material of rail

Rails are Prone to Rust, So Why Not Use Stainless Steel?

One of the core components of the railway is the rail, which carries the weight and speed of the train and ensures the smooth and safe operation of the train. However, have you ever noticed that the surface of rails is usually rusty, looks old and dirty, and even has cracks and signs of wear in some places.

Can such rails really ensure the safety of trains? Why not use materials like stainless steel to make rails? Isn’t stainless steel more durable, more beautiful, and more environmentally friendly?

1. Why do rails rust?

Railway track is the abbreviation of railway track, which is made of steel with high hardness and high toughness. Steel is an iron-carbon alloy that contains a certain proportion of carbon and other elements, such as manganese, silicon, phosphorus, sulfur, etc. The performance and use of steel depend on its composition and structure. Different steels have different grades and standards.

The steel used for rails is usually high manganese steel, which contains high levels of manganese and carbon. This gives the rails high strength and toughness, and can withstand the high pressure of trains and the friction loss of wheels. However, steel also has a fatal disadvantage, which is that it rusts easily.

Rust not only affects the appearance of steel, it also reduces its strength and toughness, making it brittle and prone to breakage. If the rails are severely rusted, it will endanger the safe operation of the trains. So why do railroad tracks rust?

This is mainly because the working environment of railway tracks is very harsh and is often affected by natural factors such as sun, rain, wind, sand, and changes in temperature. These factors will accelerate the oxidation reaction of steel, causing more rust to form on the surface of the railway tracks.

In addition, when trains are running, they will also produce some waste, such as soot, oil, debris, etc. These wastes will adhere to the rails and promote corrosion of steel. In order to prevent the rails from rusting, railway workers will regularly inspect and maintain the rails, such as cleaning debris on the rails, applying anti-rust oil, replacing damaged rails, etc.

At the same time, the design and manufacturing of the rail will also take into account its corrosion resistance, such as adding some antioxidant elements to the steel, such as chromium, nickel, molybdenum, etc., or performing some surface treatment on the steel surface, such as painting, electroplating, oxidation, etc., to increase the corrosion resistance of the steel.

2. Why not use stainless steel to make rails?

First of all, the manufacturing cost of stainless steel is relatively high because it requires the use of scarce minerals such as chromium, nickel, molybdenum, etc. These minerals are relatively expensive and the supply is unstable. Therefore, the price of stainless steel is also much higher than that of ordinary steel. If stainless steel is used to make rails, the construction cost of the railway will be greatly increased, which is detrimental to the economic benefits of the railway.

Secondly, the strength of stainless steel is relatively low because of its low carbon content, an important element that increases the strength of steel. The tensile strength of stainless steel is generally between 500-800 MPa, while the tensile strength of high-manganese steel used for rails can reach 900-1200 MPa, which means that the load-bearing capacity and deformation resistance of stainless steel are worse than that of high-manganese steel.

If stainless steel is used to make rails, the rails will be more likely to bend, break or deform, affecting the quality and safety of the train. In addition, the toughness of stainless steel is relatively poor, because it has a large grain and fewer grain boundaries, which is an important factor to improve the toughness of steel.

The impact toughness of stainless steel is generally between 50-100 J/cm2, and the impact toughness of high manganese steel for rail can reach 200-300 J/cm2, which means that the impact resistance and fatigue resistance of stainless steel are worse than that of high manganese steel. If the rails are made of stainless steel, the rails are more likely to crack, fall off, or break, leading to train failures or accidents.

Finally, the wear of stainless steel is relatively large because of its low hardness, which is an important indicator for improving the wear resistance of steel. The hardness of stainless steel is generally between 200-300 HB, while the hardness of high-manganese steel used for rails can reach 300-400 HB, which means that the wear resistance and scratch resistance of stainless steel are worse than that of high-manganese steel.

3. Are the rail materials used today safe?

Since stainless steel is not used to make rails, are the rail materials used now safe? The answer to this question is yes, because the rail materials currently used have been scientifically designed and optimized, have high performance and reliability, and can meet the operating needs and safety standards of the railway. In addition to high manganese steel, the rail materials currently used include the following two types:

High chromium steel:

High chromium steel is an improved rail material. It is characterized by high chromium content, which makes it have good corrosion resistance and can resist the erosion of air, water, acid, alkali and other chemical substances. The disadvantages of high-chromium steel are higher cost and lower strength and toughness. Therefore, the cross-sectional area and weight of the rail need to be increased to ensure the stability and safety of the rail.

High speed steel:

High-speed steel is a new type of rail material. It is characterized by containing more alloy elements, such as molybdenum, tungsten, vanadium, etc., which makes it have high hardness and wear properties and can withstand the high temperature and pressure of high-speed trains. The disadvantages of high-speed steel are its higher cost and poor toughness, so a special heat treatment process is required to improve the toughness and life of the rails.

The above three rail materials have their own advantages and disadvantages, but they can all ensure the safety and reliability of the rails. However, under different railway lines and operating conditions, it is necessary to choose the appropriate rail materials to achieve the best results and efficiency. .

Glory Rail’s rails are mostly made of high manganese steel, and can be coated with anti-corrosion coatings on their surfaces to ensure that the rail steel body is isolated from the external environment, effectively preventing external oxidation, rust, and corrosion of the steel and extending its service life. We can select rail materials and anti-corrosion measures according to customer requirements.