Knowledge of heavy rails: rails with a nominal weight greater than 30kg per meter. Both train rails and crane rails are heavy rails. Train rails: Used for laying railways, they must bear the pressure, impact load and friction during train operation, requiring sufficient strength and certain toughness. The quality requirements are strict. In addition to ensuring its chemical composition, it also requires inspection of mechanical properties, drop weight test and acid leaching low-magnification structure. Crane rail: that is, the crane rail, its height is low, the head width and waist thickness are large, and only the chemical composition and tensile strength are required to be tested. It is used for laying the tracks of cranes and trolleys.