GabyRust It is a constant threat to iron, which easily oxidizes both in air and in water. Even steel—a hard alloy of iron and carbon—rusts easily. However, stainless steel, as its name suggests, does not rust. So what is its secret?
In simple terms, the chemical composition of stainless steel prevents oxygen from the air and the environment from reaching the iron in the steel, thus preventing unwanted oxidation reactions.
Ordinary steel rusts when iron reacts with oxygen, forming iron oxide. Although rust is usually not harmful to humans, it can severely corrode iron.
Ordinary steel is an alloy made up of 99 percent iron and between 0.2 to 1 percent carbon. In contrast, stainless steel typically contains between 62 to 75 percent iron, about 1 percent carbon, and more than 10.5 percent chromium. Stainless steel also contains several percent of nickel, which makes it stronger and easier to work with.
Chromium is the key to the corrosion resistance of stainless steel.
This was reported to the publication. Live Science Materials scientist Tim Collins stated that chromium reacts with oxygen in the environment, usually in the air, but also underwater, forming a layer of chromium oxide (Cr2O3) on the surface. metal This layer prevents oxygen from reaching the iron in the steel and forming rust.
The Cr2O3 layer on stainless steel is only a few nanometers thick, making it invisible. This layer can self-repair if it is damaged. It is also inert, meaning it does not react chemically with other substances. Additionally, this layer does not leach out beyond the surface of the metal. This makes stainless steel suitable for food preparation, use in surgery, and more, added Tim Collins.
Random discovery
Stainless steel was invented in 1912 by English metallurgist Harry Brearley, who was studying steel alloys that would help prevent corrosion in gun barrels.
Brierley created an alloy of iron, carbon, chromium, and nickel, but it was not suitable for the barrel of a gun. So the metallurgist threw it out into the backyard, Tim Collins recounted. A few weeks later, Brierley noticed that the shiny alloy in his yard had not rusted. This discovery helped him develop stainless steel – an amazing material that was introduced to the world in 1915.
Stainless steel is valuable and irreplaceable.
Tim Collins reported that stainless steel currently accounts for about 4 percent of the approximately 2 billion tons of steel used worldwide each year.
At the same time, stainless steel is more complex and expensive to produce. Its cost is usually three to five times higher than that of regular steel. Additionally, the inclusion of special metal additives in the alloys (for example, molybdenum for underwater applications) can make stainless steel even more expensive.
As a result, in most cases where steel is needed, its standard version is used. To enhance rust resistance, the standard steel can be coated with a layer of paint or another coating.
Today, according to Collins, stainless steel is used in more areas than ever before.
Kanta Shelke, a food expert from Johns Hopkins University (USA), stated that stainless steel has numerous advantages compared to alternative materials. It is resistant to corrosion caused by food acids and cleaning agents, and it does not contaminate or spoil food. According to the scientist, stainless steel is also durable, stronger than aluminum, and hygienic; it has a non-porous surface that is easy to clean and disinfect.
