Metallurgical Properties and Industrial Processes

Material Properties in Metallurgy

Tenacity: Resistance to Impact and Fracture

Tenacity is the resistance to impact stress and fracture, or the ability of a metal to change shape without breaking. It requires both significant strength and plasticity.

Fragility: Lack of Plasticity

Fragility expresses a lack of plasticity and, consequently, tenacity. Brittle materials break within their elastic limit; that is, failure occurs spontaneously upon reviewing the load. In contrast, a material is considered tough if it possesses some capacity for expansion and breaks only after significant deformation.

Resilience: Shock Resistance

Resilience is a metal's resistance to breakage by shock. This property is often determined by the Charpy impact test.

Creep (Fluence): Slow Deformation

Creep (also known as Fluence) is the slow deformation of a material under the action of its own weight or a very small load over an extended period.

Fatigue: Failure Under Cyclic Loading

If a piece is subjected to periodic loads (alternating or intermittent), it can potentially break even with loads smaller than those that would cause immediate distortion. This phenomenon is known as fatigue.

Key Metallurgical Processes

Blast Furnace Operation

The blast furnace is a crucial component in iron production. It is loaded with coke and limestone additives, and heated fresh air is blown into the furnace. The burning coke forms carbon monoxide, which is essential for reduction, and generates the necessary heat for the process.

Preheating Stage

In the upper furnace, water is separated from the introduced sulfur ore due to heating.

Reduction Stage

Hot iron ore reacts with oxygen-containing gases, specifically carbon monoxide. During this stage, ferric oxide is reduced to iron.

Carburization Stage

At the high temperatures within the furnace, the newly formed iron absorbs carbon from the coke.

Molding and Pig Iron Production

Due to carbon absorption, the iron's melting point is lowered, and it becomes liquid. The liquid iron falls into a mold. Liquid slag, formed from limestone, floats on the iron and is separated by a runner. The resulting product, pig iron, is then either converted into ingots or transported in a liquid state to a steel mill for further processing.

Stainless Steel Production: Electric Arc Furnace

The production of stainless steel often involves an electric arc furnace. In this process, an electrical arc is generated between the material and a flux carbon electrode. The raw material used is carefully selected to be free from impurities during casting and alloying, as required. Due to the extremely high temperatures achievable in these furnaces, this procedure is especially suitable for alloying components such as hard-to-melt tungsten and molybdenum.

Typical operational parameters for an electric arc furnace include:

• Voltage: 50-100 volts (with a nominal value around 100V)
• Current Intensity: 3500-4000 Amperes
• Temperature: Approximately 3500 °C