What is steel grade Q235B?

What is steel grade Q235B?

Q235B is a common Chinese standard (GB/T 700) low-carbon structural steel, known for good strength, weldability, and plasticity, with 'Q' for yield strength, '235' for its minimum yield strength (235 MPa), and 'B' indicating a quality level with stricter limits on impurities (Phosphorus and Sulfur) than Q235A, making it ideal for general construction, bridges, and machinery parts. It's equivalent to ASTM A36 or JIS SS400 and is typically hot-rolled.

 

• Type: Carbon structural steel (mild steel).

 

• Production: Usually hot-rolled.

 

• Mechanical Properties: Yield strength ≥ 235 MPa, Tensile Strength 370-500 MPa, good elongation, toughness, and weldability.

 

• Chemical Composition (Max %): Carbon (C) ≤0.22%, Manganese (Mn) ≤ 1.4%, Silicon (Si) \(\le \) 0.35%, Phosphorus (P) ≤ 0.045%, Sulfur (S) ≤ 0.045%.

 

 

Q235B	Mechanical property						Chemical composition(%)
	Yield strength		Tensile strength		Elongation	Hardness	C	Si	Mn	S	P
	MPa	kg/mm²	MPa	kg/mm²	min	HB		≤		≤	≤
	≥	≥
	235	24	375-460	38-47	26%		0.12-0.22	0.35	0.30-0.70	0.045	0.045

 

Application of Q235B in GB Steel Track Rail

 

Classification		Height(mm)	Head (mm)	Bottom (mm)	Thick(mm)	Weight (kg/m)
Light Rail	8 KG/M	65	25	54	7	8.42
	9 KG/M	63.5	32.1	63.5	5.9	8.94
	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
	18 KG/M	80	40	80	10	18.06
	22 KG/M	93.66	50.8	93.66	10.72	22.3
	24 KG/M	107	51	90	10.9	24.46
	30 KG/M	107.95	60.33	107.95	12.3	30.1

 

Q235B vs U71Mn

 

Q235B is a general-purpose, low-carbon structural steel with good weldability, used for light loads, while U71Mn is a high-strength, wear-resistant manganese steel alloy, designed for heavy-duty applications like railways, cranes, and mining, offering superior hardness and durability for high-wear, impact environments. The primary difference lies in their composition and application: Q235B prioritizes ease of fabrication and cost for general structures, whereas U71Mn prioritizes extreme strength and wear resistance for demanding track systems.

 

U71Mn Steel

 

• Type: High-manganese steel alloy.

 

• Properties: High strength, hardness, and excellent wear resistance, achieved through higher manganese content (around 1.10%-1.50%) and carbon content (around 0.65%-0.77%).

 

• Applications: Heavy-duty applications like main railway lines, crane rails, and mining tracks requiring high performance and long life.

 

• Best For: High-wear, impact-prone environments needing long service life and stable performance.

 

 

Steel Grade	C(%)	Si	Mn	Cr	V	P	S	Tensile Strength (Rm/MPa)
U71Mn	0.65~0.76	0.15~0.58	0.70~1.40	–	–	≤0.035	≤0.030	≥880

 

How to choose the right steel rail material for your railway project?

 

Choosing the right steel rail involves matching rail specs (weight, profile, hardness) to your project's traffic (axle loads, speed, volume), environment (corrosion), and standards (UIC/AREMA), balancing wear resistance with toughness, and considering maintenance needs, with heavier rails for heavy haul and specialized alloys for high-stress areas. Key factors are traffic analysis (MGT, speed, curves), rail chemistry for hardness (Head-Hardened steel), profile compatibility, and regional standards.

 

 

• Define Project Needs: Assess traffic, speed, curves, and environment.

 

• Consult Standards: Identify applicable international or national standards.

 

• Select Rail Grade: Choose steel grade (e.g., C, Cr-Mn, Head-Hardened) based on wear/toughness needs.

 

• Match Profile & Weight: Select appropriate profile (e.g., UIC 60, QU120 for cranes) and weight.

 

• Specify Manufacturing: Consider advanced techniques like hot extrusion or laser welding for custom needs.

 

As a professional rail fastener supplier, GNEE RAIL can provide different standard steel rail such as GB,American, BS, UIC, DIN, JIS, Australian and South Africa which used in railway lines, cranes and coal mining.

 

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