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Aircraft Materials Quiz

Total questions: 31

Worksheet time: 31mins

Name
Class
Date
1.

Pure iron is rarely used in aircraft structures because:

a)

It is too brittle

b)

It is too soft and malleable

c)

It cannot be welded

2.

The main disadvantage of steel in aircraft structures is:

a)

Low strength compared to aluminum

b)

High density and susceptibility to corrosion

c)

Inability to be heat-treated

3.

Construction steels (carbon content 0.05–0.5%) are not used in aircraft mainly because:

a)

They are too expensive

b)

Their ultimate strength is too low

c)

They cannot be welded

4.

Carbon steels (carbon 0.5–0.8%) are typically used in aircraft for:

a)

Landing gear struts

b)

Springs, tools, and wires

c)

Wing spars

5.

Which alloying element increases toughness and impact strength of steel?

a)

Molybdenum

b)

Sulphur

c)

Phosphorus

6.

Stainless steels used in aircraft are abbreviated as:

a)

HHT

b)

CRS

c)

CRES

7.

“HHT” stands for:

a)

High Heat Treated

b)

High Strength Heat Treated

c)

Heat Hardened Titanium

8.

In AISI steel designation, the last two digits indicate:

a)

Nickel percentage

b)

Carbon content in hundredths of a percent

c)

Chromium percentage

9.

AISI 4130 steel is commonly used in the strength range of:

a)

125–145 ksi

b)

180–200 ksi

c)

260–280 ksi

10.

The alloy 300M is mainly used for:

a)

Wing ribs

b)

Landing gear components

c)

Hydraulic pipes

11.

One major risk in handling HHT steels is:

a)

Work hardening

b)

Notch sensitivity leading to cracking

c)

Oxidation during welding

12.

Low alloy steels are generally hardenable because they contain:

a)

Chromium above 12%

b)

A certain minimum carbon content

c)

Nickel above 10%

13.

The main risk of hardening steels only for maximum tensile strength is:

a)

Low corrosion resistance

b)

Premature brittle fracture under impact loads

c)

Excessive cost in production

14.

After quenching, steel forms a brittle structure known as:

a)

Austenite

b)

Martensite

c)

Ferrite

15.

The tempering process is applied to:

a)

Increase hardness and decrease toughness

b)

Reduce brittleness and improve toughness

c)

Eliminate carbon from the alloy

16.

Surface hardening methods such as carburizing or nitriding:

a)

Change the chemical composition of the edge zone

b)

Soften the steel uniformly

c)

Remove impurities from the surface

17.

Stress-relieving anneal is usually done:

a)

At 10–20°C below the tempering temperature

b)

At 300°C above the quenching temperature

c)

At exactly the same as the carburizing temperature

18.

Heat-treated steels must never be:

a)

Painted after machining

b)

Welded or heat-straightened

c)

Stored in humid conditions

19.

High alloy steels are classified as “CRES” when they contain:

a)

At least 12% chromium

b)

At least 10% nickel

c)

More than 5% molybdenum

20.

The letters “PH” in a steel like CRES 15-5 PH indicate:

a)

Pressure Hardening

b)

Precipitation Hardening

c)

Process Heat-treatment

21.

Martensitic steels differ from ferritic and austenitic steels because:

a)

They are hardened intensely by rapid cooling

b)

They are non-magnetic

c)

They contain no chromium at all

22.

Corrosion is best described as:

a)

Mechanical wear of metals under stress

b)

Chemical or electrochemical attack on a metal

c)

Fatigue cracking due to cyclic loading

23.

The type of corrosion that occurs between two dissimilar metals in contact with an electrolyte is:

a)

Galvanic corrosion

b)

Stress corrosion

c)

Crevice corrosion

24.

Pitting corrosion is especially dangerous because:

a)

It always spreads uniformly

b)

It causes deep localized cavities that are hard to detect

c)

It is only cosmetic and not structural

25.

Intergranular corrosion attacks:

a)

The external surface uniformly

b)

The boundaries between grains inside the metal

c)

The protective paint layer

26.

Stress corrosion cracking is promoted by:

a)

Static compressive loads only

b)

Combined tensile stress and a corrosive environment

c)

Absence of electrolytes

27.

The main protection against galvanic corrosion is:

a)

Polishing the metals until smooth

b)

Avoiding contact between dissimilar metals or using insulating barriers

c)

Reducing tensile stresses

28.

Anodizing aluminum provides protection by:

a)

Applying a zinc coating

b)

Creating a thick oxide film on the surface

c)

Depositing a layer of nickel-chromium

29.

The chemical conversion coating often used on aluminum to resist corrosion is:

a)

Chromium conversion coating (Alodine)

b)

Zinc galvanizing

c)

Powder coating

30.

Cadmium plating is mainly used on steel parts because:

a)

It improves heat resistance

b)

It provides sacrificial protection against corrosion

c)

It prevents work hardening

31.

The main advantage of composite materials in aircraft is:

a)

High weight and low stiffness

b)

High strength-to-weight ratio and corrosion resistance

c)

Easy recyclability compared to metals