Material Technology Flashcards

1
Q

Define the definition of Strength/ Tenacity?

A

This is the property of a material that enables it to resist tensile, compressive or shear forces without failure.

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2
Q

What is Strength measured in?

A

Newtons per square millimetre (N/mm2).

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3
Q

Define the definition of Toughness?

A

This is the property of a material that enables it to absorb the energy from an applied force, impact or shock load without fracture.

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4
Q

Define the definition of Elasticity?

A

This is the ability of a material to return to its original shape and size after the removal of a deforming force.

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5
Q

Define the definition of Plasticity?

A

This is the opposite of elasticity. It is the property that enables a material to be deformed under a force without fracture, the resulting deformation being non-recoverable and nonproportional to the applied force.

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6
Q

Define the definition of Ductility?

A

This is the property possessed by a material that, when subjected to a tensile force, allows permanent plastic deformation to take place before fracture.

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7
Q

Define the definition of Malleability?

A

This is the property possessed by a material that when subject to a compressive force, allows permanent plastic deformation to take place without fracture.

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8
Q

Define the definition of Hardness?

A

This is the ability of a material to resist wear, abrasion, scratching, indentation or penetration by another material. Measurement of this property can only be made relative to other materials and is given in the form of a number only (dimensionless).

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9
Q

Define the definition of Brittleness?

A

This is regarded as the opposite of ductility. It is the property possessed by a material which shows little or no plastic deformation after failure resulting from the application of
a force.

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10
Q

What are the effects of adding Manganese as an alloying element to steel?

A

Generally beneficial to surface quality especially in re-sulfurized steels.
Manganese contributes to strength and hardness, but less than carbon.

Increasing the manganese content decreases ductility and weldability, but less than carbon. Manganese has a significant effect on the hardenability of steel.

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11
Q

What are the effects of adding Phosphorus as an alloying element to steel?

A

Increases strength and hardness and decreases ductility and notch impact toughness of steel.

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12
Q

What are the effects of adding Sulphur as an alloying element to steel?

A

Decreases ductility and notch impact toughness especially in the transverse direction. Weldability decreases with increasing sulphur content.

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13
Q

What are the effects of adding Silicon as an alloying element to steel?

A

Is one of the principal deoxidizers used in steelmaking.

In low-carbon steels, silicon is generally detrimental to surface quality.

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14
Q

What are the effects of adding Copper as an alloying element to steel?

A

In significant amounts is detrimental to hot-working steels.

Copper can be detrimental to surface quality.

Copper is beneficial to atmospheric corrosion resistance

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15
Q

What are the effects of adding Lead as an alloying element to steel?

A

Is virtually insoluble in liquid or solid steel. Lead is sometimes added to carbon and alloy steels by means of mechanical dispersion during pouring to improve the machinability.

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16
Q

What are the effects of adding Boron as an alloying element to steel?

A

Is added to fully killed steel to improve hardenability

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17
Q

What are the effects of adding Chromium as an alloying element to steel?

A

Is commonly added to steel to increase corrosion resistance and oxidation resistance, to increase hardenability, or to improve high-temperature strength.

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18
Q

What are the effects of adding Nickel as an alloying element to steel?

A

Is a ferrite strengthener. Nickel increases the hardenability and impact strength of steels.

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19
Q

What are the effects of adding Molybdenum as an alloying element to steel?

A

Increases the hardenability of steel.

20
Q

What are the effects of adding Aluminium as an alloying element to steel?

A

Is widely used as a deoxidizer. Aluminium can control austenite grain growth in reheated steels and is therefore added to control grain size.

21
Q

What are the effects of adding Zirconium as an alloying element to steel?

A

Can be added to killed high-strength low-alloy steels to achieve improvements in inclusion characteristics. Improving toughness and ductility in transverse bending.

22
Q

What are the effects of adding Niobium as an alloying element to steel?

A

Increases the yield strength and, to a lesser degree, the tensile strength of carbon steel.

23
Q

What are the effects of adding Titanium as an alloying element to steel?

A

Is used to retard grain growth and thus improve toughness. Improving toughness and ductility in transverse
bending.

24
Q

What are the effects of adding Vanadium as an alloying element to steel?

A

Increases the yield strength and the tensile strength of carbon steel.

25
Q

Explain the characteristics of Grey Cast Iron?

A

The characteristic of brittleness with low tensile and low impact strength and restricting its use where high strength is important.

26
Q

List the Pros and Cons of Grey Cast Iron?

A

Pros

  • It has high compressive strength
  • It is a cheap material and has a low melting temperature (1,130 to 1,250 °C).
  • It is highly fluid when molten making it possible to manufacture large components or intricate shapes by simply pouring the metal into an impression moulded in sand.
  • The provision of good sliding and bearing surfaces on a component are possible as the graphite gives a degree of self-lubrication and helps to retain an oil film.
  • Its crystalline nature absorbs vibration and makes it an ideal material for machinery
    frames and beds.

Cons

  • Brittle at all temperatures and cannot be wrought
  • Mainly concerned with the cost and rate of production.
  • New mould for each
    casting.
  • Cannot be used for castings that are exposed to seawater, as it has a very
    low corrosion resistance.
27
Q

Explain the characteristics of White Cast Iron?

A

White cast iron is a hard, white, brittle material, which is easily broken and capable to withstand shock loading.

28
Q

Explain the characteristics of High Duty Cast Iron?

A

Developed to withstand high loads, corrosion, high temperatures and high abrasion.

29
Q

Give 6 pros to using Grade 304 Stainless Steel?

A
  • Good corrosion resistance
  • Good weldability
  • Excellent ductility giving stretch formability in pressings
  • Hygienic surfaces
  • Work hardening for spring properties
  • Ease of manufacture at the steel mill
30
Q

What applications would you use Grade 304 Stainless Steel?

A
  • Sinks, Pots & Pans
  • Catering Surfaces
  • Water treatment
  • Refrigeration Equipment
31
Q

What applications would you use Grade 316 Stainless Steel?

A
  • Topside equipment
  • Water treatment
  • Pool fittings
  • Yacht fittings
  • Heat Exchangers
32
Q

List the 7 desired properties for Propellor Materials?

A
  1. High corrosion fatigue resistance in sea water.
  2. High resistance to cavitation erosion
  3. High resistance to general corrosion
  4. High resistance to impingement attacks and crevice corrosion
  5. High strength to weight ratio
  6. Good repair characteristics, including weldability and freedom from subsequent
    cracking
  7. Good casting characteristics
33
Q

What applications would you use Aluminium Bronzes?

A
  • Bearing Brushes
  • Engine components
  • Underwater fastenings
  • Propellers
34
Q

How can you weld Aluminium Bronze?

A

Aluminium bronze can be welded using the MIG welding technique with an aluminium bronze core and pure argon gas.

35
Q

What is the most common material used for a propeller and why?

A

Nickel aluminium bronze
shows exceptionally high resistance to cavitation damage and is for that reason the alloy most commonly used for production of large marine propellers

36
Q

List the properties of Aluminium

A
  • Light weight
  • Corrosion Resistance
  • Electrical & Thermal Conductivity
  • Reflectivity
  • Ductility
  • Impermeable and Odourless
  • Recyclability
  • Machining
  • Formability
  • Conductivity
  • Non Magnetic Material.
37
Q

Provide a description of Thermoplastics?

A

These can be softened and manipulated into shape by the application of heat and pressure, the shape being retained after the removal of the heat. Further heating will cause resoftening and the material can be heated and caused to flow an indefinite number
of times.

38
Q

Provide a description of Thermosetting?

A

These can be manipulated into shape by heat and pressure, but above a certain temperature they undergo a chemical change, which prevents further manipulation. The material cannot then be re-softened

39
Q

What does GRP stand for?

A

Glass Reinforced Plastic

40
Q

Provide the Advantages and Disadvantages of using GRP as a hull material.

A

Advantages

  • Corrosion free
  • One piece hull
  • Lightweight
  • Inexpensive for mass production
  • Non magnetic

Disadvantages

  • Easily damaged
  • Poor fire resistance
  • Osmosis and delimitation
  • Expensive as a one off
  • Transmits noise and vibration
41
Q

Provide the Advantages and Disadvantages of using Steel as a hull material.

A

Advantages

  • Relatively inexpensive
  • Easy to construct
  • Not easily damaged
  • Good fire resistance
  • Easily repaired

Disadvantages

  • Corrodes
  • Heavy
  • Not easy to work
  • Magnetic, affecting compass
  • Requires constant maintenance
42
Q

Provide the Advantages and Disadvantages of using Aluminium as a hull material.

A

Advantages

  • Light weight
  • Does not rust
  • Almost maintenance free
  • Easy to work

Disadvantages

  • More expensive than steel
  • Poor fire resistance
  • Low melting point
  • Galvanic corrosion
  • Specialist welding practice required
43
Q

Explain Osmosis in GRP Hulls?

A

Water molecules migrating into and through the GRP encounter other chemicals inside the laminate, primarily water-soluble materials such as the emulsion binders used to hold the glass mat together before it is moulded, or pockets of uncured or only partly cured resins in the moulding. The water molecules can then have a chemical reaction with these substances, forming larger molecules of a new chemical,
often acidic -which unlike the original small water molecules cannot carry on passing through the GRP. These larger molecules are then trapped.

44
Q

What are some of the main causes of single skin deamination of a fibreglass hull?

A
  • Cyclic stress due to pounding
  • Collisions
  • Flexing & torsional stress
  • Low resin to fibre ratio
  • Poor resin fusion during construction
  • Uneven lifting or application of supports during out of water winter layup
45
Q

Common causes of stress cracking in fibre glass?

A
  • Inclusion of “Hard spots” (resin too thick) where the hull joins stiffeners,
  • Poor positioning of structural bulkheads
  • Layup is too stiff in critical areas
  • Insufficient transvers or longitudinal framing
46
Q

List the 12 carbon fibre properties?

A

*High Strength to weight ratio
*Rigidity
*Corrosion resistance
*Electrical Conductivity
*Fatigue Resistance
*Good tensile strength
*Fire Resistance/Not flammable
*High Thermal Conductivity
*Low coefficient of thermal expansion
*Biologically inert
*Self-Lubricating
*Excellent EMI (Electromagnetic Interference) Shielding Property

47
Q

Pros and Cons of Carbon Fibre?

A

Pros
High strength to weight
Nice finish
Corrosion resistant

Cons
Solid carbon fibre will not bend, therefore when it fails it will be suddenly and catastrophically
Very expensive
Highly skilled workers
Needs UV radiation protection