intro to metals

Question 1

How much steel was produced worldwide in 2021?

Answer 1

Over 1.95 billion metric tonnes

Question 2

Which country is the leading producer of steel?

Answer 2

China

Question 3

What percentage of the world’s annual crude steel production did China account for between 2012 and 2019?

Answer 3

50%

Question 4

Name the first structural use of cast iron.

Answer 4

Iron Bridge, Coalbrookdale, 1779

Question 5

What significant structure was built with wrought iron in 1889?

Answer 5

The Eiffel Tower

Question 6

What was the first major bridge built with wrought steel?

Answer 6

Firth of Forth Railroad Bridge, Scotland, 1890.

Question 7

During which age was bronze, an alloy of copper and tin, predominantly used?

Answer 7

The Bronze Age

Question 8

What marks the transition from the Bronze Age to the Iron Age?

Answer 8

The predominant use of iron for tools and weapons.

Question 9

What do concrete and steel have in common?

Answer 9

Same thermal expansion

Question 10

What is used for steel bridges?

Answer 10

High-strength galvanised steel

Question 11

What is a metallic bond?

Answer 11

The force of attraction between free electrons and metal ions in metals

Question 12

What is face-centered cubic (FCC) structure?

Answer 12

A crystal structure with an extra atom in the center of each face of the cubic unit

Question 13

What are grain boundaries in metals?

Answer 13

Interfaces between adjacent crystalline regions with different orientations.

Question 14

How are grain boundaries made more visible?

Answer 14

By etching with acid.

Question 15

What is responsible for the plastic deformation of metals?

Answer 15

Dislocations

Question 16

What does the presence of interstitial atoms indicate in an alloy?

Answer 16

Small atoms squeezed between larger atoms in the crystal lattice, affecting the alloy’s properties.

Question 17

What is copper made?

Answer 17

Made from malachite

Question 18

Why are pure metals not commonly used in commercial applications?

Answer 18

They are too soft due to dislocations and lack certain desired mechanical properties

Question 19

What historical structure utilized 18,038 individual parts and 2.5 million rivets?

Answer 19

The Eiffel Tower

Question 20

What are the properties affected by imperfections in metal crystals?

Answer 20

Mechanical properties such as strength and ductility

Question 21

What is the significance of similar thermal expansion properties of concrete and steel in construction?

Answer 21

It prevents structural damage due to temperature variations

Question 22

Why is steel considered the most important metal in construction?

Answer 22

Due to its volume of use and essential role in structural applications

Question 23

What is the role of substitutional atoms in alloys?

Answer 23

They replace atoms in the crystal lattice, modifying the alloy’s properties

Question 24

What are metalloids?

Answer 24

Intermediate metals

Question 25

What can be said about metals and their melting and boiling points?

Answer 25

high

Question 26

What is Hexagonal close packing?

Answer 26

A lattice structure which is able to achieve the highest packing density

Question 27

What are examples of imperfection in crystals?

Answer 27

- Substitutional atoms - Interstitial atoms - Dislocations - Vacancies

Question 28

What are vacancies?

Answer 28

Missing atom in matrix

Question 29

What is the yield stress in alloys like compared to pure metals?

Answer 29

Higher

Question 30

What are substitutional atoms?

Answer 30

Atoms of a different size

Question 31

When do grain boundaries occur?

Answer 31

You get grain boundaries as metal cools

Question 32

How has the recycling of metals impacted the environment?

Answer 32

Recycling reduces the demand for raw material extraction, lowers energy consumption, and decreases greenhouse gas emissions, contributing to environmental sustainability

Question 33

How do protective coatings enhance the longevity of metal structures?

Answer 33

Coatings such as galvanizing protect metals from corrosion, significantly extending their service life in harsh environments

Question 34

Where are dislocations generated?

Answer 34

Dislocations are generated at stress concentrations or within the material at defects and grain boundaries

Question 35

What are edge dislocation?

Answer 35

An edge dislocation occurs when an extra plane or layer of atoms extends part way into the crystal

Question 36

What is involved in forming edge dislocations?

Answer 36

- The row of bonds will break and reattach itself to a different of atoms - Change shape and structure

Question 37

What determines yield stress?

Answer 37

Dislocation motion

Question 38

What helps to stop dislocations?

Answer 38

Defects

Question 39

What is an alloy?

Answer 39

An alloy is a metal mixed with other elements

Question 40

How is the microstructure of an alloy determined?

Answer 40

Microstructure determined by processing techniques and characterised by the size and shape of the grains of different phases, and their orientation and distribution

Question 41

What is the microstructure of bronze?

Answer 41

Copper + 15% Tin alloy

Question 42

What are the two categories of bronze you can have?

Answer 42

1. Cast 2. Cast and annealed

Question 43

What is steel composed of?

Answer 43

Steel is an alloy of iron and carbon containing less than 2% carbon and 1% manganese

Question 44

How man grades of steel are there currently?

Answer 44

3500

Question 45

What are modern cars built with?

Answer 45

Modern cars built with new steels that stronger and up to 25% lighter

Question 46

What is the first strengthening mechanism?

Answer 46

Control of grain size

Question 47

What is the second strengthening mechanism?

Answer 47

Work Hardening

Question 48

How does reducing grain size change yield stress?

Answer 48

Increases

Question 49

What are the variables in the Hall-Petch equation?

Answer 49

- yield stress - d = grain size - k material constant

Question 50

What is the process of work hardening?

Answer 50

- Dislocations have an associated strain field - These interact creating a barrier to dislocation motion

Question 51

What does increased dislocation density lead to?

Answer 51

Increased interaction and higher strength

Question 52

When do dislocation increase in density?

Answer 52

Dislocations, increase in density during plastic flow

Question 53

What is the 3rd strengthening mechanism?

Answer 53

Solid solution strengthening

Question 54

How does solid solution strengthening work?

Answer 54

- Solute atoms have an associated strain field - These interact with the strain field around dislocations and inhibits motion

Question 55

What is quenching?

Answer 55

- Rapid cooling

Question 56

What is the fourth strengthening mechanism?

Answer 56

Precipitation strengthening/hardening

Question 57

How does Precipitation strengthening/hardening work?

Answer 57

Second phase particles have an associated strain field that interacts with that of dislocations and makes it harder for the dislocation to move

Question 58

What is yield stress defined as?

Answer 58

Lower yield point

Question 59

What do phase diagrams show?

Answer 59

- Which phases are present - Temperatures and compositions

Question 60

What do phase diagrams assume?

Answer 60

Equilibrium conditions