Why are railway tracks corrosion free? what is their composition basically?

Have a close look at some railway tracks and you'll see that they are far from 'corrosion free'. The sides and bottom of each rail are covered in rust. The top, running surface is kept free of rust by the passing of the train wheels. In temperate climates the shiny surface will turn orange with rust in a day or two if no trains pass - I have seen this many times on running lines that have been closed for the weekend for engineering works etc.

At the far ends of sidings, beyond where the wheels of rail vehicles reach, the last ten feet of rail will be as rusted as the sides. Also, at terminal tracks in passenger stations you may note a Zigzag of stainless steel welded to the running surface for the last twenty feet or so. This is so that the wheels continue to operate the signalling track circuits when the rails rust over, as rust is a poor conductor of electricity.

The steel used for railroad tracks is of a special grade: the specification for 'normal' UK rails is: Carbon: 0.45-0.6%; Silicon: 0.05-0.35%; Manganese: 0.95-1.25%; Phosphorous: 0.025% max; Sulphur: 0.040% max. The balance to 100% is iron. Although the rust forms very quickly on the outside surfaces, once formed it effectively seals it, and further corrosion is very slow. As others have said, lightly-used rail will last fifty years or more, and worn rails from the main running lines are often re-used in sidings.

Corrosion requires a corrosive compound to work. It should not be confused with oxidation (rust) or erosion (it is hard to dissolve steel).

So tracks are free of corrosion because the railroad does not go down the tracks spraying corrosive agents on it.

Oxidation problems have already been addressed to some degree.

But please take a look at the construction of the rail bed. It is a packed surface that has ties and ballast on it under the rail head itself. This is to provide drainage. By doing this water and other liquids have a way to leave those things that can be damaged drier and less likely to rot or have other problems associated with things left in stagnate water or fluids.

They appear corrosion free due to the fact that trains passing over them remove all signs of rust. Leave them unused for a few months and that shiny surface soon turns rusty, How often they are replaced will depend to a large extent on how intensively they are used. Rails on a lightly used branch may last 50 or more years, on a heavily used main line not as long as 10 years. Most railways now have sophisticated electronic testing rolling stock equipment which patrols all lines checking for signs of wear, cracking and other corrosion. Before the advent of such machinery, each stretch of line would be the responsibility of a group of 'gangers' whose job it was to patrol a length of track on a regular basis, deal with minor repairs such as the need to tighten fish plate bolts and report back any major work that was necessary.

Railroad tracks are not corrosion free; they are composed primarily of iron and will rust. They appear not to because of use; a railway car traveling on the tracks helps to remove signs of corrosion as will a car crossing over the tracks at an intersection.

1

Your premise is false. Tracks are not corrosion free.

do your own homework