Materials Used for Rail Spike Manufacture
Basically railroad spikes are made out of carbon and alloy steel grades. The commonly used materials are Q235 carbon steel, Q345B and Q345D carbon steel, 45 steel, 40Cr alloy steel, 35CrMoA alloy steel and 20MnTiB boron steel. Each grade offers a different balance of strength, toughness, formability and weldability, so the material choice must match the service condition of the spike.
Properties of Common Steel Grades
Q235 Carbon Steel
Q235 carbon steel features good plastic property, toughness and welding performance, and it also has good cold pressing and bending behavior. Q235 is always used for parts and welded structures with average requirements, and it is a common choice for dog spikes on light lines where the load is moderate.
45 Carbon Steel
45 steel is the most used medium carbon steel, with good comprehensive mechanical properties. It is easy to crack during cold pressing, so heating is usually applied in forming operations. 45 steel is widely used for manufacturing moving parts with higher strength, such as gears, shafts and teeth, and it is also the standard material for square head screw spikes.
Q345 Carbon Steel
Q345 carbon steel has good comprehensive mechanical properties and good processing performance with cold and hot pressing, as well as good corrosion resistance. It is typically used in welded structural parts with high loading, such as ships, boilers, pressure vessels, crude oil tanks, bridges, power plant equipment and cranes. For rail spikes, Q345 grades offer higher strength than Q235 where the track demands a stronger spike body.
40Cr Alloy Steel
After conditioning, 40Cr steel has good comprehensive mechanical properties and good toughness under low temperature impact. Its welding property is poor and it is easy to crack during welding, but it is one of the most used alloy steels, found in gears, shafts, worms, sleeves, pins, rods, screws, bolts and valves. For rail spikes, 40Cr is used where high strength and hardenability are required, for example in high-strength screw spike classes.
35CrMoA and 20MnTiB Steel
35CrMoA is a chromium molybdenum alloy steel with high strength and good toughness, suitable for heavy-duty fasteners that must resist fatigue and impact. 20MnTiB is a boron steel with good hardenability, commonly used for high-strength bolts because boron improves the hardenability of the steel at a moderate cost. Both grades allow spikes and bolts to reach the higher property classes required by demanding track applications.
Dog Spikes vs Screw Spikes and Material Selection
Generally speaking, there are two types of rail spikes, dog spikes and screw spikes, and they differ both in shape and function. Dog spikes are used to fasten the rail to wooden ties, with an L-shaped head and a square shank, while screw spikes use a thread for a stronger grip in the sleeper. When selecting the material, consider the sleeper type, the traffic load, the environment and the required property class. For light wooden sleeper lines, Q235 or 45 steel dog spikes are economical; for heavy-haul lines and turnouts, choose 45 steel, 40Cr or higher alloy grades with an appropriate surface treatment to combine strength with corrosion resistance.
Common Misconceptions
One misconception is that higher carbon content always makes a better spike. In practice, the material must be matched to the sleeper type and installation method, because overly hard steel can crack during driving and is difficult to bend or remove. Another misconception is that alloy steel is always necessary. For light lines on wooden sleepers, plain carbon steel such as Q235 or 45 steel provides sufficient performance at a much lower cost, while alloy grades should be reserved for heavy-haul, turnout and high-strength applications where their cost is justified.
Frequently Asked Questions
Which steel is most common for rail spikes? Q235 and 45 carbon steel are the most common, with alloy steels such as 40Cr for higher strength classes.
What are the characteristics of Q235 steel? Q235 has good plasticity, toughness, welding performance and cold forming behavior for average service.
Why is 45 steel widely used? 45 steel offers good comprehensive mechanical properties and is the standard material for many fasteners and moving parts.
What is 40Cr used for? 40Cr is used for high-strength parts requiring hardenability, such as high-strength screw spikes and bolts.
What is the difference between dog spikes and screw spikes? Dog spikes have an L-shaped head and square shank, while screw spikes carry a thread for a stronger grip in the sleeper.
How do I choose the spike material? Consider sleeper type, traffic load, environment and required property class, and match the steel grade and surface treatment accordingly.
