What are the properties of track rail steel?
Jan 20, 2026
What is track rail steel?
Steel rail is an essential component of the railway track: it guides the train wheels forward by withstanding the pressure pushed by the wheels, and it provides a smooth, stable and continuous rolling surface. In electrified railways or automatic block sections, the rail also works as a track circuit. The steel used for the rail depends on the duty: light rails for industrial and mining lines are often made from structural carbon steel such as Q235B, while medium and heavy rails use dedicated rail grades such as 55Q, U71Mn or the EN grades R260 and R350HT.
Properties of Q235B steel
Q235B is a low-carbon structural steel defined by GB/T 700, widely used in industrial rails, light crane tracks and warehouse transport systems. Its mechanical and chemical properties ensure reliable performance under moderate loads while keeping the steel easy to process.
Mechanical properties of Q235B
| Property | Value |
|---|---|
| Yield strength | ≥ 235 MPa |
| Tensile strength | 370 – 500 MPa |
| Elongation | ≥ 26% |
Chemical composition of Q235B (%)
| Element | Limit |
|---|---|
| Carbon (C) | 0.12 – 0.22 |
| Silicon (Si) | ≤ 0.35 |
| Manganese (Mn) | 0.30 – 0.70 |
| Sulfur (S) | ≤ 0.045 |
| Phosphorus (P) | ≤ 0.045 |
Note that GB/T 700 does not specify a hardness value for Q235B. The yield strength of at least 235 MPa allows the steel to resist permanent deformation under normal industrial loads, the tensile strength of 370–500 MPa provides the ability to endure peak stress before failure, and the minimum elongation of 26% gives the ductility that reduces cracking during handling and installation.
Properties of 55Q rail steel
55Q is a rail steel grade used for light and medium rails under GB 11264, with higher strength than Q235B for heavier service. Its characteristic values are:
| Property | Value |
|---|---|
| Tensile strength | ≥ 685 MPa |
| Carbon (C) | 0.50 – 0.60% |
| Silicon (Si) | 0.15 – 0.35% |
| Manganese (Mn) | 0.60 – 0.90% |
| Sulfur (S) | ≤ 0.04% |
| Phosphorus (P) | ≤ 0.04% |
International rail steel grades
| Grade | Standard / region | Typical composition (wt%) |
|---|---|---|
| R260 | EN 13674-1 (Europe) | C 0.67–0.80, Mn 0.90–1.20, Si ≤ 0.50 |
| R350HT | EN 13674-1 (Europe) | C 0.75–0.85, Mn 0.80–1.20, Cr 0.20–0.50 |
| Grade 260 | AREMA (North America) | C ~0.77, Mn ~1.0–1.2, Si ~0.2 |
| Grade 350 | AREMA + mill specs (USA/Canada) | C 0.78–0.83, Mn 0.90–1.20, Cr 0.2–0.6, + V/Nb microalloy |
| Bainitic rail | JIS E 1101 (Japan), adopted in EU/India | C 0.65–0.80, Mn 1.0–1.4, Cr/Mo/Ni optional |
| U71Mn | GB/T 2585 (China) | C 0.65–0.77, Mn 1.10–1.40, Si 0.15–0.35 |
| U75V | GB/T 2585 (China) | C 0.67–0.77, Mn 0.70–1.00, V 0.04–0.12 |
GB light rail sections
| Section | Height (mm) | Head (mm) | Bottom (mm) | Web thickness (mm) | Weight (kg/m) |
|---|---|---|---|---|---|
| 8 kg/m | 65 | 25 | 54 | 7 | 8.42 |
| 12 kg/m | 69.85 | 38.1 | 69.85 | 7.54 | 12.2 |
| 15 kg/m | 79.37 | 42.86 | 79.37 | 8.33 | 15.2 |
| 22 kg/m | 93.66 | 50.8 | 93.66 | 10.72 | 22.3 |
| 30 kg/m | 107.95 | 60.33 | 107.95 | 12.3 | 30.1 |
International equivalents of Q235B
Q235B has several international equivalents with similar mechanical properties. The closest are ASTM A36 (USA), JIS SS400 (Japan) and EN S235JR (Europe), with other similar grades such as ASTM A283 Grade C and IS 2062 E250 (India). Minor differences in chemical composition and yield strength exist between these grades, so engineers should verify the specification for critical applications.
| Region | Equivalent grade |
|---|---|
| USA (ASTM) | A36, A283 Grade C |
| Japan (JIS) | SS400 |
| Europe (EN) | S235JR (1.0038), formerly DIN St37-2 |
| India (IS) | IS 2062 E250 |
Key considerations for substitution
Mechanical properties: Q235B has a yield strength of at least 235 MPa and a tensile strength of 370–500 MPa, while A36 is specified at about 250 MPa minimum yield.
Chemical composition: small variations in carbon, manganese, phosphorus and sulfur affect weldability and formability.
Application: for non-critical structural use these grades are often interchangeable, but for specialised projects such as marine and bridge structures, exact grade compliance is required.
Frequently asked questions
Is Q235B the same as rail steel?
No. Q235B is a structural carbon steel per GB/T 700 used for light rails and structural parts. Dedicated rail steels such as 55Q, U71Mn and R260 are specified by rail standards with higher strength, hardness and fatigue requirements.
What is the tensile strength of Q235B?
Q235B has a tensile strength of 370–500 MPa and a minimum yield strength of 235 MPa, with a minimum elongation of 26%.
What hardness does Q235B have?
GB/T 700 does not specify a hardness for Q235B. Hardness depends on the section size and delivery condition, so it is not used as an acceptance criterion for this grade.
Which steel grades are used for light rails in China?
GB 11264 light rails use Q235, 55Q and 50Mn grades depending on the section and duty, while heavier rails follow GB 2585 with U71Mn and U75V.
Can ASTM A36 replace Q235B in a light rail project?
For light-duty industrial rails, A36 and Q235B are often considered equivalent, but the yield strength, composition and the rail profile must be checked against the project specification before substitution.
What is the difference between Q235 and Q235B?
Q235 is the family designation; the B suffix specifies the impact energy requirement at 20°C in the GB/T 700 classification. Q235B requires a guaranteed 20°C impact value of at least 27 J, while Q235A has no impact requirement.
