WO2020203050A1 - Heat-resistant magnesium alloy - Google Patents

Heat-resistant magnesium alloy Download PDF

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WO2020203050A1
WO2020203050A1 PCT/JP2020/009733 JP2020009733W WO2020203050A1 WO 2020203050 A1 WO2020203050 A1 WO 2020203050A1 JP 2020009733 W JP2020009733 W JP 2020009733W WO 2020203050 A1 WO2020203050 A1 WO 2020203050A1
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magnesium alloy
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heat
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PCT/JP2020/009733
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圭佑 矢守
宮本　武明
安秀 金津
昭彦 閤師
山本　匡昭
金孫 廖
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株式会社栗本鐵工所
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C23/00—Alloys based on magnesium
    • C22C23/02—Alloys based on magnesium with aluminium as the next major constituent

Definitions

  • the present invention relates to a heat-resistant magnesium alloy having excellent castability, mechanical properties, and corrosion resistance.
  • Magnesium alloy is lighter than steel materials and aluminum alloys, so it is used as a lightweight substitute in various fields.
  • As the magnesium alloy an AZ alloy to which Al, Mn and Zn are added and an AM alloy to which Al and Mn are added are known.
  • AZ91D Mg-9 mass% Al-1 mass% Zn
  • general-purpose magnesium alloys have reduced heat resistance (creep resistance) in a high temperature range of about 175 ° C., and cannot obtain heat resistance comparable to that of aluminum alloys.
  • a magnesium alloy to which Ca or RE (rare earth element) is added is known.
  • AE44 Mg-4 mass% Al-4 mass% RE having excellent creep resistance is used.
  • Patent Document 1 contains 2 to 6% by weight of aluminum and 0.5 to 4% by weight of calcium, the balance of which is magnesium and unavoidable impurities, and has a Ca / Al ratio of 0.8, preferably 0.
  • a heat-resistant magnesium alloy molding member which is produced by semi-melt injection molding of a magnesium alloy of 6 or less at a liquidus temperature or lower, is disclosed, which is particularly excellent in moldability and elongation while ensuring creep resistance.
  • this is a type of injection molding, not casting.
  • the semi-melt injection molding method is a method in which a material that has been heated to be in a solid-liquid coexisting state is pressurized and injection-molded into a mold.
  • Such semi-molten processing is more expensive than ordinary casting.
  • quality deterioration in a low temperature environment with a high solid phase ratio becomes a problem.
  • Specific examples of this deterioration in quality include poor hot water flow and frequent poor hot water flow.
  • the alloy and AE44 described in Patent Document 1 have a high liquidus temperature and may have difficulty in castability. For metals such as steel materials and aluminum alloys, raising the casting temperature may solve the castability problem.
  • the molten magnesium alloy is more likely to burn as the temperature rises. That is, when the liquidus temperature exceeds 610 ° C., there is a problem that the possibility of burning cannot be ignored when casting by heating from the liquidus temperature to about + 100 ° C.
  • the temperature rise from the liquidus temperature is suppressed in an attempt to suppress the possibility of burning, a problem arises in the fluidity during casting.
  • excellent corrosion resistance and mechanical properties are required to realize the expansion of the application of magnesium alloys.
  • the present invention obtains a heat-resistant magnesium alloy having excellent castability, mechanical properties typified by tensile strength and elongation at room temperature, and corrosion resistance while maintaining heat resistance typified by creep resistance. With the goal.
  • Al is more than 6.0% by mass and 12.0% by mass or less
  • Mn is 0.10% by mass or more and 0.60% by mass or less
  • Ca is 0.50% by mass or more and 2.5% by mass or less
  • Si is contained in an amount of more than 0.10% by mass and less than 0.40% by mass, and the balance is a magnesium alloy composed of Mg and unavoidable impurities, thereby solving the above-mentioned problems.
  • magnesium alloys containing Al in an amount of more than 6.0% by mass and 10.0% by mass or less tend to exhibit excellent mechanical properties in terms of both elongation and tensile strength.
  • magnesium alloys containing 8.0% by mass or more and 10.0% by mass or less of Al and 1.5% by mass or more and 2.5% by mass or less of Ca have further excellent heat resistance. Easy to demonstrate castability.
  • the magnesium alloy according to the present invention has excellent mechanical properties such as elongation and tensile strength at room temperature, and heat resistance and corrosion resistance typified by creep resistance.
  • the liquidus temperature is suppressed to 610 ° C. or lower, it is easy to manufacture various cast members using this alloy, and various members utilize the mechanical properties, heat resistance, and corrosion resistance at room temperature. be able to.
  • the present invention is a magnesium alloy containing at least Al, Mn, Ca and Si.
  • the magnesium alloy according to the present invention needs to have an Al content of more than 6.0% by mass, preferably 8.0% by mass or more. If the Al content is 6.0% by mass or less, the tensile strength will be too low. In addition, sufficient corrosion resistance cannot be ensured. When the Al content is 8.0% by mass or more, the liquidus temperature can be sufficiently suppressed, so that castability can be easily ensured. Further, by containing Al, it is expected that the strength is improved by strengthening the solid solution and the castability is improved. Furthermore, it is expected that the heat resistance will be improved by forming a compound of Al with Ca. On the other hand, the Al content needs to be 12.0% by mass or less, and preferably 10.0% by mass or less. If the Al content exceeds 12.0% by mass, the mechanical properties at room temperature will deteriorate too much. In addition, the Mg 17 Al 12 phase may be crystallized and the heat resistance may be significantly lowered.
  • the magnesium alloy according to the present invention needs to have a Mn content of 0.10% by mass or more, preferably 0.20% by mass or more.
  • Mn By containing Mn, when Fe is contained as an unavoidable impurity, an Al—Fe—Mn-based compound is formed to exert an iron removal effect, and the corrosion resistance of the alloy as a whole is expected to be improved. Further, by containing Mn, finer crystal grains are expected. If the Mn content is less than 0.10% by mass, there is a high possibility that these effects cannot be sufficiently exerted.
  • the Mn content needs to be 0.60% by mass or less, and preferably 0.50% by mass or less. If Mn is excessively contained in excess of 0.60% by mass, a large amount of coarse Al—Mn-based compounds are crystallized, which increases the possibility of leading to deterioration of mechanical properties.
  • the magnesium alloy according to the present invention needs to have a Ca content of 0.50% by mass or more, preferably 1.5% by mass or more.
  • the addition of Ca improves the flame retardancy of the molten metal during casting, but if the Ca content is less than 0.50% by mass, the effect becomes insufficient.
  • Ca forms a compound with Al, and this compound contributes to heat resistance.
  • the Ca content needs to be 2.5% by mass or less. If Ca is contained in an amount of more than 2.5% by mass, problems tend to occur in tensile strength and corrosion resistance. Further, if Ca is contained in an excessive amount, cracks may occur during casting and the seizure property may be deteriorated.
  • the magnesium alloy according to the present invention needs to have a Si content of more than 0.10% by mass.
  • Si forms an Mg-Ca-Si compound with Ca and is expected to improve heat resistance, but this effect is not sufficiently exhibited when the Si content is 0.10% by mass or less. Further, if the Si content is too insufficient, it may be difficult to secure the tensile strength. On the other hand, the Si content needs to be less than 0.40% by mass. If Si is excessively contained, the Mg—Ca—Si compound is coarsely crystallized, and there is a high possibility that the toughness is lowered.
  • the magnesium alloy according to the present invention may contain unavoidable impurities in addition to the above elements.
  • This unavoidable impurity is unavoidably contained unintentionally due to a manufacturing problem or a raw material problem.
  • elements such as Ti, Cr, Fe, Ni, Cu, Sr, Zr, Be, Ba, Zn, and RE (rare earth elements) can be mentioned.
  • Each element needs to have a content within a range that does not impair the characteristics of the magnesium alloy according to the present invention, preferably less than 0.1% by mass per element, preferably less, and below the detection limit. It is particularly preferable to have it.
  • the total content of unavoidable impurities is preferably less than 1.0% by mass, more preferably less than 0.5% by mass, further preferably less than 0.1% by mass, and below the detection limit. It is particularly preferable to have it.
  • the magnesium alloy according to the present invention can be prepared by a general method using a raw material containing the above elements so as to be in the range of the above mass%.
  • the above mass% is not a value in the raw material, but a value in the prepared alloy or a product manufactured by casting the alloy.
  • the magnesium alloy according to the present invention has excellent tensile strength and elongation at room temperature, as well as heat resistance typified by creep resistance, and also excellent corrosion resistance.
  • it can be used for casting in the same procedure as a general-purpose material of magnesium alloy, and can be particularly preferably used in applications where excellent mechanical properties, excellent heat resistance, and excellent corrosion resistance at room temperature are required.
  • a magnesium alloy was prepared so that the content of elements other than Mg was the mass% shown in each of Table 1 below, and the test required for the preparation of the d "tensile test piece" of JIS H 5203 "8.
  • An alloy material was prepared based on "collection of material” (corresponding to ISO16220-5). Elements other than those listed were below the detection limit.
  • Each alloy was tested based on the tensile test method specified in JIS Z 2241 (corresponding to ISO6892-1).
  • the test piece was prepared by machining the above-mentioned alloy material, and the tensile strength and elongation were measured using a universal testing machine (manufactured by Shimadzu Corporation: UH-500kNX).
  • test was conducted based on the creep test method specified in JIS Z 2271 (corresponding to ISO204: 2009).
  • the test piece was manufactured by machining the above alloy material, and the creep tester was manufactured by Shinko Kagaku Kikai Co., Ltd .: SK-3, the test temperature was 175 ° C, and the applied stress was 50 MPa. The creep strain (%) after 100 hours was measured.
  • liquidus temperature was derived using the integrated thermodynamic calculation software Thermo-Calc manufactured by Thermo-Cal Software. The lower the liquidus temperature, the better the castability.
  • test was conducted based on the salt spray test method specified in JIS Z 2371 (corresponding to ISO9227: 2012).
  • the test piece was formed by gravity casting and then machined.
  • a test machine manufactured by Suga Test Instruments Co., Ltd. was used, the test method was a neutral salt spray test, and the test time was 96 hours.
  • the mixture was boiled in a mixed aqueous solution of chromium (VI) oxide and silver nitrate for 1 minute to remove corrosion products, and the corrosion weight loss was measured.
  • VI chromium
  • Table 1 shows the tensile strength, elongation, creep strain, liquidus temperature and comprehensive evaluation, as well as the component ratio of each test piece.
  • the evaluation is “B” Bad, “G” Good, and “VG” Very Good from the worst.
  • the tensile strength was evaluated as “B” when it was less than 155 MPa, “G” when it was 155 MPa or more and less than 165 MPa, and "VG” when it was 165 MPa or more.
  • the growth was evaluated as “B” for less than 0.7%, “G” for 0.7% or more and less than 1.5%, and "VG” for 1.5% or more.
  • the creep strain was evaluated as "B” for more than 0.30%, “G” for more than 0.20% and 0.30% or less, and "VG” for 0.20% or less.
  • the liquidus temperature above 610 ° C. was evaluated as “B”
  • the temperature above 600 ° C. and below 610 ° C. was evaluated as “G”
  • the temperature above 600 ° C. was evaluated as "VG”.
  • the overall evaluation was “B”. If "G” or "VG” was found for all items without including “B”, the overall evaluation was set to "G”. Furthermore, when two or more items were "VG”, the overall evaluation was "VG”.
  • Comparative Examples 1 and 2 the Al content was insufficient, and the liquidus temperature exceeded 610 ° C. Further, in Comparative Example 1 in which the Al content is too small, there is a problem in the tensile strength. On the other hand, in Comparative Example 3 in which the Al content was excessive, the evaluation of the liquidus temperature was "VG", but problems occurred in both mechanical properties and heat resistance. Comparative Examples 4 and 5 in which the Ca content was excessive caused a problem in tensile strength. Comparative Example 6 in which the Si content was too low caused a problem in tensile strength.
  • Examples 1 to 10 having an Al content of more than 6.0% by mass do not have a "B" evaluation, but among them, Examples 1 to 8 having an Al content of 10.0% by mass or less are preferable in terms of comprehensive evaluation. The result was. Further, among them, Examples 4, 5, 7, and 8 having an Al content of 8.0% by mass or more and 10.0% by mass or less and a Ca content of 1.5% by mass or more and 2.5% by mass or less , Excellent heat resistance, low liquidus temperature, excellent castability, and 3 VG items, making it excellent overall.
  • Table 2 below shows the corrosion weight loss as well as the component ratio of each test piece.
  • Examples 11 and 12 showed good corrosion resistance of less than 1.00 mcd (mg / cm 2 / day). However, Comparative Examples 7 and 8 had 1.00 mcd or more, and the corrosion resistance was not sufficient. In Comparative Example 7, it is considered that the corrosion resistance deteriorated because the Al content was not sufficient. Further, in Comparative Example 8, it is considered that the corrosion resistance deteriorated because the Ca content was excessive.

Abstract

Provided is a heat-resistant magnesium alloy that maintains heat resistance that is typified by creep resistance but also has excellent castability and excellent mechanical properties that are typified by room-temperature tensile strength and elongation. A magnesium alloy that contains more than 6.0 mass% but no more than 12.0 mass% of Al, at least 0.10 mass% but no more than 0.60 mass% of Mn, at least 0.50 mass% but no more than 2.5 mass% of Ca, and more than 0.10 mass% but less than 0.40 mass% of Si, the remainder being Mg and unavoidable impurities.

Description

耐熱性マグネシウム合金Heat resistant magnesium alloy
　この発明は、鋳造性や機械的性質、さらに耐食性に優れた耐熱性マグネシウム合金に関する。 The present invention relates to a heat-resistant magnesium alloy having excellent castability, mechanical properties, and corrosion resistance.
　マグネシウム合金は鉄鋼材料やアルミニウム合金よりも軽量であるため、様々な分野で軽量代替材として利用されている。マグネシウム合金として、Ａｌ、Ｍｎ、Ｚｎを添加したＡＺ系合金や、Ａｌ、Ｍｎを添加したＡＭ系合金が知られている。特に、ダイカスト用途としては、室温での強度および耐食性に優れるＡＺ９１Ｄ（Ｍｇ－９質量％Ａｌ－１質量％Ｚｎ）が汎用材として多種の用途に用いられている。しかし、汎用のマグネシウム合金は１７５℃程度の高温域にて耐熱性（耐クリープ性）が低下し、アルミニウム合金に匹敵する耐熱性を得ることができない。 Magnesium alloy is lighter than steel materials and aluminum alloys, so it is used as a lightweight substitute in various fields. As the magnesium alloy, an AZ alloy to which Al, Mn and Zn are added and an AM alloy to which Al and Mn are added are known. In particular, as a die casting application, AZ91D (Mg-9 mass% Al-1 mass% Zn), which is excellent in strength and corrosion resistance at room temperature, is used as a general-purpose material for various purposes. However, general-purpose magnesium alloys have reduced heat resistance (creep resistance) in a high temperature range of about 175 ° C., and cannot obtain heat resistance comparable to that of aluminum alloys.
　耐クリープ性を改善する方法として、ＣａあるはＲＥ（希土類元素）を添加したマグネシウム合金が知られている。このような例としては、耐クリープ性に優れるＡＥ４４（Ｍｇ－４質量％Ａｌ－４質量％ＲＥ）などが用いられている。 As a method for improving creep resistance, a magnesium alloy to which Ca or RE (rare earth element) is added is known. As such an example, AE44 (Mg-4 mass% Al-4 mass% RE) having excellent creep resistance is used.
　さらに近年では、高価なＲＥを含有させないで耐クリープ性を改善したＭｇ－Ａｌ－Ｃａ系合金が提案されている。例えば、特許文献１には、アルミニウム２～６重量％及びカルシウム０．５～４重量％を含有し、残部がマグネシウムと不可避の不純物からなり、Ｃａ／Ａｌ比が０．８、好ましくは０．６以下のマグネシウム合金を液相線温度以下で半溶融射出成形することにより作製される、耐クリープ特性を確保しつつ、特に成形性、伸び率に優れる耐熱マグネシウム合金成形部材が開示されている。ただし、これは鋳造ではなく射出成形の一種である。 Further, in recent years, Mg—Al—Ca alloys having improved creep resistance without containing expensive RE have been proposed. For example, Patent Document 1 contains 2 to 6% by weight of aluminum and 0.5 to 4% by weight of calcium, the balance of which is magnesium and unavoidable impurities, and has a Ca / Al ratio of 0.8, preferably 0. A heat-resistant magnesium alloy molding member, which is produced by semi-melt injection molding of a magnesium alloy of 6 or less at a liquidus temperature or lower, is disclosed, which is particularly excellent in moldability and elongation while ensuring creep resistance. However, this is a type of injection molding, not casting.
　ここで、半溶融射出成形法とは、加熱して固液共存状態にしたものを、加圧して鋳型に射出成形する方法である。このような半溶融加工は、通常の鋳造に比べてコストが割高になる。また、高固相率となる低温環境での品質低下が問題となる。この品質低下としては具体的には、湯流れが悪くなり湯流れ不良が多く発生することが挙げられる。 Here, the semi-melt injection molding method is a method in which a material that has been heated to be in a solid-liquid coexisting state is pressurized and injection-molded into a mold. Such semi-molten processing is more expensive than ordinary casting. In addition, quality deterioration in a low temperature environment with a high solid phase ratio becomes a problem. Specific examples of this deterioration in quality include poor hot water flow and frequent poor hot water flow.
　鋳造の場合、マグネシウム合金の液相線温度よりも少なくとも＋５０℃以上、好ましくは＋８０℃から＋１００℃程度の温度で鋳造することが多い（例えば非特許文献１の図１）。鋳造温度が液相線温度に近いとその分流動性が悪化し、狙い通りの鋳造部品の製造が難しくなる。 In the case of casting, it is often cast at a temperature of at least + 50 ° C. or higher, preferably about + 80 ° C. to + 100 ° C. than the liquidus temperature of the magnesium alloy (for example, FIG. 1 of Non-Patent Document 1). If the casting temperature is close to the liquidus temperature, the fluidity deteriorates accordingly, and it becomes difficult to manufacture the cast parts as intended.
特開平９－２７２９４５号公報JP-A-9-272945
　しかしながら、特許文献１に記載の合金やＡＥ４４は、液相線温度が高く、鋳造性に難がある場合があった。鉄鋼材料やアルミニウム合金などの金属は鋳造温度を上げることで鋳造性の問題を解決できる可能性がある。しかしながら、マグネシウム合金の溶湯は高温になるほど燃えてしまう可能性が高くなることが問題となる。すなわち、液相線温度が６１０℃を超えると、液相線温度から＋１００℃程度まで加熱して鋳造した場合に、燃える可能性が無視できなくなってくるという問題があった。しかし、燃える可能性を抑えようとして液相線温度からの温度上げ幅を抑制すると、今度は鋳造時の流動性に問題が生じてしまう。また、マグネシウム合金の適用拡大を実現するためには優れた耐食性および機械的性質が必要となる。 However, the alloy and AE44 described in Patent Document 1 have a high liquidus temperature and may have difficulty in castability. For metals such as steel materials and aluminum alloys, raising the casting temperature may solve the castability problem. However, there is a problem that the molten magnesium alloy is more likely to burn as the temperature rises. That is, when the liquidus temperature exceeds 610 ° C., there is a problem that the possibility of burning cannot be ignored when casting by heating from the liquidus temperature to about + 100 ° C. However, if the temperature rise from the liquidus temperature is suppressed in an attempt to suppress the possibility of burning, a problem arises in the fluidity during casting. In addition, excellent corrosion resistance and mechanical properties are required to realize the expansion of the application of magnesium alloys.
　そこでこの発明は、耐クリープ性に代表される耐熱性を維持しながら、鋳造性や、室温における引張強さ及び伸びに代表される機械的性質、耐食性にも優れた耐熱性マグネシウム合金を得ることを目的とする。 Therefore, the present invention obtains a heat-resistant magnesium alloy having excellent castability, mechanical properties typified by tensile strength and elongation at room temperature, and corrosion resistance while maintaining heat resistance typified by creep resistance. With the goal.
　この発明は、Ａｌを６．０質量％超１２．０質量％以下、Ｍｎを０．１０質量％以上０．６０質量％以下、Ｃａを０．５０質量％以上２．５質量％以下、及び、Ｓｉを０．１０質量％超０．４０質量％未満、含有し、残部がＭｇと不可避不純物からなるマグネシウム合金により、上記の課題を解決したのである。 In the present invention, Al is more than 6.0% by mass and 12.0% by mass or less, Mn is 0.10% by mass or more and 0.60% by mass or less, Ca is 0.50% by mass or more and 2.5% by mass or less, and , Si is contained in an amount of more than 0.10% by mass and less than 0.40% by mass, and the balance is a magnesium alloy composed of Mg and unavoidable impurities, thereby solving the above-mentioned problems.
　また、上記のマグネシウム合金のうち、Ａｌを６．０質量％超１０．０質量％以下含有するマグネシウム合金は、伸びと引張強さの両方で優れた機械的性質を発揮しやすい。 Further, among the above magnesium alloys, magnesium alloys containing Al in an amount of more than 6.0% by mass and 10.0% by mass or less tend to exhibit excellent mechanical properties in terms of both elongation and tensile strength.
　さらに、上記のマグネシウム合金のうち、Ａｌを８．０質量％以上１０．０質量％以下かつＣａを１．５質量％以上２．５質量％以下含有するマグネシウム合金は、さらに優れた耐熱性と鋳造性を発揮しやすい。 Further, among the above magnesium alloys, magnesium alloys containing 8.0% by mass or more and 10.0% by mass or less of Al and 1.5% by mass or more and 2.5% by mass or less of Ca have further excellent heat resistance. Easy to demonstrate castability.
　この発明にかかるマグネシウム合金は、室温での伸び及び引張強さといった機械的性質や耐クリープ性に代表される耐熱性、耐食性が優秀である。また、液相線温度を６１０℃以下に抑制したものになるため、この合金を用いた様々な鋳造部材を製造しやすく、様々な部材で室温における機械的性質や、耐熱性、耐食性を活用させることができる。 The magnesium alloy according to the present invention has excellent mechanical properties such as elongation and tensile strength at room temperature, and heat resistance and corrosion resistance typified by creep resistance. In addition, since the liquidus temperature is suppressed to 610 ° C. or lower, it is easy to manufacture various cast members using this alloy, and various members utilize the mechanical properties, heat resistance, and corrosion resistance at room temperature. be able to.
　以下、この発明について詳細に説明する。
　この発明は、少なくともＡｌ、Ｍｎ、Ｃａ、Ｓｉを含有するマグネシウム合金である。 Hereinafter, the present invention will be described in detail.
The present invention is a magnesium alloy containing at least Al, Mn, Ca and Si.
　この発明にかかるマグネシウム合金は、Ａｌの含有量が、６．０質量％超である必要があり、８．０質量％以上であると好ましい。Ａｌの含有量が６．０質量％以下になると引張強さが低下しすぎてしまう。また、十分な耐食性を確保することができなくなってしまう。Ａｌの含有量が８．０質量％以上であると液相線温度を十分に抑制できるため、鋳造性を確保しやすくなる。また、Ａｌを含有することで、固溶強化による強度向上効果と、鋳造性の向上も見込まれる。さらに、ＡｌがＣａとの化合物を形成することにより、耐熱性の向上も見込まれる。一方で、Ａｌの含有量が、１２．０質量％以下である必要があり、１０．０質量％以下であると好ましい。Ａｌの含有量が１２．０質量％を超えると室温での機械的性質が低下しすぎてしまう。また、Ｍｇ１７Ａｌ１２相を晶出させて耐熱性が著しく低下するおそれもある。 The magnesium alloy according to the present invention needs to have an Al content of more than 6.0% by mass, preferably 8.0% by mass or more. If the Al content is 6.0% by mass or less, the tensile strength will be too low. In addition, sufficient corrosion resistance cannot be ensured. When the Al content is 8.0% by mass or more, the liquidus temperature can be sufficiently suppressed, so that castability can be easily ensured. Further, by containing Al, it is expected that the strength is improved by strengthening the solid solution and the castability is improved. Furthermore, it is expected that the heat resistance will be improved by forming a compound of Al with Ca. On the other hand, the Al content needs to be 12.0% by mass or less, and preferably 10.0% by mass or less. If the Al content exceeds 12.0% by mass, the mechanical properties at room temperature will deteriorate too much. In addition, the Mg 17 Al 12 phase may be crystallized and the heat resistance may be significantly lowered.
　この発明にかかるマグネシウム合金は、Ｍｎの含有量が、０．１０質量％以上である必要があり、０．２０質量％以上であると好ましい。Ｍｎを含有することで、不可避不純物としてＦｅが含まれた際に、Ａｌ－Ｆｅ－Ｍｎ系化合物を形成することで脱鉄効果を発揮して、合金全体としては耐食性の向上が見込まれる。また、Ｍｎを含有することで結晶粒の微細化も見込まれる。Ｍｎの含有量が０．１０質量％未満であると、これらの効果を十分に発揮し得なくなる可能性が高くなる。一方、Ｍｎの含有量が、０．６０質量％以下である必要があり、０．５０質量％以下であると好ましい。Ｍｎが０．６０質量％を超えて過剰に含まれると粗大なＡｌ－Ｍｎ系化合物が多く晶出し、機械的性質の低下に繋がるおそれが高くなる。 The magnesium alloy according to the present invention needs to have a Mn content of 0.10% by mass or more, preferably 0.20% by mass or more. By containing Mn, when Fe is contained as an unavoidable impurity, an Al—Fe—Mn-based compound is formed to exert an iron removal effect, and the corrosion resistance of the alloy as a whole is expected to be improved. Further, by containing Mn, finer crystal grains are expected. If the Mn content is less than 0.10% by mass, there is a high possibility that these effects cannot be sufficiently exerted. On the other hand, the Mn content needs to be 0.60% by mass or less, and preferably 0.50% by mass or less. If Mn is excessively contained in excess of 0.60% by mass, a large amount of coarse Al—Mn-based compounds are crystallized, which increases the possibility of leading to deterioration of mechanical properties.
　この発明にかかるマグネシウム合金は、Ｃａの含有量が、０．５０質量％以上である必要があり、１．５質量％以上であると好ましい。Ｃａを加えることで鋳造時の溶湯の難燃性が向上するが、Ｃａの含有量が０．５０質量％未満ではその効果が不十分になってしまう。また、ＣａはＡｌとの間で化合物を形成し、この化合物が耐熱性に寄与する。一方、Ｃａの含有量が２．５質量％以下である必要がある。Ｃａが２．５質量％を超えて含有されると引張強さや耐食性に問題を生じやすくなる。また、Ｃａが過剰に含まれることで、鋳造時に割れの発生や焼着き性の悪化に繋がるおそれもある。 The magnesium alloy according to the present invention needs to have a Ca content of 0.50% by mass or more, preferably 1.5% by mass or more. The addition of Ca improves the flame retardancy of the molten metal during casting, but if the Ca content is less than 0.50% by mass, the effect becomes insufficient. In addition, Ca forms a compound with Al, and this compound contributes to heat resistance. On the other hand, the Ca content needs to be 2.5% by mass or less. If Ca is contained in an amount of more than 2.5% by mass, problems tend to occur in tensile strength and corrosion resistance. Further, if Ca is contained in an excessive amount, cracks may occur during casting and the seizure property may be deteriorated.
　この発明にかかるマグネシウム合金は、Ｓｉの含有量が０．１０質量％超である必要がある。ＳｉはＣａとの間でＭｇ－Ｃａ－Ｓｉ系化合物を形成し、耐熱性向上が見込めるが、Ｓｉの含有量が０．１０質量％以下ではこの効果が十分に発揮されない。また、Ｓｉの含有量が不足しすぎると引張強さが確保しにくくなるおそれもある。一方で、Ｓｉの含有量が０．４０質量％未満である必要がある。Ｓｉが過剰に含有されると、上記Ｍｇ－Ｃａ－Ｓｉ系化合物が粗大に晶出し、靭性の低下を招くおそれが高くなる。 The magnesium alloy according to the present invention needs to have a Si content of more than 0.10% by mass. Si forms an Mg-Ca-Si compound with Ca and is expected to improve heat resistance, but this effect is not sufficiently exhibited when the Si content is 0.10% by mass or less. Further, if the Si content is too insufficient, it may be difficult to secure the tensile strength. On the other hand, the Si content needs to be less than 0.40% by mass. If Si is excessively contained, the Mg—Ca—Si compound is coarsely crystallized, and there is a high possibility that the toughness is lowered.
　この発明にかかるマグネシウム合金は、上記の元素の他に、不可避不純物を含有してもよい。この不可避不純物とは、製造上の問題あるいは原料上の問題のために、意図に反して含有することが避けられないものである。例えば、Ｔｉ、Ｃｒ、Ｆｅ、Ｎｉ、Ｃｕ、Ｓｒ、Ｚｒ、Ｂｅ、Ｂａ、Ｚｎ、ＲＥ（希土類元素）などの元素が挙げられる。いずれの元素もこの発明にかかるマグネシウム合金の特性を阻害しない範囲の含有量であることが必要であり、一元素あたり０．１質量％未満であることが好ましく、少ないほど好ましく、検出限界未満であると特に好ましい。また、不可避不純物を合計した含有量が、１．０質量％未満であると好ましく、０．５質量％未満であるとより好ましく、０．１質量％未満であるとさらに好ましく、検出限界未満であると特に好ましい。 The magnesium alloy according to the present invention may contain unavoidable impurities in addition to the above elements. This unavoidable impurity is unavoidably contained unintentionally due to a manufacturing problem or a raw material problem. For example, elements such as Ti, Cr, Fe, Ni, Cu, Sr, Zr, Be, Ba, Zn, and RE (rare earth elements) can be mentioned. Each element needs to have a content within a range that does not impair the characteristics of the magnesium alloy according to the present invention, preferably less than 0.1% by mass per element, preferably less, and below the detection limit. It is particularly preferable to have it. Further, the total content of unavoidable impurities is preferably less than 1.0% by mass, more preferably less than 0.5% by mass, further preferably less than 0.1% by mass, and below the detection limit. It is particularly preferable to have it.
　この発明にかかるマグネシウム合金は、上記質量％の範囲となるように上記の元素を含む原料を用いて、一般的な方法で調製可能である。なお、上記の質量％は、原料における値ではなく、調製された合金やそれを鋳造などによって製造した製品における値である。 The magnesium alloy according to the present invention can be prepared by a general method using a raw material containing the above elements so as to be in the range of the above mass%. The above mass% is not a value in the raw material, but a value in the prepared alloy or a product manufactured by casting the alloy.
　この発明にかかるマグネシウム合金は室温で引張強さと伸びに優れるとともに、耐クリープ性に代表される耐熱性、さらに耐食性にも優れたものとなる。また、マグネシウム合金の汎用材と同程度の手順で鋳造に用いることができ、室温における優れた機械的性質や優れた耐熱性、優れた耐食性が求められる用途において特に好適に用いることができる。 The magnesium alloy according to the present invention has excellent tensile strength and elongation at room temperature, as well as heat resistance typified by creep resistance, and also excellent corrosion resistance. In addition, it can be used for casting in the same procedure as a general-purpose material of magnesium alloy, and can be particularly preferably used in applications where excellent mechanical properties, excellent heat resistance, and excellent corrosion resistance at room temperature are required.
　この発明にかかるマグネシウム合金を実際に調製した例を示す。Ｍｇ以外の元素の含有成分が下記の表１のそれぞれに記載の質量％となるようにマグネシウム合金を調製し、ＪＩＳ　Ｈ　５２０３「８．検査」のｄ「引張試験片の作製に必要な供試材の採取」（ＩＳＯ１６２２０－５に対応する）に基づき合金素材を作製した。なお、記載以外の元素については検出限界未満であった。 An example of actually preparing the magnesium alloy according to the present invention is shown. A magnesium alloy was prepared so that the content of elements other than Mg was the mass% shown in each of Table 1 below, and the test required for the preparation of the d "tensile test piece" of JIS H 5203 "8. An alloy material was prepared based on "collection of material" (corresponding to ISO16220-5). Elements other than those listed were below the detection limit.
　それぞれの合金についてＪＩＳ　Ｚ　２２４１（ＩＳＯ６８９２－１に対応する）に定める引張試験方法に基づいて試験を行った。試験体は前述の合金素材に機械加工を施して作製し、試験機には万能試験機（（株）島津製作所製：ＵＨ－５００ｋＮＸ）を用いて、引張強さおよび伸びを測定した。 Each alloy was tested based on the tensile test method specified in JIS Z 2241 (corresponding to ISO6892-1). The test piece was prepared by machining the above-mentioned alloy material, and the tensile strength and elongation were measured using a universal testing machine (manufactured by Shimadzu Corporation: UH-500kNX).
　また、ＪＩＳ　Ｚ　２２７１（ＩＳＯ２０４：２００９に対応する）に定めるクリープ試験方法に基づいて試験を行った。試験体は前記の合金素材に機械加工を施して作製し、クリープ試験機には神港科学器械（株）製：ＳＫ－３を用いて、試験温度は１７５℃、与えた応力は５０ＭＰａとして、１００時間経過後のクリープ歪（％）を測定した。 In addition, the test was conducted based on the creep test method specified in JIS Z 2271 (corresponding to ISO204: 2009). The test piece was manufactured by machining the above alloy material, and the creep tester was manufactured by Shinko Kagaku Kikai Co., Ltd .: SK-3, the test temperature was 175 ° C, and the applied stress was 50 MPa. The creep strain (%) after 100 hours was measured.
　さらに、Ｔｈｅｒｍｏ－Ｃａｌｃ　Ｓｏｆｔｗａｒｅ製の統合型熱力学計算ソフトウェアＴｈｅｒｍｏ－Ｃａｌｃを用い、液相線温度を導出した。なお、この液相線温度が低いほど鋳造性が良くなる。 Furthermore, the liquidus temperature was derived using the integrated thermodynamic calculation software Thermo-Calc manufactured by Thermo-Cal Software. The lower the liquidus temperature, the better the castability.
　また、ＪＩＳ　Ｚ　２３７１（ＩＳＯ９２２７：２０１２に対応する）に定める塩水噴霧試験法に基づいて試験を行った。試験体は重力鋳造で成形した後、機械加工を施し、作製した。試験機はスガ試験機（株）製を使用し、試験方法は中性塩水噴霧試験、試験時間は９６時間とした。試験後、酸化クロム（ＶＩ）および硝酸銀の混合水溶液中で１分間煮沸し、腐食生成物を除去し、腐食減量を測定した。 In addition, the test was conducted based on the salt spray test method specified in JIS Z 2371 (corresponding to ISO9227: 2012). The test piece was formed by gravity casting and then machined. A test machine manufactured by Suga Test Instruments Co., Ltd. was used, the test method was a neutral salt spray test, and the test time was 96 hours. After the test, the mixture was boiled in a mixed aqueous solution of chromium (VI) oxide and silver nitrate for 1 minute to remove corrosion products, and the corrosion weight loss was measured.
　下記表１に各試験体の成分比とともに、引張強さ、伸び、クリープ歪み、液相線温度および総合評価を示す。評価は悪い方から「Ｂ」Ｂａｄ、「Ｇ」Ｇｏｏｄ、「ＶＧ」ＶｅｒｙＧｏｏｄとする。引張強さは１５５ＭＰａ未満を「Ｂ」、１５５ＭＰａ以上１６５ＭＰａ未満を「Ｇ」、１６５ＭＰａ以上を「ＶＧ」と評価した。伸びは０．７％未満を「Ｂ」、０．７％以上１．５％未満を「Ｇ」、１．５％以上を「ＶＧ」と評価した。クリープ歪みは０．３０％超を「Ｂ」、０．２０％超０．３０％以下を「Ｇ」、０．２０％以下を「ＶＧ」と評価した。液相線温度は６１０℃を超えるものを「Ｂ」、６００℃を超えて６１０℃以下のものを「Ｇ」、６００℃以下のものを「ＶＧ」と評価した。上記４つの項目について、「Ｂ」が一つ以上あれば総合評価を「Ｂ」とした。「Ｂ」を含まず、全ての項目について「Ｇ」あるいは「ＶＧ」があれば総合評価を「Ｇ」とした。さらに、２つ以上の項目が「ＶＧ」の場合、総合評価を「ＶＧ」とした。 Table 1 below shows the tensile strength, elongation, creep strain, liquidus temperature and comprehensive evaluation, as well as the component ratio of each test piece. The evaluation is "B" Bad, "G" Good, and "VG" Very Good from the worst. The tensile strength was evaluated as "B" when it was less than 155 MPa, "G" when it was 155 MPa or more and less than 165 MPa, and "VG" when it was 165 MPa or more. The growth was evaluated as "B" for less than 0.7%, "G" for 0.7% or more and less than 1.5%, and "VG" for 1.5% or more. The creep strain was evaluated as "B" for more than 0.30%, "G" for more than 0.20% and 0.30% or less, and "VG" for 0.20% or less. The liquidus temperature above 610 ° C. was evaluated as "B", the temperature above 600 ° C. and below 610 ° C. was evaluated as "G", and the temperature above 600 ° C. was evaluated as "VG". For the above four items, if there was one or more "B", the overall evaluation was "B". If "G" or "VG" was found for all items without including "B", the overall evaluation was set to "G". Furthermore, when two or more items were "VG", the overall evaluation was "VG".
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　比較例１及び２はＡｌの含有量が不足しており、液相線温度が６１０℃を超えてしまった。またＡｌの含有量が少なすぎる比較例１は引張強さにも問題を生じてしまった。一方、Ａｌの含有量が過剰な比較例３は、液相線温度の評価が「ＶＧ」であったが、機械的性質と耐熱性の両方に問題を生じてしまった。Ｃａの含有量が過剰な比較例４、５は引張強さに問題を生じてしまった。Ｓｉの含有量が少なすぎる比較例６は引張強さに問題を生じてしまった。 In Comparative Examples 1 and 2, the Al content was insufficient, and the liquidus temperature exceeded 610 ° C. Further, in Comparative Example 1 in which the Al content is too small, there is a problem in the tensile strength. On the other hand, in Comparative Example 3 in which the Al content was excessive, the evaluation of the liquidus temperature was "VG", but problems occurred in both mechanical properties and heat resistance. Comparative Examples 4 and 5 in which the Ca content was excessive caused a problem in tensile strength. Comparative Example 6 in which the Si content was too low caused a problem in tensile strength.
　Ａｌの含有量が６．０質量％を超える実施例１～１０はいずれも「Ｂ」評価が無いが、その中でも１０．０質量％以下である実施例１～８が総合評価の点で好ましい結果となった。さらにその中でも、Ａｌの含有量が８．０質量％以上１０．０質量％以下かつＣａの含有量が１．５質量％以上２．５質量％以下の実施例４、５、７、８は、耐熱性に優れ、さらに液相線温度も低く、鋳造性にも優れ、ＶＧの項目が３つあり総合的に優れたものとなった。 Examples 1 to 10 having an Al content of more than 6.0% by mass do not have a "B" evaluation, but among them, Examples 1 to 8 having an Al content of 10.0% by mass or less are preferable in terms of comprehensive evaluation. The result was. Further, among them, Examples 4, 5, 7, and 8 having an Al content of 8.0% by mass or more and 10.0% by mass or less and a Ca content of 1.5% by mass or more and 2.5% by mass or less , Excellent heat resistance, low liquidus temperature, excellent castability, and 3 VG items, making it excellent overall.
　下記表２に、各試験体の成分比とともに、腐食減量を示す。 Table 2 below shows the corrosion weight loss as well as the component ratio of each test piece.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表２に示すように実施例１１および１２は１．００ｍｃｄ（ｍｇ／ｃｍ２／ｄａｙ）未満と良好な耐食性を示した。しかしながら、比較例７および８は１．００ｍｃｄ以上と耐食性は十分でなかった。比較例７はＡｌの含有量が十分でないために、耐食性が悪化したと考えられる。また、比較例８はＣａの含有量が過剰であったために耐食性が悪化したと考えられる。 As shown in Table 2, Examples 11 and 12 showed good corrosion resistance of less than 1.00 mcd (mg / cm 2 / day). However, Comparative Examples 7 and 8 had 1.00 mcd or more, and the corrosion resistance was not sufficient. In Comparative Example 7, it is considered that the corrosion resistance deteriorated because the Al content was not sufficient. Further, in Comparative Example 8, it is considered that the corrosion resistance deteriorated because the Ca content was excessive.

Claims (4)

  1. 　Ａｌを６．０質量％超１２．０質量％以下、Ｍｎを０．１０質量％以上０．６０質量％以下、Ｃａを０．５０質量％以上２．５質量％以下、及び、Ｓｉを０．１０質量％超０．４０質量％未満、含有し、残部がＭｇと不可避不純物からなるマグネシウム合金。 Al is more than 6.0% by mass and 12.0% by mass or less, Mn is 0.10% by mass or more and 0.60% by mass or less, Ca is 0.50% by mass or more and 2.5% by mass or less, and Si is 0. .A magnesium alloy containing more than 10% by mass and less than 0.40% by mass, with the balance consisting of Mg and unavoidable impurities.
  2. 　Ａｌを６．０質量％超１０．０質量％以下含有する請求項１に記載のマグネシウム合金。 The magnesium alloy according to claim 1, which contains Al in an amount of more than 6.0% by mass and not more than 10.0% by mass.
  3. 　Ａｌを８．０質量％以上１０．０質量％以下含有し、Ｃａを１．５質量％以上２．５質量％以下含有する請求項２に記載のマグネシウム合金。 The magnesium alloy according to claim 2, which contains 8.0% by mass or more and 10.0% by mass or less of Al and 1.5% by mass or more and 2.5% by mass or less of Ca.
  4. 　請求項１から３のいずれか１項に記載の鋳造用マグネシウム合金。 The magnesium alloy for casting according to any one of claims 1 to 3.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09271919A (en) * 1996-04-04 1997-10-21 Mitsui Mining & Smelting Co Ltd Production of heat resistant magnesium alloy member, magnesium alloy used to it and formed member made of magnesium alloy
JP2001316753A (en) * 2000-05-10 2001-11-16 Japan Steel Works Ltd:The Magnesium alloy and magnesium alloy member excellent in corrosion resistance and heat resistance
JP2009007676A (en) * 2008-07-30 2009-01-15 Toyota Industries Corp Heat resistant magnesium alloy for casting, and heat resistant magnesium alloy casting
JP2014001428A (en) * 2012-06-19 2014-01-09 Kurimoto Ltd Thermostable magnesium alloy

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09271919A (en) * 1996-04-04 1997-10-21 Mitsui Mining & Smelting Co Ltd Production of heat resistant magnesium alloy member, magnesium alloy used to it and formed member made of magnesium alloy
JP2001316753A (en) * 2000-05-10 2001-11-16 Japan Steel Works Ltd:The Magnesium alloy and magnesium alloy member excellent in corrosion resistance and heat resistance
JP2009007676A (en) * 2008-07-30 2009-01-15 Toyota Industries Corp Heat resistant magnesium alloy for casting, and heat resistant magnesium alloy casting
JP2014001428A (en) * 2012-06-19 2014-01-09 Kurimoto Ltd Thermostable magnesium alloy

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