Processing Flashcards
What are the most common forms of iron ore?
Hematite (Fe2O3), Magnetite (Fe3O4), Iron carbonate (FeCO3), and Iron Pyrite (FeS2)
What are the raw materials needed to make iron?
Iron ore, coke, limestone (CaCO3), and hot air
What is the main impurity in iron ore?
Silica (SiO2)
What does limestone do in the process?
Upon heating, it decomposes into CaO and combines with impurities like SiO2 to form slag
How much carbon does pig iron have?
3-4.5%
How do we remove excess carbon from steel?
Basic-oxygen process: controlled oxidation of pig iron
Steel undergoes ____ ______ during hot rolling
dynamic recrystallization
Why should hot rolling be finished above recrystallization temperature? (aka normalization)
So a fine grain size is obtained
Why does hot rolling improve ductility?
Because grain size is reduced
Why does yield stress increase with finer grain size?
The amount of applied stress necessary to move a dislocation across a grain boundary is increased
What are the bulk forming processes?
Forging, extrusion, rolling, deep drawing, wire-drawing
Direct compression
> primary process to reduce ingot size
> forging and rolling
Indirect compression
> secondary process for producing final shape
> tensile; drawing and extrusion
What does forming pressure depend on?
> reduction geometry Δh = ho - hf
die/workpiece friction μ
material flow strength σf
What happens to the work hardening exponent and strain rate sensitivity parameter with increase in temperature?
Work hardening exponent decreases, and strain rate sensitivity parameter increases
