Axle is one of the most important moving and bearing parts in all kinds of vehicles. As the axle bears dynamic load, the stress state is relatively complex, such as bending load, torsion load, bending and torsion combined load, and is subject to certain impact, especially high-speed emu axle, its stress state is more complex. Therefore, the axle of high-speed emu may be broken due to fatigue, bending, torsion or tensile stress during service. In order to ensure the safe operation of vehicles, the axle of high-speed emu must have sufficient reliability and fatigue safety factor. The axle material of high-speed emu is one of the key factors to determine the service life and reliability of the axle.
With the rapid development of China's high-speed railway, the demand for the axle of the emu train group has increased sharply, but it is still mainly dependent on imports. Therefore, it is urgent to develop new material axle steel with high strength, high toughness and long fatigue life, which is suitable for China's railway development. In recent years, anti-fatigue axle steel has been developed at home and abroad. For example, the anti-fatigue axle steel in Chinese patent application 201110417295.9 still adopts the high C content of traditional carbon axle steel. The C content (0.42~0.45%) is high, which makes the toughness of the steel poor and cannot meet the requirements of the emu axle on toughness, and the improvement of the anti-fatigue performance is limited. Chinese patent application 201210384581.4 a new type of hollow axle alloy steel, although the carbon content is low, with good strength and toughness, but the fatigue strength is still low. Imported from Europe the emu alloy EA4T conditioning treatment is used in the main to the axle, although the chemical composition and mechanical performance requirements are given, but gave no key heat treatment process parameters, more important is the influence of steel hardenability of the alloy element content is low, leading to large size of the emu axle the internal organization of the () is not allowed to exist ferrite and performance (near the core strength, toughness and fatigue resistance on the low side) are often difficult to meet the standard requirements. These are limited in practical application, the more critical is the axle steel fatigue resistance can improve the range are limited, affecting its application.
Applied to containing niobium high-speed emu axle steel production process, the process includes the following steps: electric arc furnace and converter smelting, LF refining furnace - RH or VD vacuum degassing 4 casting 4 slab reheating furnace heating 4 dairy - axle billet forging - axle billet casting axle coarse car - axle together face processing - containing niobium emu car axle steel heat treatment process - axis cylindrical finish turning machining - axle hole boring - cylindrical grinding - inspection.
