Steel Rail Classification

Classification by weight. Rail models are usually classified by weight. For example, the 50 rail we often say refers to a rail weighing 50kg/m. By analogy, there are 38 rails, 43 rails, 50 rails, 60 rails, 75 rails, etc. Of course, there are 24 rails and 18 rails, but those are all old news. Among them, rails of 43 rails and above are generally called heavy rails.

Classification by manufacturing process. According to the manufacturing process, rails can be mainly divided into hot-rolled rails and heat-treated rails. In fact, rails are all produced by hot rolling process. Heat-treated rails are heat-treated again after hot rolling. They are divided into online heat treatment and offline heat treatment. Online heat treatment has become the mainstream, which is more energy-saving and more efficient.

Classification by strength. Rails are a complex alloy. In addition to the main component of iron (Fe), there are five major elements, carbon (C), manganese (Mn), silicon (Si), phosphorus (P), sulfur (S), and of course some decisive trace elements such as vanadium (V), chromium (Cr), and some rare earth elements. The three most important factors in considering the performance of rails are strength, hardness, and toughness (generally measured by elongation after fracture), which are interrelated. Among them, the most important is strength, so there is also a method to classify rails according to strength grades. We will see 780Mp, 880Mp, and as high as 1450Mp, etc., and choose according to different needs. Generally speaking, the strength of subway rails is between 880-1180Mp.

Classification by purpose. Classification by purpose is basically the most common practice. Now all kinds of rail transportation construction are in the ascendant, and the uses of rails are also diverse. Let's talk about the scope of national railways first.

First of all, high-speed railways basically use 60-gauge tracks in the station yard (part of the parking line uses 50-gauge tracks), and the main line (including station lines and auxiliary lines) also uses 60-gauge tracks. However, the requirements for high-speed rail rails are very high, and the requirements for straightness and dimensions of each part are higher. There are also ordinary railways, which are basically 50-gauge tracks for vehicle depots and parking lots, and 60-gauge tracks for the main line.

Then there are some special railways. One is heavy-duty railways, such as the Daqin, Shuohuang Railway and Shenhua Coal Transportation Line. The characteristics are that the train axle weight is large and the total weight is large. The load of a train can reach more than 10,000 tons. This type of railway generally uses specially manufactured 75-gauge tracks, which can greatly increase the service life. The second is the high-cold railway, specifically the Qinghai-Tibet Line, which crosses the permafrost zone and has high requirements for the cold resistance and corrosion resistance of the rails. It uses specially manufactured 60-gauge tracks.