What are the chemical properties of 136 RE steel rail?
The chemical properties of 136 RE steel rail are governed by the AREMA (American Railway Engineering and Maintenance-of-Way Association) specifications to ensure a precise balance of hardness, toughness, and weldability. For a 136re rail profile to withstand the extreme axle loads of Class I railroads, the steel must contain specific percentages of Carbon, Manganese, and Silicon. High carbon content is the primary factor that provides the necessary wear resistance, while other alloying elements are controlled to prevent brittleness and internal defects.
- Carbon-Manganese Balance: The AREMA 136RE rail typically utilizes a high-carbon steel chemistry (often 0.72%–0.82% Carbon), which allows the rail to maintain its shape under millions of gross tons of pressure.
- Alloying Elements: Elements like Silicon and Manganese are added to improve the internal structural integrity of the 136re rail section during the cooling process, ensuring the steel is "clean" and free from harmful inclusions.
- Purity Standards: Strict limits are placed on Phosphorus and Sulfur (≤ 0.035% and ≤ 0.040% respectively) to ensure the 136RE heavy rail does not become brittle, especially in cold weather environments.
Chemical Composition of AREMA Rail Steel：
| AERMA 2019 | Strength Grade | C | Si | Mn | P | S | Ni | Cr | V |
|---|---|---|---|---|---|---|---|---|---|
| Carbon Steel | 0.74–0.86 | 0.10–0.60 | 0.75–1.25 | ≤0.020 | ≤0.020 | ≤0.25 | ≤0.30 | ≤0.010 | |
| Low Alloy Steel | Standard Strength (SS) | 0.72–0.82 | 0.10–0.50 | 0.80–1.10 | ≤0.020 | ≤0.020 | ≤0.15 | 0.25–0.40 | ≤0.010 |
| Intermediate Strength (IS) | 0.72–0.82 | 0.10–1.00 | 0.70–1.25 | ≤0.020 | ≤0.020 | ≤0.15 | 0.40–0.70 | ≤0.010 | |
| High Strength / Head Hardened (HH) | 0.72–0.82 | 0.10–1.00 | 0.70–1.25 | ≤0.020 | ≤0.020 | ≤0.15 | 0.40–0.70 | ≤0.010 |
Mechanical Properties of AREMA Rail Steel：
| AREMA 2019 | Strength Grade | Yield Strength N/mm2 |
Tension Strength N/mm2 |
Elongation % |
Brinell Hardness HBW |
|---|---|---|---|---|---|
| Carbon Steel | Standard Strength (SS) | 511MIN | 983MIN | 10MIN | 310MIN |
| Intermediate Strength (IS) | 724MIN | 1069MIN | 10MIN | 350MIN | |
| High Strength / Head Hardened (HH) | 828MIN | 1179MIN | 10MIN | 370MIN | |
| Low Alloy Steel | Standard Strength (SS) | 511MIN | 983MIN | 10MIN | 310MIN |
| Intermediate Strength (IS) | 552MIN | 1014MIN | 8MIN | 325MIN | |
| High Strength / Head Hardened (HH) | 828MIN | 1179MIN | 10MIN | 370MIN |
Which material is the most durable for Arema 136re rail?
For the AREMA 136RE rail, the most durable material available is High Strength / Head Hardened (HH) steel.While standard 136RE rail is already designed for heavy-duty use, the "HH" grade is specifically engineered to survive the extreme mechanical stresses of heavy-haul freight and high-traffic mainline tracks.
1. Hardness Levels (The Primary Durability Metric)
Durability in railway steel is measured largely by its Brinell Hardness (HBW). A harder rail head resists "rolling contact fatigue" (shelling and cracking) and abrasive wear from wheels.
- Standard Strength (SS): ≥ 310 HBW
- Intermediate Strength (IS): ≥ 325 HBW
- Head Hardened (HH): ≥ 370 HBW
The HH grade provides a significantly harder running surface, extending the time between grinding cycles and increasing the total tonnage the rail can carry before replacement.
2. Superior Mechanical Properties
The Head Hardened 136RE rail undergoes a specialized heat-treatment process that creates a fine pearlitic microstructure. This results in the highest strength ratings under the AREMA standard:
- Yield Strength: ≥ 828 N/mm2 (approx. 120,000 psi)
- Tensile Strength: ≥ 1179 N/mm2 (approx. 171,000 psi)
- Elongation: ≥ 10% (maintaining toughness so the rail doesn't become brittle)
What are the standard dimensions of 136 RE steel rail?
The AREMA 136RE rail (often referred to as TR68) is one of the most widely used heavy rail sections in North America. Its dimensions are standardized by the American Railway Engineering and Maintenance-of-Way Association (AREMA) to ensure compatibility with heavy-haul infrastructure.
Below are the standard 136RE rail dimensions required for technical drawings and procurement specifications.
| Profile | Standard | Dimensions mm | Section S | Mass m | ||||
|---|---|---|---|---|---|---|---|---|
| H | B | C | D | E | cm² | kg/m | ||
| American standard | ||||||||
| 136RE (TR68) | AREMA | 185,70 | 152,40 | 74,60 | 49,20 | 17,50 | 85,90 | 67,50 |
Frequently Asked Questions
- What is the carbon content of 136RE rail?
The carbon content of 136 RE steel rail typically ranges from 0.72% to 0.82%. This high carbon level is what gives the 136re rail profile its exceptional hardness and ability to withstand wear.
- Does TR68 have the same chemical properties as 136RE?
Yes, TR68 is the metric name for the same profile. The chemical properties are identical to AREMA 136RE rail, as both follow the same metallurgical standards for heavy-haul performance.
- How does sulfur affect the 136RE rail section?
Sulfur is kept below 0.040% because high sulfur levels can cause "hot shortness," leading to cracks during the rolling of the 136re rail dimensions. Low sulfur ensures a cleaner, stronger 136re rail section.
- Why is Manganese used in 136RE heavy rail?
Manganese (0.70%–1.10%) is used to increase the toughness and wear resistance of the 136 pound rail. It also helps remove oxygen and sulfur during the steelmaking process.
- Can 136RE rail chemistry be customized?
While the basic AREMA 136RE chemistry is standard, "Head-Hardened" versions may include slight adjustments to the alloying elements to increase the Brinell hardness of the 136re rail profile head.
- Does GNEE RAIL provide chemical analysis reports?
Yes, every order of 136 RE steel rail includes a Mill Test Certificate (MTC) which provides a full chemical heat analysis, confirming that the 136re rail weight and material comply with the project specifications.
GNEE RAIL provides 136RE rail manufactured strictly to current AREMA specifications, ensuring that the chemical properties and physical dimensions meet all technical requirements for heavy-haul infrastructure. Through the use of vacuum degassing and spectral analysis, material consistency and purity are guaranteed across every batch. Comprehensive logistics support and Mill Test Certificates (MTC) are provided to ensure that every 136 RE steel rail order is delivered with verified metallurgical data for project compliance.
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