US3405015A - Copper alloy - Google Patents

Description

United States Patent No Drawing. Filed Dec. 3, 1965, Ser. No. 511,467 3 Claims. (Cl. 148-32) ABSTRACT OF THE DISCLOSURE This invention relates to a base alloy which has a homogeneous structure and which is substantially devoid of alpha gamma eutectoid areas, said alloy consisting of 7 to 7.5 percent by weight aluminum, 10 to 16 percent by weight nickel, 2.5 to 6 percent by weight iron, and a balance of copper. The alloy has increased thermal and physical properties and is particularly suitable for use in the preparation of glass mold components.

This invention relates to a copper alloy. More particularly, this invention is concerned with a copper alloy that is useful in the formation of mold components.

Copper base alloys have been widely used in the past as a material for the manufacture of mold components. These alloys generally contain various alloying metals such as aluminum, magnesium, lead, tin, boron, nickel, iron, etc., in a wide range of proportions. Generally, these prior art alloys are disadvantageous for use as a mold component material when the mold component is to be subjected to intermittent or continuous high temperature use in the range of 1000 to 1200 F. With regard to this high temperature use, these prior art compositions exhibit poor thermal fatigue life properties. Because of this poor thermal fatigue life, when mold components formed from these prior art alloys are thermally cycled, they have a definite tendency to crack during use. This cracking results from the thermal shock incurred during use. Likewise, these prior art compositions are not particularly suited for the formation of mold components in that they are difllcult to fabricate. That is, their casting qualities are relatively poor and they are diflicult to machine.

Accordingly, the primary object of this invention is to produce a copper base mold component material which has excellent thermal fatigue life. Another object of this invention is to produce a new mold component material which has excellent casting properties and can be easily machined or otherwise fabricated.

Still another object of this invention is the production of a mold component material which is particularly suited to the formation of molds which will be utilized in the shaping of molten glass. Finally, an object of this information is the production of superior mold components.

The copper base alloy of this invention generally has the composition as is listed in Table I.

Table I Percent Aluminum 7.0-7.5

Nickel 10-16 Iron 2.5-6 Copper Balance A more preferred alloy in accordance with this invention is as represented by Table II.

, 3,405,015 Patented Oct. 8, 1968 A most preferred alloy ofthe subject invention has the composition as is represented by Table III.

Table III Percent Aluminum 7.0 Nickel 14.5 Iron 3.0 Copper 75.5

While the applicant is not sure, it is thought that the strength of the subject alloy results from the aluminum content. High aluminum content favors high strength at the expense of ductility whereas alloys having a low aluminum content are characterized by lower strength levels.

The function of both the iron and nickel is one of grain refinement. Also, they tend to increase both strength and hardness in the as-cast condition. Iron, likewise, tends to suppress the self-annealing tendency of these alloys. The exact mechanism by which self-annealing is prevented by the presence of iron is not clearly understood.

An alloy having a prior art composition is represented by Table IV.

The structure of the alloy of Table IV incorporates a plurality of alpha gamma eutectoid areas. The alpha is a primary phase made up of aluminum, copper and nickel. The gamma is a secondary decomposition phase which is formed from the alloying elements and copper. While applicant is not sure, it is thought that these phases are responsible for the poor casting, machining, etc., qualities of this alloy. Likewise, it is thought that these phases may be responsible for the poor thermal fatigue life of this alloy. This alloy is commonly used in the trade as a high temperature mold component material, being sold under the trade name Incrament 800.

The composition of another prior art alloy is represented by Table V.

Again, it is to be noted that the structure incorporates a plurality of relatively large clusters of alpha gamma eutectoid as described above. Likewise, as mentioned above, it is thought that these phases are responsible for the poor fabricating and thermal fatigue properties of this alloy. This alloy is commonly sold under the trade name Minox.

The alloy of this invention having the composition as is described in Table II above is extremely homogeneous having no large clusters of the eutectoid phase. The structure generally consists of alpha solid solution of the alloying elements in copper in a beta matrix which is a secondary phase. This beta phase is an enrichment of the alloying elements.

In addition to the properties mentioned above, the alloy composition of this invention exhibits excellent oxidation resistant properties as compared to other commonly used mold materials, for example cast iron. Likewise, the alloy tends to resist the corrosion that results from the constant hot application of release agents to the i mold.

As was mentioned above, the casting properties of a mold alloy are particularly important. This is due to the fact that the first step in forming a mold component is to form a rough casting. These rough castings are then machined to a finished mold component. If the casting properties of the alloy utilized are poor, defects such as inclusions, bubbles, etc., are often included into the rough casting. These defects often are not obvious until the time and expense of machining to the final shape has been expended on the rough casting. When the alloys of the subject invention are utilized, castings of excellent quality can be readily produced which are easily convertible into finished mold components. Because of these excellent casting qualities, the reject rate resulting from casting defects is minimal.

The compositions of this invention are likewise desirous as a mold component in that they do not tend to soften or anneal when held at a temperature of 1000 to 1500 F. for appreciable periods of time. This is particularly undesirable as when a mold component tends to soften or anneal during use, its useful life is drastically shortened.

Tin, antimony, arsenic and lead are undesirable constituents in the alloy of this invention. Accordingly, these constituents can be present up to a maximum of 0.01%.

The alloy of the subject invention can be prepared by starting with a known copper base alloy containing any one of the constituents and added thereto the other constituents. Likewise, the alloy of this invention can be prepared by adding the individual elemental components to a furnace and melting the same until a homogeneous mass is produced. These preparatory techniques are better exemplified by the examples listed below.

The following examples will illustrate the subject invention. These examples are given for the purpose of illustration and not for purpose of limiting this invention. All parts percent are given by weight unless otherwise specified.

Example I A melt was prepared by adding 75 pounds of copper to an induction furnace. Current was then applied to effect the melting of the copper charge, the temperature of the melt was then raised to 2100 F. 15 pounds of nickel and three pounds of iron were then added to the molten copper. The melt was then stirred until a homogeneous mass was produced. Finally, 8 pounds of aluminum were added with stirring. It is preferred that the aluminum be added last in order to prevent its oxidation. The temperature of the melt was then increased to 2200 F. and a plunger casting was made by pouring the molten 3 4 metal into a sand mold in a conventional manner. Upon removal of the rough casting, said cast was machined in a conventional manner to produce a finished glass plunger. The casting qualities of the melt were excellent. Likewise, the rough casting was easily machined to produce a glass plunger having an excellent overall appearance and critical tolerances.

- Example 11 A melt was prepared by adding 82 pounds of an alloy which comprises 75% copper and 8% aluminum to an induction furnace. To this melt were added 15 pounds of nickel and 3 pounds of iron. The temperature of the melt was then raised to 2200 F. and the melt stirred until a homogeneous mass was produced. Several glass mold components were prepared in accordance with the description given in Example I. The resulting glass mold components exhibited excellent thermal fatigue properties in that it showed no signs of stress cracking after two years of continuous use. Likewise, these mold components resisted corrosion and oxidation during this period of use.

What is claimed is:

1. As an article of manufacture, a glass mold component having increased corrosion and oxidation resistance at elevated temperatures and consisting essentially of a copper base alloy containing 7 to 7.5 percent by weight aluminum, 10 to 16 percent by weight nickel, 2.5 to 6 percent by weight iron, and a balance of copper, said alloy being substantially devoid of alpha gamma eutectoid areas and having a structure consisting of alpha solid solution in a beta matrix.

2. The article of claim 1 wherein the alloy contains 7 to 7.5 percent by weight aluminum, 14 to 16 percent by weight nickel, 2.5 to 3 percent by weight iron and a balance of copper.

3. The article of claim 1 wherein the alloy contains 7 percent by weight aluminum, 14.5 percent by weight nickel, 3 percent by weight iron, and 75.5 percent by weight copper.

References Cited UNITED STATES PATENTS 1,369,818 3/1921 Kosugi 75l59 1,481,782 1/1924 Iytaka 75159 FOREIGN PATENTS 220,791 8/ 1924 Great Britain. 674,127 6/ 1952 Great Britain. 655,932 1/ 1938 Germany. 319,321 3/1902 France.

CHARLES N. LOVELL, Primary Examiner.