200523373 (1) 九、發明說明 【發明所屬之技術領域】 本發明係關於質輕且比剛性高的鎂合金，特別係關於 壓鑄用鎂合金以及使用此壓鑄用鎂合金的鎂壓鑄製品。 【先前技術】 在被大量地使用的合金中，鎂合金是最質輕且比剛性 高的合金，以筆記型電腦、手機爲首，被使用於攜帶型電 動器具等之中的鑄造用Mg合金，幾乎爲AZ91合金。此 AZ91合金，強度、耐蝕性、成形性等方面優異，作爲均 衡性佳的鑄造用合金，而廣泛地被使用在壓鑄用，但是並 不適用於被要求高拉伸、彎曲、耐熱性的機械特性之汽 車、機車等的用途中。因此，對於這些用途，通常是使用 減少 A1量來改善拉伸性之 AM60系合金或 AM50系合 金。 近年來，隨著對於汽車零件的輕量化要求的提高，同 時更靠近引擎的蓋類也要M g合金化，所以賦予耐熱性能 的新合金的開發，熱烈地進行（例如參照專利文獻1 )。 根據此習知技術的合金，係改良AM50合金或AM60合金 而成的合金；以 A1: 2〜9%、Sr: 0.5〜7°/。作爲基質，理 想爲作成六1:4〜6%及八1:4.5〜5.5%且 211:0.35%以下 (AM合金標準）。又，關於根據前述習知技術所作成的 合金和AZ系合金的比較，例如記載於非專利文獻1。第 1 7圖係表示被記載於此文獻中的比較內容的圖。 -5- 200523373 (2) 【專利文獻1】日本特表2003-517098號公報 【非專利文獻 1】pegureryutu 、 Balil共著 「Development of C r e e p R e s i s t a n t M g - A1 - S r A11 〇 y s」 Magnesium Technology 200 1 ( TMS) 【發明內容】 (發明所欲解決之課題） 但是，前述習知的合金（改良AM50合金或AM60合 金而成的合金），存在以下的課題。 第1 7圖的下段係表示前述習知技術的合金（以下適 當地稱爲習知合金）的一例，與AZ9 1合金比較，室溫 (常溫）下的拉伸強度，大約低1 5 %。而在1 7 5 °C時的拉 伸強度，雖然被改善7%程度，但是室溫、175。(：下的拉伸 率低。潛變特性値等，確實被改善，但是材料實際使用 時，由於係暴露在自室溫開始至1 7 5 t爲止的高溫的環境 中’所以無法無視於室溫下的物性。前述習知技術，並未 考量此點，而無法防止在室溫下的強度的降低。 本發明的目的在於提供一種壓鑄用鎂合金以及使用此 壓鑄用鎂合金的鎂壓鑄製品，不會招致室溫強度的降低， 並能夠提升高溫潛變性能。 (解決課題所用的手段） 爲了達成前述目的，根據第1發明的壓鑄用鎂合金， 其特徵爲：對於鋁7 · 0〜1 1 . 0重量％、鋅〇,]〜2 · 5重量％、 -6 - 200523373 (3) 錳0 · 1〜0 · 5重量之A Z 9 1系合金，作爲結晶微細化劑， 添加鈣及鋸。 就本案的弟1發明而S ’係將成爲基質的合金，設爲 含有鋁7.0〜1 1 . 0重量％、鋅0 · 1〜2 · 5重量％、錳0 . 1〜〇 . 5 重量％之所謂的AZ9 1系合金，而對於此合金作成添加了 C a、S r的組成。藉由將基質設爲A Z 9 1系合金，能夠防止 如AM 6 0系合金般的室溫的強度特性降低的情況。而且， 藉由對此AZ91系合金添加Ca、Sr來作爲結晶微細化劑， 改良合金組織來使結晶粒徑尺寸微細化，而能夠得到與以 高溫潛變性能且耐熱性鎂合金聞名的A S 2 1合金同等的優 異特性。結果，不會招致室溫強度的降低，並能夠實現高 溫潛變性能已經提高的合金。 爲了達成前述目的，根據第2發明的壓鑄用鎂合金， 其特徵爲：對於鋁7.0〜1 1 · 0重量％、鋅0 . 1〜2.5重量。/〇、 錳0.1〜0.5重量％之AZ91系合金，添加鈣1.0〜3.5重量 %、緦 〇 · 1〜1 . 5重量％，其他成分則爲不可避免地被包 含。 就本案的第2發明而言，係將成爲基質的合金，設爲 含有鋁7.0〜11.0重量％、鋅0.1〜2.5重量％、錳0.1〜0.5 重量％之所謂的AZ9 1系合金，而對於此合金作成添加了 Ca、Sr的組成。藉由將基質設爲AZ91系合金，能夠防止 如AM60系合金般的室溫的強度特性降低的情況。而且， 藉由對此AZ91系合金添加Ca、Sr來作爲結晶微細化劑， 改良合金組織，而能夠使結晶粒徑尺寸微細化。此時，特 -7- 200523373 (4) 別是藉由將鈣和鋸的添加量設爲鈣1 · 〇〜3 . 5重量〇/。、總 0.1〜1.5重量％，能夠確實地使結晶粒徑尺寸作成20μιη 以下，而能夠得到與以高溫潛變性能且耐熱性鎂合金聞名 •的AS2 1合金同等的優異特性。結果，不會招致室溫強度 的降低，並能夠確實地實現高溫潛變性能已經提高的合 金。 爲了達成前述目的，根據第3發明的鎂壓鑄製品，其 特徵爲··使用壓鑄用鎂合金，被進行壓鑄鑄造而構成；而 該壓鑄用鎂合金係對於鋁7.0〜1 1 · 〇重量％、鋅0 . 1〜2.5 重量％、錳0.1〜0.5重量％之ΑΖ91系合金，作爲結晶微 細化劑，添加鈣及緦而成的合金。 就本案的第3發明而言，作爲在鎂壓鑄製品中所使用 的合金，係使用對於含有鋁 7 · 0〜1 1 · 〇重量％、鋅〇 . 1〜 2.5重量。/〇、錳0· 1〜0.5重量％之所謂的ΑΖ91系合金，添 力口了 Ca、Sr的組成之合金。藉由將合金的基質設爲ΑΖ91 系合金，能夠防止如AM60系合金般的室溫的強度特性降 低的情況。而且，藉由對此AZ91系合金，添加Ca、Sr， 來作爲即使爲了壓鑄而再熔解也不會損害效果之結晶微細 化劑，不會損害熔湯流動性，改良合金組織來使結晶粒徑 尺寸微細化，同時能夠得到與以高溫潛變性能且耐熱性鎂 合金聞名的A S2 1合金同等的優異特性。結果，使用不會 招致室溫強度的降低且高溫潛變性能已經提高的合金，能 夠製造出成形性佳的壓鑄製品。 爲了達成前述目的，根據第4發明的鎂壓鑄製品，其 -8- 200523373 (5) 特徵爲：使用壓鑄用鎂合金，被進行壓鑄鑄造而構成； 而該壓鑄用鎂合金係對於鋁7 · 0〜1 1 · 0重量％、鋅0 . 1 〜2.5重量％、f孟0.1〜0.5重量％之AZ91系合金’添加金丐 1 . 0〜3 . 5重量％、緦0 . 1〜1 . 5重量％，其他成分則爲不可 避免地被包含而成的合金。 就本案的第4發明而言，作爲在鎂壓鑄製品中所使用 的合金，係使用對於含有鋁7.0〜11.0重量％、鋅0.1〜 2.5重量％、錳0.1〜0.5重量％之所謂的AZ91系合金，添 加了 Ca、Sr的組成之合金。藉由將合金的基質設爲AZ91 系合金，能夠防止如AM60系合金般的室溫的強度特性降 低的情況。而且，藉由對此AZ91系合金，添加Ca、Sr， 來作爲即使爲了壓鑄而再熔解也不會損害效果之結晶微細 化劑，不會損害熔湯流動性，並能夠改良合金組織來使結 晶粒徑尺寸微細化。此時，特別將鈣和緦的添加量設爲鈣 1 · 〇〜3 · 5重量％、緦〇 .丨〜1 . 5重量％，能夠確實地將結晶 粒徑尺寸作成2 0 μπι以下，而能夠得到與以高溫潛變性能 且耐熱性鎂合金聞名的A S 2 1合金同等的優異特性。結 果’使用不會招致室溫強度的降低且高溫潛變性能確實已 經提高的合金，能夠製造出成形性佳的壓鑄製品。 【實施方式】 (實施發明的最佳形態） 以下’一邊參照圖面一邊說明本發明的一實施形態。 本發明的發明人，如前所述，根據不會如習知合金般 -9- 200523373 (6) 地招致室溫強度的降低，並提升高溫潛變性能的觀點，針 對一面維持AZ9 1合金的優異特性一面改善高溫潛變特性 之壓纟S用鎂合金以及壓鑄製品進彳了各式各樣的檢討。以 下’依序地說明其思考方式及檢討結果。 (1 )結晶粒徑尺寸的微細化 首先，本發明的發明人，以AZ9 1合金壓鑄品的特性 改善爲目標，進行檢討。將AZ9 1合金壓鑄鑄造後的結晶 粒徑尺寸，大約爲40μιη，與大約爲200〜3 00μιη之通常的 重力鏡造的情況比較’結晶粒相當微細化。因此，被使用 在習知重力鑄造中的結晶微細化劑，在壓鑄鑄造中被視爲 不需要。本發明的發明人，刻意將微細化劑添加在壓鑄合 金中，嘗試以此合金的鑄錠來進行壓鑄成形。 在文獻等之內’各種微細化劑之中，如六氯乙烷般， 即使微細化效果高，在添加時會發生氯氣；或是如金屬 Na般的在處理上會伴隨著相當的危險。作爲用於壓鑄且 即使再熔解也不會損害效果的微細化劑，選擇C a、S r，並 進行複合添加的檢討。 最初’關於AZ91合金和將Cal% + Sr0.5%添加入AZ91 中而成合金’利用爐內冷卻法測量熔點。由該結果可知， 添加了 Ca、Sr的合金，與AZ91合金比較，熔點稍低（參 照第1圖）。將雙方的熔湯再度熔解，分別注入鑄模內， 確認了雙方的熔湯的流動性（在應用於壓鑄製品的情況， 相當於壓鑄成形性）完全沒有問題，是良好的。 -10- 200523373 (7) 接著’在鋁塗層後的鐵坩堝中，熔解 AZ91合金 3kg ’保持在6 8 0。(：之後，添加規定量的Ca和Sr，然後利 用柄勺每次100g快速地澆鑄在預先溫熱成1〇〇。(：的管狀金 屬模（管壁厚度3 m m、內徑3 2 m m 0、深度5 3 m m )中， 而作出試料。試料在中間部往橫向切斷，並爲了使結晶粒 界鮮明化，進行4 1 0 °C、2小時的熔體化處理，再硏磨成 鏡面之後，利用6%苦味酸乙醇溶液進行蝕刻，並用顯微 鏡檢查。結晶粒徑尺寸，係利用鋼鐵JIS的結晶粒度測量 法的切片法來求得。 第2圖係表示將C a添加在A Z 9 1合金中的情況的結晶 粒徑的測量結果；第3圖係表示同樣地在已經添加有 Cal %之AZ91合金熔湯中，添加Sr時的結果。第4圖係 AZ91CaSr合金的熔製例。並將改變Ca和Sr的添加量， 對每個試料測量結晶粒徑尺寸後的結果，集中表示於第5 圖。 如這些第2圖、第3圖、第4圖及第5圖所示，可 知：無添加的情況，結晶尺寸爲40 μπι，而在單獨地Ca或 Sr的情況，結晶粒徑無法爲20μηι以下，但是在複合添加 的情況，在虛線所包圍的範圍內，則能夠在2 0 μπι以下。 此範圍係C a 1 · 0重量°/❶以上、3 . 5重量％以下，s r 0 . 1重量％ 以上、1 . 5重量％以下的範圍。 將Ca和Sr添加在AZ91合金中而成的合金，對其進 行壓鑄成形，當與AZ9 1合金比較時，壓鑄成形品的結晶 粒徑尺寸，係成爲澆鑄在管狀金屬模內時的結晶粒徑尺寸 -11 - 200523373 (8) 的1.03倍；另一方面，相對於AZ91合金之AZ9ICaSr合 金的結晶粒徑尺寸比，即使是在相異的鑄造·成形條件 下，可知結晶粒係以0.34之一定的比例微細化（參照第6 圖）。以往，關於壓鑄品，由於結晶粒微細化劑係被視爲 無用的，故此爲新的創見。 如此的結晶粒徑尺寸的微細化，由於粒界的網絡表面 光滑細緻，材料強度增加，且析出在粒界的/3相的厚度變 薄，由於成爲腐蝕原因之容易在粒界生成的粗大的金屬間 化合物，變成不易生成，所以能夠提高腐蝕性。 (2 )室溫強度及拉伸特性和熔湯流動性 接著，本發明的發明人，依據前述（1 )的結果，檢 討如前述般地將Ca、Sr添加在AZ91合金中而成的合金 (以下，適當地簡稱爲「Ca、Sr添加合金」）的室溫強度 特性及特性。 使用第7圖所示的合金鑄錠，利用冷式壓鑄成形機， 成形溫度（熔解爐溫度）650 °C，並使用1 .5mm厚、B5尺 寸的平坦的試驗金屬模，以金屬模溫度200 °C的狀態下， 分別成形8 0枚。將成形板5枚橫方向分割3等分、縱方 向分割2等分，而作成的6枚小片，利用水置換法來測量 其密度’再根據另外分析出來的成分値和化學便覽記載的 原子密度表’加以累計所求得的理論密度，計算模內的充 塡率。進而，從成形板5枚，切出常溫拉伸試驗片，再利 用英式拉伸試驗機（instr〇n tensile tester )測量室溫下的 200523373 (9) 拉伸強度、拉伸率（拉伸値）。 第8圖係表示壓鑄成形後的前述試驗板的充塡率（本 發明組成的平均値）。由此圖可知，若添加C a、S r，充塡 率提高。 第9圖係表示壓鑄成形品的室溫拉伸強度。又，合倂 表示壓鑄試驗片進行4 1 0 °C、2小時熔體化處理後的測量 結果。如該圖所示可知，as-cast的情況，Ca、Sr添加合 金比AZ91合金高7%左右的値。又，AZ91合金，若進行 熔體化處理，則強度下降，而根據試驗片觀察的結果，散 見氣泡，此被認爲是使物性降低、充塡率下降的原因。而 根據添加了 Ca、Sr之本發明的實施形態的合金（以下適 當地簡稱爲「Ca、Sr添加合金」），即使進行熔體化處 理，強度不會降低，也沒有觀察到氣泡。 又，將拉伸率表示於第10圖中，Ca、Sr添加合金大 致與AZ91合金相同。可知若將Ca和Sr添加在AZ91合 金中’在壓鑄時，沒有氣泡捲入，由於提高充塡率同時提 高拉伸強度，所以壓鑄成形性被改善。 再者，本發明的發明人，不是檢討Ca、Sr的添加 量’而是也另外檢討被添加側的 AZ9 1合金的成分對於室 溫拉伸強度的影響；得知若A1的含量比率低於7重量°/〇， 則前述室溫拉伸強度的改善效果消失。因此，爲了改善室 溫拉伸強度，A1的含量比率，設爲7重量％以上是適當 的。 -13- 200523373 (10) (3 )高溫潛變特性 接著，本發明的發明人，依據前述（1 ) 、 （ 2 )的結 果，檢討Ca、Sr添加合金的高溫潛變特性。 由壓纟#成形品5枚’切出試驗片，並利用定速式汽严 潛變試驗機，求出在1 75 t時的潛變資料。再者，爲了進 行比較，關於通常的A Z 91合金或其他的a Z系合金，也 進行同樣的測量。 在第11圖、第12圖及第13圖中，表示在i7yc時的 定速法高溫潛變試驗的結果。 第1 1圖係表示應變速度和流動應力的關係。將c a、 Sr添加在AZ91合金中所得到的本實施形態的ca、Sr添 加合金，與AZ91合金比較，在各應變速度下，提高1〇〜 2 0%流動應力，可知耐潛變性變高。 第12圖係表示潛變拉伸率的資料。AZ61合金以及 AZ 9 1合金，會由於潛變速度的不同，拉伸率會有在25% 以下的情況；相對於此，Ca、Sr添加合金，不論應變速度 爲何，拉伸率皆在29%以上。 第1 3圖係爲了與其他的合金比較，在日本鎂協會的 資料庫的圖表上，記載這些結果所得到的圖。協會的測量 方法爲定應力法。不論是何種方法，原理上皆是評價相同 物性的方法。再者，也一倂表示其他合金在1 7 5 °C時的文 獻資料。再者，圖中，「Mercer」係表示根據文獻 「W.E.Mercerll “Magnesium Die Cast Alloys for Elevated200523373 (1) IX. Description of the invention [Technical field to which the invention belongs] The present invention relates to a magnesium alloy that is lightweight and has a high specific rigidity, and particularly relates to a magnesium alloy for die casting and a magnesium die-casting product using the magnesium alloy for die casting. [Prior art] Among the alloys that are widely used, magnesium alloys are the lightest and more rigid alloys. Mg alloys for casting are used in portable electric appliances such as notebook computers and mobile phones. , Almost AZ91 alloy. This AZ91 alloy is excellent in strength, corrosion resistance, and formability. It is widely used as a die-casting alloy with good balance, but it is not suitable for machinery that requires high tensile, bending, and heat resistance. Characteristics of automotive, locomotive, etc. Therefore, for these applications, AM60-based alloys or AM50-based alloys that reduce the amount of A1 to improve stretchability are generally used. In recent years, with the increase in requirements for weight reduction of automobile parts, at the same time, the covers that are closer to the engine also need to be alloyed with Mg. Therefore, the development of new alloys that impart heat resistance has been actively carried out (for example, refer to Patent Document 1). The alloy based on this conventional technology is an alloy modified from AM50 alloy or AM60 alloy; A1: 2-9%, Sr: 0.5-7 ° /. As the substrate, it is desirable to prepare six 1: 4 to 6% and eight 1: 4.5 to 5.5% and 211: 0.35% or less (AM alloy standard). A comparison between an alloy made by the conventional technique and an AZ-based alloy is described in Non-Patent Document 1, for example. Fig. 17 is a diagram showing comparison contents described in this document. -5- 200523373 (2) [Patent Document 1] Japanese Patent Publication No. 2003-517098 [Non-Patent Document 1] "Development of C Reep Resistant M g-A1-S r A11 〇ys" co-authored by Pegureryutu and Balil Magnesium Technology 200 1 (TMS) [Summary of Invention] (Problems to be Solved by the Invention) However, the aforementioned conventional alloys (alloys modified from AM50 alloy or AM60 alloy) have the following problems. The lower part of FIG. 17 shows an example of the alloy of the conventional technique (hereinafter referred to as a conventional alloy). Compared with the AZ9 1 alloy, the tensile strength at room temperature (normal temperature) is approximately 15% lower. Although the tensile strength at 17.5 ° C is improved by about 7%, the room temperature is 175. (: The elongation rate is lower. The creep properties, etc., are indeed improved, but when the material is actually used, it is not exposed to room temperature because it is exposed to a high temperature environment from room temperature to 17 5 t. The foregoing conventional technology does not take this into consideration, and cannot prevent a reduction in strength at room temperature. An object of the present invention is to provide a magnesium alloy for die casting and a magnesium die casting product using the magnesium alloy for die casting. (Means for Solving the Problems) In order to achieve the aforementioned object, the magnesium alloy for die-casting according to the first invention is characterized in that it does not cause a decrease in the strength of the room temperature and the high temperature creep property. 1.0% by weight, zinc 〇,] ~ 2.5% by weight, -6-200523373 (3) AZ 9 1 series alloy with 0. 1 ~ 0.5% manganese, as a crystal refiner, adding calcium and saw With respect to the invention of the first invention of the present case, the alloy S 'is to be a matrix, and is set to contain 7.0 to 11.0% by weight of aluminum, 0. 1 to 2 · 5% by weight of zinc, and 0.1 to 0.5% by weight of manganese. % Of the so-called AZ9 1 series alloy, and this alloy is made by adding The composition of C a and S r. By using the matrix as an AZ 9 1-based alloy, it is possible to prevent a decrease in the strength characteristics at room temperature like the AM 6 0-based alloy. Furthermore, by adding Ca to this AZ91-based alloy Sr and Sr are used as crystal micronizers, and the alloy structure is improved to make the crystal grain size finer, so that it can obtain the same excellent characteristics as the AS 2 1 alloy known for its high temperature creep properties and heat resistant magnesium alloy. As a result, it will not An alloy that causes a decrease in the strength at room temperature and an improved high-temperature creep property. In order to achieve the foregoing object, the magnesium alloy for die-casting according to the second invention is characterized by 7.0 to 1 1 · 0% by weight of aluminum, zinc 0.1 to 2.5% by weight. 〇, 0.1 to 0.5% by weight of AZ91 series alloy of manganese, 1.0 to 3.5% by weight of calcium, 缌 0.15 to 1.5% by weight, and other components are inevitably included. In the second invention of the present application, the alloy to be a matrix is a so-called AZ9 1-series alloy containing 7.0 to 11.0% by weight of aluminum, 0.1 to 2.5% by weight of zinc, and 0.1 to 0.5% by weight of manganese. Alloy made of Ca and Sr Composition. By using a matrix of AZ91-based alloy, it is possible to prevent a decrease in strength characteristics at room temperature like AM60-based alloy. In addition, by adding Ca and Sr to this AZ91-based alloy as a crystal refiner, it is improved The alloy structure can make the crystal grain size smaller. At this time, -7-200523373 (4) In addition, the amount of calcium and saw is set to calcium 1 · 〇 ~ 3.5 weight 0 /., With a total amount of 0.1 to 1.5% by weight, it is possible to reliably make the crystal grain size to 20 μm or less, and it is possible to obtain excellent characteristics equivalent to the AS2 1 alloy, which is known for its high temperature creep performance and heat resistant magnesium alloy. As a result, it is possible to surely realize an alloy having an improved high-temperature creep property without causing a decrease in the strength at room temperature. In order to achieve the foregoing object, the magnesium die-casting product according to the third invention is characterized by using a magnesium alloy for die-casting and being formed by die-casting; and the magnesium alloy for die-casting is 7.0 to 1 1% by weight of aluminum, An AZ91-based alloy containing 0.1 to 2.5% by weight of zinc and 0.1 to 0.5% by weight of manganese is an alloy formed by adding calcium and hafnium as a crystal refiner. According to the third invention of the present invention, as the alloy used in the magnesium die-casting product, 7.1 to 2.5 wt% of aluminum and 0.1 to 2.5 wt% of zinc are used. / 〇, manganese 0.1 to 0.5% by weight of the so-called AZ91-based alloy, added Ca and Sr composition alloy. By making the matrix of the alloy an AZ91-based alloy, it is possible to prevent a decrease in the strength characteristics at room temperature like the AM60-based alloy. In addition, by adding Ca and Sr to this AZ91-based alloy, it is used as a crystal micronizing agent that does not impair the effect even if it is remelted for die-casting, does not impair the fluidity of the molten soup, and improves the alloy structure to make the crystal grain size. Reducing the size, it is possible to obtain the same excellent characteristics as the A S2 1 alloy, which is known for its high temperature creep properties and heat resistant magnesium alloy. As a result, the use of an alloy that does not cause a decrease in the strength at room temperature and an increase in the high-temperature creep property makes it possible to produce a die-cast product having excellent formability. In order to achieve the foregoing object, the magnesium die-casting product according to the fourth invention is characterized in that -8-200523373 (5) is characterized in that a magnesium alloy for die-casting is formed by die-casting; and the magnesium alloy for die-casting is aluminum 7 · 0 ~ 1 1 · 0 wt%, zinc 0.1 ~ 2.5 wt%, f ~ 0.1 ~ 0.5 wt% of AZ91 series alloy 'added gold beggar 1.0 ~ 3.5 wt%, 缌 0.1 ~ 1.5 % By weight, and other components are alloys inevitably contained. In the fourth invention of the present application, as the alloy used in the magnesium die-casting product, a so-called AZ91-based alloy containing 7.0 to 11.0% by weight of aluminum, 0.1 to 2.5% by weight of zinc, and 0.1 to 0.5% by weight of manganese is used. Alloys with the composition of Ca and Sr. By making the matrix of the alloy an AZ91-based alloy, it is possible to prevent a decrease in the strength characteristics at room temperature like the AM60-based alloy. In addition, by adding Ca and Sr to this AZ91 series alloy, it can be used as a crystal micronizing agent that does not impair the effect even if it is remelted for die-casting. Refinement of particle size. In this case, in particular, the amount of calcium and rhenium added is set to calcium 1 · 〇 ~ 3.5% by weight and 缌 〇. 丨 ~ 1.5% by weight, and the crystal grain size can be reliably made to 20 μm or less, and It has the same excellent characteristics as AS 2 1 alloy, which is known for its high temperature creep properties and heat resistant magnesium alloy. As a result, the use of an alloy that does not cause a decrease in the strength at room temperature and indeed an improvement in the high-temperature creep property makes it possible to produce a die-cast product having excellent formability. [Embodiment] (Best Mode for Carrying Out the Invention) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As described above, the inventor of the present invention, from the viewpoint of not lowering the strength of the room temperature and improving the high temperature creep properties as would be the case with conventional alloys-9-200523373 (6), maintains the The excellent properties of magnesium alloys and die-casting products for improving the high temperature creep characteristics have undergone various reviews. The following ’sequentially explain the way of thinking and the results of the review. (1) Refinement of crystal grain size First, the inventors of the present invention conducted a review with the goal of improving the characteristics of AZ9 1 alloy die-casting products. The crystal grain size of the AZ9 1 alloy after die-casting is about 40 µm, and the crystal grains are considerably finer compared with the case of ordinary gravity mirror manufacturing of about 200 to 3 00 µm. Therefore, the crystal micronizer used in the conventional gravity casting is considered unnecessary in the die casting casting. The inventors of the present invention deliberately added a micronizing agent to a die-casting alloy, and tried to perform die-casting with an ingot of this alloy. Among the various types of micronizing agents, such as hexachloroethane, even if the micronizing effect is high, chlorine gas may be generated during the addition, or a metal Na-like material may be accompanied with considerable danger in handling. As a micronizing agent for die-casting that does not impair the effect even after remelting, select Ca and S r and review the compound addition. Initially, "the AZ91 alloy and the alloy formed by adding Cal% + Sr0.5% to AZ91" measured the melting point by the furnace cooling method. From this result, it can be seen that the alloy containing Ca and Sr has a slightly lower melting point than the AZ91 alloy (see Fig. 1). The molten soup from both sides was melted again and injected into the mold respectively, and it was confirmed that the fluidity of the molten soup (when applied to a die-cast product, which is equivalent to die-casting formability) was completely satisfactory, and was good. -10- 200523373 (7) Next, in an iron crucible after aluminum coating, 3 kg of AZ91 alloy is melted and maintained at 6 8 0. (: After that, add a predetermined amount of Ca and Sr, and then use a handle spoon to quickly cast 100g each time to warm up to 100. (: tubular metal mold (thickness of tube wall 3 mm, inner diameter 3 2 mm 0 , Depth 5 3 mm), to make a sample. The sample is cut in the middle to the lateral direction, and in order to make the crystal grain boundary clear, melt treatment at 4 10 ° C for 2 hours, and then honing to a mirror surface After that, it was etched with a 6% picric acid ethanol solution and inspected with a microscope. The crystal grain size was determined by the slicing method using the crystal grain size measurement method of steel JIS. Figure 2 shows the addition of Ca to AZ 9 1 The results of measurement of the crystal grain size in the case of the alloy; Fig. 3 shows the results when Sr is added to the AZ91 alloy molten soup to which Cal% has been added. Fig. 4 shows an example of melting of the AZ91CaSr alloy. The results of changing the amount of Ca and Sr and measuring the crystal grain size for each sample are collectively shown in Figure 5. As shown in Figures 2, 3, 4, and 5, : Without addition, the crystal size is 40 μm, while Ca or S alone In the case of r, the crystal grain size cannot be less than 20 μm, but in the case of compound addition, it can be less than 20 μm within the range surrounded by the dotted line. This range is C a 1 · 0 weight ° / ° or more, 3 5% by weight or less, sr 0.1% by weight or more and 1.5% by weight or less. An alloy formed by adding Ca and Sr to an AZ91 alloy and die-casting it. When compared with AZ9 1 alloy. The crystal grain size of the die-casting product is 1.03 times that of the crystal grain size when cast into a tubular metal mold-11-200523373 (8); on the other hand, the crystal grain size of the AZ9ICaSr alloy relative to the AZ91 alloy The size ratio shows that the crystal grains are refined at a certain ratio of 0.34 even under different casting and forming conditions (refer to Figure 6). Conventionally, in the case of die-casting products, crystal grain miniaturizing agents have been regarded as It is useless, so it is a new idea. The miniaturization of the crystal grain size is because the network surface of the grain boundary is smooth and fine, the strength of the material is increased, and the thickness of the / 3 phase precipitated at the grain boundary becomes thinner. Coarse intermetallic compounds that are easily formed in the grain boundary are not easily formed, so they can improve the corrosion resistance. (2) Room temperature strength and tensile properties and melt fluidity Next, the inventors of the present invention according to the above (1) As a result, the room temperature strength characteristics and characteristics of the alloy obtained by adding Ca and Sr to the AZ91 alloy (hereinafter, referred to as "Ca and Sr added alloy" as appropriate) as described above are reviewed. Use Figure 7 A cold die-casting molding machine is used to form the alloy ingot, the forming temperature (melting furnace temperature) is 650 ° C, and a flat test metal mold with a thickness of 1.5 mm and a size of B5 is used, and the mold temperature is 200 ° C. Form 80 pieces respectively. Five formed plates were divided into three equal parts in the horizontal direction and two equal parts in the vertical direction. The density of the six small pieces was measured by the water displacement method, and the atomic density described in the chemical analysis and the chemical composition was also used. The calculated theoretical density is calculated in Table 'to calculate the filling rate in the mold. Furthermore, a normal-temperature tensile test piece was cut out of five formed plates, and then an instrone tensile tester was used to measure 200523373 at room temperature. (9) Tensile strength and elongation (tensile) value). Fig. 8 is a graph showing the filling rate of the test plate after die casting (the average filling rate of the composition of the present invention). From this figure, it can be seen that if Ca and S r are added, the charge rate is increased. Figure 9 shows the room-temperature tensile strength of the die-cast product. In addition, the combination shows the measurement result after the die-casting test piece was melt-treated at 4 10 ° C for 2 hours. As shown in the figure, in the case of as-cast, Ca and Sr addition alloys are approximately 7% higher than AZ91 alloy. In addition, when the AZ91 alloy is melt-treated, the strength decreases, and bubbles are scattered according to the results of observation of the test piece, which is considered to be a cause of lowering the physical properties and lowering the filling rate. On the other hand, according to the alloy of the embodiment of the present invention to which Ca and Sr are added (hereinafter referred to as "Ca and Sr added alloy" as appropriate), even if the melt treatment is performed, the strength does not decrease and no bubbles are observed. The elongation is shown in Fig. 10. The Ca and Sr added alloys are almost the same as the AZ91 alloy. It can be seen that if Ca and Sr are added to the AZ91 alloy, there is no air bubble entanglement during the die-casting. Since the filling rate is increased and the tensile strength is increased, the die-casting formability is improved. In addition, the inventors of the present invention did not review the amount of Ca and Sr added, but also reviewed the effect of the composition of the AZ9 1 alloy on the added side on the tensile strength at room temperature. 7 weight ° / 〇, the effect of improving the room temperature tensile strength disappears. Therefore, in order to improve the tensile strength at room temperature, it is appropriate that the content ratio of A1 is 7% by weight or more. -13- 200523373 (10) (3) High temperature creep characteristics Next, the inventors of the present invention reviewed the high temperature creep characteristics of Ca and Sr added alloys based on the results of (1) and (2) above. A test piece was cut out from 5 pieces of the pressed product #, and the creep data at 1 75 t was obtained by using a constant-speed steam severe creep tester. In addition, for comparison, the same measurement was performed on a normal A Z 91 alloy or other a Z-based alloy. The results of the constant-temperature method high-temperature creep test at i7yc are shown in Figs. 11, 12, and 13. Figure 11 shows the relationship between strain rate and flow stress. Compared with AZ91 alloy, the ca and Sr additive alloys of this embodiment obtained by adding c a and Sr to AZ91 alloy have increased the flow stress by 10 to 20% at each strain rate, and it is found that the latent resistance is increased. Figure 12 is data showing creep elongation. For AZ61 alloy and AZ 9 1 alloy, due to different creep speeds, the elongation rate may be less than 25%. In contrast, Ca and Sr added alloys have an elongation rate of 29% regardless of the strain rate. the above. Fig. 13 is a graph obtained by describing these results on a graph in the database of the Japan Magnesium Association for comparison with other alloys. The measurement method of the association is the constant stress method. Regardless of the method, it is a method of evaluating the same physical properties in principle. In addition, the literature of other alloys at 175 ° C is also shown. In the figure, "Mercer" means that according to the document "W.E. Mercerll" "Magnesium Die Cast Alloys for Elevated"
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Applications ”，SAEApplications ”, SAE
PaperPaper
No.900788, 200523373 (11) SAEWarrendale，PA，U.S.A，1990.」的資料；「長岡技大」 則是表示根據文獻「後閑康裕、鎌土重晴、武田秀他著： “Mg-Zn-Al-Ca-RE系合金壓鑄材的顯微組織及高溫強度特 性”輕金屬學會第 103回秋期大會演講槪要集？-1 6，P . 3 7 5」的資料。 第1 3圖所示的本發明的發明人的潛變試驗與日本鎂 協會的潛變試驗的測量條件，表示於第1 4圖中。 第13圖中的長岡技大的ZACE05411合金，與AS21 交叉而立起。其他的資料係關於Mercer的基本的合金的 資料，能夠看淸耐熱鎂合金的AS41、AS21、AS42的耐潛 變性，位於何種水準。 根據本實施形態的Ca、Sr添加合金，係位於AS21合 金的潛變曲線的延長線上，在1 7 5 t時的耐潛變性可以被 認爲與 AS21相等。亦即，可知利用將Ca、Sr添加在 AZ91中，可以得到具有與高溫潛變性高的AS21相等的高 溫潛變性之合金。 再者，本發明的發明人，與前述相同，不是檢討C a、 S r的添加量，而是也另外檢討被添加側的AZ9 1合金的成 分對於室溫拉伸強度的影響；得知若A1的含量比率若超 過1 1重量％，則拉伸率的劣化將會超過1 %，所以爲了提 高高溫潛變性，A1的含量比率，設爲1 1重量％以上是適 當的。 又，相對方令AS21添力口 Si 、 AE4 2或ZACE054 1 1添力口 希土類，皆是對成形性產生不良影響的元素；本實施形態 -15- 200523373 (12) 的Ca、Sr添加合金，即使是關於壓鑄成形性，也如前述 (2 )所述般地改善。 (4 )耐蝕性 A Z 9 1合金係在M g合金中的耐蝕性優異的合金；本實 施形態的合金，係添加了作爲微細化劑的新的元素Ca、 Sr。若因而造成耐蝕性大幅地劣化則不耐實用。因此，本 發明的發明人，藉由對本實施形態的Ca、Sr添加合金和 通常的 AZ9 1合金進行鹽水噴霧試驗，進行耐蝕性的確 認。 鹽水噴霧試驗的槪要係如下述般地進行。首先，作爲 原料鑄錠，係使用第1 5圖所示的鑄錠。關於壓鑄成形， 係對試驗合金A、B，以620 °C、65 0 °C、680°C各成形溫度 (熔解爐溫度）進行壓鑄成形，並作成板狀。又，作爲鹽 水噴霧試驗用試樣形狀，成形板的厚度設爲0.7mm，並切 出9 5mm X 1 30mm的形狀。作爲前處理條件，並不進行化 成處理，而是以丙酮擦拭表面。 作爲試驗方法，使用腐蝕鹽水噴霧試驗機（Suga試驗 機股份有限公司製造），試驗槽內溫度設爲3 5 t、噴霧壓 力設爲0.09 8MPa ( lkgf/cm2)。以此條件連續噴霧2小時 之後’以流水沖洗試料後，放置1 6小時，再藉由目視以 五階段評價「幾乎沒有腐鈾-〜5」、「稍微腐蝕+〜4」、 「有腐蝕++〜3」、「全面地腐蝕+ + +〜2」、「全面顯著 地腐蝕〜1」來評價腐蝕發生的程度。 -16- 200523373 (13) 桌1 6圖係表不其結果。如第1 6圖所示，根據本實施 形態之 AZ91+Cal.0% + Sr0.5%的合金，係前述「有腐蝕+ + 〜3」’通常的 AZ91合金也是「有腐蝕〜3」。亦即， 關於腐蝕性，前述兩種合金之間沒有大的差異，可知本實 施形態的Ca、Sr添加合金，也確保有與通常的AZ合金大 致相等的耐蝕性。 如前所述，若根據本實施形態，能夠得到一種壓鑄用 鎂合金，一面確保良好的壓鑄成形性及腐蝕性，一面具有 與A Z 9 1合金同等的室溫拉伸強度，並具有與高溫潛變性 高的AS2 1合金同等的高溫潛變性。根據本實施形態的合 金’對於能夠發揮輕量化效果的變速器蓋、承油盤、或是 車用空調活塞部外殼、氣囊蓋、引擎蓋等的用途，作爲涵 蓋自室溫區域至高溫區域爲止的鎂壓鑄製品，是特別有用 的。 〔發明之效果〕 若根據本發明，由於作成對AZ91系合金添加了 Ca、 S r的組成，所以能夠防止室溫的強度特性降低；又，藉由 Ca、Sr添加，改良合金組織，使結晶粒徑尺寸微細化，能 夠提升高溫潛變性能。 【圖式簡單說明】 第1圖係表示將C a和S r添加在a Z 9 1合金中所得到 的合金的熔點特性的圖。 -17- 200523373 (14) 第2圖係表示將Ca添加在AZ9 1合金中的情況的結晶 粒徑的變化特性的圖。 第3圖係表示將Ca和Sr添加在AZ91合金中的情況 的結晶粒徑的變化特性的圖。 第4圖係AZ9 1CaSr合金的熔製例的圖。 第5圖係表示在本發明的一實施形態中，將Ca和Sr 添加在AZ9 1合金中的比例的範圍的圖。 第6圖係表示AZ91合金和AZ91CaSr合金的結晶粒 徑尺寸比的變化動態的圖。 第7圖係表示合金鑄錠的組成的圖。 第8圖係表示合金的充塡率動態的圖。 第9圖係表示合金的室溫拉伸強度的動態的圖。 第1 〇圖係表示合金的室溫拉伸特性的動態的圖。 第1 1圖係表示合金的高溫應變速度和流動應力之間 的關係的動態的圖。 第1 2圖係表示合金的高溫應變速度和潛變拉伸率之 間的關係的動態的圖。 第1 3圖係表示在各種鎂合金中的高溫潛變速度和應 力之間的關係的圖。 第1 4圖係表示潛變試驗的試驗條件的圖。 第1 5圖係表示在耐蝕性試驗中所使用的原料鑄錠的 組成的圖。 第1 6圖係表示耐蝕性試驗的結果的圖。 第I 7圖係表示被記載於習知技術文獻中的合金特性 -18- 200523373 (15) 的比較內容的圖。No. 900788, 200523373 (11) SAE Warrendale, PA, USA, 1990. ";" Nagaoka University of Technology "means that according to the literature" Houxian Kangyu, Kazuto Shigeharu, Takeda Hideo: "Mg-Zn-Al- Microstructure and high-temperature strength characteristics of Ca-RE alloy die-casting materials. "Summary of lectures of the 103rd Autumn Conference of the Light Metal Society?-1, 6, P. 3 7 5". The measurement conditions of the inventors' creep test and the Japanese Magnesium Association creep test shown in Fig. 13 are shown in Fig. 14. The ZACE05411 alloy of Nagaoka Technical University in Figure 13 crosses AS21 and stands up. The other materials are about Mercer's basic alloys. You can see the level of latent resistance of AS41, AS21, and AS42 of the heat-resistant magnesium alloy. The Ca and Sr addition alloys according to this embodiment are located on the extension of the latent curve of the AS21 alloy, and the latent resistance at 175 t can be considered to be equivalent to that of AS21. That is, it was found that by adding Ca and Sr to AZ91, an alloy having a high temperature latent property equivalent to AS21 having a high high temperature latent property can be obtained. In addition, the inventors of the present invention, like the foregoing, did not review the addition amounts of Ca and Sr, but also reviewed the effect of the composition of the AZ9 1 alloy on the added side on the tensile strength at room temperature; If the content ratio of A1 exceeds 11% by weight, the deterioration of elongation will exceed 1%. Therefore, in order to increase the high temperature latent property, it is appropriate to set the content ratio of A1 to 11% by weight or more. In addition, the opposite party makes AS21 Timor Si, AE4 2 or ZACE054 1 1 Timorim, all of which are elements that have an adverse effect on formability; Ca, Sr added alloys of this embodiment -15-200523373 (12), Even in the case of die-casting moldability, it improved as described in said (2). (4) Corrosion resistance The A Z 9 1 alloy is an alloy having excellent corrosion resistance among M g alloys; the alloy according to this embodiment is added with new elements Ca and Sr as micronizers. If the corrosion resistance is greatly deteriorated as a result, it is not practical. Therefore, the inventors of the present invention performed a salt water spray test on the Ca and Sr addition alloys and the normal AZ9 1 alloy in this embodiment to confirm the corrosion resistance. The salt spray test is carried out as follows. First, as the raw material ingot, the ingot shown in Fig. 15 was used. Regarding die-casting, the test alloys A and B were die-casted at respective forming temperatures (melting furnace temperatures) of 620 ° C, 65 ° C, and 680 ° C, and formed into a plate shape. As a sample shape for a salt water spray test, the thickness of the formed plate was set to 0.7 mm, and a shape of 9 5 mm × 1 30 mm was cut out. As a pretreatment condition, a chemical conversion treatment was not performed, but the surface was wiped with acetone. As a test method, a corrosive saline spray tester (manufactured by Suga Tester Co., Ltd.) was used, and the temperature in the test tank was set to 3 5 t and the spray pressure was set to 0.09 8 MPa (lkgf / cm2). After 2 hours of continuous spraying under this condition, the sample was rinsed with running water, left for 16 hours, and evaluated by visual inspection in five stages: "Almost no rot uranium-~ 5", "Slightly corroded + ~ 4", "Corrosive + "+ ~ 3", "All-round corrosion + + + ~ 2", "All-round significant corrosion ~ 1" to evaluate the degree of corrosion occurrence. -16- 200523373 (13) Table 16 shows the results. As shown in Fig. 16, according to this embodiment, the AZ91 + Cal.0% + Sr0.5% alloy is the aforementioned "corrosive + + to 3", and the normal AZ91 alloy is also "corrosive to 3". That is, regarding the corrosion resistance, there is no large difference between the two alloys described above, and it is understood that the Ca and Sr addition alloys of the present embodiment also have substantially the same corrosion resistance as the ordinary AZ alloy. As described above, according to this embodiment, it is possible to obtain a magnesium alloy for die-casting, while ensuring good die-casting formability and corrosion resistance, while having room temperature tensile strength equivalent to that of AZ 9 1 alloy, and having latent potential at high temperatures. The high-density AS2 1 alloy has the same high-temperature latent denaturation. The alloy according to this embodiment is used for magnesium, which covers a range from room temperature to high temperature, for use in transmission covers, oil pans, or automotive air-conditioning piston parts housings, airbag covers, and hoods that can reduce weight. Die-cast products are particularly useful. [Effects of the Invention] According to the present invention, since the composition of Ca and Sr is added to the AZ91-based alloy as a pair, it is possible to prevent the reduction of the strength characteristics at room temperature; and by adding Ca and Sr, the alloy structure is improved and crystallized. Refinement of particle size can improve high temperature creep performance. [Brief description of the drawings] Fig. 1 is a graph showing the melting point characteristics of an alloy obtained by adding Ca and S r to an a Z 9 1 alloy. -17- 200523373 (14) Fig. 2 is a graph showing a change characteristic of a crystal grain size when Ca is added to an AZ9 1 alloy. Fig. 3 is a graph showing the change characteristics of the crystal grain size when Ca and Sr are added to the AZ91 alloy. Fig. 4 is a view showing a melting example of the AZ9 1CaSr alloy. FIG. 5 is a diagram showing a range of a ratio of adding Ca and Sr to the AZ9 1 alloy in one embodiment of the present invention. Fig. 6 is a graph showing the dynamic change of the size ratio of the crystal grain size of the AZ91 alloy and the AZ91CaSr alloy. Fig. 7 is a view showing the composition of an alloy ingot. Fig. 8 is a graph showing the filling rate dynamics of the alloy. Fig. 9 is a graph showing the dynamics of the tensile strength of the alloy at room temperature. Figure 10 is a graph showing the dynamics of the tensile properties of the alloy at room temperature. Fig. 11 is a graph showing the relationship between the high-temperature strain rate and the flow stress of the alloy. Figure 12 is a graph showing the dynamics of the relationship between the high-temperature strain rate and the creep elongation of the alloy. Figure 13 is a graph showing the relationship between the high temperature creep rate and the stress in various magnesium alloys. FIG. 14 is a view showing test conditions of a creep test. Fig. 15 is a diagram showing the composition of a raw material ingot used in a corrosion resistance test. FIG. 16 is a graph showing the results of the corrosion resistance test. Fig. 17 is a diagram showing a comparison of alloy characteristics -18-200523373 (15) described in the conventional technical literature.
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