Questions

Question 1

What happens to the steel at ‘arrest’ or ‘critical’ points as it is heated?

Answer 1

The metal temperature stops rising, heat absorbed changes the micro-structure

Question 2

Steel containing .83% carbon has how many arrest points?

Answer 2

One

Question 3

What is the softening heat treatment?

Answer 3

Annealing

Question 4

Which heat treatment restores the crystalline structure and therefore increases strength?

Answer 4

Normalising

Question 5

What other heat treatment process is carried out prior to tempering?

Answer 5

Hardening

Question 6

What properties does small amounts of Molybdenum bring to chrome alloy steel?

Answer 6

Helps to improve the properties of the steel.

Question 7

What are the advantages of Maraging steel?

Answer 7

Tougher, simpler heat treatments, less distortion during heat treatment, easier to work, easier to weld, resistance to corrosion and hydrogen embrittlement

Question 8

What is surface hardening?

Answer 8

Given the material a hardener external surface, supported by a tough and
shock-resisting core.

Question 9

Why is aluminium not often used in aircraft construction in its pure state?

Answer 9

It has very little strength

Question 10

Aluminium alloys are classified as wrought or casting. How are they further classified?

Answer 10

Heat treatable and non-heat treatable

Question 11

How are non heat treatable aluminium alloys strengthened?

Answer 11

By Cold working

Question 12

What is Alclad?

Answer 12

A sandwich type of sheet metal with a core of 95% of the thickness which is an aluminium alloy with upper and lower surfaces of pure aluminium for corrosion protection

Question 13

What process must be carried out before forming or shaping aluminium?

Answer 13

Annealing

Question 14

How can age hardening be delayed?

Answer 14

Storing the solution heat treated material in a refigerator

Question 15

How many times can Alclad be heat treated?

Answer 15

3 times, any more the alloying materials start to bleed into the pure aluminium cladding.

Question 16

Describe a malleable metal.

Answer 16

One that can be deformed by compression before it shows signs of cracking

Question 17

Describe a ductile metal.

Answer 17

One which can be deformed a great deal by Tension before it fractures.

Question 18

What is measured by an impact test?

Answer 18

A test of the toughness of a material and its ability to resist mechanical shock.

Question 19

What is the yield point?

Answer 19

The point where the properties of a material under tension go from Elastic to Plastic.

Question 20

Define Creep.

Answer 20

The permanent extension of a material when subjected to tension and heat.

Question 21

How is hardness determined when using Brinell or Vickers hardness test equipment?

Answer 21

A ball or diamond shape indenter is fired into the surface of a material. The hardness is indicated by the dimensions of the- indent left in the material.

Question 22

Which test for toughness would be used at low or high temperatures?

Answer 22

When there is a requirement for testing at low or high temperatures the Charpy test is recommended.

Question 23

What causes cyclic fatigue?

Answer 23

Repeated fluctuating loads, such as take-off, landing, turbulence and pressurisation

Question 24

What type of test results in a graph where stress(S) is plotted against number of reversals(N)?

Answer 24

Fatigue testing.

Question 25

What affect has surface finish be found to have on the endurance limit of a test piece?

Answer 25

A polished test piece has a much greater endurance limit than a roughly
turned test piece.