Size parameters of the No. 8 rail

The size parameters of the No. 8 rail include rail height, rail head width, rail bottom width, web thickness, bolt hole diameter and spacing, etc. According to national standards, the size parameters of the No. 8 rail are as follows:

Rail height: 134mm
Rail head width: 70mm
Rail bottom width: 114mm
Web thickness: 13mm
Bolt hole diameter: 32mm
Bolt hole spacing: 76mm

The material of the No. 8 rail is generally carbon structural steel, and its chemical composition and mechanical properties should comply with relevant national standards. Specifically, the chemical composition of the No. 8 rail should include elements such as carbon, silicon, manganese, phosphorus, and sulfur, among which the carbon content should be between 0.65% and 0.77%. In terms of mechanical properties, the No. 8 rail should have good tensile strength, yield strength, elongation, and impact toughness.

The mechanical performance parameters of the No. 8 rail mainly include tensile strength, yield strength, elongation, and impact toughness. Among them, tensile strength refers to the maximum load-bearing capacity of the rail when subjected to tension, which should generally not be less than 880MPa; yield strength refers to the maximum load-bearing capacity of the rail when subjected to pressure, which should generally not be less than 685MPa; elongation refers to the degree of plastic deformation of the rail when subjected to tension or pressure, which should generally not be less than 14%; impact toughness refers to the resistance of the rail when subjected to impact load, which should generally not be less than 47J/cm2.

The process parameters of No. 8 rail mainly include smelting method, continuous casting method, rolling process and heat treatment process. For No. 8 rail, the converter smelting + continuous casting method is generally adopted, and then the four-roll reversible rolling mill is used for rolling, and finally quenching and tempering treatment is carried out. In addition, during the rolling process, the process parameters such as temperature, speed and pressure reduction should be controlled to ensure the dimensional accuracy and mechanical properties of the rail.

In addition to the above-mentioned dimensional parameters, material parameters and mechanical performance parameters, there are other parameters for No. 8 rail that need attention. For example, the straightness of the rails should meet the relevant standards, without obvious bending or twisting; the surface quality of the rails should also meet the requirements, without cracks, folds, scars and other defects; the cross-sectional shape of the rails should meet the design requirements, without abnormal conditions such as eccentricity and ellipse. In addition, the length of the rails should generally be determined according to specific needs, but should not be less than 5 meters.