Bethlehem Steel Seamless tube RQC ASTM A678 RQC80, Steel Seamless tube

Bethlehem Steel Seamless tube RQC ASTM A678 RQC80 3/16 to 3/4 in. thick, Steel Seamless tube plate Product Information -:- For detailed product information, please contact sales. -: Bethlehem Steel Seamless tube RQC ASTM A678 RQC80 3/16 to 3/4 in. thick, Steel Seamless tube plate Synonyms -:- For detailed product information, please contact sales. -:

Bethlehem Steel RQC ASTM A678 RQC80 3/16 to 3/4 in. thick, steel plate Product Information -:- For detailed product information, please contact sales. -: ## **Product Datasheet: Bethlehem Steel RQC ASTM A678 RQC80 Steel Plate** **Product Overview** Bethlehem Steel RQC ASTM A678 RQC80 is a premier, high-strength, quenched and tempered (Q&T) structural steel plate from the proprietary RQC (Rapid Quenched Carbon) series. Engineered to deliver a superior balance of **80 ksi minimum yield strength**, exceptional low-temperature toughness, and excellent weldability, this grade represents the high-strength tier of the RQC family. Utilizing Bethlehem's optimized heat treatment process, it achieves a fine-grained, tempered martensitic microstructure that provides outstanding resistance to fracture and fatigue. The RQC80 is specifically designed for critical applications where maximum strength-to-weight ratio and structural integrity under extreme conditions are required. This plate is available in thicknesses ranging from **3/16 inch (4.8 mm) to 3/4 inch (19.1 mm)**. **Key International Standards & Specifications** * **Primary Performance Standard:** **ASTM A678 / A678M** - While "RQC80" is a proprietary Bethlehem Steel designation, the product is manufactured to meet and exceed the mechanical and toughness requirements aligned with the 80 ksi yield strength category within the ASTM A678 framework. * **Proprietary Designation:** The **"RQC80"** trademark signifies Bethlehem Steel's specialized production route for achieving high toughness at this strength level, differentiating it from standard A678 Grade D. * **Mandatory Supplementary Requirements:** Certification typically included stringent impact testing, aligning with: * **ASTM A6 Supplementary Requirement S1 (Charpy V-Notch Impact Testing):** Guaranteed with high minimum energy values at low temperatures (typically **-50°F / -46°C**). * **ASTM A6 S5 (Maximum Carbon Equivalent):** Strictly controlled to ensure superior weldability for its strength class. * **Industry Context:** Often specified as a premium alternative to **ASTM A678 Grade D** where guaranteed ultra-high toughness was non-negotiable, or as a more weldable and tough counterpart to ultra-high-strength alloy steels. **Chemical Composition (Weight % - Typical RQC80 Aim for Thickness ≤ 0.75")** Chemistry is meticulously balanced to achieve the high hardenability needed for full martensitic transformation upon quenching in this thickness range, while maintaining lean alloying for weldability and toughness. | Element | Typical RQC80 Aim / Range | Key Purpose | | :--- | :--- | :--- | | **Carbon (C)** | 0.14 - 0.19% | Lowered to maximize toughness and weldability while providing a strong martensitic base. | | **Manganese (Mn)** | 1.20 - 1.50% | Primary agent for strength and hardenability. | | **Phosphorus (P)** | ≤ 0.015% | Ultra-low for enhanced fracture resistance. | | **Sulfur (S)** | ≤ 0.008% | Ultra-low for improved ductility and reduced anisotropy. | | **Silicon (Si)** | 0.15 - 0.30% | Deoxidizer. | | **Aluminum (Al)** | 0.02 - 0.05% | Grain refiner (fine grain practice). | | **Nickel (Ni)** | 0.40 - 0.70% | Significantly improves hardenability and, crucially, low-temperature toughness without a severe carbon equivalent penalty. | | **Chromium (Cr)** | 0.40 - 0.65% | Enhances hardenability and tempering resistance. | | **Molybdenum (Mo)** | 0.15 - 0.25% | Critical for achieving full hardenability and suppressing temper embrittlement. | | **Vanadium (V)** | 0.03 - 0.07% | Contributes to strength via precipitation. | | **Boron (B)** | 0.001 - 0.003% | Trace addition to significantly boost hardenability efficiently. | | **Carbon Equivalent (C.E. IIW)** | Typically 0.48 - 0.55 | Well-managed for an 80 ksi Q&T steel, facilitating controlled welding. | **Physical & Mechanical Properties** | Property | RQC80 Minimum/Target Requirement | Typical Performance | | :--- | :--- | :--- | | **Yield Strength (Min)** | 80 ksi (550 MPa) | 85 - 95 ksi (586 - 655 MPa) | | **Tensile Strength** | 95 - 115 ksi (655 - 795 MPa) | 100 - 110 ksi (690 - 759 MPa) | | **Elongation in 2" (Min)** | 16% | 17 - 20% | | **Yield-to-Tensile Ratio** | -- | Typically 0.85 - 0.88 | | **Modulus of Elasticity** | ~29,000 ksi (200 GPa) | ~29,000 ksi (200 GPa) | | **Density** | 0.284 lb/in³ (7.85 g/cm³) | 0.284 lb/in³ (7.85 g/cm³) | | **Charpy V-Notch Toughness (Hallmark)** | **Exceptionally High (e.g., 35-50 ft-lb @ -50°F / -46°C)** | The defining achievement of the RQC80 grade. It delivers impact values often associated with much lower strength steels, providing a massive safety margin against brittle fracture. | | **Key Feature** | **Ultra-High Toughness at 80 ksi Yield:** Successfully combines the highest commonly specified structural yield strength (80 ksi) with Charpy toughness levels that rival many 50-60 ksi steels, enabling breakthrough designs for critical, weight-sensitive applications in severe environments. | **Product Applications** Bethlehem Steel RQC80 was specified for the most highly stressed components in safety-critical structures and equipment operating under dynamic or impact loading, often in low-temperature conditions. * **Advanced Mobile Equipment:** Critical boom and arm sections, pivot points, and main frames for the largest excavators, cranes, and forestry equipment where weight savings directly translate to performance and payload. * **Offshore & Marine Structures:** Critical node joints, tendon sleeves, and other highly constrained welds in offshore oil & gas platforms and ice-class vessel components. * **Defense & Aerospace:** Armor vehicle structural members, landing gear components, and launch system structures requiring high strength with certified toughness. * **Energy Infrastructure:** Critical sections for advanced reactor components, high-pressure manifolds, and high-stress parts in hydroelectric turbines. * **Heavy Transportation:** Key structural members in heavy-haul truck frames, logging equipment, and specialized railcar components. **Advantages & Fabrication Notes** * **Optimized Weldability for its Strength Class:** While requiring strict low-hydrogen procedures, its controlled chemistry makes it significantly more weldable than other 80 ksi Q&T steels with higher carbon or alloy content. Preheat and interpass temperature control (typically 300-400°F / 149-204°C) are essential. * **Unmatched Fracture Resistance:** Provides an unparalleled combination of strength and toughness, effectively pushing the boundary of the structural steel performance envelope. * **Fatigue Performance:** The clean, homogeneous Q&T microstructure offers excellent resistance to crack initiation under cyclic loading. * **Formability Considerations:** Cold forming is limited and requires large bend radii. Hot forming is not recommended without subsequent re-austentizing, quenching, and tempering. * **Legacy Product Note:** The RQC80 was a flagship high-performance product of Bethlehem Steel. Modern equivalents include proprietary **"HSLA 80"** or **"HY-80" type grades** from specialty plate producers, and advanced **"S690QL"** or **"S690Q"** grades per EN 10025-6, though chemistry and processing may differ. **Disclaimer:** This datasheet describes the historical **Bethlehem Steel RQC80** product. For current projects requiring this performance level, engineers must specify **80 ksi min YS, 95-115 ksi UTS, and guaranteed high Charpy V-Notch values at the design low temperature** (e.g., **40 ft-lb min @ -50°F**). Additionally, specify **maximum CE** (e.g., 0.55) to ensure weldability. Engage with mills specializing in high-performance Q&T plate to source an equivalent material, such as a plate meeting **ASTM A678 Grade D with enhanced supplemental toughness requirements** or a mill-proprietary grade. Fabrication requires welding procedure qualification on representative material, and all thermal processes must follow the producer's strict guidelines. -:- For detailed product information, please contact sales. -: Bethlehem Steel RQC ASTM A678 RQC80 3/16 to 3/4 in. thick, steel plate Specification Dimensions Size： Diameter 20-1000 mm Length <4675 mm Size:We can customized as required Standard： Per your request or drawing We can customized as required Properties（Theoretical） Chemical Composition -:- For detailed product information, please contact sales. -: Bethlehem Steel RQC ASTM A678 RQC80 3/16 to 3/4 in. thick, steel plate Properties -:- For detailed product information, please contact sales. -:

Applications of Bethlehem Steel Seamless tube RQC ASTM A678 RQC80 3/16 to 3/4 in. thick, Steel Seamless tube plate -:- For detailed product information, please contact sales. -: Chemical Identifiers Bethlehem Steel Seamless tube RQC ASTM A678 RQC80 3/16 to 3/4 in. thick, Steel Seamless tube plate -:- For detailed product information, please contact sales. -:

Packing of Bethlehem Steel Seamless tube RQC ASTM A678 RQC80 3/16 to 3/4 in. thick, Steel Seamless tube plate -:- For detailed product information, please contact sales. -: Standard Packing: -:- For detailed product information, please contact sales. -: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and Steel Seamless tube drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 1146 gallon liquid totes Special package is available on request. E FORUs’ is carefully handled to minimize damage during storage and transportation and to preserve the quality of our products in their original condition