Material Properties, Ferrous Metals, and Steel Production Processes
Material Properties
Sensorial Properties
- Touch: Includes texture, shape, and feel.
- Smell: Odor characteristics of materials.
- Color/Optic: Material reaction when light falls on it.
- Opaque: Do not allow light to pass.
- Translucent: Allow light to pass, but not clearly.
- Transparent: Allow light to pass clearly.
Thermal Properties
Reactions against heat. Insulating materials prevent heat transfer.
Magnetic Properties
Capacity of a ferrous metal to be magnetized.
Chemical Properties
Attraction or repulsion. The most important is related to oxidation and corrosion.
Efforts (Mechanical Properties)
When a force acts on an object, deformation tends to occur. This depends on the direction and point of application of the force.
- Traction: Force lengthens the object, acting perpendicular to the surface holding it.
- Compression: Force shortens the object, acting perpendicularly to the surface.
- Inflection: Force curves the object, acting parallel to the surface.
- Torsion: Force twists the object, acting parallel to the surface.
- Cut: Force is parallel to the break and passes through it.
- Buckling: Similar to compression, occurs in objects with small and large longitudinal sections.
Ferrous Metals
Metals containing iron as a key base element, possibly with small proportions of others.
Principal Deposits
Currently, it is often more profitable to import minerals. Open-cast mining is common. Principal minerals include magnetite, hematite, limonite, and siderite. These minerals are abundant and contain high proportions of iron.
High Furnace (Raw Material Processing)
The high furnace processes raw materials: 60% iron ore, 30% coking coal, and 10% flux, introduced from the top.
- Iron Ore: Undergoes preliminary treatments, including shredding and separation of ore.
- Coking Coal: Creates an artificial fuel. The furnace’s heat produces the necessary energy for ore reduction and chemical reactions, transforming iron oxide into iron.
- Flux: Composed of limestone, it reacts chemically to form gangue and slag with a low fusion point, separating it from the iron.
High Furnace Operation
The high furnace operates continuously. Materials descend through the furnace, reaching temperatures up to 1650°C. Iron ore transforms into liquid iron, deposited in the crucible. Lime reacts with gangue to form slag, which is extracted. Periodically, liquid iron (cast iron or first fusion iron) is extracted. Almost all this iron becomes steel through a converter process. The hot air blast enters through nozzles in the lower part of the furnace.
Obtaining Steel from Scrap
Electric furnaces are used, with components including:
- Electric Transformer: Converts voltage to 900V and transforms AC to DC.
- Flexible Cables: Conduct electricity to the electrodes.
- Electrode Arms: Adjust electrode position to create an arc with the scrap metal.
- Electrode Restraints with Hydraulic Arms: Manage the furnace lid for adding scrap, ferroalloys, and flux.
- Smoke Chilling Output: Filters fumes to remove particles.
- Oscillating Structure: Tilts the furnace to pour out molten steel.
Casting of Steel
Conventional Casting
Pouring liquid steel into molds to achieve the desired shape.
Continuous Casting
A more modern and economical method. Liquid steel is continuously poured into a mold without a bottom, solidifying as it passes through, forming a specific cross-section.
Ingot Casting
Used when demand is low. Liquid steel is poured into molds and cooled.
Ferrous Material Classification
Sorting
- Iron: Carbon content between 0.01% and 0.03%. Very soft and difficult to obtain.
- Steel: Alloys with carbon content between 0.03% and 1.76%.
- Cast Iron: Alloys with carbon content between 1.76% and 6.67%.
- Graphite: Achieved when carbon content exceeds 6.67%. Very brittle.
Commercial Steel Presentations
Common forms of steel include:
- Sheet Metal: Sheets are typically 1×2 meters or 3×3 meters.
- Bars: Long pieces with solid, variable sections. If the section is round and the diameter is less than 5mm, they are called wires.
- Profiles: Hollow parts with variable sections, lengths between 5 and 12 meters.