201111521 六、發明說明： 【發明所屬之技術領域】 本發明係關於在殼體及各種元件等的材料上合適的鎂 合金板、使用該合金板之鎂合金構件及關於鎂合金板之製 造方法者。尤其在低溫具有優異的耐衝撃性之鎂合金板及 錶合金構件者。 【先前技術】 鎂之中含有各種添加元素之鎂合金可利用於行動電話 或筆記型電腦等的可攜式電子機械類的殻體或汽車的元件 等之構件的材料。 鎂合金由於具有六方晶的晶體結構（hep構造），致使在 常溫下缺乏塑性加工性，因此，該殼體等的鎂合金構件爲 經由模鑄法或觸變成形（thixomold)法之鑄造材爲主流。近 來有在來檢討ASTM規格的AZ31合金所構成之板材上進行 加壓加工，來形成上述殼體。專利文獻1揭示與ASTM規 格的AZ91合金相當的合金所構成之壓延板，其係有優異的 加壓加工性之板材。 專利文獻 [專利文獻1]特開2007-098470號公報 【發明內容】 發明所欲解決之課題 鎂合金因爲重量輕且優異的比強度與比剛性’因此期 望不僅使用在0〜30 °C左右的常溫環境下，而且使用在冰點[Technical Field] The present invention relates to a magnesium alloy sheet suitable for a material such as a casing and various components, a magnesium alloy member using the alloy sheet, and a method for manufacturing a magnesium alloy sheet. . Especially for magnesium alloy sheets and table alloy members which have excellent impact resistance at low temperatures. [Prior Art] A magnesium alloy containing various additive elements in magnesium can be used for a material such as a portable electronic mechanical case such as a mobile phone or a notebook computer, or a member of an automobile. Since the magnesium alloy has a hexagonal crystal structure (hep structure), the plastic workability is lacking at normal temperature. Therefore, the magnesium alloy member such as the shell is casted by a die casting method or a thixomold method. Mainstream. Recently, there has been a press working on a sheet made of an ASM31 alloy which has been reviewed for ASTM specifications to form the above casing. Patent Document 1 discloses a rolled sheet composed of an alloy equivalent to the AZ91 alloy of the ASTM specification, which is a sheet material having excellent press workability. [Patent Document 1] JP-A-2007-098470 SUMMARY OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION The magnesium alloy is expected to be used not only at a temperature of 0 to 30 ° C because of its light weight and excellent specific strength and specific rigidity. Under normal temperature, and used at freezing point
[SI -4 - 201111521 下之寒冷地或冷凍倉庫等。但是到目前爲止如此之低溫環 境下，關於鎂合金之機械的特性不曾全部的進行測試。 相較於鎂合金的壓延材或加壓成形之構件，鎂合金的 鑄造材具有差的強度。又’經本發明者調查AZ31合金的加 壓構件在低溫環境下強度並不完全且耐衝撃性差。 另一方面’如專利文獻1記載之AZ91所構成之壓延板 或在該壓延板進行加壓加工之加壓構件與A Z3 1所構成之 板或AZ31合金的加壓構件比較也有較高的強度。但是經本 發明者調査得知即使AZ 91合金所構成之壓延板或在該壓 延板上進行加壓加工等的塑性加工之構件，在低溫下也有 不完全具有耐衝擊性的情形。 因此’本發明的目的之一，爲提供即使在低溫環境下 也有優異的耐衝擊性的鎂合金構件及適於該構件之原料的 鎂合金板。又，本發明的另一目的爲提供該鎂合金板之製 造方法》 解決課題之手段 本發明者以各種條件製作鎂合金板，在所獲得的板上 進行加壓加工等的塑性加工來製作鎂合金構件，關於該鎂 合金板或構件，在低溫環境調査耐衝撃特性（耐凹性）或機 械特性。此結果得知不易形成凹痕的鎂合板的特定組成係 小且少之結晶物。又，得知經由特定組成之結晶物爲小且 少的鎂合金板，得到亦難有凹痕的鎂合金構件，該構件也 與原料的板相同，特定組成之結晶物小且少。而且得知在 [S] 201111521 製造如上述的鎂合金板時，爲了控制上述結晶物的最大直 徑及其個數，即，減少結晶物的數量及粗大的結晶物係在 特定條件下進行連續鑄造，在所獲得的鑄造板進行壓延爲 較佳。本發明係根據上述之得知見解者。 本發明的鎂合金板由含有A1及Μη之鎂合金所構成， 在上述鎂合金板的厚度方向，自該合金板的表面至該合金 板的厚度的30%之領域作爲表面領域，自該表面領域取出 任意的50 // m2的小領域時，相對於該小領域，含有Α1及 Μη兩者之結晶物之最大直徑爲0.1/zm以上l^m以下之粒 子爲15個以下。又，相對於Μη之A1的質量比：Al/Mn而 言，該結晶物的粒子爲2以上5以下。 具有上述特定組織之本發明的鎂合金板例如經由以下 的本發明製造方法可製造。本發明的鎂合金的製造方法具 備以下的鑄造步驟與壓延步驟。 鑄造步驟：板狀鑄造含有A1與Μη之鎂合金之步驟。 壓延步驟：經由上述鑄造步驟壓延所獲得的鑄造板之 步驟。 尤其，該鑄造爲經由雙輕連續鑄造法來進行。又，該 鑄造係以輥溫度爲100°C以下’經由該鑄造所獲得之鑄造板 的厚度爲5mm以下的方式來進行。 本發明的鎂合金構件係在上述本發明鎂合金板上進行 加壓加工等之塑性加工所形成者。該合金構件也與上述本 發明鎂合金板有相同的組織’即’自上述表面領域取出任 201111521 意的50 #m2的小領域時，具有上述特定的大且組成的結晶 物的粒子爲1 5個以下之組織。 由於可急冷凝固之雙輥連續鑄造法的連續鑄造法中降 低氧化物或離析等’可降低粗大的結晶物之生成，可視爲 微細的結晶物。尤其，在本發明製造方法中設定上述特定 範圍之輥溫度與鑄造板的厚度，因爲冷却速度非常快速， 可降低結晶物本身之生成。因此，在板狀材中，尤其容易 受到衝撃之表面側的領域之組織，可視爲僅微細的結晶物 存在之組織。又，因爲結晶物微小且少，所以由於結晶出 粗大的結晶物或大量的結晶物，認爲母相中之A1固體溶量 少量降低，伴隨A1量降低之固溶強化亦少量降低。又，藉 由急冷凝固’可得到具有小的平均結晶粒徑微細的組織之 鑄造板。該鑄造板因爲形成破裂或變形等原因之粗大結晶 物爲少，因此壓延等之塑性加工性爲優異，且進行壓延可 提高強度或延伸率。 因此，藉由上述製造方法所得的本發明合金板，因爲 減低粗大的結晶物且結晶物本身亦少，因此尤其容易受衝 撃之表面側之領域中’減低粗大結晶物、僅微細的結晶物 存在之組織’因爲較佳組織爲結晶物實質上不存在，因此 即使受到落下等的衝撃’也難以形成破裂或龜裂。又，因 爲如上述的結晶物本身爲少，所以可抑制固溶A1量的降 低’因爲A1完全固溶溶解’因此可以維持高強度而且藉由 壓延可進一步的提高強度。因此，本發明合金板即使受到[SI -4 - 201111521 under cold or frozen warehouses. However, in such a low temperature environment so far, the mechanical properties of magnesium alloys have not been fully tested. The cast material of the magnesium alloy has poor strength compared to the rolled material of the magnesium alloy or the member formed by press molding. Further, the inventors investigated that the pressure member of the AZ31 alloy is incomplete in strength and poor in punching resistance in a low temperature environment. On the other hand, the rolled sheet composed of AZ91 described in Patent Document 1 or the pressurizing member subjected to press working on the rolled sheet has higher strength than the pressed member of AZ31 or AZ31 alloy. . However, it has been found by the inventors that even a rolled plate formed of an AZ 91 alloy or a member subjected to plastic working such as press working on the rolled plate may not have impact resistance at a low temperature. Therefore, one of the objects of the present invention is to provide a magnesium alloy member having excellent impact resistance even in a low-temperature environment, and a magnesium alloy sheet suitable for the material of the member. Further, another object of the present invention is to provide a method for producing the magnesium alloy sheet. The present inventors have produced a magnesium alloy sheet under various conditions, and subjected to plastic working such as press working on the obtained sheet to produce magnesium. For the magnesium alloy sheet or member, the alloy member is investigated for impact resistance (concavity resistance) or mechanical properties in a low temperature environment. As a result, it was found that the specific composition of the magnesium plate which is less likely to form pits is small and few crystals. Further, it has been found that a magnesium alloy sheet having a small and a small crystal of a specific composition is obtained, and a magnesium alloy member which is hard to be dented is obtained. This member is also the same as the material of the raw material, and the crystal of the specific composition is small and small. Further, it is known that when [S] 201111521 is used to manufacture the magnesium alloy sheet as described above, in order to control the maximum diameter of the crystallized material and the number thereof, that is, the amount of crystallized matter is reduced and the coarse crystal system is continuously cast under specific conditions. It is preferred to carry out calendering on the obtained cast sheet. The present invention is based on the above findings. The magnesium alloy sheet of the present invention is composed of a magnesium alloy containing A1 and Μη, and in the thickness direction of the magnesium alloy sheet, from the surface of the alloy sheet to 30% of the thickness of the alloy sheet, as a surface field, from the surface When an arbitrary field of 50 // m2 is taken out from the field, the maximum diameter of the crystals containing both Α1 and Μη is 0.1/zm or more and 15 or less particles are less than the smaller area. Further, the mass ratio of A1 to Μη is Al/Mn, and the particles of the crystallized material are 2 or more and 5 or less. The magnesium alloy sheet of the present invention having the above specific structure can be produced, for example, by the following production method of the present invention. The method for producing a magnesium alloy of the present invention has the following casting step and calendering step. Casting step: a step of casting a magnesium alloy containing A1 and Μη. Calendering step: a step of calendering the obtained cast sheet through the above casting step. In particular, the casting is carried out by a double light continuous casting method. Further, the casting is carried out so that the thickness of the cast sheet obtained by the casting is 5 mm or less. The magnesium alloy member of the present invention is formed by plastic working such as press working on the above-described magnesium alloy sheet of the present invention. The alloy member also has the same structure as the above-described magnesium alloy sheet of the present invention, that is, when the small surface of 50 #m2 of 201111521 is taken out from the surface area, the particles having the above-mentioned specific large crystal composition are 1 5 . The following organizations. The reduction of oxides or segregation in the continuous casting method of the twin-roll continuous casting method which can be rapidly solidified can reduce the formation of coarse crystals, and can be regarded as fine crystals. In particular, in the manufacturing method of the present invention, the above-described specific range of the roll temperature and the thickness of the cast sheet are set because the cooling rate is very fast, and the formation of the crystal itself can be reduced. Therefore, in the sheet material, the structure of the field which is particularly susceptible to the surface side of the punching can be regarded as a structure in which only fine crystal grains exist. Further, since the crystals are minute and small, it is considered that a large amount of crystals or a large amount of crystals are crystallized, and it is considered that the amount of the A1 solid solution in the matrix phase is slightly decreased, and the solid solution strengthening with a decrease in the amount of A1 is also slightly decreased. Further, a cast sheet having a structure having a small average crystal grain size can be obtained by quenching and solidifying. Since the cast plate has a large amount of coarse crystals due to cracking or deformation, etc., the plastic workability such as rolling is excellent, and rolling or rolling can increase the strength or elongation. Therefore, the alloy sheet of the present invention obtained by the above-described production method is reduced in coarse crystals and has a small amount of crystals itself, so that it is particularly susceptible to the reduction of coarse crystals and only fine crystals in the field of the surface side which is easily washed. The organization 'because the preferred structure is that the crystal is substantially absent, and it is difficult to form cracks or cracks even if it is subjected to the smashing of falling or the like. Further, since the crystal material itself is small as described above, the decrease in the amount of solid solution A1 can be suppressed. Since A1 is completely dissolved in solution, high strength can be maintained and the strength can be further improved by calendering. Therefore, the alloy plate of the present invention is subjected to even
[SI 201111521 衝撃也難有凹痕，不限於室溫（20°C左右），即使小於〇t之 低溫環境下也具有優異的耐衝撃特性。又，具有上述特定 的組織之本發明合金板，係具有優異塑性加工性，可容易 進行加壓加工等，所得到的本發明合金構件也與本發明合 金板相同，尤其在容易受衝撃之表面側之領域，具有結晶 物小且少之組織。因此，本發明合金構件即使在低溫環境 下，也具有高強度及延伸率之機械特性，及優異的耐衝撃 性。 以下進一步詳細說明本發明。 《組成》 構成本發明鎂合金板及本發明鎂合金構件之鎂合金， 可列舉在添加元素中含有圭少A1與Μη之各種的組成者（殘 餘部分：Mg及不純物）。除了 Ai及Μη以外之添加元素，可 列舉選自 Zn、Si ' Ca、Sr、Υ、Cu、Ag ' Ce、Zr 及稀土類 元素（除了 Y、Ce)中之一種以上之元素。尤其，含有5質量 %以上12質量％以下之A1、質量％以上2.0質量％以 下之Μη爲較佳。因爲在上述範圍含有/^及Μη，因此強度 及延伸率之機械特性優異而且耐蝕性也優異。但是，上述 元素的含量過多時’導致塑性加工性的降低等。Α1,Μη以 外的添加元素之含量可列舉Zn :0.2〜7.0質量％、Si:0.2〜 1.0 質量 ％、Ca:0.2 〜6.0 質量 ％ ' Sr:0.2 〜7.0 質量 ％、 Υ:1·0 〜6.0 質量 ％、Cu:0.2 〜3.0 質量 ％ ' Ag:0.5 〜3.0 質量 %、Ce:0.05 〜1.0 質量 ％、zrihi.o 質量 ％、RE(稀土類 201111521 兀素（除了 Y、Ce)):1.0〜3.5質量％。不僅A1及Μη，而且 因爲含有此等之元素，因此進一步提高機械的特性。在上 述範圍含有Α1及Μη與此等的元素中一種以上當作合金之 組成，例如在ASTM規格可列舉ΑΖ系合金（Mg-Al-Zn系合 金、ΖικΟ.2〜1.5質量％)、AM系合金（Mg-A卜Μη系合金、 Μη:0.15〜0.5質量％ )等。尤其’ Α1的含量（以下稱爲A1 量）越多’機械的特性和耐蝕性越優異爲較佳，A1量爲5.8 質量％以上10質量％以下爲更佳。A1量爲5.8〜10質量％ 之鎂合金，例如在Mg-Al-Zn系合金係ΑΖ61合金、ΑΖ80合 金' AZ81合金' AZ91合金；Mg-Al-Mn系合金，以AM60 合金、AM100合金等爲適合的組成。尤其，A1量爲8.3〜 9.5質量％之AZ91合金與其他的Mg-A1系合金之比較，具 有更優異的耐蝕性和強度、耐塑性變形性之機械特性。 《鎂合金板及鎂合金構件之形態》 本發明合金板具有對向的一對之一面及其他面，該二 面代表平行關係，通常在使用時爲正背的關係。該一面及 其他面爲可以是平面也可以是曲面。該一面與其他面之間 的距離爲鎂合金板的厚度。因爲在如上述厚度爲5 mm以下 之鑄造板進行壓延而獲得本發明合金板，本發明合金板的 厚度爲小於5mm。尤其，本發明合金板之加壓加工係進行 塑性加工，因爲利用在薄且輕量的殼體或各種的構件之原 料上，因此當該合金板的厚度爲0.3mm〜3mm左右，尤其 0.5mm以上2.0mm以下爲較佳，當在該範圍中越厚越具有 201111521 優異的強度，越薄越適合薄型輕量的殼體等。根據期望的 用途，調整鑄造條件或壓延條件，可選擇最終的所獲得的 鎂合金板之厚度。 本發明合金構件係在上記述鎂合金板上進行加壓加工 之塑性加工而形成各種的形狀，例如具有底面部與自底面 部設立的側壁部之3狀材或箱狀材等爲代表。在該鎂合金 構件中，隨者加壓加工等的塑性加工，實質未進行變形之 平坦處的厚度，係與構成原料之鎂合金板有大致相同的厚 度，具有大致相同的組織。即，在上述表面領域，最大直 徑爲0.1〜lym之AI-Mn系結晶物爲15個以下MOym2。 本發明合金板係除了壓延鑄造材之壓延板之外，可列 舉在該壓延板上進一步進行熱處理或加壓加工、硏磨加工 等之處理板。本發明合金構件除了在上述合金板上進行上 述加壓加工等之塑性加工者之外，在塑性加工後，包含進 行熱處理或硏磨加工者。上述壓延板或處理板、合金構件 可進一步具有防蝕處理層或塗布層。 《機械的特性》 本發明合金板或本發明合金構件即使在如上述之低溫 環境下也具有優異的強度及伸長之機械的特性、受到落下 等的衝撃時也難有凹痕。例如在-30 °C之張力試驗中，實質 上未進行本發明合金板或本發明合金構件中隨者加壓加工 等之塑性加工之變形（例如經由伸拉成形加工之變形等）之 平坦處（與原料的板大致相同之處）具有張力強度爲350MPa[SI 201111521 It is also difficult to dent, not limited to room temperature (about 20 °C), and it has excellent impact resistance even in low temperature environments less than 〇t. Further, the alloy sheet of the present invention having the above specific structure has excellent plastic workability, can be easily subjected to press working, and the like, and the obtained alloy member of the present invention is also the same as the alloy sheet of the present invention, particularly on the surface which is easily subjected to scouring. In the field of the side, there are tissues with small crystals and few. Therefore, the alloy member of the present invention has mechanical properties of high strength and elongation, and excellent impact resistance even in a low temperature environment. The invention is further described in detail below. <<Composition>> The magnesium alloy constituting the magnesium alloy sheet of the present invention and the magnesium alloy member of the present invention may be exemplified by various constituents (residual portions: Mg and impurities) containing the elements A1 and Μη in the additive element. In addition to the additive elements other than Ai and Μη, one or more elements selected from the group consisting of Zn, Si ' Ca, Sr, yttrium, Cu, Ag ' Ce, Zr and rare earth elements (except Y and Ce) may be mentioned. In particular, it is preferable to contain 5 η of 5% by mass or more and 12% by mass or less of A1, mass% or more and 2.0% by mass or less. Since it contains /^ and Μη in the above range, it is excellent in mechanical properties of strength and elongation, and also excellent in corrosion resistance. However, when the content of the above elements is too large, "the plastic workability is lowered." Α1, the content of the additive element other than Μη is Zn: 0.2 to 7.0% by mass, Si: 0.2 to 1.0% by mass, and Ca: 0.2 to 6.0% by mass 'Sr: 0.2 to 7.0% by mass, Υ: 1·0 to 6.0 % by mass, Cu: 0.2 to 3.0% by mass ' Ag: 0.5 to 3.0% by mass, Ce: 0.05 to 1.0% by mass, zrihi.o% by mass, RE (rare earth 201111521 兀 (except Y, Ce)): 1.0~ 3.5% by mass. Not only A1 and Μη, but also because of these elements, the mechanical properties are further improved. In the above range, Α1 and Μη and one or more of these elements are used as an alloy. For example, in the ASTM specification, a lanthanide alloy (Mg-Al-Zn alloy, ΖικΟ. 2 to 1.5% by mass), and an AM system are mentioned. Alloy (Mg-A Μ Μ-based alloy, Μη: 0.15 to 0.5% by mass) and the like. In particular, the content of Α1 (hereinafter referred to as A1 amount) is more excellent, and the mechanical properties and corrosion resistance are more excellent, and the amount of A1 is preferably 5.8 mass% or more and 10 mass% or less. A magnesium alloy having a A1 amount of 5.8 to 10% by mass, for example, a Mg-Al-Zn alloy ΑΖ61 alloy, a ΑΖ80 alloy 'AZ81 alloy' AZ91 alloy, a Mg-Al-Mn alloy, an AM60 alloy, an AM100 alloy, or the like Suitable composition. In particular, the AZ91 alloy having an A1 amount of 8.3 to 9.5 mass% has mechanical properties superior to corrosion resistance, strength, and plastic deformation resistance as compared with other Mg-A1 alloys. <<Form of Magnesium Alloy Sheet and Magnesium Alloy Member>> The alloy sheet of the present invention has a pair of one side and the other side which are opposite to each other, and the two sides represent a parallel relationship, and are usually in a positive-back relationship at the time of use. The one side and the other side may be either a flat surface or a curved surface. The distance between the one side and the other side is the thickness of the magnesium alloy sheet. Since the alloy sheet of the present invention is obtained by calendering a cast sheet having a thickness of 5 mm or less as described above, the thickness of the alloy sheet of the present invention is less than 5 mm. In particular, the press working of the alloy sheet of the present invention is plastic working because it is used in a thin and lightweight casing or various members, so that the thickness of the alloy sheet is about 0.3 mm to 3 mm, especially 0.5 mm. The above 2.0 mm or less is preferable, and the thicker in this range, the more excellent the strength of 201111521, and the thinner the thinner the more suitable for a thin and lightweight casing. Depending on the intended use, the casting conditions or calendering conditions can be adjusted to select the final thickness of the obtained magnesium alloy sheet. The alloy member of the present invention is formed into various shapes by plastic working by press working on the magnesium alloy sheet, and is, for example, a tabular material or a box-shaped material having a bottom surface portion and a side wall portion formed from the bottom surface portion. In the magnesium alloy member, the thickness of the flat portion which is not substantially deformed by the plastic working such as press working is substantially the same as the thickness of the magnesium alloy sheet constituting the raw material, and has substantially the same structure. That is, in the surface area described above, the AI-Mn-based crystal having a maximum diameter of 0.1 to lym is 15 or less MOym2. The alloy sheet of the present invention may be a treatment sheet which is further subjected to heat treatment, press working, honing processing or the like on the rolled sheet in addition to the rolled sheet of the rolled cast material. The alloy member of the present invention includes a plasticizer such as the above-described press working on the above alloy sheet, and includes a heat treatment or a honing process after plastic working. The above calendered sheet or treated sheet and alloy member may further have an anticorrosive treatment layer or a coating layer. <<Mechanical characteristics>> The alloy sheet of the present invention or the alloy member of the present invention is excellent in strength and mechanical properties of elongation even in a low-temperature environment as described above, and is difficult to be dent when subjected to dropping or the like. For example, in the tensile test at -30 ° C, the flat portion of the plastic sheet of the alloy sheet of the present invention or the alloy member of the present invention, which is subjected to press working such as press working (for example, deformation by stretch forming processing, etc.) is substantially not performed. (substantially the same as the board of the raw material) has a tensile strength of 350 MPa
[SI -10- 201111521 以上' 0.2%耐力爲280MPa以上、延伸2%以上。 《組織》 <結晶物> 本發明合金板進行自該表面側之領域任意取出的小領 域之組織觀察時，粗大的結晶物實質上不存在，具有僅有 微細的結晶物存在之組織。更具體而言，在上述合金板之 厚度方向，自該合金板之表面至該合金板的厚度之30%之 領域作爲表面領域，自該表面領域取出任意選擇之50〆m2 之小領域，測定在一小領域存在之全部結晶物之粒徑。因 此’測定各結晶物的最大直徑時，相對於一小領域，最大 直徑爲0.1/zm以上l//m以下之微細結晶物爲15個以下。 僅存在最大直徑爲0.5/zm以下之結晶物爲更佳。若存在超 過lym之粗大結晶物，受到落下等的衝撃時，因爲破裂等 起源於該粗大結晶物，容易產生破裂或龜裂，且降低耐衝 撃性。又，相對於50// m2而言，即使最大直徑爲IV 111以 下之結晶物若存在超過15個，因爲破裂和龜裂的來源變 多，引起強度的減少、降低耐衝撃性。最大直徑爲〇.1〜1 之結晶物之粒子越少越傾向優異的耐衝撃性’ 1〇個以 下爲更佳，理想的0個爲最佳。上述結晶物含有A1與Μη 兩者。最大直徑的測定方法係詳細如後述。再者’在本發 明被認爲難於形成破裂的起因之極微細的結晶物’即，容 許最大直徑小於之結晶物之存在，但沒有如上述之 結晶物的存在爲較佳。 [S1 -11 - 201111521 <平均結晶粒徑> 本發明合金，可列舉小的平均結晶粒徑、且具有20// m以下之微細組織者。進行如上述特定條件的連續鑄造可 獲得具有微細組織鑄造板，因爲在該鑄造板進行壓延，所 以可當作具有上述微細組織之壓延板。具有該微細組織之 本發明合金板有優異的強度及延伸率之機械的特性，即使 在低溫環境下也可提高耐衝撃性。又，藉由具有上述微細 組織之鎂合金板或在該壓延板上進行校平處理等之矯正處 理之處理板獲得之本發明合金構件可具有平均結晶粒徑爲 2〇vm以下之微細組織，具優異耐衝撃性。平均結晶粒徑 爲O.lym以上l〇/zm以下爲較佳。 [製造方法] 《鑄造》 在本發明製造方法中係利用雙輥連續鑄造法。在該鑄 造中利用鑄型之輥的溫度爲1 〇〇°c以下，使所獲得的鑄造板 之厚度爲5mm以下。該鑄造板之厚度薄，且因爲使輥溫度 低，因此藉由急冷凝固抑制如上述之結晶物之生成，可視 爲結晶物小且少之鑄造板。輥溫度爲1 〇〇°C以下，可列舉利 用水冷等的強制冷卻係可能的輥。使輥溫度越低，又，鑄 造板的厚度越薄，可抑制加速冷却速度之結晶物的生成。 因此，輥溫度爲60°C以下、鑄造板的厚度爲4.0mm以下爲 更佳。該鑄造步驟（亦包含冷卻步驟）係爲了防止錶合金的 氧化等，在惰性氣體環境下進行爲較佳。 [.S1 -12- 201111521 《壓延》 壓延條件可列舉例如原料的加熱溫度：2 0 0〜4 0 0 °C、 壓延輥之加熱溫度：150〜300°C、1輥延（pass)左右之縮減 率：5〜50%，可以以成爲期望的厚度的方式複數輥延。亦 可利用在專利文件1中記載的控制壓延。因在上述鑄造材 進行壓延’可當作並不是鑄造的金屬組織之壓延組織等。 又’因進行壓延而容易得到平均結晶粒徑爲20/zm以下之 微細組織’且降低鑄造時所謂的離析或縮孔或空隙（孔）之 內部欠陥、表面缺陷等，可獲得優異的表面性狀之壓延 板。若當作在最終的壓延後進行最終熱處理之平均結晶粒 徑爲20 #ιη以下的微細再結晶組織，可獲得之壓延板的強 度或耐蝕性更容易提高。 《塑性加工》 本發明合金構件以在上述壓延板（亦包含實施熱處理 等者）上形成期望的形狀的方式，進行所謂的加壓加工（亦 包含沖孔）' 深拉成型加工、鍛造加工、吹模成型加工、 彎曲加工之塑性加工而獲得。該塑性加工若在200〜280°C 的溫度之間進行，可減低壓延板的組織成爲粗大的再結晶 組織、機械特性或耐蝕性的劣化。亦可在上述塑性加工 後，進行熱處理或防蝕處理，形成塗布層。 [發明效果] 本發明鎂合金板及本發明鎂合金構件在低溫環境下有 優異的耐衝撃性。本發明鎂合金板的製造方法可製造上述 [S] -13- 201111521 本發明鎂合金板。 【實施方式】 以下說明本發明的實施型態》 [試驗例1] 使用在表1所示之鎂合金所構成的鑄錠（ing〇t)(均爲市 售），在各種的條件下，製作鎂合金板或鎂合金構件（殼體）， 進行所獲得之鎂合金板或鎂合金構件組織觀察'張力試驗 (低溫）、衝撃試驗（低溫）。製作條件如下述。 (條件A:雙輥鑄造—壓延） 在惰性氣體環境下，在700°C加熱鎂合金的鑄錠以製作 熔液，使用該熔液，在上述惰性氣體環境下藉由雙輥連續 鑄造法’製作複數厚度4.0mm(< 5mm)之鑄造板。以該鑄造 之輥溫度變爲60 °C (<100 °C)的方式，一邊冷卻輥—邊進 行。所得到的各鑄造板做爲原料，原料的加熱溫度：2〇〇〜 400°C，壓延輥之加熱溫度：150〜300°C，每1輥延的縮減 率〜50%的條件，進行複數回壓延原料的厚度至〇.6mm, 製作壓延板。所得到的壓延板（鎂合金板）作爲試料（板）。 又，在所獲得的壓延板上以加熱溫度：250°C進行角伸拉$ 型加工，製作斷面C狀的箱狀體，該箱狀體（鎂合金構件） 作爲試料（殼體）。 上述濤造後’可進行用以均質化組成之熱處理（溶體化^ 處理）或進行時效處理等、進行在壓延中的中間熱處理、進 行最終的壓延後的最終熱處理。又，在壓延板進行校平加 [S] -14 - 201111521 工或硏磨加工，可藉由矯正提高平坦度，藉由硏磨可平滑 化表面。這幾點與後述之試驗例2相同。 (條件B:模具鑄造） 市售的模具鑄造品（斷面c狀的箱狀體，底面部分的厚 度：0.6mm)。 (條件C:市售板） 市售的AZ31合金所構成的板（厚度：〇.6mm)。 (條件D:市售殻體） 在AZ31合金所構成的板（厚度：〇.6mm)上進行角伸拉成 型加工，斷面C狀的箱狀體（底面部分的厚度：〇.6mm)(市售 品）。 《組織觀察》 關於所獲得之各試料，如以下的方式觀察金屬組織， 調查結晶物。試料（板）沿板厚方向切斷試料，以穿透型電 子顯微鏡（20,000倍）觀察該斷面。在該觀察像中，於試料 (板）的厚度方向’從該試料（板）之表面至該試料（板）的厚度 爲30%(0_6mmx30%=0.18mm)之領域作爲表面領域。從該 表面領域任意選擇5處的5 0 e m2之小領域，測定在各小領 域中存在全部的大結晶物。結晶物的判定藉由組成來進 行。鏡面硏磨上述斷面後，例如使用E D X等所代表之定性 分析與半定量分析’可求出在斷面上所存在之粒子之組 成’將包含A1及Μη之粒子作爲結晶物。再者，關於包含 Α1及Μη之各結晶物的粒子，Α1的質量與Μη的質量之比[SI -10- 201111521 or more ' 0.2% endurance is 280 MPa or more, and extension is 2% or more. <<Organization>> <Crystalline> When the alloy sheet of the present invention is observed in a small area in which the field is arbitrarily taken out from the surface side, the coarse crystal is substantially absent, and has a structure in which only fine crystals exist. More specifically, in the thickness direction of the above alloy sheet, from the surface of the alloy sheet to 30% of the thickness of the alloy sheet, as a surface field, a small field of 50 〆 m2 which is arbitrarily selected is taken out from the surface field, and the measurement is performed. The particle size of all crystals present in a small area. Therefore, when the maximum diameter of each crystal is measured, the number of fine crystals having a maximum diameter of 0.1/zm or more and 1/m or less is 15 or less with respect to a small area. It is more preferable that only crystals having a maximum diameter of 0.5/zm or less are present. When coarse crystals exceeding lym are present and are subjected to dropping or the like, since cracks or the like originate from the coarse crystals, cracking or cracking easily occurs, and the impact resistance is lowered. Further, with respect to 50//m2, even if there are more than 15 crystals having a maximum diameter of less than or equal to IV 111, since the source of cracking and cracking increases, the strength is reduced and the impact resistance is lowered. The smaller the number of particles having a maximum diameter of 〇.1 to 1 is, the more excellent the impact resistance is, and the optimum is preferably less than 1 Å. The above crystals contain both A1 and Μη. The method of measuring the maximum diameter is described in detail later. Further, in the present invention, it is considered that it is difficult to form a very fine crystal of the cause of cracking, i.e., the maximum diameter is allowed to be smaller than that of the crystal, but the presence of the crystal as described above is preferable. [S1 -11 - 201111521 <Average crystal grain size> The alloy of the present invention includes a small average crystal grain size and has a fine structure of 20 / / m or less. The continuous casting having the specific conditions as described above can be obtained as a microstructured cast sheet, since the cast sheet is calendered, so that it can be regarded as a rolled sheet having the above-described fine structure. The alloy sheet of the present invention having such a fine structure has excellent mechanical properties of strength and elongation, and can improve impact resistance even in a low temperature environment. Moreover, the alloy member of the present invention obtained by the magnesium alloy sheet having the fine structure or the treatment sheet subjected to the correction treatment such as the leveling treatment on the rolled sheet may have a fine structure having an average crystal grain size of 2 〇vm or less. Excellent resistance to punching. The average crystal grain size is preferably O.lym or more and l〇/zm or less. [Manufacturing Method] "Casting" In the manufacturing method of the present invention, a two-roll continuous casting method is used. In the casting, the temperature of the roll using the mold is 1 〇〇 ° C or less, and the thickness of the obtained cast sheet is 5 mm or less. Since the cast sheet has a small thickness and the roll temperature is low, the formation of the crystals as described above can be suppressed by rapid solidification, and it can be considered that the crystallized material is small and the cast sheet is small. The roll temperature is 1 〇〇 ° C or less, and may be a roll which may be forced cooling such as water cooling. The lower the temperature of the roll, the thinner the thickness of the cast sheet, and the formation of crystals at an accelerated cooling rate can be suppressed. Therefore, it is more preferable that the roll temperature is 60 ° C or less and the thickness of the cast plate is 4.0 mm or less. This casting step (including the cooling step) is preferably carried out in an inert gas atmosphere in order to prevent oxidation of the surface alloy or the like. [.S1 -12- 201111521 "Rolling" The calendering conditions include, for example, the heating temperature of the raw material: 2 0 0 to 4 0 0 ° C, the heating temperature of the calender roll: 150 to 300 ° C, and 1 roll extension (pass) Reduction rate: 5 to 50%, and the plurality of rolls can be formed in a desired thickness. The controlled rolling described in Patent Document 1 can also be utilized. The rolling of the cast material described above can be regarded as a rolled structure of a metal structure which is not cast. Further, 'the fine structure having an average crystal grain size of 20/zm or less is easily obtained by rolling, and the internal surface defects such as segregation or shrinkage cavities or voids (holes) at the time of casting are reduced, and excellent surface properties can be obtained. Calendered sheet. When the fine recrystallized structure having an average crystal grain size of 20 #ιη or less after the final heat treatment is finally used, the strength or corrosion resistance of the obtained rolled sheet can be more easily improved. <<Plastic Machining>> The alloy member of the present invention performs so-called press processing (including punching) so as to form a desired shape on the rolled sheet (including heat treatment or the like), deep drawing processing, forging processing, Obtained by plastic working of blow molding and bending. When the plastic working is carried out at a temperature of 200 to 280 ° C, the structure of the low-pressure extension plate can be reduced to deteriorate the coarse recrystallized structure, mechanical properties or corrosion resistance. It is also possible to perform heat treatment or anti-corrosion treatment after the above plastic working to form a coating layer. [Effect of the Invention] The magnesium alloy sheet of the present invention and the magnesium alloy member of the present invention have excellent impact resistance in a low temperature environment. The method for producing a magnesium alloy sheet of the present invention can produce the above-mentioned [S] -13 - 201111521 magnesium alloy sheet of the present invention. [Embodiment] Hereinafter, an embodiment of the present invention will be described. [Test Example 1] Ingots (all commercially available) composed of the magnesium alloys shown in Table 1 were used, under various conditions, A magnesium alloy sheet or a magnesium alloy member (housing) is produced, and the obtained microstructure of the magnesium alloy sheet or the magnesium alloy member is observed as a tensile test (low temperature) and a punching test (low temperature). The production conditions are as follows. (Condition A: Twin Roll Casting - Calendering) An ingot of a magnesium alloy is heated at 700 ° C in an inert gas atmosphere to prepare a molten metal, and the molten metal is used in the above inert gas atmosphere by a two-roll continuous casting method' A cast plate having a thickness of 4.0 mm (< 5 mm) was produced. The casting rolls were heated to a temperature of 60 ° C (<100 °C) while cooling the rolls. Each of the obtained cast plates is used as a raw material, and the heating temperature of the raw materials is 2 〇〇 to 400 ° C, and the heating temperature of the calender rolls is 150 to 300 ° C, and the reduction ratio of each roll is 5% to 50%, and the plural is performed. The thickness of the raw material was rolled back to 66 mm to prepare a rolled sheet. The obtained rolled sheet (magnesium alloy sheet) was used as a sample (plate). Moreover, the obtained rolled sheet was subjected to angular stretching at a heating temperature of 250 ° C to form a box-shaped body having a C-shaped cross section, and the box-shaped body (magnesium alloy member) was used as a sample (housing). After the above-mentioned formation, the heat treatment for the homogenization composition (solution treatment) or the aging treatment may be carried out, and the intermediate heat treatment in the rolling may be performed to carry out the final heat treatment after the final rolling. In addition, the calendering is performed by leveling and adding [S] -14 - 201111521 to work or honing, and the flatness can be improved by correction, and the surface can be smoothed by honing. These points are the same as Test Example 2 described later. (Condition B: Mold Casting) A commercially available mold cast product (a box-shaped body having a c-section in cross section, and a thickness of a bottom portion: 0.6 mm). (Condition C: Commercially available plate) A plate made of a commercially available AZ31 alloy (thickness: 〇.6 mm). (Condition D: Commercially available case) An angular stretch-drawing process was performed on a plate (thickness: 〇.6 mm) made of AZ31 alloy, and a box-shaped body having a section C (thickness of the bottom portion: 〇.6 mm) ( Commercial products). "Organizational Observation" Regarding each of the obtained samples, the metal structure was observed as follows, and the crystals were investigated. The sample (plate) was cut along the thickness direction of the sample, and the section was observed with a transmission electron microscope (20,000 times). In this observation image, the field of the thickness direction of the sample (plate) from the surface of the sample (plate) to the thickness of the sample (plate) of 30% (0_6 mm x 30% = 0.18 mm) was used as the surface area. From the surface area, five small fields of 50 e m2 were arbitrarily selected, and it was measured that all of the large crystals existed in each small domain. The determination of the crystallized matter is carried out by composition. After the above-mentioned cross section is mirror-finished, for example, qualitative composition and semi-quantitative analysis represented by E D X or the like can be used to determine the composition of the particles existing in the cross section. The particles containing A1 and Μη are used as crystals. Further, regarding the particles including the respective crystals of Α1 and Μη, the ratio of the mass of Α1 to the mass of Μη
[SI -15- 201111521[SI -15- 201111521
Al/Mn經測定’試料Νο·1-1，ΐ-2中任一 Al/Mn=2〜5。於 是’關於在上述斷面中各結晶物的粒子，在該斷面拉出平 行的直線’在各粒子中橫切的該直線之長度最大値做爲該 粒子的最大直徑’最大直徑爲0.1/zm以上1/zm以下之大 小的結晶物的數目作爲該小領域之結晶物之數目，以該試 料之結晶物之數目/50/zm2作爲5處小領域的平均》在試料 (殼體）方面，在試料中不伴隨伸拉變形之平坦部分之底面 部’沿板厚方向將其切斷，觀察與上述試料（板）相同之該 斷面，測定結晶物數目/50/zm2。但是，在上述觀察像中， 發現最大直徑超過5/zm以上之粗大結晶物時，將小領域的 面積當作200 # m2，測定在該200以m2內存在之結晶物的最 大直徑及結晶物的數目/200 y m2。再者，上述各小領域若 滿足上述之各面積，雖不特別考慮形狀但容易利用矩形狀 (正方形爲代表）等。測定結果顯示於表1。 《張力試験（低溫）》 從各試料（厚度：0.6mm)製作IIS 13B號的板狀試驗片 (JIS Z 2201(1998))，基於 JIS Z 2241(1998)的金屬材料張力 試驗方法，進行張力試驗。在此，以試料（板）做爲標點距 離GL = 50mm，試料（殻體）作爲標點距離GL=15mm，任何試 料均在試驗溫度爲-30°C進行張力速度爲5mm/min之張力試 驗，測定張力強度（MPa)、0.2%耐力（MPa)、延伸率（％)(評 價數：任一之n = l)。該結果顯示於表1。再者，試料（殼體） 方面，從在試料中不伴隨伸拉變形之平坦部分之底面部， [S] -16 - 201111521 切割出上記張力試驗的試驗片及製作後述之衝撃試驗的試 驗片。 《衝撃試験（低溫）》 .從各試料切出30mmx30mm的板片，將該切出的板片作 爲試驗片。該試驗如第1圖所示，準備在水平的面具有直 徑d=20mm之圓洞21之支撐台20。圓洞21的深度係可讓 後述之圓柱棒10完全插入之大小。以堵住該圓洞21的方 式配置試驗片1，在該狀態從距離試驗片1高度爲200mm 之地點，將重量100g、頂端r=5mm、陶瓷製之圓柱棒10 以與該中心軸及圓洞 21的中心軸形成同軸的方式來配 置。於是，朝向試驗片1，自上述配置地點（高度200mm) 自由落下圓柱棒10之後，測定試驗片1的凹痕量。凹痕量 (mm)係取出連接直線試驗片1對向之兩邊的直線，使用點 測驗千分尺（point micrometer)測定自該直線至最凹陷部 分的距離。該衝撃試驗在-3(TC之低溫環境進行。該結果 顯示於表1。凹痕量0.5mm以下爲〇、超過0.5mm超以X來 表示，產生碎裂凹痕量不可測定時，表示爲「破裂」，產生 裂縫（龜裂）時，表示爲「裂縫」。再者，關於在試料（殼體） 中製作之上記30mmx30mm的試驗片，任意的4處的厚度經 測定後，任何一處均等於原料的板厚度（厚度0.6mm)(試驗 片的厚度：〇.6mm)。 [S3 -17- 201111521 [表1] AI-Mn結晶物 張力試驗 衝擊試驗 合金 製造 試料 最大直徑 個/50/m2 張力強度 0.2耐力 延伸率 凹痕量 編號 成分 條件 形狀 (βτα) (※：個働㈣2) (MPa) (MPa) (%) (mm) 1-1 AZ91 A 板 0.4//m 11個 408 369 2.3 0(0.5) 1-2 AZ91 A 殻體 0.3//m 10個 381 300 5.7 0(0.5) 101 AZ91 B 殼體 15/zm 1個* 203 192 0.2 x(破裂） 102 AZ31 c 板 \3βτη 1個* 319 261 15.0 x(0_9) 103 AZ31 D 殻體 ll βπι 1個* 296 225 16.5 χ(0·9) 如表1所示，相對於自表面領域任意選擇之50 // m2， 最大直徑爲0.1/zm以上1/zm以下之AbMn結晶物爲15 個以下之鎂合金板或鎂合金構件，係與相同組成的鑄造材 或展伸材（AZ31合金）比較，得知在-30°C的低溫環境凹痕量 少' 耐衝撃性優異。這理由被認爲因爲即使在低溫環境也 具有優異的張力強度或延伸率等之機械特性。尤其，在該 試驗方面，在上述耐衝撃性優異的試料No.1-1，1-2中僅有 最大直徑爲O.Sym以下的結晶物存在。又，上述耐衝撃性 優異的試料No ·1-1，1-2中未觀察到最大直徑超過lem之 Al-Μη結晶物，認爲在最小限度的表面領域中實質上不存 在。相對於此，在特定的鑄造條件下未製造成市售品之試 料係在表面領域存在粗大的結晶物，因爲存在該粗大的結 晶物’因此認爲容易產生破裂等。而且，得知相對於自表 面領域任意選擇之50/zm2，最大直徑爲0.1/ζιη以上lym [S] -18- 201111521 以下之Α1-Μη結晶物爲15個以下之鎂合金板上藉由進行加 壓加工等的塑性加工，可獲得優異的耐衝撃性之鎂合金構 件。 [試驗例2] 使用在表2所示之鎂合金所構成之鑄錠（均爲市販）’ 在各種的條件下製作鎂合金板或鎂合金構件（殼體），進行 與試驗例1相同之所獲得的鎂合金板或鎂合金構件之組織 觀察、衝撃試驗（低溫）。其結果顯示於表2。 製造條件「鑄造—壓延」藉由雙輥連續鑄造法進行鑄 造，輥溫度及鑄造板的厚度如表2所示之條件。壓延條件 與試驗例1相同。但是，該試驗在壓延中，以原料保持在 150 °C〜250 °C的溫度範圍之總計時間成爲45分鐘或90分 鐘的方式，調整原料的加熱時間或壓延速度、壓延時的冷 卻速度等。再者，在試驗例1中，上述總計時間爲60分左 右。在表2中形狀爲「板」就是表示試料爲壓延板（鎂合金 板），所謂「殼體」就是表示試料爲自該壓延板以與試驗例 1相同的條件來製作箱狀體（鎂合金構件）。 在製造條件「條件B」、「條件C」、「條件D」係與 試驗例1之條件B(模具鑄造）、條件C(市售板）、條件D(市 售殼體）相同。製造條件「押出—壓延」係準備市售的押出 材，在該押出材上以與上述「鑄造—壓延」之情況相同之 條件進行壓延，所獲得之壓延板作爲試料（板），從該壓延 板以與上述「鑄造—壓延」情況相同之條件下製作箱狀體 [S] -19- 試料 編號 合金 成分 製造條件 試料 形狀 鑄造條件 Al-Μη結晶物 衝擊試驗 輥酿 厚度 最大直徑 (Mm) 個/50//m2 (※：個/200//m2) 凹陷量 (mm) 2-1 AZ91 鑄造一壓延 板 25°C 4mm 0.3//m 8個 0(0.4) 2-2 AZ91 鑄造一壓延 殼體 25〇C 4mm 0.3/z m 7個 0(0.4) 2-3 AZ91 鑄造一壓延 板 60°C 2mm 0.3//m 7個 0(0.4) 2-4 AZ91 鑄造一壓延 殼體 60°C 2mm 0.3//m 7個 0(0.4) 2-5 AZ91 鑄造-壓延 板 60°C 4mm ΟΛμτη 11個 0(0.5) 2-6 AZ91 鑄造一壓延 殼體 60°C 4mm 0.3//m 10個 0(0.5) 201 AZ91 鑄造一壓延 板 60°C 6mm 3.5//m 4個 x(裂縫） 202 AZ91 鑄造一壓延 殼體 60°C 6mm 3.5//m 4個 χ(裂縫） 203 AZ91 鑄造一壓延 板 12(TC 4mm 1.1 /zm 16個 χ(裂縫） 204 AZ91 鑄造—壓延 殼體 120°C 4mm ΙΛμχη 16個 χ(裂縫） 205 AZ91 條件B 殻體 15βτη 1個* χ(破裂） 206 AZ31 條件C 板 13βτη 1個* χ(0.9) 207 AZ31 條件D 殼體 ll βχη χ(0,9) 208 AZ91 押出—壓延 板 Ί fim 2個* χ(破裂） 209 AZ91 押出一壓延 殼體 6 βχη 2個* χ(破裂） 210 AZ91 押出—壓延 板 8/zm 2個* χ(破裂） 211 AZ9I 押出—·壓延 殼體 7/zm 之個8* χ(破裂） 201111521 作爲試料（殼體）。 [表 _ m -20- 201111521 如表2所示，得知在雙輥連續鑄造法之輥溫度爲loo °c 以下，且鑄造板的厚度爲5mm以下之鑄造，在鑄造板上進 行壓延，可製得相對自表面領域所選擇的任意之50ym2， 最大直徑爲O.lym以上lgm以下之Al-Mn結晶物爲15 個以下之鎂合金板和鎂合金構件。相對於此，得知若不以 上述特定的鑄造條件來製造，將存在粗大的結晶物。又， 與試驗例1相同，得知相對於自表面領域所選擇之任意的 5〇em2，最大直徑爲0.1，m以上lAm以下之Al-Mn結晶 物爲15個以下之鎂合金板或鎂合金構件，係即使在-30°C 之低溫環境也具有優異的耐衝撃性。又，試料No.2-1〜2-6 中各結晶物之粒子的Al/Mn經測定，任一試料亦爲Al/Mn =2 〜5。 進一步而言，根據該試驗可謂：（1)與製作的鑄造材之 厚度相同時，輥溫度越低越可減低結晶物，（2)與輥溫度相 同時，製作的鑄造材的厚度越薄越可減低結晶物。 又，上述之實施形態並未脫離本發明之要旨，可適當 的變更，並未限定於上述之構成。例如鎂合金之組成、鑄 造後及壓延後之板厚、鑄造時的輥溫度等可適當變更。 又，所獲得的壓延板或進行加壓加工之構件上可設置防腐 蝕處理或塗布層。 [產業上之利用可能性] 本發明鎂合金構件因爲在低溫環境下具有優異的耐衝 撃性，因此在低溫環境下所使用的各種殼體或元件可適當 [S] -21- .201111521 的利用。本發明鎂合金扳可適當利用於上述本發明鎂合金 構件之構成材料。本發明鎂合金板之製造方法可適當的利 用於本發明鎂合金板之製造。 【圖式簡單說明】 第1圖係說明衝擊試驗之槪略說明圖。 【主要元件符號說明】 1 試驗片 10 圓柱棒 20 支持台 21 圓洞 [S} -22-Al/Mn was measured as 'any of the samples Νο·1-1, ΐ-2, Al/Mn = 2 to 5. Then, 'the particle of each crystal in the above cross section, the straight line drawn in the cross section' has the largest length of the straight line cross-cut in each particle as the maximum diameter of the particle' maximum diameter of 0.1/ The number of crystals having a size of zm or more and 1/zm or less is taken as the number of crystals in the small field, and the number of crystals of the sample/50/zm2 is taken as the average of 5 small fields" in terms of the sample (housing) The bottom surface portion of the flat portion which was not accompanied by the tensile deformation in the sample was cut in the thickness direction, and the same cross section as the sample (plate) was observed, and the number of crystals was measured / 50 / zm 2 . However, in the above observation image, when a coarse crystal having a maximum diameter of more than 5/zm or more is found, the area of the small area is regarded as 200 #m2, and the maximum diameter and crystal form of the crystal present in the 200 m2 are measured. Number of /200 y m2. Further, in the above-mentioned small areas, the above-described respective areas are satisfied, and the shape is not particularly considered, but a rectangular shape (represented by a square) or the like is easily used. The measurement results are shown in Table 1. "Tensile test (low temperature)" A plate-shaped test piece of IIS 13B (JIS Z 2201 (1998)) was prepared from each sample (thickness: 0.6 mm), and the tension was measured based on the tensile test method of the metal material of JIS Z 2241 (1998). test. Here, the sample (plate) is used as the punctuation distance GL = 50 mm, the sample (shell) is used as the punctuation distance GL = 15 mm, and any sample is subjected to a tensile test at a tensile temperature of 5 mm/min at a test temperature of -30 ° C. Tensile strength (MPa), 0.2% proof stress (MPa), and elongation (%) (number of evaluations: n = l) were measured. The results are shown in Table 1. In addition, in the sample (housing), the test piece of the tensile test of the above-mentioned tensile test and the test piece of the punching test described later were cut out from the bottom surface portion of the flat portion which was not subjected to the tensile deformation in the sample, [S] -16 - 201111521. . "Crushing test (low temperature)". A sheet of 30 mm x 30 mm was cut out from each sample, and the cut piece was used as a test piece. In the test, as shown in Fig. 1, a support table 20 having a circular hole 21 having a diameter of d = 20 mm was prepared. The depth of the circular hole 21 allows the cylindrical rod 10 to be described later to be fully inserted. The test piece 1 was placed in such a manner as to block the round hole 21, and in this state, a weight of 100 g, a tip r = 5 mm, and a cylindrical rod 10 made of ceramics were placed at a height of 200 mm from the test piece 1 to the center axis and the circle. The central axis of the hole 21 is configured to be coaxial. Then, the test piece 1 was allowed to freely drop the cylindrical rod 10 from the above-mentioned arrangement position (height 200 mm), and then the amount of dent of the test piece 1 was measured. The amount of dent (mm) is taken out by connecting a straight line connecting the two sides of the straight test piece 1, and the distance from the straight line to the most depressed portion is measured using a point micrometer. The punching test was carried out in a low temperature environment of -3 (TC). The results are shown in Table 1. The amount of the dent is 0.5 mm or less, and the value exceeding 0.5 mm is represented by X. When the amount of dents is not measured, it is expressed as When the crack (cracking) occurs, it is expressed as a "crack." Further, a test piece of 30 mm x 30 mm is prepared in the sample (housing), and any of the four thicknesses are measured, and then any one is measured. Both are equal to the thickness of the material (thickness 0.6 mm) (thickness of the test piece: 〇.6 mm) [S3 -17- 201111521 [Table 1] AI-Mn crystal tension test impact test alloy manufacturing sample maximum diameter / 50 / M2 Tensile strength 0.2 Endurance elongation Dent amount No. Component condition shape (βτα) (※: 働 (4) 2) (MPa) (MPa) (%) (mm) 1-1 AZ91 A plate 0.4//m 11 408 369 2.3 0(0.5) 1-2 AZ91 A Housing 0.3//m 10 381 300 5.7 0(0.5) 101 AZ91 B Housing 15/zm 1 * 203 192 0.2 x (breaking) 102 AZ31 c Board \3βτη 1 * 319 261 15.0 x (0_9) 103 AZ31 D Housing ll βπι 1 * 296 225 16.5 χ (0·9) As shown in Table 1, relative to the self-surface field Select 50 // m2, AbMn crystals with a maximum diameter of 0.1/zm or more and 1/zm or less are 15 or less magnesium alloy sheets or magnesium alloy members, and cast or stretched materials of the same composition (AZ31 alloy) In comparison, it is found that the amount of dent is low in a low-temperature environment at -30 ° C, and the punching resistance is excellent. This reason is considered to be because it has excellent mechanical properties such as tensile strength or elongation even in a low-temperature environment. In the test No. 1-1 and 1-2 which are excellent in the above-mentioned squeezing resistance, only the crystal having a maximum diameter of O.Sym or less is present. Further, the sample No. 1-1 excellent in the rinsing resistance is No Al-Μη crystals having a maximum diameter exceeding lem were observed in 1-2, and it was considered that they were not substantially present in the minimum surface area. In contrast, samples which were not manufactured into commercial products under specific casting conditions were not produced. There is a large crystal in the surface area, because the coarse crystal is present, so it is considered to be prone to cracking, etc. Moreover, it is known that the maximum diameter is 0.1/ζιη or more lym with respect to 50/zm2 arbitrarily selected from the surface field. [S] -18- 201111521 Following Α 1- η crystals is 15 or less of magnesium alloy sheet by pressurization processing for plastic working, can be obtained having excellent properties of impact-resistant magnesium alloy clicks member. [Test Example 2] A magnesium alloy sheet or a magnesium alloy member (housing) was produced under various conditions using ingots (all commercially available) composed of the magnesium alloys shown in Table 2, and the same procedure as in Test Example 1 was carried out. The microstructure observation and the ramming test (low temperature) of the obtained magnesium alloy sheet or magnesium alloy member. The results are shown in Table 2. The manufacturing conditions "casting-calendering" were cast by a two-roll continuous casting method, and the roll temperature and the thickness of the cast sheet were as shown in Table 2. The rolling conditions were the same as in Test Example 1. However, in the test, the heating time of the raw material, the calendering speed, the cooling rate of the pressurization, and the like were adjusted so that the total time during which the raw material was maintained at a temperature ranging from 150 °C to 250 °C was 45 minutes or 90 minutes. Further, in Test Example 1, the above total time was about 60 minutes. In the case of Table 2, the shape of the "plate" means that the sample is a rolled plate (magnesium alloy plate), and the "shell" means that the sample is a box-shaped body (magnesium alloy) from the rolled plate under the same conditions as in Test Example 1. member). The production conditions "Condition B", "Condition C", and "Condition D" are the same as those of Test B (Mold Casting), Condition C (commercially available), and Condition D (commercially available) of Test Example 1. The manufacturing condition "extraction-calendering" is to prepare a commercially available extruded material, and the extruded material is rolled under the same conditions as the above-mentioned "casting-calendering", and the obtained rolled sheet is used as a sample (plate) from the rolling The box is made under the same conditions as the above-mentioned "casting-calendering". [S] -19- Sample No. Alloy composition Manufacturing conditions Sample shape Casting conditions Al-Μη crystal impact test roll Maximum thickness (Mm) /50//m2 (※: one /200//m2) Depression (mm) 2-1 AZ91 Casting a rolled sheet 25°C 4mm 0.3//m 8 0(0.4) 2-2 AZ91 Casting a calendered shell Body 25〇C 4mm 0.3/zm 70(0.4) 2-3 AZ91 Casting a rolled sheet 60°C 2mm 0.3//m 7 0(0.4) 2-4 AZ91 Casting a calendered shell 60°C 2mm 0.3 //m 7 0(0.4) 2-5 AZ91 Cast-rolled sheet 60°C 4mm ΟΛμτη 11 0(0.5) 2-6 AZ91 Casting a calendered shell 60°C 4mm 0.3//m 10 0 (0.5 201 AZ91 Casting a rolled sheet 60°C 6mm 3.5//m 4 x (cracks) 202 AZ91 Casting a calendering shell 60°C 6mm 3.5//m 4 χ (crack) 203 AZ91 casting one pressure Plate 12 (TC 4mm 1.1 /zm 16 χ (crack) 204 AZ91 Casting - calendering shell 120 ° C 4mm ΙΛμχη 16 χ (crack) 205 AZ91 Condition B Housing 15βτη 1 * χ (rupture) 206 AZ31 Condition C Plate 13βτη 1* χ(0.9) 207 AZ31 Condition D Shell ll βχη χ(0,9) 208 AZ91 Extrusion—rolled sheet Ί fim 2* χ(rupture) 209 AZ91 Extruded a calendered shell 6 βχη 2* χ (rupture) 210 AZ91 Extrusion - calendering plate 8 / zm 2 * χ (rupture) 211 AZ9I Extrusion - · 8* 压 (rupture) of the calendered shell 7/zm 201111521 As a sample (housing). m -20- 201111521 As shown in Table 2, it is found that in the twin-roll continuous casting method, the roll temperature is loo °c or less, and the thickness of the cast plate is 5 mm or less, and rolling is performed on the cast plate to obtain a relative Any of 50ym2 selected from the surface field, and the Al-Mn crystal having a maximum diameter of O.lym or more and lgm or less is a magnesium alloy plate and a magnesium alloy member of 15 or less. On the other hand, it has been found that coarse crystals are present unless they are produced under the above-described specific casting conditions. Further, in the same manner as in Test Example 1, it was found that the Al-Mn crystal having a maximum diameter of 0.1, m or more and 1 Am or less was 15 or less of a magnesium alloy sheet or a magnesium alloy with respect to any 5 〇em2 selected from the surface field. The member has excellent impact resistance even in a low temperature environment of -30 °C. Further, in the samples No. 2-1 to 2-6, the Al/Mn of the particles of the respective crystals was measured, and any of the samples was also Al/Mn = 2 to 5. Further, according to the test, (1) when the thickness of the cast material to be produced is the same, the lower the roll temperature, the lower the crystal grain, and (2) the lower the thickness of the cast material, the thinner the thickness of the cast material produced. Can reduce crystals. Further, the above-described embodiments are not departing from the gist of the present invention, and may be appropriately modified, and are not limited to the above configuration. For example, the composition of the magnesium alloy, the thickness of the sheet after casting and rolling, the roll temperature at the time of casting, and the like can be appropriately changed. Further, an anticorrosive treatment or coating layer may be provided on the obtained rolled sheet or the member subjected to press working. [Industrial Applicability] Since the magnesium alloy member of the present invention has excellent impact resistance in a low-temperature environment, various housings or components used in a low-temperature environment can be suitably used [S] -21-.201111521 . The magnesium alloy of the present invention can be suitably used as a constituent material of the above-mentioned magnesium alloy member of the present invention. The method for producing a magnesium alloy sheet of the present invention can be suitably used for the production of the magnesium alloy sheet of the present invention. [Simple description of the drawings] Fig. 1 is a schematic diagram illustrating the impact test. [Explanation of main component symbols] 1 Test piece 10 Cylindrical rod 20 Support table 21 Round hole [S} -22-