Why are the railway rails not stainless steel but rusty iron?

railway rails

The railway rails are the established running track of the train. And it is an indispensable mode of the current train and railway technology. Everyone should have noticed that basically, all the railway rails are rusty, even the newly built train tracks are like this. Rusty iron products will not only shorten their lifespan but also become very fragile.

Rail is the abbreviation of railway rail track. It is made of high hardness and high toughness steel. The reason is that manganese steel is hard and wear-resistant and has a certain impact toughness, which meets the conditions for manufacturing rails.

The density of manganese steel rail is very high. When the oxide film is formed on the surface, it will form a protective effect on the inside and will not affect the use. Iron and steel are distinguished by their carbon content. Iron-carbon alloys with a carbon content of less than 2% are called steel, and those with a carbon content of more than 2% are called pig iron.

From a metallurgical point of view, there is no such thing as stainless steel. Stainless steel is also a kind of steel. Steel should have both toughness, elasticity, and rigidity. As far as rust is concerned, rust means that it is not resistant to corrosion. The main element that determines the corrosion resistance of stainless steel is chromium.

Steel with a chromium content of more than 10.5% will not rust. At this time, the oxidation of chromium and corrosive medium will form an oxide film on its surface, which can prevent basic further corrosion.

The cost of making iron is lower than that of stainless steel. In the design and manufacture of some short-term use, and the iron quality can meet the requirements of the material, of course, iron will be used.

Rail is a customary term, it is a steel rail, in order to improve the compressive and wear resistance, manganese is usually added. In order to resist oxidation and corrosion, stainless steel usually adds chromium and molybdenum elements. The use of railway rails should comprehensively consider strength, wear resistance, flexibility, plasticity, corrosion resistance, etc., but high strength and wear resistance are the first choices, and stainless steel cannot meet the requirements and will not be used.

The reason why stainless steel is not acceptable is that it is not durable enough to expand with heat and contract with cold, and it is easily damaged. Under daily wind, rain, and exposure, stainless steel will be more easily damaged. And although this kind of tall and fierce rail looks rusty, there is only a layer of rust on the surface, and the inside is still intact.

In addition, the density of manganese steel rail is very high. When the oxide rust film is formed on the surface, it will form a protective effect on the inside and will not affect the use.

First of all, from a technical point of view: most people think that stainless steel is rust-free, but the actual situation is that stainless steel like other alloys, is also rusty, but the color of the oxide film(rust) on the surface of stainless steel after rust is the appearance color of stainless steel, and this layer of an oxide film is relatively dense, which can protect the internal organization from further oxidation and rust.

However, this oxide film can still be corroded under certain conditions, especially in a humid acidic environment.

Therefore, stainless steel cannot be used in many cases. There are many varieties of stainless steel, and the hardness of stainless steel(especially austenitic stainless steel) is relatively low. The bright stainless steel plate is easily scratched because of its soft texture.

In terms of resources, nickel and chromium used in stainless steel are relatively scarce minerals, especially nickel is relatively scarce. The useful things, always need to use the key place, and can not be used at will.

In terms of cost, the cost of buying materials, making parts, and installing machines will all be considered. The price of stainless steel is not only a little bit higher than that of ordinary steel, aluminum, magnesium-aluminum alloy, plastic, and other materials, but is several times higher. As long as cheap materials can meet the requirements, who will use expensive materials?

In addition, even if other materials are rusted and not resistant to corrosion, there are many surface treatment technologies that can protect materials from corrosion, such as: painting, powder spraying, electroplating, electrophoresis, surface oxidation, surface chemical treatment(nitridation, cyanide, etc.) can improve the material surface corrosion problem. So it is necessary that rusty materials cannot be used in places with corrosion.

Glory Rail has a complete supply system. rust costing and deep anti-corrosion coating, the products are widely used in tunnels, coastal, or special chemical environments. The company uses advanced sandblasting and rust removal processing lines to pre-process the rails so that the surface coating of the rails can be firmer, the service life is longer, and the operation efficiency of the rails can be effectively improved.