Why use the Q235B to manufacture Light Rail?

Why light rail is a different job from mainline rail

Steel rails play an important industrial role: from rail transportation to lifting and handling, the rail is the basis on which equipment operates. With the development of modern industry there is more and more demand for different types of steel rail, from common light rails and heavy rails to lifting rails and special-shaped rails for particular situations. Light rail carries modest axle loads at low speed, so it does not need the high carbon and manganese content of heavy rail steels such as U71Mn or R350HT; instead, the priorities are adequate strength, easy welding, economy and availability.

The five reasons Q235B is used for light rail

1. Good mechanical properties

Q235B has a yield strength of at least 235 MPa and a tensile strength of 370–500 MPa, which provides sufficient structural integrity to support light vehicles without excessive wear or deformation. Its moderate hardness keeps a balance between strength and ease of machining and forming.

2. Excellent weldability

Urban and industrial light rail systems often require frequent joint welding or repair. The low carbon content of Q235B allows easy welding without specialised preheating, which reduces construction and maintenance cost.

3. Cost efficiency

Compared with higher-grade rail steels, Q235B is more economical to produce and procure, which makes it ideal for light rail lines where cost-effectiveness is crucial.

4. Adequate wear resistance for light loads

Q235B is not as hard as U71Mn or R350HT, but its wear resistance is sufficient for low-speed, low-load tramways and industrial light rail, particularly when it is used with the correct fasteners, sleepers and rail pads.

5. International availability and standard compliance

Q235B conforms to GB/T 700, which facilitates standardised production, quality assurance and interchangeability for light rail systems in China and international markets. Its equivalents include ASTM A36, JIS SS400 and EN S235JR.

Mechanical and chemical data for Q235B

Property	Value
Yield strength	≥ 235 MPa
Tensile strength	370 – 500 MPa
Elongation	≥ 26%
Carbon (C)	0.12 – 0.22%
Silicon (Si)	≤ 0.35%
Manganese (Mn)	0.30 – 0.70%
Sulfur (S)	≤ 0.045%
Phosphorus (P)	≤ 0.045%

Other rail steels for comparison

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

Light rail sections and grades by standard

Standard	Section	Typical grades
GB 11264-1989	8, 12, 15, 18, 22, 24, 30 kg/m	Q235, 55Q
GB 11264-1989	38, 43 kg/m	50Mn, U71Mn
GB 2585-2007	50, 60, 75 kg/m	U71Mn, U75V
TB/T 2344-2012	50, 60, 75 kg/m	U71Mn, U75V, U77MnCr, U78CrV
GB crane rails	QU70 – QU120	U71Mn

Within the GB 11264 range, the lighter sections (8–30 kg/m) are normally supplied in Q235 or 55Q, while the heavier 38 and 43 kg/m sections use 50Mn or U71Mn for higher strength and wear resistance.

Frequently asked questions

Why not use Q235B for heavy rail?

Heavy rail carries high axle loads at speed and needs the wear resistance, hardness and fatigue strength of dedicated rail steels such as U71Mn, U75V or R260. Q235B would wear quickly and deform under those loads.

What is the difference between Q235 and Q235B?

Q235 is the family name in GB/T 700. The B suffix guarantees an impact energy of at least 27 J at 20°C; the A grade has no impact requirement, and C and D add lower-temperature impact guarantees.

Can Q235B light rail be welded with ordinary electrodes?

Yes. The low carbon content of Q235B allows conventional manual arc welding without preheating for normal section sizes, which is one of the main reasons it is specified for light rail and repair work.

Is Q235B light rail suitable for outdoor use?

Yes, with normal surface protection. Light rails are supplied plain, painted or with other finishes, and the fastening and drainage should be arranged so that water does not stand against the rail foot.

Which international grades are equivalent to Q235B?

ASTM A36 (USA), JIS SS400 (Japan) and EN S235JR (Europe) are the common equivalents, with minor differences in yield strength and composition that should be verified for critical applications.

What rail sections can be made from Q235B?

Q235B is used for light rail sections from about 8 kg/m to 30 kg/m under GB 11264. Above that range, 50Mn, 55Q or U71Mn grades are specified instead.