Understanding Heat Treatments and Corrosion

What is the primary purpose of annealing in heat treatment processes?

• To increase the hardness of the metal

• To relieve internal stresses and improve ductility

• To create a protective oxide layer

• To increase the carbon content

Which type of corrosion is characterised by small, localised holes on the surface of a metal?

• Intergranular corrosion

• Galvanic corrosion

• Pitting corrosion

• Oxidation

In the iron-carbon thermal equilibrium diagram, what is the eutectoid composition of carbon in steel?

• 0.76%

• 1.2%

• 0.15%

• 2.14%

What is the main difference between normalising and annealing?

• Normalising is done at a higher temperature than annealing

• Normalising results in a softer material than annealing

• Normalising is followed by slow cooling, while annealing is followed by air cooling

• Normalising is followed by air cooling, while annealing is followed by slow cooling

Which type of defect is considered non-critical?

• A defect that affects the structural integrity of a component

• A defect that is purely cosmetic and does not affect functionality

• A defect that causes a component to fail under load

• A defect that requires immediate repair to prevent failure

What is the primary purpose of tempering in the heat treatment of steel?

• To increase the carbon content

• To harden the steel

• To reduce brittleness and increase toughness

• To create a protective oxide layer

Which type of corrosion occurs when two different metals are in electrical contact in a corrosive environment?

• Pitting corrosion

• Intergranular corrosion

• Galvanic corrosion

• Leaching

What is the main characteristic of intergranular corrosion?

• It occurs uniformly across the surface

• It occurs along the grain boundaries of a metal

• It results in the formation of a protective oxide layer

• It is caused by the presence of dissimilar metals

What is the effect of hardening on the microstructure of steel?

• It transforms austenite into martensite

• It increases the grain size

• It reduces the carbon content

• It forms a protective oxide layer

Which of the following is a common method to prevent oxidation corrosion?

• Applying a protective coating

• Increasing the carbon content

• Using dissimilar metals

• Increasing the temperature