Materials and Hand Tools
What is tested
Materials and Hand Tools tests material properties, heat treatment and the safe selection of spanners, sockets, hammers, chisels, files, hacksaws, punches and torque wrenches.
Core rules
- Mild steel is ductile and weldable; high-carbon steel is harder and takes an edge but is less tough; cast iron is brittle in tension and good in compression; aluminium is light and corrosion-resistant but soft.
- Annealing softens and relieves stress; normalizing refines grain; hardening heats and quenches; tempering reduces brittleness after hardening.
- Use a six-point socket on a damaged hex, a ring spanner on a tight nut, and a torque wrench for critical fasteners. Pull a spanner rather than push it where possible.
- A chisel head must be ground to a dome, not mushroomed; a file must have a handle; a hacksaw blade must be tensioned and the teeth pointed forward.
- Never use a file as a pry bar, a hammer as a punch, or an extension pipe on a ratchet beyond its rated capacity.
Worked example
A carbon-steel cold chisel loses its edge and turns blue at the tip after grinding. The blue colour indicates overtempering from overheating. The correct action is to re-grind with light passes and cool the tip in water, then temper to a straw colour for the required toughness. The reasoning is that excessive heat softens the hardened edge, so the tool will dull quickly and can chip.
Traps
Using an imperial spanner on a metric fastener, which rounds the flats; quenching a complex high-carbon part in water and cracking it; and using a mushroomed chisel that can send metal fragments into the eye. Also, a tight bolt is not a torque setting-critical joints need the specified value and sequence.