- Characteristics of ferrous alloys
- Uses of ferrous alloys
- Effects of alloying elements on iron alloys
- Bibliographic references
The ferroalloys are mainly combinations homogeneous iron which is added carbon.
Of the most used metals, mostly alloyed, there are: Iron (Fe), Copper (Cu), Chromium (Cr), Zinc (Zn), Aluminum (Al), Titanium (Ti), Nickel (Ni), Cobalt (Co), Manganese (Mn), Tin (Sn), Magnesium (Mg), Lead (Pb) and Molybdenum (Mo).
Metals and their alloys are classified into 2 groups: (1) ferrous, those based on iron and (2) non-ferrous, all others.
Characteristics of ferrous alloys
Alloys with less than 2% Carbon (C) are classified as steels, while those with more than 2% C are known as cast or cast iron.
In castings, as the name implies, cast irons are produced primarily as castings. In contrast, in steels they are produced for the most part as deformed and shaped products after molding.
In cast iron, the preferred form of carbon is elemental graphite, while in steels carbon is usually found in a combined form with other metallic elements.
Uses of ferrous alloys
The steel industry is divided into numerous branches depending on its use:
- Ordinary carbon steels, mainly used in the construction of both buildings and engineering equipment.
- Stainless steels, for parts of machinery, silverware or medical instruments.
- Tool steels, to which other compounds are added to make them more resistant.
Effects of alloying elements on iron alloys
The influence of alloying elements on ferrous alloys depends on the type of element that is combined.
- Carbon is the main hardening element.
- Manganese contributes to strength and toughness, and remove excess sulfur to increase its ease of hot work.
- Silicon is a main deoxidizer.
- Aluminum is used to finish the deoxidation reaction.
- Phosphorus is mainly an impurity, it decreases resistance and ductility.
- Sulfur only works to increase machinability, but in most cases it is as unwanted as phosphorus.
- Copper is added to increase resistance to atmospheric corrosion.
- Cobalt increases the hardness and improves the consistency when cutting the material, providing stability of the properties at high temperatures.
- Nickel is added to increase tensile strength.
- Tungsten provides high toughness, resistance to corrosion and high temperatures.
Generally a combination of 2 or more alloying elements impart better properties than alone.
Cr - Ni steels develop good hardening properties with excellent ductility, while Cr - Ni - Mo steels develop even better hardening but with a slight decrease in ductility.
For chemical industries where a heat exchange process is strictly required, it is mandatory to use equipment that fulfills this function.
The most commonly used equipment are double tube or tube and shell exchangers. The pipe material is mainly made of ordinary carbon steel, due to its low cost in the market and its high thermal conductivity to transport heat.
Properties of some ferrous alloys
Behavior of the ductility of a ferrous alloy as a function of the percentage of carbon
Bibliographic references
- Material properties.. Available at: materials23.blogspot.com
- Alloys. Available at: es.wikipedia.org. Retrieved December 8, 2017.
- Guanipa, V. (2011) Selection of engineering materials. (Second edition). Venezuela. University of Carabobo.
- Incropera, F. (1999). Fundamentals of Heat Transfer. (Sixth edition). Mexico. Editorial Pretince Hall Hispanoamericana SA