Chapter 11 Flashcards
What are the two classifications of metal alloys?
Ferrous and nonferrous
What are the two categories of ferrous/iron-based metal alloys?
Steels and cast irons
What wt% C are steels and cast irons?
Steel: <1.4 wt% C
Cast Irons: 3-4.5 wt% C
What are the three microstructures of cast irons?
ferrite, graphite, cementite
What are the two categories of steels?
Low alloy and high alloy
What are the three different types of low alloy steels? How do they behave? How much does the high steel alloy have?
low carbon: <0.25 wt% C
med carbon: 0.25-0.6 wt% C
high carbon: 0.6-1.4 wt% C
As it moves from low to high carbon content, the steel increases strength and decreases ductility
High alloy: stainless steel > 11% Cr
What are the properties of cast irons?
Low melting point, easy to cast, brittle
What does cementite decompose into?
ferrite and graphite
What is graphite formation usually promoted by?
1) Si> 1st%
2) slow cooling
What are the five types of cast iron?
1) gray iron
2) ductile iron
3) white iron
4) malleable iron
5) compacted graphite iron
What are the characteristics of gray iron?
5 characteristics
1) graphite flakes
2) weak & brittle in tension
3) stronger in compression
4) excellent vibrational dampening
5) wear resistant
What are the characteristics of ductile iron?
3 characteristics
1) add Mg and/or Ce
2) graphite as nodules not flakes
3) matrix often pearlite- stronger but less ductile
What are the characteristics of white iron?
3 characteristics
1) <1 wt% Si
2) pearlite + cementite
3) very heard and brittle
What are the characteristics of compacted graphite iron?
1) relatively high thermal conductivity
2) good resistance to thermal shock
3) lower oxidation at elevated temperatures
What are the characteristics of malleable iron?
3 characteristics
1) heat treat white iron at 800-900 C
2) graphite in rosettes
3) reasonably strong and ductile
