Q690D/E Ultra-High Strength Structural Steel Plate - Ultimate Strength and Toughness for Critical Load-Bearing Structures
Product Overview
Q690D/E is an ultra-high strength grade structural steel under GB/T 1591-2018, featuring a minimum yield strength of 690 MPa. The ‘D’ and ‘E’ grades respectively require excellent low-temperature impact toughness at -20°C and -40°C. Employing advanced metallurgical techniques and strictly controlled thermomechanical rolling processes, this product achieves extreme strength while ensuring sufficient toughness and weldability. It represents the ultimate choice for manufacturing ultra-heavy-duty, lightweight, high-safety core structural components.
Core Characteristics and Advantages
Ultimate Strength and Lightweighting
Extreme weight reduction: Yield strength up to 690MPa permits significant structural thinning and optimisation, particularly suited for high-end equipment manufacturing where weight sensitivity is paramount.
Ultra-high load-bearing: Meets the most demanding load requirements for critical power transmission and load-bearing structures within equipment.
Exceptional Low-Temperature Toughness
Grade D/E High-Standard Toughness: Offers Grade D (-20°C) or higher Grade E (-40°C) products tailored to operational environments (e.g., frigid regions, cryogenic conditions), ensuring absolute structural integrity in extreme conditions.
Controlled Weldability
Advanced Composition Process: Despite its exceptional strength, clean steel smelting and TMCP processing maintain a relatively low carbon equivalent. Reliable welding is achievable under strict welding procedure qualification and controlled measures.
Specialist Welding Guidance: We provide tailored welding procedure recommendations for Q690D/E.
Enhancing Core Product Competitiveness
A Marker of Technological Leadership: The adoption of Q690D/E directly signifies equipment advancement towards high-end, large-scale, and lightweight applications, significantly enhancing product market competitiveness and technological prestige.
Typical Application Fields
Q690D/E is primarily employed in core structural components for ultra-heavy-duty, lightweight designs:
Premium construction machinery: Main booms for ultra-heavy-tonnage cranes; booms and platforms for super-large excavators.
Specialised vehicles and port machinery: All-terrain crane chassis, container crane booms for port operations, fire engine aerial ladders.
Energy equipment: Critical sections of wind turbine towers, drilling platform structures.
Heavy mining equipment: Chassis for 300-tonne+ mining dump trucks, structural components for large electric shovels.
Technical Parameters (Compliant with GB/T 1591-2018 Standard)
| Item | Parameter Specification (e.g. Q690D) | Remarks |
| :--- | :--- | :--- |
| Yield Strength Rp0.2, MPa | ≥ 690 | |
| Tensile Strength Rm, MPa | 770 - 940 | |
| Elongation at Break A, % | ≥ 14 | |
| Impact Energy KV2 | Grade D: ≥ 47 (-20°C) <br> Grade E: ≥ 47 (-40°C) | Enhanced low-temperature toughness |
| Chemical Composition (Melt Analysis), % | | Ultra-low Carbon Equivalent Design |
| Carbon (C) ≤ | 0.18 | |
| Silicon (Si) ≤ | 0.60 | |
| Manganese (Mn) ≤ | 2.20 | |
| Phosphorus (P) ≤ | 0.020 | |
| Sulphur (S) ≤ | 0.010 | |
| Other Alloying Elements | Precise addition of niobium (Nb), vanadium (V), titanium (Ti), etc. | Grain refinement and precipitation hardening |
(Note: The above are typical values. Specific parameters shall be subject to the material certificate provided by our company.)
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Mail:zhen.li@bgtsteel.com
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