80 Questions
What is the primary purpose of the last two digits in the alloy numbering system?
To identify the different alloys in the group
Which of the following is a key feature of aluminium 1xxx series alloys?
Strain-hardenability and high formability
What is the primary alloying element in the 2xxx series of aluminium alloys?
Copper
What is a major drawback of aluminium-copper alloys?
Susceptibility to intergranular corrosion
Which of the following aluminium alloys is commonly used in the construction of aircraft skins and rivets?
2017
What is the primary alloying element in the 3xxx series of aluminium alloys?
Manganese
Which of the following statements about 3xxx series aluminium alloys is true?
They are generally considered non-heat-treatable
What type of change occurs in the grain structure of aluminium when it is mixed with copper?
Certain metallic changes take place in the resultant alloy's grain structure
What is the recommended method for extinguishing a fire involving magnesium?
Smother the fire with dry sand or other dry material
What is the effect of solution heat treatment on the properties of magnesium alloys?
It increases tensile strength, ductility and resistance to shock
What is the effect of precipitation heat-treatment (artificial aging) on magnesium alloys after solution heat-treatment?
It increases hardness and yield strength
What is the primary reason titanium and its alloys are used extensively in the civilian aerospace industry?
Their high strength-to-weight ratio
What is the process required to convert titanium into a usable form?
Conversion to titanium dioxide with chlorine gas and a reducing agent
Which of the following is NOT a key property of titanium and its alloys?
Poor corrosion resistance
What is the primary application of solution heat-treated magnesium alloys?
Gearbox and generator housings
Why must titanium be converted to titanium dioxide before it can be used?
Because the metal is sensitive to both nitrogen and oxygen
What is the purpose of the T-designation in the heat treatment of aluminum alloys?
To indicate the type of heat treatment the alloy has undergone
What is the difference between the T4 and T6 temper designations for aluminum alloys?
T4 is solution heat-treated and naturally aged, while T6 is solution heat-treated and artificially aged
What is the purpose of the second digit in the T-designation for aluminum alloys?
To indicate the percentage of cold reduction applied to the alloy
Why is the number of solution heat treatments limited for clad aluminum alloys?
To prevent excessive diffusion of the core material into the cladding, which can decrease corrosion resistance
What is the purpose of heat-treating rivets made from 2017 or 2024 aluminum alloys?
To soften the rivets so they can be easily deformed during installation
What is the difference between the T3 and T5 temper designations for aluminum alloys?
T3 is solution heat-treated and strain-hardened, while T5 is artificially aged after rapid cooling from a fabrication process
What is the purpose of the T36 temper designation for aluminum alloys?
To indicate the alloy has been solution heat-treated and then cold-rolled to a 5% reduction in thickness
How do the T4 and T6 temper designations differ in their heat treatment processes?
T4 is solution heat-treated and naturally aged, while T6 is solution heat-treated and artificially aged
What is the typical titanium content in modern jet transport structural alloys?
10% to 15%
Which of the following is NOT one of the two most commonly used nickel alloys mentioned?
Waspaloy
What property of Monel allows it to be used in exhaust systems?
High strength and corrosion resistance at elevated temperatures
What component of a turbine engine is Inconel commonly used for?
Nozzle supports and fan casings
Which property allows Monel to be used for gears and high-strength parts?
Heat-treatable to high tensile strengths
What is the primary reason for the use of nickel alloys in turbine engines?
Ability to maintain strength and corrosion resistance at high temperatures
What type of aircraft components can Monel rivets be used for?
Structural applications
What are the primary alloying elements in Monel?
Nickel and copper
What is the purpose of the letter designation separated from the alloy designation by a dash?
To indicate the metal's hardness or temper
What does the number following the H1, H2, and H3 designations represent?
The degree of strain-hardening
What does the designation 'O' indicate in the context of metal hardness?
Annealed state
Which of the following statements about magnesium alloys is true?
They are commonly used for aircraft structures
What is one of the drawbacks of using magnesium mentioned in the text?
High susceptibility to corrosion
How is the tendency of magnesium to crack when formed overcome?
By heating the parts when forming
What is the primary advantage of using magnesium alloys in aircraft structures?
High strength-to-weight ratio
What is a concern when using magnesium in a dust or small particle form?
Readiness to burn or ignite
What does the number following the H1, H2, and H3 designations represent?
The degree of strain-hardening
Which of the following is a key drawback of using magnesium mentioned in the text?
High susceptibility to corrosion
How is the tendency of magnesium to crack when formed overcome?
By using a higher forming temperature
What is the primary advantage of using magnesium alloys in aircraft structures?
Higher strength-to-weight ratio
What is the purpose of the letter designation separated from the alloy designation by a dash?
To indicate the temper or hardness of the metal
What is the primary reason for the readiness of magnesium to burn in a dust or small particle form?
High surface area-to-volume ratio
What is the primary method used to overcome the high susceptibility to corrosion of magnesium?
Treating the surface with chemicals
What is the primary reason for the use of magnesium alloys in aircraft wheel assemblies?
High strength-to-weight ratio
What is the primary purpose of the Alclad coating applied to aluminium alloy sheets used in aircraft construction?
To make the alloy more resistant to corrosion
What is the main concern if the Alclad coating is penetrated or damaged on aircraft aluminium alloy sheets?
Corrosive agents can attack the alloy underneath
How does heat treatment affect the properties of aluminium alloys?
Both a and b are correct
What is a potential issue that can arise from abrasions or scratches on clad aluminium alloy used in aircraft construction?
Corrosive agents can attack the alloy at those points
What is the primary difference between the T4 and T6 temper designations for heat-treated aluminium alloys?
T4 involves solution heat treatment, T6 involves precipitation heat treatment
What is the primary purpose of the heat treatment process for aluminium alloys used in aircraft construction?
To increase the strength and hardness of the alloy
What is a key limitation of the heat treatment process for clad aluminium alloys used in aircraft construction?
The number of solution heat treatments is limited
What is a key advantage of using Alclad aluminium alloy sheets in aircraft construction compared to uncoated aluminium alloys?
Greater corrosion resistance
What is the primary use of copper in aircraft?
Electrical wiring
Which of the following copper alloys is commonly used for bearings and bushings?
Beryllium copper
What is a concern associated with the use of beryllium copper?
It is a hazardous material
Which of the following is NOT a common use of brass in aircraft?
Structural members
What is the primary reason for using copper alloys in aircraft?
Good electrical and thermal properties
Which of the following statements about Inconel is true?
It is commonly used in gas turbine engines
How can Inconel be differentiated from stainless steel?
Through a chemical test
Which of the following copper alloys is used in fuel metering valves?
Bronze
What is the primary purpose of using aluminium alloys in aircraft structures?
To achieve a lightweight yet strong structure
Which aluminium alloy series is known for providing exceptionally high strength and elasticity?
The 8xxx series
What is the purpose of using clad aluminium alloys (Alclad) in aircraft construction?
To protect the external aircraft surfaces from corrosion
Which aluminium alloy series is typically used for aircraft skins and rivets?
The 2xxx series
What is the primary advantage of using magnesium alloys in aircraft structures?
Lightweight and high strength-to-weight ratio
Which aluminium alloy series is known for its high compressive strength-to-weight ratio?
The 7xxx series
What is the primary concern when using magnesium in a dust or small particle form?
Potential for fire or explosion hazard
Which aluminium alloy series is known for its superior stress corrosion resistance?
The 7xxx series (specifically the 7055 alloy)
What does the 'T' designation indicate in the heat treatment of aluminum alloys?
The alloy has been solution heat-treated
What is the purpose of the T3 temper designation?
Solution heat-treated and strain-hardened
Which temper designation represents solution heat-treatment followed by natural aging at room temperature?
T4
What does the T6 temper designation signify?
Solution heat-treated and artificially aged
What is the purpose of reheat treatment for aluminum alloys?
To restore the alloy to a softer condition
What is the reason for limiting the number of solution heat treatments for clad aluminum alloys?
To preserve corrosion resistance
What does the second digit in the T-designation for aluminum alloys indicate?
The amount of strain-hardening
What is the purpose of the T5 temper designation?
Artificially aged after rapid cooling from fabrication
Study Notes
Aluminium and Alloys
- Aluminium alloy designations: 1xxx to 9xxx series
- Last two digits have no special significance, serving only to identify the different alloys in the group
1xxx Series Alloys
- Made of pure aluminium
- Features: strain-hardenable, high formability, corrosion resistance, electrical conductivity
- Used in electrical and chemical applications
2xxx Series Alloys
- Utilize copper as the principle alloying agent
- Features: increased strength, susceptibility to intergranular corrosion when improperly heat-treated
- Commonly used in aircraft structures: 2017 and 2024 alloys
3xxx Series Alloys
- Utilize manganese as the principle alloying element
- Features: non-heat-treatable, requires caution when grinding and machining
- Important: extinguish magnesium fires with dry sand or other dry material that excludes air from the metal and cools its surface
Titanium and Its Alloys
- Lightweight metals with high strength, excellent corrosion resistance
- Used extensively in civilian aerospace industry
- Important: sensitive to nitrogen and oxygen, must be converted to titanium dioxide with chlorine gas and a reducing agent before use
Heat Treatment of Aluminium Alloys
- Heat treatment: series of operations involving heating and cooling of metals in their solid state
- Aims to make metal more useful, serviceable, and safe for a definite purpose
- Can make metal harder, stronger, and more resistant to impact, or softer and more ductile
Aluminium Alloy Temper Designations
- Heat-treatable alloys: designated by letter T followed by one or more numbers
- T - Solution heat-treated
- T3 - Solution heat-treated, followed by strain-hardening
- T4 - Solution heat-treated, followed by natural aging at room temperature to a stable condition
- T5 - Artificially aged after being rapidly cooled during a fabrication process
- T6 - Solution heat-treated, followed by artificial aging (precipitation heat-treated)
Clad Aluminium Alloy (Alclad)
- Pure aluminium coating rolled onto both surfaces of a heat-treated aluminium alloy sheets
- Increases corrosion resistance of aluminium alloy
- Protect from scratches and abrasions to prevent corrosive agents from attacking the alloy within
Other Alloy Types
- Copper and its Alloys: used in electrical wiring and components due to excellent electrical and thermal conductivity
- Nickel and its Alloys: used in turbine engines, nozzle supports, fan casings, and blades
- Magnesium and Its Alloys: used in castings, sheets, bars, tubing, and extrusions, with applications in aircraft structures
- Inconel and Stainless Steel: used in high-temperature applications, similar in appearance, differentiated through chemical tests
Learn about the identification system used for aluminium alloys in the 1xxx series based on the consecutive assignment of digits. This quiz covers the features and characteristics of pure aluminium alloys within the 1xxx series.
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