August U. S. DEPARTMENT OF COMMERCE Letter 1957 NATIONAL BUREAU OF STANDARDS Circular
WASHINGTON 25, D. C s LC 1028
NOMENCLATURE OF COPPER ALLOYS - BRASS AND BRONZE
The National Bureau of Standards receives many requests concerning the proper use of the names ''brass’' and "bronze”, as well as for advice concerning suitable alloys which are adequate to meet certain service requirements* This Letter Circular has been prepared as an aid in replying to such inquiries.
I . Introduction
Brass and bronze castings have been traced back thousands of years, and the available histories (of these parts) clearly indicate that bronze, the alloy of copper and tin, was the predecessor of brass, the alloy of copper and zinc. Even today, the definitions of these terms make clear their differences with respect to the alloying addition.
Well after the early use of copper castings, it was accidently discovered that a "mixture" of ores resulted in much stronger and more corrosion resistant materials* These "mixtures" came into general use, and the alloys became symbolic of our Bronze Age. Much later, zinc was also used in these alloys ; thus the brasses. Developments through the centuries bring us to where it is now recognized that, weight-for-weight , tin is more effective than zinc in enhancing the mechanical properties of copper. Today, either or both of these metals, as well as many others, are added to copper in order to achieve special properties. Thus, it becomes extremely difficult to classify currently used alloys strictly by definition; for, while the term "brass" has had no serious degree of misuse, the term "bronze" is currently used "in the trade" for a wide variety of alloys, some of which contain little or no tin. In fact, the situation is so complex that, to clarify, the original copper-tin alloy is now designated as "tin-bponze."
Because of this complexity, it is recommended that the reader, when encountering any of the currently used descriptive or trade-names indicated as being "brass" or "bronze", refer to standard metallurgical references such 1 as the National Metals Handbook^ ), Classifications and Materials Specifica- tions established by the American Society for Testing Materials^ or the ^) ) , American Standards Association 9 data from the Copper and Brass Research Association^) , or to the strictly technical literature usually provided gratis by the producers of these alloys. II. Glassification of Alloys
In the interests of classifying the many copper-base alloys in current use, A. S. T. M* has established a Classification of Cast Copper-Base Alloys (B 119-1*5), and has developed many specifications for particular classes of alloys, for general purpose as well as specific applications, including both cast and wrought materials.
For specific information, the reader should refer to such specifications. However, as an aid to the present discussion. Table I presents a much abbreviated version of such a classification for casting alloys, while Table II denotes the nominal compositions and cites a few applications of some of the alloys characterised by particular names.
In addition to the alloys listed in the two tables, there are a host of alloys offered by the producers under trade names, the compositions of which may or may not be classified or standardised.
From a perusal of Table 2, it is quite evident that industrial terminology has indeed departed materially from strict definitions, particu- larly with respect to "bronzes". This has been carried to even further extremes in other instances concerning decorative finishes wherein "bronzed” covers a multitude of applications. Also, the term "bronzing paints" has been aborted with respect to metallic particle paints, whether of copper, copper-zinc, or aluminum.
III. "Standard 11 Alloys
1, There is a widespread misconception that the names of many of these alloys imply that they are the standard alloys for such application. This is particularly pertinent with respect to "Government Bronze", "Naval Brass (or Bronze)", "Statuary Bronze", and others. Most of these names derive from some particular application in the past, and they must not be considered as the typical, specified, or standard alloy for the purpose supposedly indicated. Actually, most of the copper-base alloys are classified and standardized on the basis of chemical composition, as indicated in Table 1.
2. For ary particular application, the potential user should select an alloy which has physical, mechanical, chemical, or corrosion properties which fulfill his service requirements! then specify this alloy in terms of ( ASA, ASTM, SAE'(5 * , AMS -• , Federal, or the appropriate specification of the Department of the Amy, or Navy, or Air. -3 -
Ref. 1. National Metals Handbook, American Society for Metals, 7301 Euclid Avenue, Cleveland 3, Ohio 2. ASTM Standards, Part 2, American Society for Testing Materials,
1916 Race Street, Philadelphia 3 } Pennsylvania 3. American Standards Association, 70 East Forty-fifth Street, New York 17, New York k* Copper and Brass Research Association, 'U20 Lexington Avenue, New York 17, New York 5. Society of Automotive Engineers 6. Aeronautical Materials Specifications
Supersedes LClj.87 , dated 1/8/37 Prepared by: LLW/ADY Chemical Metallurgy Section Metallurgy Division National Bureau of Standards £ 8 , £
Table 1. Classified Casting Alloys
Weight Percent ASM Alloy Cu Sn Pb Zn Other Spec,
Leaded Red Brass 82-86 3-6 k-7 A— — B 62, ll*£ Leaded Semi-Red Brass 75-82 3 £-8 7-17 — B lii£ Silicon Brass bal - .£-1 12-16 Si 2.£-£ B 198 Yellow Brass bal 0-6 0-.£ 17+ Al, Mn, Ni, Fe,& Si, 0-2 Leaded Yellow Brass 60-7ii 1 3 25-29 = B 1U6 High-Strength Yellow £5-68 0-1 »£ o^l. £ bal Ni 0-.£, B 1U7 Brass Fe .1*4*, (Manganese Bronze) A1 .£-?£, Mn 0-£ Leaded High-Strength £6-62 0-1 e £ .£-!.£ bal Fe 0-3 B 132, 1hi Yellow Brass Al 0—l.£j (Leaded Manganese Mn 0-3 «£ Bronze) Nickel Brass bal - 0-.£ 10+ Ni 11+ CB3 (Nickel Silver) (German Silver) Leaded Nickel Brass £3-£8 1-3 8-11 bal Ni 11-lU, B 1U9 (Leaded Nickel Fe 0-1 .£, Silver) Mn 0-.£ (German Silver) Aluminum Bronze 81-89 Fe 1-A, B I48 Ni 0-U, Al 9-11 Beryllium Bronze 98 — 2 Be or Be —
-rv; f . tL, plus others Manganese Bronze ££-68 0-1. 0-1. £ bal Ni 0-.£, b m? Fe O.U-Uj Al 0.£-7.£
+ Mn 0-£ Nickel Bronze bal 10 0e£ less Ni 10 (Nickel Silver) than (German Silver) Sn Leaded Nickel Bronze 63-67 3 *£-£.£ i.£ bal Ni 19, £-27, B ll;9 (Nickel Silver) Fe 0-1. £ (German Silver) Silicon Bronze bal 0—1 o.£ £ i-£ si, B 198 Fe 0-2. Al 0-1. £ Mn 0-1. £, Mn 0-1 Tin Bronze 88 8-10 — css B 22, 1U3 Leaded Tin Bronze 87-88 6-8 1-2 h B 61, lii3 High-Leaded Tin 70-8£ £-10 7-2 £ 0—3 Ni 0,£0- B 22, 66 , Bronze 0«7£ max 67 , lAA 1 1
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