This is a medium carbon steel with 0. One of the noticeable features of this steel is the high manganese content. This is a requirement for good reason — it allows for deeper heat treatment.
For railroad tracks to perform well in the long term, there are two really important qualities that the steel needs to have: high wear resistance and resistance to fracturing. The deeper heat treatment allows the steel to have higher strength properties.
As you can imagine, trains are heavy and put an extraordinary amount of stress on anything below them. Depending on the size of the trains and rate of use, a track could be expected to last anywhere from 5 to years. A more ideal hardness is around Rc, where the metal is sufficiently tough to resist cracking.
Main lines will commonly be pounds per yard, whereas smaller lines could get to around 70 pounds. For very small lines, like old ones for hand carts in mines, you might find it even smaller. Electronic structure is the arrangement of electrons in different orbit of the atom. A crystal is formed by a non-repeating cell in uni-direction. Nuclear structure can be studied by Mossbauer studies. Tritium has a half-life of What fraction of original Tritium will remain undecayed after 25 years?
Suggested Test Series. Suggested Exams. Which of the following statements are correct for carbon boil? Agitating the bath, causes thorough mixing. Reduction of carbon, nitrogen and hydrogen. Bring non-metallic into contact with slag and hence cleans the metal. When an alloy solidifies over a range of temperature, the resulting casting structure is.
Testbook Edu Solutions Pvt. Our Apps. Actually different types of metal are also mixed in the steel used in rail tracks.
The gaps left between successive rails on a railway track, the reason is that the rails expand in summer. The gap is provided to allow for this expansion.
If no gap is left, the expansion in summer will cause the rails to bend sideways. That will result in train accidents. Why are railroad tracks rust-colored? Because they are made of steel and iron. The iron in the steel oxidizes when oxygen gets to it. Therefore the surface of the rails are covered in surface rust because the iron on the surface of the steel rail is in contact with the oxygen in the air.
A penny left on a track does not typically derail a train. The quality of steels needed by railways varies with the application. The quality of steels used are mild steel, other plain carbon steels, alloy steels, high strength steels, wear resistant steels, corrosion resistant steels, spring steels, electrical steels, and stainless steels etc.
Further some steels need special processing to meet the specific requirements of railways. The requirement of various steels is getting updated on a continuous basis with the advancement of rail engineering.
For this, railways and the steel industry work in close co-ordination with each other. The rail track is known as a stable structure. It ensures the transportation of trains through providing a dependable surface for their wheels.
As to the development of rail track, it has a long history. The first rail track was made of wood and had continued for about 50 years. Later in order to reduce wear of the wooden rail tracks, iron straps were mostly added to the wooden rails. Then it was replaced by cast iron rails. Cast iron rails were used till the steel production by Bessemer converter became possible. And since then, steel has become the material which is used for rail tracks.
Presently, steel rails are used which are rolled from steel blooms produced in a continuous casting machine. Over the years, the shape of rails has changed a lot.
Since first rolled in , the? Rail track can be divided into main four components namely i rails, ii sleepers, iii fish plates, and iv rail fasteners Fig 1. These components along with the steels needed for them are described below. Rails are the members of the track laid in two parallel lines to provide an unchanging, continuous, and level surface for the movement of trains.
To be able to withstand stresses, they are made of high carbon steel carbon Some grades of steel contain chromium Cr- 0. Rails are also produced from special steels containing niobium Nb- 0. Recently rails made from corrosion resistant steels have also been developed.
Rail is the most expensive material in the track. Rail is the steel section that has been rolled into an inverted T shape. Rails vary in weight and shape. The rail section has a shape which looks like an inverted T and has a hardened head and a flat bottom. The flat bottom with an inverted T type cross section enables the rail to be fixed directly to the sleepers with the help of spikes.
The flat bottom rail is also known as vignole rail. Another advantage of the flat bottom rail is that it is a more economical design, giving greater strength and lateral stability to the track. Rail sections are similar to steel girders. These are provided to perform the following functions in a track. The main parts of a rail section are i head, ii web, iii foot, iv fishing angle, and v height of the rail.
The requirements, as well as the main considerations, for the design of these rail parts are as follows. The weight of rail is based on how much the rail weighs is in kilograms per metre.
The weight of a rail and its section is decided after considerations such as i heaviest axle load, ii maximum permissible speed, iii depth of ballast cushion, iv type and spacing of sleepers, and v other miscellaneous factors.
The length of the rail should be as long as it is feasible to produce and transport the rail. The longer the rail, the lesser the number of joints and fittings required and the lesser the cost of construction and maintenance. Longer rails are economical and provide smooth and comfortable rides. Rail is produced from fully killed steel and each section of the rail is to be accurately rolled to its respective template within permissible tolerance or variations.
It is to be free from all detrimental defects such as cracks of all kinds, flaws, piping, and lack of metal that have an unfavourable effect on the behaviour of rails in service. It is also to be absolutely straight.
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