The Influence of Impurities on Steel Ingots
Steel ingots come in all shapes and sizes, determined by the particular application for which they are required. Regardless of size and shape, steel ingots must remain free of impurities in order for them to maintain their structural strength and integrity. To understand why impurities can effect the quality and performance of steel ingots, one must understand the various types of impurities, their affects and how to reduce or eliminate them.
Impurities can be broken down into two main categories; Non-Metallic and Metallic. Non metallic impurities are typically comprised of sulfur, oxygen and phosphorus. They are present as a result of the manufacturing process or can originate from other sources such as atmospheric contamination. These types of impurities impair the ductility, malleability, and formability of the steel. Non metallic impurities also reduce the tensile strength, hardness, wear resistance and toughness of the steel.
Metallic impurities can be broken down further into two individual categories of ferrous and non-ferrous. Ferrous impurities contain iron and are the most common type of metallic impurity found in steel ingots. These types of impurities reduce the strength and ductility of the steel by forming a thin layer on the surface which hinders the ability of the steel to deform under stress. Non-ferrous impurities are generally comprised of lead and zinc, both of which are highly detrimental to steel ingots. These impurities have an effect upon the melting point of the steel, creating brittleness and weakening the strength properties.
In order to reduce or eliminate impurities in steel ingots, good manufacturing processes and quality control is key. The melting and casting temperatures must be well regulated in order to reduce the potential of non metallic impurities. Any products used during the manufacturing process, such as fluxes and alloys, should also be of the highest standard. This applies in particular to furnaces and moulds, as any build up of scale and slag on these surfaces can lead to impurities forming.
In addition to good manufacturing processes, quality control testing should also be conducted in order to detect any levels of impurities in the steel. Liquid and atomic absorption spectroscopies are two of the most commonly used methods of testing for impurities in steel ingots. Both technologies measure the concentration of impurities on the atomic and molecular level, giving a highly accurate representation of the levels present and allowing for adjustments to be made as necessary.
In conclusion, impurities can have a detrimental effect on the quality and performance of steel ingots, however with the right levels of quality control it is possible to reduce or completely eliminate the negative effects that they can have. Good manufacturing processes, high quality products and regular testing are all key elements to ensuring the success of any steel ingot project.
