High strength of track bolt
The track bolt plays a crucial role in ensuring smooth train operation on railway tracks by securely fastening rails to the foundation or fishplate. However, the increasing load of high-speed trains and heavy-duty transportation has led to challenges such as fatigue-induced cracking and fracturing of bolts and nuts, posing risks to railway safety.
The most common method of fastening, bolt and nut connection, is susceptible to root stress concentration due to the triangular thread structure. To enhance fastening strength, methods such as increasing fillet radius in thread roots, augmenting bolt thread trails, and modifying bolt and nut structures have been employed. While high-strength bolts are commonly used to address these issues, limitations exist in altering thread form and increasing production costs for structural modifications.
One effective approach involves reducing maximum axial tensile stress on track bolts, primarily concentrated on the nut surface. By strategically cutting away portions of the nut thread to reduce rigidity and alter stress distribution, the strength of track bolts can be significantly enhanced without complex manufacturing processes.
High-strength track bolts, typically used in bridge and turnout sections, are crafted from materials like 45# steel, 40# steel, 20 Manganese Titanium Alloy steel, and 35CrMoA steel, in contrast to ordinary bolts made from Q235 steel.