Material selection and connection reliability of fishplates
- What are the common materials of fishplates and their advantages and disadvantages?
Fishplates made of Q235 steel are relatively low in price and have good processing performance, which can meet the basic connection needs of ordinary railways. However, their strength is relatively low, and they are easy to deform in heavy - haul railways. Q345 steel fishplates have good strength and toughness, are suitable for railways with medium traffic volume and speed, and can bear large loads, but their corrosion resistance is general, and anti - corrosion measures need to be strengthened in humid environments. Fishplates made of 45# steel have high hardness and wear resistance, and are often used in lines with frequent starting and braking, such as marshalling yards, but their cost is relatively high. Ductile iron fishplates have good shock absorption performance, can reduce the noise when trains pass, and are suitable for areas with high noise requirements. However, their strength is lower than that of steel, so they are not suitable for heavy - haul lines.
- How to select the material of fishplates according to the characteristics of railway lines?
For ordinary railway lines with low train loads and speeds, Q235 steel fishplates can be selected to reduce costs. For example, in some local branch railways, the requirement for strength is not high, and Q235 steel fishplates can meet the use. For busy trunk railways with large traffic volume and high speed, Q345 steel fishplates should be selected to ensure connection reliability. Heavy - haul railways carry large - axle - load trains and need high - strength fishplates. 45# steel is more suitable because it can bear huge pressure. In urban rail transit and other areas sensitive to noise, ductile iron fishplates are a better choice, which can not only meet the connection needs, but also effectively reduce noise.
- What impact does the material of fishplates have on their connection reliability?
Fishplates made of high - strength materials, such as Q345 steel and 45# steel, can provide stronger connecting force, reduce the displacement at the rail joint, and improve connection reliability. Good toughness of the material can prevent the fishplate from breaking under train impact. For example, Q345 steel fishplates are not easy to brittle fracture when bearing impact. Corrosion - resistant materials can ensure the performance of fishplates in harsh environments. For example, in coastal areas, the use of corrosion - resistant alloy steel fishplates can prevent the reduction of connection strength due to corrosion. Appropriate hardness of the material can reduce the wear between the fishplate and the rail. 45# steel fishplates have high hardness, which can reduce wear and prolong the service life of connecting parts.
- What are the differences in service life among fishplates of different materials?
Q235 steel fishplates have a service life of about 5 - 8 years in ordinary environments, and may be shortened to 3 - 5 years in harsh environments due to their limited strength and corrosion resistance. Q345 steel fishplates have a service life of 8 - 12 years, with good comprehensive performance, and can maintain connection stability for a long time. Due to their high hardness and wear resistance, 45# steel fishplates can have a service life of 10 - 15 years under normal use, especially in heavy - haul and severely worn lines. Ductile iron fishplates have a service life of about 6 - 10 years in medium - load environments such as urban rail transit, and their service life will be greatly shortened if used in heavy - haul lines.
- What safety hazards will unreliable fishplate connections bring?
Unreliable connections will cause large displacement at the rail joint, resulting in strong impact when the train passes, which may break the fishplate and bolts, cause the rail to disconnect, and seriously endanger driving safety. The displacement of the rail joint will change the gauge, make the contact between the wheel and the rail abnormal, and increase the risk of derailment, especially at high speeds, the consequences will be more serious. Loose connections will aggravate the wear of fishplates and rails, cause premature damage to rails and fishplates at the joint, increase maintenance workload and cost, and affect the smoothness of train operation. Long - term unreliable connections will also lead to a decline in the overall stability of the track structure, causing other track diseases such as ballast compaction and sleeper loosening, which further threaten the safety of railway operation.