The FraudHawk alloy guide

One material.
Many ingredients.

What is brass actually made of? What puts the stainless in steel? See the ingredients, compare their proportions, and read the recipe behind the name.

Explore 10 alloy examples

Read the composition

A recipe, with room to vary.

An alloy combines a metal with one or more other elements. Its name may describe a whole family; a grade identifies a more specific composition.

Every chart totals 100% by mass. A 30% share means 30 grams in a 100-gram sample. It is not a count of atoms, a volume percentage, or a picture of the material’s internal structure.

Nominal means a published reference recipe. Illustrative means selected proportions within published limits, with minor constituents grouped into a labeled remainder. A reported example describes one documented historical object. None authenticates an unidentified object.

Composition atlas

Meet the mixtures.

10 sourced examples
Percentages by mass throughout

Copper alloy

Brass

C26000 · Cartridge brass

Copper + zinc. The familiar 70/30 recipe is one grade in the brass family.

Nominal recipe% by mass

Copper Cu: 70%
Zinc + minor constituents Zn: 30%

70/30 nominal view. Permitted minor constituents are grouped with the zinc remainder.

The word brass alone does not specify the copper-to-zinc ratio.

Published grade limits

C26000 · Cartridge brass · % by mass
Constituent	Amount
Copper	68.5–71.5%
Zinc	Balance
Lead	≤ 0.07%
Iron	≤ 0.05%

Wieland Concast cites ASTM B927/B927M-23. Copper plus named elements is at least 99.7%.

Iron alloy

Stainless steel

304 · UNS S30400

Iron + chromium + nickel. An 18/8 shorthand describes the major additions, not the whole composition.

Illustrative recipe% by mass

Iron + minor constituents Fe: 74%
Chromium Cr: 18%
Nickel Ni: 8%

18% chromium and 8% nickel illustration. The 74% remainder includes iron and all minor constituents; it is not 74% pure iron.

304 is a grade name. The 18/8 shorthand is not a complete chemical specification.

ATI’s published grade limits

304 · UNS S30400 · % by mass
Constituent	Amount
Iron	Balance
Chromium	17.5–19.5%
Nickel	8–10.5%
Manganese	≤ 2%
Silicon	≤ 0.75%
Nitrogen	≤ 0.1%
Carbon	≤ 0.07%
Phosphorus	≤ 0.045%
Sulfur	≤ 0.03%

Limits follow ATI’s 304 product table. Check the applicable product specification and revision for a particular order.

Copper alloy

Phosphor bronze

C51000 · 5% tin bronze

Copper + tin + a small phosphorus addition. This is a specific bronze recipe, not a definition of every bronze.

Illustrative recipe% by mass

Copper + minor constituents Cu: 94.8%
Tin Sn: 5%
Phosphorus P: 0.2%

An illustration with 5% tin and 0.2% phosphorus, within the published limits. Other permitted constituents are grouped with copper.

A small constituent can belong in the specification even when its slice is barely visible.

Published grade limits

C51000 · 5% tin bronze · % by mass
Constituent	Amount
Copper	Balance
Tin	4.2–5.8%
Phosphorus	0.03–0.35%
Zinc	≤ 0.3%
Iron	≤ 0.1%
Lead	≤ 0.05%

Copper Development Association: copper plus named elements is at least 99.5%.

Iron alloy

Stainless steel

316 · UNS S31600

Iron + chromium + nickel + molybdenum. Compare the added molybdenum with the 304 example.

Illustrative recipe% by mass

Iron + minor constituents Fe: 68.5%
Chromium Cr: 17%
Nickel Ni: 12%
Molybdenum Mo: 2.5%

Mid-range illustration for chromium, nickel, and molybdenum. The remainder groups iron with minor constituents.

304 and 316 belong to the same family but have different composition limits.

ATI’s published grade limits

316 · UNS S31600 · % by mass
Constituent	Amount
Iron	Balance
Chromium	16–18%
Nickel	10–14%
Molybdenum	2–3%
Manganese	≤ 2%
Silicon	≤ 0.75%
Nitrogen	≤ 0.1%
Carbon	≤ 0.08%
Phosphorus	≤ 0.045%
Sulfur	≤ 0.03%

ATI’s plate composition table, citing ASTM A240 / ASME SA-240. Product specifications and revisions can differ.

Copper alloy

Cupronickel

75/25 · U.S. five-cent recipe

Copper + nickel. The U.S. Mint’s five-cent alloy is mostly copper, despite the coin’s name.

Nominal recipe% by mass

Copper Cu: 75%
Nickel Ni: 25%

The U.S. Mint’s stated five-cent composition, expressed by mass.

This 75/25 example describes the five-cent alloy, not every cupronickel or every layer of a clad coin.

Published nominal composition

75/25 · U.S. five-cent recipe · % by mass
Constituent	Amount
Copper	75% nominal
Nickel	25% nominal

The linked public coin specifications state a composition, not manufacturing tolerance ranges.

Copper alloy

Nickel silver

C75200 · CuNi18Zn17

Copper + nickel + zinc. This silvery-looking alloy has no silver in its nominal recipe.

Nominal recipe% by mass

Copper Cu: 65%
Nickel Ni: 18%
Zinc + minor constituents Zn: 17%

Wieland’s 65% copper / 18% nickel reference composition. Zinc is the remainder; permitted minor constituents are grouped with it.

Nickel silver is an alloy name, not a silver purity claim. Any silver plating is a separate layer.

Published grade limits

C75200 · CuNi18Zn17 · % by mass
Constituent	Amount
Copper (including silver)	63–66.5%
Nickel (including cobalt)	16.5–19.5%
Zinc	Balance
Lead	≤ 0.05%
Iron	≤ 0.25%
Manganese	≤ 0.5%

CDA reports copper including silver and nickel including cobalt for specification accounting. This does not make silver an intentional ingredient in the nominal recipe.

Aluminum alloy

6061 · Magnesium–silicon alloy

Mostly aluminum, with magnesium and silicon plus smaller additions of copper and chromium.

Illustrative recipe% by mass

Aluminum + minor constituents Al: 98%
Magnesium Mg: 1%
Silicon Si: 0.6%
Copper Cu: 0.25%
Chromium Cr: 0.15%

Selected values within Hydro’s limits. The 98% remainder combines aluminum with iron and other permitted minor constituents.

6061 names an alloy. Its temper, such as T6, describes a material condition separately from the composition.

Hydro’s published grade limits

6061 · Magnesium–silicon alloy · % by mass
Constituent	Amount
Aluminum	Balance
Magnesium	0.8–1.2%
Silicon	0.4–0.8%
Copper	0.15–0.4%
Chromium	0.04–0.35%
Iron	≤ 0.7%
Manganese	≤ 0.15%
Zinc	≤ 0.25%
Titanium	≤ 0.15%

Hydro’s extrusion datasheet also limits other elements to 0.05% each and 0.15% total. Aluminum is the remainder.

Silver alloy

Sterling silver

925 · Silver–copper example

A silver-rich alloy. The traditional recipe illustrated here pairs 92.5% silver with 7.5% copper.

Nominal recipe% by mass

Silver Ag: 92.5%
Copper Cu: 7.5%

The Royal Mint’s silver–copper example, not a universal recipe for all sterling products.

925 describes silver fineness. It does not identify every ingredient in the remaining 7.5% of every sterling formulation.

Published example recipe

925 · Silver–copper example · % by mass
Constituent	Amount
Silver	92.5% nominal
Copper	7.5% nominal

The Royal Mint’s classroom reference gives 925 parts silver and 75 parts copper per 1,000. These are recipe proportions, not tolerance limits.

Tin alloy

Pewter

92/6/2 · Manufacturer’s recipe

Tin + antimony + copper in this maker’s pewter. The word pewter covers more than one formulation.

Nominal recipe% by mass

Tin Sn: 92%
Antimony Sb: 6%
Copper Cu: 2%

Pewter.co.uk’s stated recipe. Other pewter formulations can differ.

A composition statement for one maker’s pewter does not establish the recipe of an unidentified object.

Published manufacturer’s recipe

92/6/2 · Manufacturer’s recipe · % by mass
Constituent	Amount
Tin	92% nominal
Antimony	6% nominal
Copper	2% nominal

The manufacturer states that it adds no lead. No manufacturing tolerance ranges are supplied in this reference.

Gold–silver alloy

Electrum

Gold–silver · Historical example

Gold + silver. Electrum can occur naturally and was used in early coinage and ancient jewelry.

Reported example% by mass

Gold Au: 55%
Silver Ag: 45%

Rounded composition reported for British Museum torc 2005,1103.1: about 55% gold and 45% silver. Other electrum objects can have different proportions and additional constituents.

Electrum has no single fixed gold-to-silver ratio. The chart describes one historical jewelry example, not a standard for ancient coins.

Reported historical example

Gold–silver · Historical example · % by mass
Constituent	Amount
Gold	≈ 55%
Silver	≈ 45%

The British Museum reports this approximate analysis for one torc. These are rounded object-specific proportions, not grade limits or a universal electrum recipe. The Met documents electrum in ancient jewelry and early coinage.

Beyond the chart

The details change the meaning.

Balance means the remainder.: Subtract the other constituents from 100%. A balance entry is not an extra ingredient to add on top.
Limits are not a recipe.: A maximum is a ceiling. Range endpoints and separate maxima do not describe one sample and should not be added together.
Small slices stay small.: Charts keep the same 100% scale. Tiny additions can be hard to see; every displayed component also has a written percentage.
Color is only a chart key.: The same element keeps the same color across the guide. Those colors do not represent an alloy’s appearance or establish what an object contains.