Q355 / Q390 / Q420 / Q460 Structural Plates for Heavy-Duty Engineering Projects

Low alloy high strength steel plates combine excellent strength, weldability, and cost-efficiency, making them widely used in structural engineering, equipment fabrication, and infrastructure. At CJM, we offer full-grade coverage of Chinese and international standards, including Q355, Q390, Q420, and Q460.

With over 1 million tons of inventory, we provide fast delivery, full certifications, and professional export packaging for overseas buyers.

Applications of Low Alloy Structural Steel

These plates are engineered for load-bearing structures in industries such as:

• Bridge and Highway Engineering
• Heavy Machinery and Equipment Frames
• Offshore & Marine Structures
• Power Station Steel Structures

They are especially ideal for regions requiring high strength-to-weight ratios, fatigue resistance, and reliable weld performance.

Available Grades and Standards

Grade	Standard	Yield Strength (MPa)	Typical Uses
Q355B/C/D	GB/T 1591	≥355	General construction
Q390B/C/D	GB/T 1591	≥390	Equipment and steel structure bridges
Q420B/C/D	GB/T 1591	≥420	Modular plants, platforms, cranes
Q460C/D/E	GB/T 1591	≥460	Complex welded structures, towers

Chemical Composition

Grade	C (%)	Mn (%)	Si (%)	P (%)	S (%)
Q355D	≤0.18	≤1.70	≤0.50	≤0.030	≤0.030
Q390D	≤0.20	≤1.70	≤0.50	≤0.030	≤0.030
Q420D	≤0.20	≤1.70	≤0.50	≤0.025	≤0.025
Q460C	≤0.20	≤1.60	≤0.50	≤0.025	≤0.025

Mechanical Properties

Grade	Yield (MPa)	Tensile (MPa)	Elongation (%)
Q355D	≥355	470–630	≥21
Q390D	≥390	510–680	≥20
Q420D	≥420	550–710	≥19
Q460C	≥460	550–720	≥17

Dimensions & Tolerances

Spec	Range
Thickness	6 mm – 100 mm
Width	1500 mm – 3200 mm
Length	3000 mm – 12000 mm
Standard	GB/T 709, EN10029, ASTM A6

Frequently Asked Questions

• Is welding required for low alloy plates?
  Yes, these grades are designed for excellent weldability using standard low-hydrogen electrodes.
• Can these be used in seismic-resistant structures?
  Yes, especially Q355D and Q460C with good ductility and notch toughness.
• Are certifications provided?
  Yes, we offer MTC (EN 10204 3.1) and optional SGS/BV inspection.
• What surface finish is available?
  Blasted and primed surfaces are optional for corrosion resistance and paint preparation.
• What is the MOQ for export orders?
  Flexible—mixed grades and partial loading supported.

Export Packaging & Delivery

Each low alloy high strength steel plate is packed using steel strapping and waterproof wrapping. Plates are stacked on wooden pallets or reinforced edges, with protective corner guards. They are loaded into containers or bulk vessels with rust-proof paper, edge protectors, and clear markings for sea transportation. All packaging conforms to export standards and is tailored per customer request.

About CJM

CJM is a professional supplier and exporter of low alloy high strength steel plates based in China. We serve global clients across Asia, the Middle East, Africa, Europe, and South America with timely supply, technical support, and flexible export services. Our stock system supports urgent orders and full third-party certification.

📩 Contact Us for Your High-Strength Steel Needs

Email: info@cjmstainlesssteel.com

WhatsApp: +8618191906640

Q: What is your company’s main products/services?

A: We are a professional manufacturer for Carbon Steel, Alloy Steel and Profile products. We have the experience of steel business for more than 10 years and our products are exported to Mid East,South America,Southeast Asia,Africa,South and East Asia etc.

Q: Can I go to your factory for a visit?

A: Of course, we welcome customers from all over the world to visit our factory.

Q: What are your terms of payment?

A: 30% T/T deposite and 70% balance before shipment.

Q: What is your delivery time?

A: For stocks,we could transport the goods to loading port within 7 days after we received the deposit; For production,it usually takes about 15-30 days after receiving the deposit.

Q: Do you provide samples? Are they free or paid?

A: Samples are available for free,but the courier freight will be covered by customer account.

Q: Do you accept the third party inspection?

A:Yes, we fully accept ‌third-party inspections.

Q: Why should I buy from you not from other suppliers?

A: Integrating the superior resources of China’s steel industry, we provide customers with high-quality steel products at preferential prices, and can ensure that the goods are delivered to customers in a timely manner.

Q:How can you guarantee quality?

A: Always a pre-production sample before mass production;Always 100% inspected before shipment