Design & Technology students often learn about ferrous metals, non-ferrous metals and their alloys. This article summarises the properties, stock forms, and uses of common metals, helping students to revise these topics.
Metals are separated into two categories: ferrous and non-ferrous.
Ferrous Metals
- Contain iron (“ferrous” comes from the Latin word “ferrum,” meaning iron – this is why the symbol of iron is Fe)
- Magnetic (although some alloys, like stainless steel are not always magnetic)
- Generally have high tensile strength (hence valuable for construction and manufacturing)
- Prone to rust when exposed to oxygen and moisture due to iron content
- Become less malleable as more carbon is added
An alloy is a mixture of two or more elements, where at least one of these is a metal. Many alloys are mixtures of 2 or more metals. These are combined to improve appearance or properties.
FERROUS METALS & THEIR ALLOYS
Cast iron
Properties
Uses
Wrought iron is different (has less carbon) and is hammered/forged into shape
Mild steel
Properties
Uses
High-carbon steel
Properties
Uses
Medium carbon steel is useful for things like a woodworking vise etc
High-speed steel
Properties
Uses
Stainless steel
Properties
Uses
Non-ferrous metals
- Do not contain iron
- Not magnetic
- Generally more corrosion resistant than ferrous metals
- Often more expensive
NON-FERROUS METALS & THEIR ALLOYS
Aluminium
Properties
Uses
Malleable – hammered and pressed into shape without breaking
Ductile – stretches into wire without breaking
Copper
Properties
Uses
Gets a green patina with age as it oxidises upon exposure to air and moisture
Lead
Properties
Uses
Tin
Properties
Uses
Rarely used in pure form as it is very soft
Zinc
Properties
Uses
Titanium
Properties
Uses
Tungsten
Properties
Uses
Duralumin
Properties
Uses
Learn about other modern materials contain metals, including metal foams and super alloys, as well as smart materials
shape memory alloys (SMA): nickel, titanium;
- These are special metallic materials that can “remember” and return to a predetermined shape when subjected to heat or other stimuli
- At a cool temperature they are flexible and easily deformed
- Very elastic (can undergo large deformations without damage)
- When heated, the crystal structure transforms and recovers its prior shape
- Can be repeated for thousands of cycles, generating significant force
Nitinol (Nickel-Titanium) is the most widely used SMA, comprising roughly equal parts nickel and titanium. Other types include copper-based alloys and iron-based SMAs.
SMAs are used in diverse fields including medical devices (stents, orthodontic wires, surgical instruments), aerospace (actuators, couplings), automotive (engine components), and consumer products (eyeglass frames, clothing fasteners).
smart materials, modern materials
Common stock forms
Environmental Considerations
- Metals are made from elements in the Earth’s crust (non-renewable), however, they are highly recyclable
- Don’t degrade when recycled (unlike plastic)
- Steel/iron can be melted and reused infinitely
- Not biodegradable, but corrode/oxidize instead (rust, or develop a patina coating like copper)
- They change form but remain as metal compounds
- Can persist for centuries/millennia
- Environmental issue: Heavy metals like lead and mercury can accumulate in soil/water, so recycling is important.
Amiria has a Bachelor of Architectural Studies, Bachelor of Architecture (First Class Honours) and a Graduate Diploma of Teaching. She is a CIE Accredited Art & Design and Design & Technology Coursework Assessor. Amiria now teaches Art, Design & Technology at ACG Parnell College.