Steel rails are primarily used to make railway lines.
Purpose of Steel Rails
Steel is the material of choice for railway lines due to several key properties that ensure safety and efficiency for train travel.
Based on the provided information, steel is used for this purpose because:
- Flexibility: Steel is described as being "very flexible." While modern rails are designed for rigidity under load, this property within material science allows steel to absorb shocks and stresses.
- Ability to Expand: Steel has the "ability to expand." This refers to thermal expansion, a natural property where materials increase in size when heated.
- Shape Retention During Expansion: Crucially, when steel expands, "it does not change its shape, it only becomes bigger." This means the rail maintains its structural form, just on a larger scale, rather than distorting.
- Ensuring Safety: The combination of these properties, particularly the ability to expand while maintaining shape, is essential for "making sure it is safe to travel by train." Proper rail design and installation account for this expansion, preventing buckling or other issues that could derail a train.
In essence, steel rails provide the robust, stable, yet accommodating track surface necessary to support heavy trains moving at speed across varying temperatures.
Key Properties for Rail Lines
The use of steel for railway lines hinges on properties that handle the immense forces and environmental conditions they face:
- Strength: Steel can withstand the massive weight of trains and the dynamic forces generated during movement.
- Durability: It resists wear and tear from constant friction with train wheels and exposure to weather.
- Predictable Expansion: As mentioned, its thermal expansion is predictable, allowing engineers to design tracks with expansion joints or continuous welded rail to manage changes in length safely.
- Maintainability: Steel rails can be inspected, repaired, or replaced efficiently.
