Alloy steels

Question 1

Elements that dissolves in ferrite

Answer 1

Nickel, Manganese

boron silicon

Question 2

Effects on adding elements that dissolves in ferrite

Answer 2

improve toughness and ductility

lower critical temperature

Question 3

2 elements if added in large amount will make austenite present in rtp

Answer 3

nickel or manganese

Question 4

What is the problem with adding elements that dissolve in ferrite? and how can it be sovled?

Answer 4

Graphitisation

Solved by adding Chromium (stabiliser)

Question 5

effects on adding elements that combine with carbon to form carbides

Answer 5

improve hardness and wear resistance
improve strength
raise critical temp

Question 6

Which element helps with corrosion resistance to steel

Answer 6

Aluminium, silicon, chromium

Question 7

Starting numbers that proves it is an alloy steel

Answer 7

2 to 4 (e.g. 23xx, 31xx, 43xx)

Question 8

Requirements of a tool steel

Answer 8

Good hardness and wear resistance

good mechanical strength and toughness

Question 9

Alloying element in stainless steel

Answer 9

Chromium

Question 10

What compound is coated on steel surface to make it “stainless”

Answer 10

chromium oxide

Question 11

Properties of ferritic stainless steels

Answer 11

magnetic (due to alpha iron)
soft
readily machinable

Question 12

Applications of ferritic stainless steels

Answer 12

kitchen sinks
forks and spoons
furnace parts

Question 13

Properties of martensitic stainless steels

Answer 13

magnetic

good combi of strength, hardness, toughness and resistances

Question 14

Applications of martensitic stainless steels

Answer 14

cutlery
sharp-edge tools
knives
surgical instrument
golf sticks

Question 15

Properties of austenitic stainless steel

Answer 15

soft and ductile
non-magnetic
good corrosion resistance

Question 16

Applications of austenitic stainless steels

Answer 16

hand rails of staircase
food handling equipment
surgical implants

Question 17

standard grades for ferritic, martensitic, austenitic stainless steels

Answer 17

ferritic: 430
martensitic: 410
austenitic: 302 (18/8 stainless steel)

Question 18

What do each of the numbers mean in alloy numbering system?

Answer 18

e.g. 4340

first digit: represents type of steel and its major alloying element
second digit: approx. % of alloying elements
3rd and 4th: points of carbon (0.40 %C)