4. Materials Research

Materials Research

Malleable

A metal is said to be malleable when it can be extended in width and length (by being made thinner through hammering, rolling or pressing) without fracturing. To be malleable requires a metal to be plastic, i.e. tend to act like plasticine.

Ductility

Ductility is the ability of a metal to be drawn out lengthwise (by stretching) without fracturing. This is essential for a metal which is to be drawn out into wire. Copper and gold are both excellent examples of ductile metals.

Tenacity

Tenacity is the power of a metal to resist any tendency to stretch or fracture when placed under strain.

Chains used for lifting loads are good examples of how tenacious metals are used. The chains pictured will not stretch when a force is applied to them. They are also not likely to fracture/shatter when a force is applied.

Properties of Common Metals

Mild Steel

Common uses: Nails, bolts, screws, wire, building frames, car bodies, engine parts, ships, trains

Main characteristics: Strong under tension of compression, ductile, malleable, relatively inexpensive, easy to weld and forge, prone to rusting

Black mild steel is steel direct from a hot rolling forming process, which still has a scale coating on its surface, is not precise in its dimensions, nor straightness or flatness. It is used for general non-critical work, especially where welding is performed. Black Mild steel has a dark blue oily surface and is not as accurate as bright mild steel because bright steel undergoes additional processes to produce higher quality material. Mild steel is reasonably soft and ductile. It is easily cut and machined and is a good material to practice welding on. The reason for this is its carbon content, which varies between 0.15% and 0.3%. Some of the uses of Mild Steel are Ship Hulls, Garden Gates, Girders, General Structural Steel, etc.

Tool Steel

Common uses: Wood and metal working tools, springs, wire cables

Main characteristics: Tenacious, ductile, malleable, can be hardened and tempered, more difficult to weld than mild steel, prone to rusting

The name ”tool steel” describes a range of carbon and alloy steels that are especially well-suited for use in the production of tools. These steels are distinguished by their hardness, resistance to wear, toughness, and resistance to softening at high temperatures. These properties make them suitable candidates for tool manufacturing, including reamers, drills, machine dies, and hand tools.

They are divided into numerous categories based on their features and makeup. There are seven main types of tool steel: water-hardening, hot-work, cold-work, shock-resisting, mold steels, high-speed steels, and special purpose tools steel. The presence of carbide-forming elements like chromium, vanadium, molybdenum, and tungsten are key identifying features of high-speed tool steels, for example. Their performance at high temperatures is enhanced by the addition of cobalt or nickel. Tool steels are typically heat treated to increase their hardness and used for metal stamping, forming, shearing, cutting, and plastic forming.

Sourced from xometry.

Cast Iron

Common uses: Engine blocks, cylinder heads, machinery (lathes, shapers)

Main characteristics: Good wearing and machining qualities, high compression strength, easy to cast, brittle

Cast iron, an alloy of iron that contains 2 to 4 percent carbon, along with varying amounts of silicon and manganese and traces of impurities such as sulfur and phosphorus. It is made by reducing iron ore in a blast furnace. The liquid iron is cast, or poured and hardened, into crude ingots called pigs, and the pigs are subsequently remelted along with scrap and alloying elements in cupola furnaces and recast into molds for producing a variety of products.

Most cast iron is either so-called gray iron or white iron, the colours shown by fracture. Gray iron contains more silicon and is less hard and more machinable than is white iron. Both are brittle, but a malleable cast iron produced by a prolonged heat treatment was developed in France in the 18th century, and a cast iron that is ductile as cast was invented in the United States and Britain in 1948. Such ductile irons now constitute a major family of metals that are widely used for gears, dies, automobile crankshafts, and many other machine parts.

Sourced from Britannica.

Stainless Steel

Common uses: Cooking utensils, cutlery, sinks, wash troughs, milk tankers, marine fittings, tools

Main characteristics: Tenacious, ductile, malleable, machinable, extremely resistant to corrosion

Stainless Steels is also classed as an Alloy Steel. The main alloying elements are Nickel and Chromium. It has a very high resistance to corrosion and as a result is ideal for areas where clenliness is important. Resistance to corrosion and staining, low maintenance, and familiar luster make stainless steel an ideal material for many applications where both the strength of steel and corrosion resistance are required. Moreover, stainless steel can be rolled into sheets, plates, bars, wire, and tubing. These can be used in cookware, cutlery, surgical instruments, major appliances, vehicles, construction material in large buildings, industrial equipment (e.g., in paper mills, chemical plants, water treatment), and storage tanks and tankers for chemicals and food products.

Tin Plate

Common uses: Food and drink cans, kitchenware

Main characteristics: Similar to mild steel, less prone to rusting, does not contaminate food

Tinplate consists of sheets of steel, coated with a thin layer of tin. Before the advent of cheap milled steel the backing metal was iron. While once more widely used, the primary use of tinplate now is the manufacture of tin cans. Tinplate is made by rolling the steel (or formerly iron) in a rolling mill, removing any mill scale by pickling it in acid and then coating it with a thin layer of tin. Plates were once produced individually (or in small groups) in what became known as a pack mill. In the late 1920s pack mills began to be replaced by strip mills which produced larger quantities more economically. Formerly, tinplate was used for cheap pots, pans and other holloware. This kind of holloware was also known as tinware and the people who made it were tinplate workers.

For many purposes, tinplate has been replaced by galvanised (zinc-coated) vessels, though not for cooking as zinc is poisonous. The zinc layer prevents the iron from rusting through sacrificial protection with the zinc oxidizing instead of the iron, whereas tin will only protect the iron if the tin-surface remains unbroken.

Galvanised Iron/Steel

Common uses: Roofing, guttering, water tanks, garage doors

Main characteristics: Similar to mild steel, rust resistant. Zinc coating provides protection from rust.

Galvanized iron is the same as standard iron, the only difference is that it features a layer of zinc. The added layer of zinc helps to protect the iron from rust and corrosion. Without it, the iron will be exposed to moisture and oxygen from its surrounding environment. If left unchecked, this will trigger a chemical reaction with the iron known as oxidation. Oxidation will cause the iron to rust and corrode.

Galvanised construction steel is the most common use for galvanised metal, and hundreds of thousands of tons of steel products are galvanised annually worldwide. In developed countries most larger cities have several galvanising factories, and many items of steel manufacture are galvanised for protection. Typically these include: street furniture, building frameworks, balconies, verandahs, staircases, ladders, walkways, and more. Hot dip galvanised steel is also used for making steel frames as a basic construction material for steel frame buildings.

Aluminium

Common uses: Aircraft, small boats, window and door frames, roofing, cooking utensils, car engines, caravans

Main characteristics: Light in weight, resists corrosion, malleable, ductile, good conductor of heat and electricity, easy to cast

Aluminium is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one-third that of steel. Aluminium is a natural element and can be found on the periodic table. This metal is commonly mixed with copper and zinc to create other alloy materials. Aluminium is a lightweight material used to manufacture cans for food products and building products such as window frames.

Copper

Common uses: Electrical wire, water pipes, heaters, boat fastenings, soldering bits

Main characteristics: Very malleable, ductile, excellent conductor of electricity and heat, resistant to corrosion

Copper is a chemical element with the symbol Cu (from Latin: cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orange color. Copper is used as a conductor of heat and electricity, as a building material, and as a constituent of various metal alloys, such as sterling silver used in jewelry, cupronickel used to make marine hardware and coins, and constantan used in strain gauges and thermocouples for temperature measurement.

Copper is one of the few metals that can occur in nature in a directly usable metallic form (native metals). This led to very early human use in several regions, from c. 8000 BC. Thousands of years later, it was the first metal to be smelted from sulfide ores, c. 5000 BC; the first metal to be cast into a shape in a mold, c. 4000 BC; and the first metal to be purposely alloyed with another metal, tin, to create bronze, c. 3500 BC.

Brass

Common uses: Plumbing taps, valves, electrical fittings, machine bearings, marine fittings, radiator tanks

Main characteristics: Malleable, ductile, tenacious, casts well, machines well, good conductor of heat and electricity, resists corrosion

Brass is an alloy of copper and zinc, in proportions which can be varied to achieve varying mechanical, electrical, and chemical properties. Brass is similar to bronze, another alloy containing copper that uses tin instead of zinc. Historically, the distinction between the two alloys has been less consistent and clear and modern practice in museums and archaeology increasingly avoids both terms for historical objects in favor of the more general "copper alloy".

Brass has long been a popular material for decoration due to its bright, gold-like appearance; being used for drawer pulls and doorknobs. It has also been widely used to make utensils due to properties such as having a low melting point, high workability (both with hand tools and with modern turning and milling machines), durability, and electrical and thermal conductivity.

Brass is still commonly used in applications where corrosion resistance and low friction are required, such as locks, hinges, gears, bearings, ammunition casings, zippers, plumbing, hose couplings, valves, and electrical plugs and sockets. It is used extensively for musical instruments such as horns and bells, and also used as a substitute for copper in making costume jewelry, fashion jewelry, and other imitation jewelry. The composition of brass, generally 66% copper and 34% zinc, makes it a favorable substitute for copper based jewelry, as it exhibits greater resistance to corrosion. Brass is not suitable for such items as boat propellers because the zinc reacts with minerals in salt water, leaving porous copper behind. The tin in bronze will not react with these minerals.

Brass is often used in situations in which it is important that sparks not be struck, such as in fittings and tools used near flammable or explosive materials.

Lead

Common uses: Roof flashing, soft solder, car battery plates, weights, acid containers, underground cable casting, bullets

Main characteristics: Very soft malleable, very resistant to corrosion, heavy, low melting point

Lead (Pb), a soft, silvery white or grayish metal in Group 14 (IVa) of the periodic table. Lead is very malleable, ductile, and dense and is a poor conductor of electricity. Known in antiquity and believed by the alchemists to be the oldest of metals, lead is highly durable and resistant to corrosion, as is indicated by the continuing use of lead water pipes installed by the ancient Romans. The symbol Pb for lead is an abbreviation of the Latin word for lead, plumbum.

Lead has many other applications, the largest of which is in the manufacture of storage batteries. It is used in ammunition (shot and bullets) and as a constituent of solder, type metal, bearing alloys, fusible alloys, and pewter. In heavy and industrial machinery, sheets and other parts made from lead compounds may be used to dampen noise and vibration. Because lead effectively absorbs electromagnetic radiation of short wavelengths, it is used as a protective shielding around nuclear reactors, particle accelerators, X-ray equipment, and containers used for transporting and storing radioactive materials.

Sourced from Britannica.

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