US2188203A - Aluminum base alloy - Google Patents

Description

Patented Jan. 23, 1 940 I i v i 7 No Drawing. Application November 20, 1936, Serial No. 111,907

. 6 Claims. (01. 75-138) My invention relates to aluminum base allo'ys titanium in effective amounts up to 3%, or withand, more particularly, to aluminum base alloys titanium and manganese in the proportions spehaving improved physical and casting properties. cified.

Manganese has heretofore been added to alu- It is therefore an object of my invention to 5 minum to increase its tensile strength. Alumiprovide an aluminum base alloy having good 5 num manganese alloys, however, are difficult to casting and physical properties. cast and while titanium has been found efiective Another object of my invention is to provide in improving to a certain extent the casting propan aluminum base alloy having good casting erties of such alloys, they do not have the desired and. physical properties containing one or more .0 grain structure which is required in high grade metals or ingredients which are particularly UNITED STATES PATENT OFFICE castings. effective in improving the casting and physical In accordance with my invention I have found properties of aluminum-manganese alloys. that if a special alloying metal or ingredient is A further object of my invention is to provide added to aluminum base alloys containing copan improved aluminum base alloy.having good .5 per, nickel or zinc, or a mixture of two or more physical and casting properties which is substanof these metals, or to aluminum base alloys conftially free from manganese or in which the taining manganese, or to aluminum base alloys amount of manganese is comparatively low. containing manganese and one or more metals A still further object of my invention is to proselected from a group consisting of copper, vide an improved aluminum base alloy contain- 0 nickel and zinc, an alloy will be produced that ing boron or a member of the tungsten group, or has good casting properties from which castings a mixture of a tungsten group metal and boron, may be prepared which have improved physical and more particularly an alloy containing one properties. 1 or both of these ingredients in combination with The special alloying ingredients which I have titanium or titanium and manganese. V I found to be efiective in this respect are metals In" practicing my invention. a metal of the -25 of the tungsten group, such as tungsten, molybtungsten group, such as tunsten, molybdenum denum or uranium, or a metal, such as columor uranium, or a metal such as columbium, tanbium, tantalum, berylliumor boron. Either one talum, beryllium or boron, or a combination of or a mixture of two or more of such metals may two or more of such metals is added to aluminum be employed. While the special alloying metal or in effective amounts up to 3%. While the spe- 30 ingredient improves the physical and casting cial alloying metal or'ingredient may be present properties of .the alloy, it is especially effective in an amount ranging up to 3%, it is preferably when employed in combination with titanium. added in amounts ranging from .05% to 1%.

By adding one or more of the special alloying The alloy may be prepared in any desired ingredients to the alloy, it is possible to provide manner, such as by introducing the special al- 35 an aluminum base alloy without utilizing the loying ingredient into molten aluminum, or if high amount of manganese which s rmerly other ingredients are present the special alloying been employed and it is even possible to provide metal or ingredient may be alloyed with such a satisfactory alloy when manganese is absent metals and introduced into the molten bath.

40 or is present only as an impurity. I do not Another method is to prepare a rich alloy of desire, however, to limit my invention to alumithe special alloying ingredient and aluminum n manganese oy of small m n n se c n? and introduce the alloy into the molten alumitent, as one or more of the special alloying metals num. I .may also add the special alloying inor ingredients are effective in improving the gredient in the presence of or in the form of a p y l properties f the alleys n when manfluoride in a manner similar to that disclosed 45 ganese is present in amounts ranging up to 5%. for the addition of antimony in Patent No. 1,997,-

The amount of manganese, however, is prefer- 494, granted to me on April 9, 1935. y maintained below Wh le any one of In preparing an alloy for casting purposes in th special alloying metals or i i n s menaddition to aluminum and the special alloying tioned may bg employed,'I have found that boron ingredient, my improved alloy may also contain or a metal of" the tungsten group, and more parcopper, nickel or zinc, or a mixture of two or ticularly tungsten itself, or a mixture of boron more of these metals in an amount ranging from and tungsten, are particularly effective when almore than incidental-impurities up to 15%, prefloyed with aluminum or aluminum alloys, and erably from approximately .5% .to 12%. The

especially when employed in combination with copper or nickel, when present, increases the 5 tensile strength and hardness of the alloy. Zinc, when present, tends to improve the casting properties. To further increase the hardness of the alloy it is desirable to have some magnesium present. The amount of magnesium which is "present, however, should be maintained below 2% and preferably below .5% as magnesium'in large amounts has a' very pronounced effect, upon the hot shortness of aluminum alloys, a property which is very deleterious in producing alloys in permanent or semi-permanent molds or by the die casting process. If a large amount of magnesium is present, the machinability of castings produced from the alloy is decreased and excessive breakage occurs in trimming.

The following specific example will serve toillustrate and explain my invention, although it will be understood that I do not desire to limit myself to the particular ingredients or proportions specified. An aluminum base'alloy was prepared by adding the following ingredients to aluminumin approximately the proportions indicated:

7 Percent Copper 1.3 Manganese 1.4 Magnesium .23 Boron .05

The alloy was cast in a sand mold and was found to have a good grain structure. It had a tensile strength of 22,400 pounds per square inch and an elongation of about 8% in 2 inches. Upon adding tungsten to this alloy, it was found that the tensile strength was increased to about 25,000 pounds per square inch and the elongation in 2 inches was increased to about 14%.

From the foregoing example it is apparent that aluminum base alloys may be improved by the -addition of boron or tungsten, or a mixture Percent Copper 1.35 Manganese 1.35 Titanium .18 Magnesium .25

The alloy was difficult to cast. When tungsten was added to the alloy in proportions varying up to 25%, however, the casting properties were greatly improved.

In such alloys the titanium may be entirely replaced by the tungsten or titanium may be present in amounts ranging up to .5% and the tungsten may be present in amounts ranging up to .5%. the total amount of both metals ranging up to 1%. Tungsten or titanium, or both. may be replaced in whole or part by boron in which case the boron may be varied from .01% to .5%.

Molybdenum is also effective in improving the casting properties of aluminum base alloys. For example, approximately .'75% of .molybdenum was added to an aluminum base alloy containing about 3% manganese. Sand castings prepared fromsuch an alloy had improved properties and when copper was added to the alloy the physical and casting properties were still more marked.

In order to obtain satisfactory castings, the

amount of the special alloying metal or ingredient should preferably be at least .05%. When boron is employed, however, it is effective when the amount is even less than .05%. The amount of aluminum which is present will of course depend upon the alloying ingredients and may range from approximately 75% to 97%. Ordinarily 90% to 97% of aluminum will be present.

By employing a special alloying metal or ingredient, such as one or more of those specified and particularly a metal of the tungsten group, or boron, or a mixture or a combination of boron or tungsten with titanium and an aluminum base metal, it is possible to provide an alloy having good casting properties when manganese isentirely absent or is present only as an incidental impurity. In such alloys, however, copper, nickel or zinc, or a mixture of two or more of these metals should be present. For instance, an aluminum base alloy containing 3.1% copper was cast in a sand mold. It had a tensile strength of 15,500 pounds per square inch, an elongation of 3.12% in 2 inches and-a fracture of the casting showed a mixed crystalline grain structure; Upon adding 2% of tungsten to the alloy and casting in a similar manner, the tensile strength was increased to 17,150 pounds per square inch and the elongation to 4.3% in 2 inches. A fractureof the casting showed a good fine grain structure.

The special alloying metal or ingredient not only improves the grain structure of the metal but also counteracts to a certain extent the presence of iron and consequently whereas it has previously been necessary to maintain the iron below 1.5% and preferably below 1.25%, iron may be present in my improved alloy in amounts ranging from approximately 1.5% to 4% Secondary aluminum may accordingly be employed in preparing my-"improved alloys. Silicon may also be present in amounts ranging from effective amounts up to 15%, but preferably is maintained below 12%.

It will also be apparent that by providing a special alloying metal or ingredient, the amount of manganese which is present may be omitted or may be present in small amounts or only as incidental impurities.

To those skilled in the art many modifications and widely differing embodiments and applications of my invention will suggest themselves without departing from the spirit and scope thereof. My disclosure and the description herein are not intended to be in any sense limiting.

What Iclaim is: j

1. An alurninum-manganese-boron alloy having better casting properties, a finer grain structure and a higher tensile strength than an aluminum-manganese alloy of a similar composition, said alloy consisting of effective amounts up to 5%. manganese, boron in effective amounts up to .5% and the remainder of aluminum and any other metal or metals which are not subversive of the above characteristics.

2. An aluminum-'manganese-boron alloy having better casting properties, a finer grain structure and a higher tensile strength than an aluminum-manganese alloy of a similar composition, said alloy consisting of effective amounts up to 5% manganese, from 01% to .5% boron and the remainder of aluminum and any other 7 metal or metals which are not subversive of the above characteristics.

3. An aluminum-manganese-boron alloy having better casting properties, a finer grain sition, said alloy consisting of eflective amounts up to 5% manganese, boron in effective amounts up to 5%, copper in efiective amounts up to 12%, magnesium in efiective amounts up to'2%', and the remainder consisting of aluminum and any other metal or metals which are not subversive of the above characteristics.

20 5. An alumlnum-manganese-boron alloy having better casting properties a finer grain structure. and a higher tensile strength than an aluminum-manganese alloyof similar composition, said alloy consisting of effective amounts up-to 5% manganese, boron in eifectlve amounts up to .5%, nickel in effective amounts up to 12%, and. the remainder consisting of aluminum and any other metal or metals which are not subverslve of the above characteristics.

6. An aluminum-manganese-boron alloy having better casting properties, more ductility and a finer grain structure than an aluminum-manganese alloy of similar composition, said alloy consisting of effective amounts up to 5% manganese, boron in eflective amounts up to .5%. tungsten in effective amounts up to 3%, and the remainder consisting of, aluminum and any other metal or metals which are not subversive, of the above characteristics. Y

E. MANSFIELD.