Stainless Steels and Cast Irons

Question 1

Steel

Answer 1

An iron carbon alloy with less than 2.1% Carbon by weight

Question 2

Alloy Steel

Answer 2

Has significant alloying content from elements other than carbon.

The most important class of high alloy steels

Question 3

Stainless steel

Answer 3

An iron alloy with at least 11% Chromium content

Question 4

AISI/SAE Naming Convention for Steels

Answer 4

4 or 5 digit numbers

The first two digits indicate chemistry

The last two or three digits indicate carbon content

Question 5

Ferritic steels

Answer 5

Major addition of Chromium (up to 30%) stabilizes ferritic phase at all temperatures

Cant be heat treated into martensite (no austenite region)

Strengthening by solid solution and cold working

magnetic

Question 6

Martensitic steels

Answer 6

Less chromium than Ferritic leaves both ferrite and austenite regions, permitting heat treatment into martensite

Excellent strength and good corrosion resistance

Possibly magnetic

Question 7

Austenitic Steels

Answer 7

Major addition of Chromium and Nickel stabilizes austenite at all temperatures

Cant be heat treated into martensite (no ferrite region)

Strengthening by solid solution and cold working. Work hardens a lot

Non-magnetic

Question 8

Cast Iron

Answer 8

An iron-carbon alloy with between 2.1% and 6.7% C by weight

Question 9

White cast iron

Answer 9

Most of microstructure is Fe3C

Extremely hard and brittle, so practically unusable unless the only important characteristic is hardness/wear resistance

Usually used only as an intermediate form in the creation of malleable cast iron

Question 10

Gray Cast Iron

Answer 10

Flat flakes of graphite in ferrite or pearlite

Poor strength, poor ductility, poor toughness because of crack-like graphite inclusions

Extremely high vibration absorption

Used in situations where stresses are low and vibration absorption is important

Question 11

Malleable Cast Iron

Answer 11

Roundish graphite in ferrite or pearlite

Good strength, poor ductility, poor toughness because of crack-like graphite inclusions

Extremely high vibration absorption

Used in situations where stresses are low and vibration absorption is important

Question 12

Ductile Cast Iron

Answer 12

Round graphite clusters in ferrite or pearlite

Good strength, ductility, and toughness. One of two types of Cast Iron suitable for stress-bearing structures

Ferritin modular Cast Iron is more ductile, pearl it is is stronger