#2 - Phenomena behind the effects of Sulphur & Phosphorus.

There are two phenomena that clearly relate to the contents of Sulphur and phosphorus: “Hot-Shortness” and “Cold-Shortness”. These phenomena help us understand why such non-metallic elements have the potential to cause havoc.
Hot shortness is caused by an excess of sulphur, while cold shortness results from an excess of phosphorus. Both can cause serious damage to a steel bar, such as cracking or corrosion. The degree of damage depends on the amount of sulphur or phosphorus present in the steel.

Hot shortness occurs when a steel bar is heated over its recrystallization temperature due to an excess amount of sulphur in it. This causes the bar to become brittle and lose its ductility, resulting in cracks forming around bends and welds. Cold shortness is based on an excess amount of phosphorus content which weakens the structure and increases brittleness during cooling after welding or forging processes are complete. It leads to reduced impact strength and increased susceptibility to stress corrosion cracking at low temperatures.

To avoid hot shortness, it is important to keep track of your sulphur content levels during production stages and ensure that they remain below 0.06%. To avoid cold shortness, you should ensure that your phosphorus content levels do not exceed 0.05%. This helps maintain good mechanical properties such as ductility, tensile strength, weldability, toughness, and fatigue behaviour for long-term performance in service conditions with minimal risk of premature failure due to material defects.

It is important to note that such phenomena are activated in extreme temperatures, i.e., way above 100 degrees Centigrade and below sub-zero temperature levels. This means that the effects of sulphur and phosphorus at temperatures seen in the Indian regions will not give rise to activations in steel within the concrete, or be the cause of activation due to the surrounding environment. Even at a slightly higher content level of Phosphorous, it will have almost a negligible contribution towards failure as compared to other factors involved during construction activities. However, the same cannot be said for the contents of Sulphur in steel as it is just an impurity rather than a property-enhancement element. Sorry Sulphur, you’re just a Bad Guy!

In the interim, we also strongly advise that the methods and practices used in on-site construction need to be strictly carried out using the civil building codes and other published standard specifications. One such example highly stressed by our engineers is that during on-site bending or re-bending of steel bars, it is often found that the workers try to heat the bar using burners so that it is convenient for them to bend the bar easily. This is absolutely an incorrect practice because it changes the properties of the steel when it is reheated. The entire process of manufacturing the graded steel is nullified by such treatments.

Overall, understanding how hot shortness and cold shortness affect reinforcement steel bars is essential for ensuring safe construction projects that meet quality standards. With careful monitoring and control over sulphur and phosphorus contents during production stages, we deliver the end-user a strong product that will perform well under varying temperatures without any risk of cracking or corrosion issues arising down the line.
 
STAY STRONG, STAY BLESSED!