ENCN221 Study Exam Questions & Answers 2024/2025
How much carbon is in steel? - ANSWERSLess than 1.4% wt
How much carbon in cast iron? - ANSWERS2-4.5% wt
How much carbon in structural steel? - ANSWERSLess than 0.3%
What are some non-ferrous metal alloys? - ANSWERSAluminum, Copper, Mag...
How much carbon is in steel? - ANSWERSLess than 1.4% wt
How much carbon in cast iron? - ANSWERS2-4.5% wt
How much carbon in structural steel? - ANSWERSLess than 0.3%
What are some non-ferrous metal alloys? - ANSWERSAluminum, Copper, Magnesium, Titanium
What are the three types of iron ore? - ANSWERSLimonite (brown, Fe2O3.nH20), Hematite (red, Fe2O3),
Magnetite (Black, Fe3O4)
What are the steel production steps? - ANSWERSReduce iron ore to pig iron, refine pig iron to steel, form
the steel into products.
What three materials go into a blast furnace? - ANSWERSOre, coke (baked coal, lots of carbon), and
limestone (CaCo3)
What is slag? - ANSWERSThe mixture of silicates and illuminates from the purification of the iron ore.
How is cast iron made? - ANSWERSBy resmelting pig iron with carbon in a smaller furnace
What is its problem in structural usage? - ANSWERSExtremely brittle, fails with little warning.
Any other useful properties? - ANSWERSEasy to cast, melts at 1,232 C, doesn't soften on reheating,
reasonable corrosion resistance in water.
, What is the difference between gray and ductile cast iron? - ANSWERSDuctile iron has Mg or Ce, graphite
is in nodules. Often has pearlite matrix, is more ductile.
Grey uron has graphite flakes. It is weak and brittle under tesnion but hard wearing and strong under
compression. Also has vibration damping.
What is wrought iron? - ANSWERSIron made from further smelting of cast iron, it is almost pure iron.
Less than 0.1% carbon.
Benefits of wrought iron? - ANSWERSDuctile, can be cold worked, forged and welded. Becomes soft on
reheating but does not melt until 1,538 C. Also reasonably corrosion resistant.
What is the name of the process that allowed steel to be made in quantities over 30 kilo? -
ANSWERSKelly-Bessemer Process (1885). An air blast is used to help burn impurities such as silicon,
carbon and manganese. Produced steel first, then soft wrought iron.
How is pig iron and scrap steel refined into steel? - ANSWERSExcess carbon is removed using oxidation in
another furnace. A Basic Oxygen Furnace can create 300 tons in 25 minutes, while an electric arc furnace
is used with scrap steel.
Name four strategies to strengthen metals - ANSWERSReduce grain size, solid solutions, precipitation
strengthening and finally cold working.
Why does reducing grain size increase strength? - ANSWERSGrain boundaries are barriers to slip. More
grain -> More grain barriers -> less slip -> more strength.
How do solid solutions increase strength? - ANSWERSBy introducing a substitutional or interstitial atom,
the lattice is deformed. This resists the deformation advancing past the impurity.
How do precipitates increase strength? - ANSWERSHard precipitates are difficult to shear. Large shear
stress is needed to move dislocation towards the precipitate and shear (break) it.
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