Once solidified, metals can undergo further mechanical working to enhance their properties for intended use.
For more information on this, visit the NDT resource centre.Mechanical working can include:
- Thermal treatments
Strength and Hardening
- Alloying - This involves adding another element to the crystalline (being a point defect which you can find more information about here).
- Managing Grain Size - This involves decreasing the continuity of atomic planes.
- Introducing Strain - A metal can be hardened by introducing many dislocations which become tangled against each other.
- Grain Growth
- Brass - Copper and Zinc.
- Bronze - Copper, Zinc and Tin.
- Pewter - Tin, Copper, Bismuth and Antimony.
- Cast Iron - Iron, Carbon, Manganese and Silicon.
- Steel - Iron and Carbon (plus small amounts of other elements).
- The alloy is formed as a single phase or a homogeneous structure of consisting of identical crystals.
- The alloy is formed of two (or more) separate types of crystals creating a heterogeneous microstructure of two or more phases.
- Any solid solution of carbon up to 2% in FCC iron is called austenite.
- The very dilute solution up to 0.02% carbon in BCC iron is called ferrite (although we generally consider ferrite as pure iron).
- Below 723 degrees Celsius, the austenite transforms by forming alternate layers of ferrite and cementite (known as pearlite).
- Austenite begins to solidify at 1500 degrees Celsius and is completely solid at 1450 degrees Celsius.
- Austenite begins to change to ferrite as new small crystals at the austenite grain boundaries (upper critical point).
- Remembering that ferrite will hold very little carbon, the bulk of the carbon must remain in the shrinking crystals of the austenite.
- At 723 degrees Celsius, there is a mixture of ferrite and austenite crystals (at the lower critical point).