Duralumin is an alloy, a trade name given to the earliest types of the age hardenable aluminum
alloys. It is an alloy made up of 90% aluminum,4% copper, 1% magnesium and 0.5% to 1%
manganese. It is a very hard alloy. These alloys are used in places where hard alloys are
required, for example in the vehicle armor that is used in the defense industry. These alloys
were the first widely used deformable aluminum alloys.
Duralumin is a hard, but a lightweight alloy of aluminum. It has a typical yield strength of 450
Mpa, and there are certain other variations, that depend on the composition, type and temper.
Duralumin Metal
Duralumin is actually a metal, which us an alloy of aluminum, copper, magnesium and
manganese. Duralumin is a special kind of metal, and is made strong by subjecting it to heat
treatment. It may be well spun, tempered, riveted, welded or machinated. The duralumin,
which is effectively given heat treatment, can be effectively being resistant to corrosion. It can
carry heavy loads, and is ductile. It is specially suited for aircraft construction. When copper is
added to the alloy, its strength increases, but then it also makes it susceptible to corrosion. For
the duralumin sheet products, the metallurgical bonding of the highly pure metal layer can
increase the corrosion resistance. These sheets are called alclad, and are generally used by the
aircraft industry.
Duralumin Properties
Duralumin is a strong, light weighted and hard alloy of aluminum. It is also reflective and
impermeable. It is a malleable metal, and can be easily shaped. It is a very good conductor of
heat and electricity. It is odorless, and reacts with the oxygen that is around, and forms
aluminum oxide. It is resistant to corrosion. It has a thin surface, which is made up of a layer of
pure aluminum, which is corrosion resistant, and covers the core of the strong duralumin.
Generally, Duralumin alloys are soft, ductile and workable when they are in normal state. They
can be easily rolled, folded or forged. They can also be drawn into a variety of shapes and
forges. It has a high strength, which can be easily lost during wielding. So it can be easily
transformed, and hence is used in aircraft construction. It is suited for aircraft construction
because of its lightweight and high strength.
Duralumin has the following uses:
It is used for making wire, bar and rods for the screw machine products. It is used in
places where good strength and good machinability are required.
It is used in heavy-duty forgings, wheels, plates, extrusions, aircraft fittings, space
booster tankage and trauck frame, and other suspension components. It finds
applications in places where high strength is required, and services at elevated
temperatures.
It is used for making Aircraft structure, truck wheels, screw machine products, rivets and
other structural application products.
It is used as a sheet for the auto body panels.
It is also used in forgings, in aircraft engine pistons, impellers of the jet enginesand the
compressor rings.
It is also used for making die and hand forgings.
The alloy can be rolled, forged and extruded into various forms and products. The tensile
strength of duralumin is higher than aluminum, although its resistance to corrosion is poor. The
electrical and heat conductivity of duralumin is less than that of pure aluminum and more than
that of steel. It was initially used in rigid airship frames, and its heat-treatment methods and
composition were wartime secret. With the introduction of new monocoque construction
methods in early 1930s, duralumin was widely used in the aircraft industry.
The light weight and high strength of duralumin when compared to steel enabled its application
in aircraft construction. However, a special laminated form of duralumin called alclad is used in
the aircraft industry as it tends to lose strength during welding.
Chemical Composition
Mechanical properties
The mechanical properties of duralumin are displayed in the following table.
Properties Metric Imperial
Hardness, Brinell 115-135 115-135
Tensile strength 420-500 MPa 60900-72500 psi
Elongation at break ≤ 22% ≤ 22%
Tensile modulus 73 GPa 10600 ksi
Izod impact, unnotched 0.08 – 0.22 J/cm 0.150 – 0.412 ft.lb/in
Pewter
tin-based alloy used as a material from which domestic utensils were fashioned. A brief
treatment of pewter follows. The use of pewter dates back at least 2,000 years to Roman times.
Ancient pewter contained about 70 percent tin and 30 percent lead. Such pewter, also called
black metal, darkened greatly with age, and the lead readily leached out in contact with acidic
foods.
Pewter with little or no lead is of finer quality, and alloys that include antimony and bismuth are
more durable and brighter of sheen. Modern pewter is about 91 percent tin, 7.5 percent
antimony, and 1.5 percent copper; the absence of lead makes it safe to use for dishes and
drinking vessels. The surface of modern pewter is bluish white with either a crisp, bright finish
or a soft, satin sheen. It resists tarnish, retaining its colour and finish indefinitely. Pewter work is
usually cast, then further finished by hammering, turning on a lathe, burnishing, and sometimes
engraving. Some items, such as snuffboxes, were constructed from separate pewter pieces and
then soldered together. Some modern pewter work is formed by stamping presses. Most
pewter alloys are quite ductile and easily worked. Cold-working does not cause the metal to
harden sufficiently to require annealing.
All About Pewter: The “Other” Fine Jewelry Metal
What metals do jewelry makers most commonly use to make jewelry? Average men and women might
correctly guess gold and silver. A few might also add platinum to the list. It’s likely that few would think
of pewter. Even though lots of jewelry makers and owners favor pewter jewelry for good reasons,
people may not always recognize this valuable alloy when they see it. Worldwide, pewter is actually the
fourth-most-common metal for jewelry making.
Sometimes, jewelers polish pewter to mimic silver, platinum, and other white metals. In other
cases, they might antique or darken the surface for a more bronzed look. Often, they use pewter
as a base and add gold or silver plating. Because pewter has been used to produce so many
different kinds of pieces, it’s possible to miss its importance for jewelry making.
Why is Pewter Such an Important Metal for Jewelry Making?
People have been making the metal alloy called pewter for a long time. It’s possible to find
examples in museums and collections that date back to Ancient Egyptians, Romans, and Celts.
Perhaps since the alloy is too soft for tools or weapons, there was no real Pewter Age as there
was a Bronze and Iron Age. However, people probably learned to make pewter at about the
same time that they learned to make bronze.
While bronze is made mostly of copper, pewter is made mostly of tin. Thus, bronze is harder,
but pewter has other qualities that make it ideal for making jewelry. During many historical
periods, the useful alloy gained prominence as a common material to fashion many different
items. These pewter pieces include jewelry, eating utensils, tableware, and candlesticks.
Consider some reasons why pewter was an important historical metal alloy and remains still a
popular choice today:
Affordability: Since pewter contains mostly tin, typically along with traces of copper,
antimony, or other harder metals, the alloy certainly costs less than gold, platinum, and
even silver. Most pewter jewelry and other products are valued for their beauty and
workmanship more than for the cost of the metal. When compared to precious metals,
the lower cost of pewter obviously contributes to its popularity.
Versatility: Because tin is soft, pewter is also rather soft, even though the other metals
in the mix harden it somewhat. Still, this pliable quality allows artisans to create
distinctive and complex designs with this metal. Pewter pieces are often quite prized for
their artistic merit and craftsmanship.
Durability: Again, the softness of this alloy means that owners need to take some care
with their pieces. On the other hand, they won’t have to worry about pewter tarnishing
like silver and other metals do.
Some benefits of using pewter for jewelry include the lower price, lack of concern over
tarnishing, and especially, the pliability of pewter that make it possible to create elegant
and complex designs. Many fine jewelry makers use pewter because they can offer more
affordable jewelry; however, others focus on pewter because it is the right metal for their
designs.
