The influence of fishplate material on connection strength
- What are the common materials of fishplates?
Common materials include Q235 steel, 45# steel, and Q345 steel. Q235 steel is used for ordinary railways, with low cost and moderate strength; 45# steel has high strength, used for heavy-haul railways; Q345 steel has good toughness, suitable for low-temperature areas. Material selection must match rail strength to avoid connection failure due to mismatched strength.
- How much higher is the strength of 45# steel fishplates than Q235 steel?
The tensile strength of 45# steel fishplates is ≥600MPa, and Q235 steel ≥375MPa, the former is about 60% higher than the latter. The shear strength of 45# steel is ≥350MPa, and Q235 steel ≥235MPa, with more obvious differences. Heavy-haul railways use 45# steel, which can bear larger axle loads and reduce the risk of deformation and fracture. But 45# steel costs 20%-30% more than Q235 steel.
- Why is Q345 steel fishplate preferred in low-temperature areas?
Q345 steel has good low-temperature toughness, with impact energy ≥34J at -40℃, while Q235 steel's impact energy may drop below 20J at -20℃, easy to brittle fracture. Using Q345 steel in low-temperature areas can reduce the risk of winter fishplate fracture and ensure reliable connection. Railways in cold regions such as Northeast and Northwest China mostly use this material.
- What problems can unqualified materials cause?
Insufficient material strength will deform the fishplate, expand bolt holes, loosen connections, and make gauge deviation exceed ±1mm. Poor toughness will lead to easy fracture under impact load, especially in turnouts and curves. Uneven materials will cause local stress concentration, shortening service life by more than 50%. Material sampling inspection is required to ensure compliance with standards.
- How to identify whether the fishplate material is qualified?
Check the material certificate to confirm that composition and mechanical properties meet standards. Use a hardness tester: 45# steel has hardness HB197-241, Q235 steel HB135-175, with obvious differences. If necessary, sample for tensile test to measure tensile strength. High-speed railway fishplates need 100% material re-inspection, and ordinary railways 10% sampling.