piece 4 are shown in Table 1.

  In addition to these measurements, tissue observation was also performed. FIG. 3 shows the result of observing the structure of the test piece 1 manufactured under conditions without water cooling with an optical microscope. As shown in the figure, a dendritic structure formed by precipitation of zinc crystals in a dendritic shape was observed. In FIG. 3, a black part is a zinc crystal and a white part is a eutectic.

  FIG. 4 shows the result of observing the structure of the test piece 4 manufactured under conditions with water cooling with an optical microscope. As shown in the figure, an acicular structure formed by precipitation of zinc crystals in an acicular shape was observed. Furthermore, the zinc crystal was finer than the alloy wire of FIG. 3 manufactured under conditions without water cooling.

  Thus, when the cooling water was sprayed and rapidly cooled, the mechanical properties of the alloy wire were improved. Furthermore, the earlier the timing of spraying the cooling water, the better results were obtained. Specifically, as is apparent from the measurement results of the tensile test, the test pieces 2 to 4 manufactured under the condition with water cooling have a higher tensile strength than the test piece 1 manufactured under the condition without water cooling. Improved by about 20%, and the growth improved significantly. Moreover, it was shown that it was hard to fracture | rupture from the measurement result of the bending test. The Vickers hardness was high.

  Even in the case of an alloy wire manufactured under the same water cooling conditions, the test piece 3 in which the timing of injecting the cooling water was earlier than the test piece 2 was less likely to break. Compared to the test piece 3, the test piece 4 whose timing of injecting the cooling water was earlier than that of the test piece 3 was larger in elongation.

  For this reason, when an alloy wire having a diameter of 10 mm is processed into an alloy wire having a diameter of 1.6 mm by a wire drawing machine as described above, breakage may occur when the test piece 1 manufactured under conditions without water cooling is obtained. Although it was seen, no disconnection occurred when obtaining test pieces 2 to 4 manufactured under conditions with water cooling.

  As described above, by producing under conditions with water cooling, the zinc crystal can be refined and the mechanical properties of the alloy wire can be improved. Furthermore, by increasing the timing of spraying the cooling water, it was possible to promote the refinement of zinc crystals and improve ductility in particular.

[Example 2]
Heat treatment was applied.
That is, in the same manner as in Example 1, a material having Sn of 30% by mass, Mg of 0.3% by mass, and the balance of Zn was melted, and the molten metal at 350 ° C. was cooled to 50 ° C. by water cooling for 15 seconds. Thus, an alloy wire having a diameter of 10 mm was obtained. This was cut into a length of 300 mm and then machined to obtain a No. 4 test piece defined in JIS Z2201 (metallic material tensile test piece). Specifically, a plurality of tensile test pieces having a parallel part diameter of 6 mm, a parallel part length of 30 mm, and a gauge distance of 20 mm were obtained.

  About each tensile test piece, the heat processing of 70 degreeC, 100 degreeC, 130 degreeC, 150 degreeC, and 170 degreeC was performed. And the tensile test was done about the thing without heat processing, and what performed said heat processing, and measured elongation. The result is shown in FIG. As shown in the figure, the elongation without heat treatment was 8.0%, but the elongation, that is, the improvement in ductility was observed by the heat treatment.

  Specifically, when the heat treatment temperature is 70 ° C., no substantial increase in elongation was observed. At 100 ° C., the elongation improvement rate was 20% or more when heated for 60 minutes or more, and a substantial improvement in elongation was recognized. At 130 ° C. to 170 ° C., the elongation improvement rate was 20% or more when heated for 30 minutes or more, and a substantial improvement in elongation was recognized. Although not shown in FIG. 5, when heated at 180 ° C. to 200 ° C., Sn in the alloy slightly melted, so that the test piece tended to soften easily.

  In addition to these measurements, tissue observation was also performed. FIG. 6 shows the structure of a test piece that was only water-cooled but not heat-treated, and shows the same structure as FIG. 4 but with a lower magnification. As in the case of FIG. 4, the black portion is a zinc crystal and the white portion is a eutectic, but an acicular structure formed by precipitation of the zinc crystal in an acicular shape was observed.

  FIG. 7 shows the structure of the test piece that was heat-treated at 150 ° C. for 2 hours after water cooling, and the crystals were larger than those that were not heat-treated, thereby confirming that the elongation was improved.

  Similarly to the specimen having the structure shown in FIG. 7, wire drawing was performed using the wire obtained after water cooling and heat treatment at 150 ° C. for 2 hours. As a result, disconnection did not occur and processing could be performed satisfactorily.

DESCRIPTION OF SYMBOLS 101 Continuous casting machine 103 Molten metal 104 Molten metal being solidified to a linear cast body 105 Alloy wire 113 Spray nozzle

Claims (4)

  A molten metal obtained by dissolving and melting a material in which Sn exceeds 1% by mass and less than 80% by mass, Mg exceeds 0.01% by mass and is less than 5% by mass, and Zn is the balance. The Zn-Sn-Mg alloy is characterized in that it is solidified and the molten metal being solidified is cooled from the eutectic temperature of the Zn-Sn-Mg alloy to 50 ° C or less at a cooling rate of 20 ° C / second or more. Production method.   The method for producing a Zn-Sn-Mg alloy according to claim 1, wherein cooling water is sprayed on the molten metal being solidified.   The method for producing a Zn-Sn-Mg alloy according to claim 1 or 2, wherein heat treatment is performed after cooling.   The method for producing a Zn-Sn-Mg alloy according to claim 3, wherein the heat treatment is performed at 100 ° C or higher.