Chapter 12 - Ferrous Alloys Flashcards
how does Boron effect Steel?
Improves hardness without loss of machinability & formability
how does Calcium effect Steel?
Deoxidizes steels, improves toughness, and may improve formability and machinability
how does Carbon effect Steel?
improves hardenability, strength, hardness, and wear resistance; it
reduces ductility, weldability, and toughness
How does Cerium effect steel?
controls the shape of inclusions and improves toughness in high-strength
low alloy steels; it deoxidizes steels
How does Chromium effect steel?
improves toughness, hardenability, wear and corrosion resistance, and
high-temperature strength; it increases the depth of the hardness penetration
resulting from heat treatment by promoting carburization
How does Cobalt effect steel?
improves strength and hardness at elevated temperatures
How does Copper effect steel?
improves resistance to atmospheric corrosion and, to a lesser extent,
increases strength with little loss in ductility; it adversely affects the hot-working
characteristics and surface quality
How does Lead effect steel?
improves machinability; it causes liquid-metal embrittlement
How does Magnesium effect steel?
Same as cerium
How does Manganese effect steel?
improves hardenability, strength, abrasion resistance, and
machinability; it deoxidizes the molten steel, reduce shot shortness, and decreases
weldability
How does Molybdenum effect steel?
improves hardenability, wear resistance, toughness, elevatedtemperature
strength, creep resistance, and hardness; it minimizes temper
embrittlement
How does Nickel effect steel?
improves strength, toughness, and corrosion resistance; it improves
hardenability
How does Niobium efect steel?
imparts fineness of grain size and improves strength and
impact toughness; it lowers transition temperature and may decrease hardenability
How does Phosphorus effect steel?
imparts fineness of grain size and improves strength and
improves strength, hardenability, corrosion resistance, and
machinability; it severely reduces ductility and toughness
How does Selenium effect steel?
Improves machinability
How does silicon effect steel?
improves strength, hardness, corrosion resistance, and electrical
conductivity; it decreases magnetic-hysteresis loss, machinability, and cold
formability
How does Sulphur effect steel?
Improves machinability when combined with manganese; it lowers impact
strength and ductility and impairs surface quality and weldability
How does Tantalum effect steel?
Has effects similar to those of niobium
How does Telletium effect steel?
improves machinability, formability, and toughness
How does Titanium effect steel?
improves hardenability; it deoxidizes steels
How does Tungsten effect steel?
has the same effects as cobalt
How does Vanadium effect steel?
improves strength, toughness, abrasion resistance, and hardness at
elevated temperatures; it inhibits grain growth during heat treatment
How does Zirconium effect steel?
Same as Cerium
What is a low alloy steel?
Alloyed steel when less than 5% of weight is alloying elements
What are the 3 common low alloy steels?
Low, Medium & High Carbon steels
What are the characteristics of Low carbon Steels?
- 0.1-0.25% Carbon
- High Formability
- High ductility
- Low strength
- Good weldability
- Can’t be hardened by heat treatment
- Hardened by cold working
What are the characteristics of Medium carbon Steels?
- 0.25 - 0.55% Carbon
- Good combination of strength and ductility
- Strengthened by heat treatment
- Weldable
Advantages of low alloy steels?
low cost, high weldability & most used
Disadvantages of low alloy steels?
Relatively low strength, low hardenability & low corrosion resistance
What are high alloy steels?
Alloyed steel when more than 5% of weight is alloying elements
Name 2 common high alloy steels?
Stainless steel
tool steels
What are stainless steels characteristics?
- Corrosion resistant
- High Strength
- Ductility
- Chromium content
What are the main alloying elements in tool steel?
Chromium, Cobalt and Manganese
How are tool steels classified?
By:
- quenching methods (Air, oil or water hardening)
- Carbon & Alloy content
What is Cast iron?
Iron with 1.7 to 4.5 wt% carbon and 0.5 to 3 wt%
silicon
What are the characteristics of cast iron?
Good castsability & low cost material
What are the advantages of cast iron?
- good castability
- antivibration properties
- low stress concentration
What are the disadvantages of cast iron?
- high brittleness
- non machinable
- cold brittleness
What is grey cast iron?
Flake graphite in a matrix of pearlite, ferrite or martensite
How does grey cast iron form?
when:
• Cooling is slow, as in heavy sections
• High silicon or carbon
What are the properties of grey cast iron?
- Machinability is excellent
- Ductility is low (0.6%), impact resistance low
- Damping capacity high
- Thermal conductivity high
- Dry and normal wear properties excellent
What is white cast iron?
- It is a particular variety of cast iron which
shows white fractures - The white colour is due to the fact that the
carbon is in the form of carbides known as
cementite
What are white cast irons characteristics?
– It has a high tensile strength and a low
compressive strength
– Extremely hard, not machinable
– Resistance to sharp objects and cracks
What is malleable cast iron?
– Malleable cast iron is obtained from white
cast iron by suitable heat treatment
What are malleable cast irons characteristics?
It is ductile and may be bent without breaking or fracturing the section – It is used for making machine parts for which steel forging would be too expensive
