Aircraft Materials and Processes Quiz
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Questions and Answers

What is the definition of strain in materials?

  • Deformation of material caused by an applied load. (correct)
  • The load acting on a material.
  • The ability of a material to resist deformation.
  • The maximum tensile load per square inch.

Which term describes the load per square inch at which a material shows a specified elongation under load?

  • Yield Strength (correct)
  • Proof Stress
  • Elastic Limit
  • Modulus of Elasticity

According to Hooke’s Law, what is the relationship between stress and strain?

  • Stress is independent of material properties.
  • They are directly proportional within the elastic limit. (correct)
  • Strain increases without any increase in stress.
  • Stress remains constant regardless of strain.

What is the maximum tensile load per square inch known as?

<p>Tensile Strength (C)</p> Signup and view all the answers

Which of the following tests is used to determine hardness in materials?

<p>Brinell Hardness Test (A)</p> Signup and view all the answers

What is the primary purpose of normalizing steel?

<p>To relieve internal strains and soften the metal (B)</p> Signup and view all the answers

What operation is involved in hardening steel?

<p>Heating the metal to above the critical range and quenching it (A)</p> Signup and view all the answers

Which statement accurately describes tempering?

<p>It involves reheating hardened steel to a temperature below the critical range. (A)</p> Signup and view all the answers

Which method is used to add carbon to steel?

<p>Carburizing (A)</p> Signup and view all the answers

What is the purpose of case hardening?

<p>To carburize and then harden the metal (C)</p> Signup and view all the answers

What type of tubing is used specifically for fuel and oil lines?

<p>Copper Tubing (B)</p> Signup and view all the answers

Which alloy is particularly noted for its high strength and is used in bearings and bushings subject to heavy loads?

<p>Hy-Ten-Sl-Bronze (C)</p> Signup and view all the answers

Which type of bronze is used for manufacturing bolts, valve discs, and electric contacts?

<p>Phosphor Bronze (C)</p> Signup and view all the answers

What is the primary alloying element in bronze, apart from copper?

<p>Tin (D)</p> Signup and view all the answers

What casting method uses sand to create complex shapes and is ideal for producing few required parts?

<p>Sand casting (C)</p> Signup and view all the answers

Which aluminum alloy casting technique utilizes a metal mold for better accuracy?

<p>Permanent-mold casting (A)</p> Signup and view all the answers

Which copper alloy is specifically designed for use in contact with salt water?

<p>Naval Brass (C)</p> Signup and view all the answers

In which scenario will pure aluminum exhibit decreased resistance to atmospheric corrosion?

<p>When alloying elements are added (B)</p> Signup and view all the answers

What is the main characteristic of brazing compared to welding?

<p>It does not involve fusion of the materials being joined. (A)</p> Signup and view all the answers

Which type of electric resistance welding method is specifically used for structural corrosion-resistant steel?

<p>Spot welding (C)</p> Signup and view all the answers

What is a key property of thermosetting synthetic adhesives used in aircraft construction?

<p>They allow bonding of various materials including metals and plastics. (D)</p> Signup and view all the answers

What type of corrosion is characterized by its invisibility and internal damage to metals?

<p>Intergranular corrosion (B)</p> Signup and view all the answers

What is the primary benefit of using cycle annealing compared to other processes?

<p>It provides better control of the final annealed structure. (A)</p> Signup and view all the answers

Which component gives steel its hardening qualities?

<p>Cementite (A)</p> Signup and view all the answers

In what welding process is a tungsten or carbon electrode used, surrounded by inert gas?

<p>Inert-arc welding (D)</p> Signup and view all the answers

Which process is suitable for increasing ductility and toughness in small sizes of deep-hardening steels?

<p>Austempering (C)</p> Signup and view all the answers

Which welding method employs power-driven rollers as electrodes to create a continuous weld?

<p>Seam welding (B)</p> Signup and view all the answers

What distinguishes gas carburizing from other carburizing methods?

<p>It treats parts in a rotating retort with gas. (A)</p> Signup and view all the answers

What occurs during the process of spheroidizing?

<p>Prolonged heating just below the critical range (D)</p> Signup and view all the answers

What is the main characteristic of annealed steel?

<p>Fine-grained and soft (C)</p> Signup and view all the answers

Which surface hardening method is known for its speed and low cost but is rarely used in aircraft work?

<p>Cyaniding (A)</p> Signup and view all the answers

Which filler metal is commonly used in soft soldering applications to make electrical connections?

<p>Tin and lead (C)</p> Signup and view all the answers

What is a notable drawback of using nitriding in welding applications?

<p>A significant amount of aluminum is burnt away. (B)</p> Signup and view all the answers

Which plating method is primarily used in aircraft construction for its corrosion resistance?

<p>Cadmium plating (D)</p> Signup and view all the answers

Which structure is typically the hardest and most brittle form of steel?

<p>Martensite (B)</p> Signup and view all the answers

Which process is specifically tailored for hardening small sizes of steel parts while minimizing distortion?

<p>Martempering (D)</p> Signup and view all the answers

During normalization, how does the ductility of steel change compared to annealed steel?

<p>It becomes less ductile (A)</p> Signup and view all the answers

Which method is primarily used to resolve ductility in the sheet and wire industries?

<p>Process annealing (D)</p> Signup and view all the answers

Which method is utilized to improve the fatigue and abrasion resistance of metal parts?

<p>Shot Peening (C)</p> Signup and view all the answers

What is the purpose of refining the core in the carburizing process?

<p>To obtain a fine, ductile grain in the core. (D)</p> Signup and view all the answers

What is the purpose of normalizing welded parts after fabrication?

<p>To reduce cracks and fatigue failures (D)</p> Signup and view all the answers

What is a key characteristic of ferrite in carbon steels?

<p>Very ductile and does not harden (D)</p> Signup and view all the answers

Flashcards

Normalizing Steel

A faster method than annealing for steel, it cools in still air, relieving internal strains and softening the metal.

Heat Treatment (Steel)

Operations (like hardening and tempering) to improve steel's physical properties.

Hardening (Steel)

Heating steel above a critical temperature, then quickly cooling (quenching) to make it very strong.

Quenching

Quickly cooling heated metal in a liquid (like oil or water).

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Carburizing

Adding carbon to steel at high heat using a carbonaceous material.

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Strain

The deformation of a material caused by an applied load.

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Stress

The load acting on a material.

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Tensile Strength

The maximum tensile load per square inch that a material can withstand before breaking.

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Elastic Limit

The maximum load per square inch a material can withstand without permanent deformation.

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Proportional Limit

The load per square inch beyond which the increase in strain is no longer directly proportional to the increase in stress.

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Pearlite

A combination of ferrite and cementite, usually appearing as a layered structure in steel. It provides strength and ductility.

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Ferrite

Pure alpha iron in carbon steels. It is very ductile but lacks hardening properties.

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Cementite

A very hard and brittle compound of iron and carbon. It provides hardness to steel.

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Austenite

A solid solution of cementite in gamma iron. It forms when steel is heated above a critical temperature.

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Martensite

A hardened form of steel formed by rapidly cooling austenite. It is extremely hard and brittle.

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Annealing

Heating and slowly cooling steel to relieve internal stresses, making it softer and more ductile.

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Normalizing

Heating steel to a specific temperature then cooling in still air. This strengthens and hardens the steel but makes it less ductile.

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Hardening

The process of heating steel and then rapidly cooling it (quenching) to increase hardness, but reducing ductility.

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Copper Tubing

Used in aircraft for fuel and oil lines. Some grades are also used for water and air lines.

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Copper-Silicon-Bronze Tubing

A strong and corrosion-resistant tubing used for fuel, oil, water, and air lines in aircraft.

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Beryllium Copper

A very strong copper alloy, available in bar, rod, sheet, strip and wire forms.

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Muntz Metal

A type of brass highly resistant to corrosion when in contact with saltwater.

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Manganese Bronze

A strong brass alloy used for machined parts in aircraft construction.

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Hy-Ten-Sl-Bronze

A very strong copper alloy ideal for bearings and bushings that handle big loads.

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Naval Brass (Tobin Bronze)

A strong brass alloy used for various parts in contact with seawater, like turnbuckles.

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Gun Metal

A hard bronze material used for casting gears and bearings.

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Inert-Arc Welding

A welding process using a tungsten or carbon electrode surrounded by helium or argon gas, preventing air contamination.

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Multiarc Welding

A relatively new welding method combining alternating and direct current with both metallic and carbon electrodes.

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Butt Welding

A resistance welding technique used for joining long sheets, bars, tubes, rods, and wires together.

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Spot Welding

A resistance welding process used for joining metal sheets together at specific points, frequently used in aircraft construction.

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Seam Welding

A resistance welding method similar to spot welding, but using rollers to create a continuous airtight weld.

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Brazing

A metal-joining process using filler metal with a melting point above 1000F but lower than the base metals, without fusion.

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Soft Soldering

A metal-joining process using tin-lead alloys with a low melting point, not used for structural aircraft joints.

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Adhesive Bonding

Joining materials with strong synthetic adhesives, creating air and liquid tight seams

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Cycle Annealing

A heat treatment method that involves heating steel to a specific temperature, holding it there for a period of time, and then slowly cooling it down. This process helps to relieve internal stresses and improve the overall ductility and toughness of the steel.

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Austempering

A heat treatment process where steel is quickly heated to above its critical temperature and then held at a moderate temperature, allowing the formation of bainite. This results in a stronger, more ductile, and more tough steel compared to traditional tempering.

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Martempering

A heat treatment process that involves heating steel above its critical temperature and then quickly cooling it to a lower temperature, allowing for the formation of martensite. This process helps to minimize distortion and cracking caused by quenching.

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Case Hardening

A heat treatment process where a thin layer of carbon is added to the surface of steel, making the surface harder while keeping the core softer. This process improves wear resistance and hardness without significantly impacting the ductility of the core.

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Cyaniding

A surface hardening process where steel is heated in contact with a cyanide salt. This process results in a thin, hard surface layer.

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Nitriding

A surface hardening process where special alloy steels are heated in contact with ammonia gas or other nitrogen-containing materials.

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Induction Hardening

A surface hardening process that uses a powerful, rapidly alternating electromagnetic field to heat the surface of metal parts. This allows for controlled hardening of specific areas.

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Study Notes

Aircraft Materials and Processes

  • Hardness: Resistance to penetration or permanent distortion. Increased by hammering, rolling, working. Heat treatment can also increase hardness in aluminum alloys. Annealing is a modified heat treatment that softens metals.
  • Brittleness: Resistance to change in molecular position. Tendency to fracture without change of shape. Harder materials tend to be more brittle.
  • Malleability: Property of metals to be bent or permanently distorted without rupture. Opposite of brittleness. Processes include bending and hammering. Products include sheet metal, bar stocks, forgings, and fabricated parts.
  • Ductility: Property of metals to be drawn out without breaking. Products include wire and tubing. Process includes drawing. Ease of forming and resistance to shock loads.
  • Elasticity: Property of returning to original shape when force is removed. All aircraft structural design is based on this property. Elastic limit is the point beyond which loading causes permanent distortion.
  • Density: Weight of a unit volume of a material.
  • Fusibility: Property of being liquefied by heat. Processes such as welding. Fuse temperature of steel is 200°F and aluminum alloys is 1100°F.

Physical-Test Terms

  • Strain: Deformation of a material caused by an applied load.
  • Stress: Load acting on a material.
  • Tensile Strength: Ultimate tensile strength, maximum tensile load per square inch. Formula: Max load/Cross-sectional Area (PSI)
  • Elastic Limit: Greatest load per square inch a material can withstand without permanent deformation.
  • Proportional Limit: Load per square inch beyond which strain increase is not directly proportional to stress increase.
  • Hooke's Law: Proportionality between stress and strain.
  • Proof Stress: Load per square inch a material can withstand without permanent elongation more than 0.0001 inch of gage length.
  • Yield Strength: Load per square inch at which a material exhibits special limiting permanent set or specified elongation under load.
  • Elongation (Percentage): Difference in gage length before and after stress and rupture.

Heat Treatment Terms

  • Critical Range: Temperature range between 1300°F and 1600°F where internal structure of steel is altered. Heat treatment of steel is based on this phenomenon.
  • Annealing: Process of heating steel above critical range, holding until uniform, and then cooling. Relieves internal strains.
  • Normalizing: Similar to annealing but cooling in still air, is faster. Relieves internal strains, and slightly softens the metal. Strength increases about 20% compared to annealing process.
  • Heat Treatment: Series of operations to improve physical properties of a material.
  • Hardening: Heating the metal above the critical range, then quenching in brine, water, or oil.
  • Quenching: Immersing heated metal in liquid (oil or water) to accelerate cooling.
  • Tempering: Reheating hardened steel to temperature below critical range, then cooled/quenched in oil or water (AKA drawing).

Testing Aircraft Materials

  • Brinell Hardness Test: Pressing a hardened steel ball under known pressure into a flat surface of the specimen being tested.
  • Rockwell Hardness Test: Measuring penetration of a diamond cone or hardened steel ball under definite loads. Larger difference between major and minor loads indicates lower hardness (softer material).

Steel and its Alloys

  • Plain Carbon Steels: Classified by carbon percentage. Contain small amounts of silicon, sulfur, phosphorus, and manganese. Silicon and manganese are beneficial, while sulfur and phosphorus are harmful impurities.
  • Carbon: Combines readily with iron to form iron carbide (cementite). Higher carbon content corresponds to higher hardness but lower ductility, malleability, toughness, and weldability. Includes low carbon steal (for deep drawing, excessive mechanical work, formed fittings, and welded parts) and high carbon steel (for great hardness).

Effect of Individual Elements (Additional elements in various steels):

  • Manganese: Deoxidizes and desulfurizes steel to produce a cleaner metal improving forging qualities.
  • Silicon: Acts as an excellent deoxidizer and improving steel's ductility.
  • Sulfur: Undesirable impurity that causes brittleness at higher temperatures.
  • Phosphorus: Undesirable impurity associated with cold shortness (brittleness at low temps).
  • Nickel: White metal, malleable, ductile, weldable, increases strength, yield point, and hardness, but slows the rate of hardening. Also improves corrosion resistance in alloys.
  • Chromium: Hard gray metal with high melting point, improves hardness, strength, wear resistance, and corrosion resistance (18-8 or 18% Cr., 8% Ni, non magnetic)
  • Tungsten: High-speed steel; used in tools that retain cutting edge even when heated.
  • Titanium: Often added to 18-8 corrosion-resisting steels for reducing embrittlement at operating temperatures of exhaust stacks or collectors.

Steel Numbering System

  • Ca-Ni-Chro-Mo-Chro-CV-Tu-Na-SM: System used for categorization and identification of various steels.

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Aircraft Materials and Processes PDF

Description

Test your knowledge on the fundamental properties of aircraft materials, including hardness, brittleness, malleability, ductility, and elasticity. Understand how these properties affect the manufacturing and structural integrity of aircraft components. This quiz covers essential concepts that are vital in the aerospace industry.

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