Ferrous Metals

Question 1

What is density

Answer 1

Mass per unit volume Kg/m3

Question 2

What is fatigue?

Answer 2

Cracks formed from cyclic loading

Question 3

What is elasticity

Answer 3

Returning to original dimensions after stretching

Question 4

What is the formula for strain

Answer 4

Extension/original length

Question 5

What are the 3 stresses

Answer 5

Tensile, Compressive and Shear

Question 6

What is combined stress

Answer 6

Tensile and shear together

Question 7

What is brittleness

Answer 7

Tendency to snap without deformation

Question 8

What is hardness

Answer 8

Resist wear or toughness

Question 9

What is strength

Answer 9

Resistance to reform due to forces

Question 10

What is ductility

Answer 10

Property of metal to withstand force over time

Question 11

What is toughness

Answer 11

Resist suddenly applied loads

Question 12

What is plasticity

Answer 12

Ability to retain shape from distortion it is the opposite of elasticity

Question 13

What is the elastic limit

Answer 13

Maximum stress to which a meatier always may be subjected to and return to its original shape

Question 14

What is yield strength

Answer 14

Maximum stress that can be applied to a material without deformation

Question 15

What is steels main two alloying ingredients

Answer 15

Carbon and Iron

Question 16

What is steel with more than 2% carbon called

Answer 16

Cast Iron

Question 17

What defines low medium and high carbon steels

Answer 17

Low 01-0.3% carbon
Medium 0.3-0.5% carbon
High 0.5 - 1.05 % carbon

Question 18

What does sulphur do to the steel

Answer 18

Decreases the ductility

Question 19

What does manganese do to steel

Answer 19

For strength and hardness but is less than carbon

Question 20

What is silicon used for

Answer 20

Deoxidising agent but can affect surface finishes

Question 21

What is Phosphorus used for in steel

Answer 21

Strength, Hardness and corrosion resistance at an expense of ductility

Question 22

What is nickel used for

Answer 22

Increase in hardness and impact strength

Question 23

What is chromium used for

Answer 23

Corrosion resistance and high temperature strength

Question 24

What does an AISI number consist of

Answer 24

Four digit code, first two will denote the steel steel and alloys, second is the percentage of carbon

Eg 1000 is plain carbon steel

Question 25

What does tempering do

Answer 25

Relieves internal stresses It is reheated and cooled slowly to give strength

Question 26

What is hardening

Answer 26

For pure iron and low carbon steels Heated to above critical temperature and cooled to specific times to get the metal hardness you need

Question 27

What is annealing

Answer 27

Softens and relieves internal stresses Is heated to above it’s critical temperature and cooled very slowly in a hot furnace or in sand for example

Question 28

What is normalising

Answer 28

Relieves internal stresses is heated to above upper critical temperature and cooled at room temperature

Question 29

What is quenching

Answer 29

Cooling down the metal quickly using water, brine, oil or still air Dictates speed of carbon precipitation

Question 30

What are the characteristics of Corrosion resistant steel (CRES)

Answer 30

It’s corrosion resistant High strength Tough material Resistant to high temperature 3 groups Austenitic Ferritic Martensitic

Question 31

What is Austenitic steel

Answer 31

Chromium and nickel alloy | Can be hardened by cold working

Question 32

What is ferritic cres

Answer 32

Very low carbon content Cannot be hardened by heat Relatively low strength Excellent corrosion resistance

Question 33

What is Martenstic cred

Answer 33

High carbon content Used in tubular applications Least corrosion resistance

Question 34

What is hydrogen embrittlement

Answer 34

Ferrous and titanium alloys are affected Hydrogen migrates to grain boundaries and combines with carbon to form methane which can lead to fractures forming Can be relieved by baking at 375 degrees for 3 hours

Question 35

What are some non stainless steel surface protections

Answer 35

``` Cadmium coating Paint Aluminium Spraying Chromium plating Silver plating ```

Question 36

What is galvanic corrosion

Answer 36

Reaction between metals which are dissimilar For example Magnesium and copper in presence of an electrolyte will corrode

Question 37

What are the methods of case hardening

Answer 37

Four methods Carburising Flame hardening Induction hardening Nitriding

Question 38

What are the 3 methods of carburising and what do they involve

Answer 38

Pack carburising- object is placed into carbon powder and heated to 900 degrees and quenched Gas carburising- object is placed into basket in furnace and through which a suitable carbon rich gas is introduced Liquid carburising- salts are usually based on sodium cyanide and a process is called cyanide hardening

Question 39

What does nitriding do

Answer 39

Provides a improved surface finish and is made by metals absorbing nitrogen