MMET 207 EXAM 3 QUESTIONS AND
ANSWERS ALL CORRECT
What are the material selection decisions that are made to reduce corrosion (and an
example or what it is for each)? (5)
-Hint: SHCCC - Answer- -Surface Finish (polishing put more energy into surface
causing corrosion)
-Heat treatment (Chromizing)
-Coatings (painting)
-Cladding (welding a layer of metal onto surface)
-Corrosion data (know how materials do in certain conditions)
What are the environment control techniques and methods to reduce corrosion?
-Hint: ACCTIV - Answer- -Aeration
-Cleaning
-Concentration
-Temp.
-Inhibitors
-Velocity
Start CAST IRONS Section - Answer- Start CAST IRONS Section
treelike structure formed by solidification of the nuclei of one atom attaching to another,
grains grow on top of this - Answer- Dendrite
Why is Columnar casting structure & Coarse grains undesirable? - Answer- they make
mechanical properties directional
the product of metals solidifying altering properties - Answer- Segregation
How do you get equiaxed grains? - Answer- casting needs to solidify all at the same
time
General purpose cast iron, high carbon, ferromagnetic - Answer- Gray Cast Iron
Gray Cast Iron:
1. Nominal Chemistry
2. Microstructure - Answer- 1. 2-4% Carbon, At least 1% Silicon
2. ferrite, pearlite, & graphite flakes
, Start CORROSION section - Answer- Start CORROSION section
Understand why corrosion occurs - Answer- Corrosion is the deterioration of a metal as
a result of chemical reactions between it and the surrounding environment. Both the
type of metal and the environmental conditions, particularly gases that are in contact
with the metal, determine the form and rate of deterioration
Galvanic Chart Series: List relative positions of steel, tin, magnesium, aluminum, gold,
zinc in order from highest to lowest energy - Answer-
Magnesium>Zinc>Aluminum>Steel>Tin>Gold (Remember MZASTG)
The ___ has more energy, and is known to be ___ since it gives away electrons. This
metal ___ corrode. - Answer- Anode, Active, Does
The ___ has less energy, and is known to be ___ since it accepts electrons. This metal
___ corrode. - Answer- Cathode, Passive, Doesn't
Requirements for Corrosion to occur? (4) - Answer- 1. Need anode and cathode
2. Need significant energy difference between anode and cathode
3. Need metal path between anode and cathode that allows electrodes to travel
4. Need electrolyte
uses a "sacrificial anode" to protect the desired metal (which is the cathode) - Answer-
Cathodic Protection
technique to control the corrosion of a metal surface by making it the anode of an
electrochemical cell and controlling the electrode potential in a zone where the metal is
passive.
-this is complicated and requires a lot of tests, uses a corrosion monitoring system and
a dc power source - Answer- Anodic Protection
anode used to ensure that the cathode/desired metal doesn't corrode - Answer-
Sacrificial Anode
What materials are suitable to be a Sacrificial Anode? - Answer- Metals that are suitable
for this must be high enough on the galvanic series chart that the desired metal won't
corrode/become the anode
How does paint protect against corrosion? - Answer- Paint acts as a barrier from an
electrode
-If there are pinholes or any cracks in the paint, metal will corrode
What metallurgical conditions affect corrosion and why? (5)
-Hint: MINCC - Answer- -Multiple phases - some phases are undesired
-Inclusions - undesired materials in metal
-Non-uniform stresses - stressed areas react differently than unstressed
ANSWERS ALL CORRECT
What are the material selection decisions that are made to reduce corrosion (and an
example or what it is for each)? (5)
-Hint: SHCCC - Answer- -Surface Finish (polishing put more energy into surface
causing corrosion)
-Heat treatment (Chromizing)
-Coatings (painting)
-Cladding (welding a layer of metal onto surface)
-Corrosion data (know how materials do in certain conditions)
What are the environment control techniques and methods to reduce corrosion?
-Hint: ACCTIV - Answer- -Aeration
-Cleaning
-Concentration
-Temp.
-Inhibitors
-Velocity
Start CAST IRONS Section - Answer- Start CAST IRONS Section
treelike structure formed by solidification of the nuclei of one atom attaching to another,
grains grow on top of this - Answer- Dendrite
Why is Columnar casting structure & Coarse grains undesirable? - Answer- they make
mechanical properties directional
the product of metals solidifying altering properties - Answer- Segregation
How do you get equiaxed grains? - Answer- casting needs to solidify all at the same
time
General purpose cast iron, high carbon, ferromagnetic - Answer- Gray Cast Iron
Gray Cast Iron:
1. Nominal Chemistry
2. Microstructure - Answer- 1. 2-4% Carbon, At least 1% Silicon
2. ferrite, pearlite, & graphite flakes
, Start CORROSION section - Answer- Start CORROSION section
Understand why corrosion occurs - Answer- Corrosion is the deterioration of a metal as
a result of chemical reactions between it and the surrounding environment. Both the
type of metal and the environmental conditions, particularly gases that are in contact
with the metal, determine the form and rate of deterioration
Galvanic Chart Series: List relative positions of steel, tin, magnesium, aluminum, gold,
zinc in order from highest to lowest energy - Answer-
Magnesium>Zinc>Aluminum>Steel>Tin>Gold (Remember MZASTG)
The ___ has more energy, and is known to be ___ since it gives away electrons. This
metal ___ corrode. - Answer- Anode, Active, Does
The ___ has less energy, and is known to be ___ since it accepts electrons. This metal
___ corrode. - Answer- Cathode, Passive, Doesn't
Requirements for Corrosion to occur? (4) - Answer- 1. Need anode and cathode
2. Need significant energy difference between anode and cathode
3. Need metal path between anode and cathode that allows electrodes to travel
4. Need electrolyte
uses a "sacrificial anode" to protect the desired metal (which is the cathode) - Answer-
Cathodic Protection
technique to control the corrosion of a metal surface by making it the anode of an
electrochemical cell and controlling the electrode potential in a zone where the metal is
passive.
-this is complicated and requires a lot of tests, uses a corrosion monitoring system and
a dc power source - Answer- Anodic Protection
anode used to ensure that the cathode/desired metal doesn't corrode - Answer-
Sacrificial Anode
What materials are suitable to be a Sacrificial Anode? - Answer- Metals that are suitable
for this must be high enough on the galvanic series chart that the desired metal won't
corrode/become the anode
How does paint protect against corrosion? - Answer- Paint acts as a barrier from an
electrode
-If there are pinholes or any cracks in the paint, metal will corrode
What metallurgical conditions affect corrosion and why? (5)
-Hint: MINCC - Answer- -Multiple phases - some phases are undesired
-Inclusions - undesired materials in metal
-Non-uniform stresses - stressed areas react differently than unstressed
