Are there any effects of boiling water on iron/steel?

Are there any effects of boiling water on iron/steel?

Rust is a common effect of oxidation that greatly affects iron and steel, who are very popular materials in many products around the world. Rust is a type of corrosion, which is a product of an electrochemical process, often disruptive to metals, caused by the reaction of oxygen, water and other materials, in the presence of compounds commonly found in the environment. Rust not only compromises the structural integrity of a material, but also its appearance. As a result, rust prevention is a critical requirement for many applications.

An interesting phenomenon regarding rust is that boiled water can contribute to its formation, a process commonly known as flash rust. Typically, iron and steel are not affected by boiling water on its own. However, pitting corrosion, a very aggressive form of rusting, can occur when boiling water is combined with oxygen, even if dissolved oxygen levels remain relatively low. The main cause of this type of rust is that in contact with water vapour, droplets quickly condense and leave behind those atmospheric materials that promote rust, such as chloride and sulphate ions.

One of the factors that comes into play with the process of flash rusting is the boiling time itself, since the longer an iron or steel material is exposed to boiling water, the more likely it is to rust. Boiling can cause air to become saturated with water vapour, creating a higher oxygen concentration in the water. Simultaneously, the absence of dissolved oxygen (DO) can result in pore formation in the steel’s surface, promoting the growth of rust.

Another factor to consider when analysing the relationship between boiling water and rusting iron and steel is the presence of other elements, such as chloride and sulphate, which can influence the formation of iron oxide. Chloride, for instance, corrodes the surface of a metal and increases its solubility. As a result, oxidation can occur more rapidly, while sulphates act as an oxidising agent that furthers the speed of the oxidation process.

Nevertheless, boiling water alone will typically not affect iron or steel materials, provided that there are no impurities present in the water. Furthermore, the amount of boiling time can significantly reduce the incidence of flash rusting, and other preventive methods such as the introduction of chemicals, galvanising, and coating to help counter the effects of boiling water should also be employed to ensure resistance to rust.