Bethlehem Steel ASTM A678 Grade C, steel

Bethlehem Steel ASTM A678 Grade C 3/16 to 3/4 in. thick, steel plate Product Information -:- For detailed product information, please contact sales. -: Bethlehem Steel ASTM A678 Grade C 3/16 to 3/4 in. thick, steel plate Synonyms -:- For detailed product information, please contact sales. -:

Bethlehem Steel ASTM A678 Grade C 3/16 to 3/4 in. thick, steel plate Product Information -:- For detailed product information, please contact sales. -: ## **Product Datasheet: Bethlehem Steel ASTM A678 Grade C Steel Plate** **Product Overview** Bethlehem Steel ASTM A678 Grade C is a high-performance quenched and tempered (Q&T) structural steel plate representing the higher-strength tier within the ASTM A678 specification. Engineered through a rigorous thermal process of austenitizing, rapid quenching, and precise tempering, this grade delivers a robust combination of 70 ksi minimum yield strength and excellent notch toughness. The resulting tempered martensitic microstructure offers superior resistance to fatigue and brittle fracture compared to as-rolled or normalized steels of equivalent strength. This plate is specifically available in thicknesses ranging from **3/16 inch (4.8 mm) to 3/4 inch (19.1 mm)**. **Key International Standards** * **Primary Standard:** **ASTM A678 / A678M** - Standard Specification for Quenched-and-Tempered Carbon and High-Strength Low-Alloy Structural Steel Plate. * **Governing Specification:** This product is manufactured to meet all chemical, mechanical, and heat treatment requirements for **Grade C** as defined in ASTM A678. * **Supplementary Requirements:** Commonly specified with supplementary requirements from **ASTM A6**, including: * **S1 (Charpy V-Notch Impact Testing):** To certify toughness at low temperatures. * **S5 (Maximum Carbon Equivalent):** To ensure weldability. * **S8 (Ultrasonic Examination):** For critical applications requiring verification of internal soundness. * **Global Equivalency:** While a proprietary U.S. standard, its performance characteristics align with international demands for high-strength, high-toughness structural steel. **Chemical Composition (Weight % - ASTM A678 Grade C Requirements & Typical Range)** The chemistry is balanced to achieve the required hardenability for a full martensitic transformation upon quenching in the specified thickness range, while maintaining sufficient alloy leanness for good weldability. | Element | ASTM A678 Grade C Requirement (Max, unless noted) | Typical Bethlehem Steel Production Range | | :--- | :--- | :--- | | **Carbon (C)** | 0.27% | 0.20 - 0.25% | | **Manganese (Mn)** | 1.60% | 1.20 - 1.50% | | **Phosphorus (P)** | 0.035% | ≤ 0.020% | | **Sulfur (S)** | 0.05% | ≤ 0.010% | | **Silicon (Si)** | 0.15 - 0.50% | 0.20 - 0.35% | | **Copper (Cu)** | 0.20% Min (when specified) | 0.20 - 0.40% | | **Nickel (Ni)** | -- | May be added (~0.25-0.50%) for enhanced toughness | | **Chromium (Cr)** | -- | May be added (~0.30-0.50%) for hardenability and strength | | **Molybdenum (Mo)** | -- | May be added (~0.10-0.20%) for hardenability and tempering resistance | | **Vanadium (V)** | 0.10% Max (if added) | May be added (~0.03-0.08%) | | **Carbon Equivalent (C.E. IIW)** | Not specified in standard | Typically 0.48 - 0.56 | **Physical & Mechanical Properties (ASTM A678 Grade C Requirements)** | Property | Requirement for Grade C | Typical Performance / Notes | | :--- | :--- | :--- | | **Yield Strength (Min)** | 70 ksi (485 MPa) | Typically 75 - 85 ksi (517 - 586 MPa) | | **Tensile Strength** | 90 - 110 ksi (620 - 760 MPa) | Typically 95 - 105 ksi (655 - 724 MPa) | | **Elongation in 2" (Min)** | 18% | Typically 20-23% | | **Elongation in 8" (Min)** | 14% | -- | | **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 (Typical)** | As specified per S1. Common specification: 20-25 ft-lb @ -50°F (-46°C). | Excellent for its strength level; the Q&T process enables consistent achievement of high impact values at low temperatures. | | **Key Feature** | **High-Strength Fracture Resistance:** Provides an optimal engineering solution where both high load-bearing capacity (70 ksi yield) and reliable performance under dynamic or impact loading (high toughness) are simultaneously required. | **Product Applications** ASTM A678 Grade C is specified for critical components in structures and machinery operating under high stress and in demanding environments. * **Advanced Structural Engineering:** Fracture-critical members in bridges, seismic-resistant moment frames in buildings, and connections in offshore structures. * **High-Performance Mobile Equipment:** Critical weldments in excavator arms, crane boom chords, and loader linkages where fatigue life and shock resistance are paramount. * **Material Handling & Lifting:** Components for heavy-duty crane hooks, sheave pins, and high-capacity forklift masts. * **Energy Sector:** Penstock sections, turbine components, and structural supports in power generation facilities. * **Transportation:** High-stress components in railcar underframes and specialized heavy-haul truck frames. * **Defense & Security:** Structural elements in military vehicles and equipment requiring high strength-to-weight ratio and ballistic integrity. **Advantages & Fabrication Notes** * **Superior Strength-Toughness Synergy:** The Q&T process is uniquely capable of delivering this combination, making Grade C a preferred choice over alternative 70 ksi plates when toughness is a design constraint. * **Controlled Weldability:** Weldable with careful procedure qualification. **Mandatory practices include:** * Use of low-hydrogen welding processes (SMAW, GMAW, FCAW). * Strict preheat and interpass temperature control (typically 250-350°F / 121-177°C) based on thickness and CE. * Selection of suitable filler metal (often matching or slightly undermatching strength). * **Excellent Fatigue Performance:** The homogeneous, fine-grained microstructure provides enhanced resistance to crack initiation under cyclic loading compared to non-Q&T steels. * **Dimensional Stability:** The heat treatment process results in relatively low residual stresses in the as-delivered plate. * **Formability:** Can be cold formed with caution, requiring significantly larger bend radii than lower-strength steels. Hot forming necessitates subsequent re-quenching and tempering. **Disclaimer:** This datasheet describes the historical product from **Bethlehem Steel Corporation** conforming to **ASTM A678 Grade C**. For current projects, specify **ASTM A678 Grade C** along with required supplementary conditions (e.g., impact test temperature/energy). Source material from modern steel producers who provide current Mill Test Certificates that include heat treatment records, certified mechanical properties, and Charpy impact test reports. Welding and fabrication must be guided by qualified procedures developed in accordance with applicable codes (e.g., AWS D1.1, D1.8) and the steel producer's recommendations. -:- For detailed product information, please contact sales. -: Bethlehem Steel ASTM A678 Grade C 3/16 to 3/4 in. thick, steel plate Specification Dimensions Size： Diameter 20-1000 mm Length <4665 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 ASTM A678 Grade C 3/16 to 3/4 in. thick, steel plate Properties -:- For detailed product information, please contact sales. -:

Applications of Bethlehem Steel ASTM A678 Grade C 3/16 to 3/4 in. thick, steel plate -:- For detailed product information, please contact sales. -: Chemical Identifiers Bethlehem Steel ASTM A678 Grade C 3/16 to 3/4 in. thick, steel plate -:- For detailed product information, please contact sales. -:

Packing of Bethlehem Steel ASTM A678 Grade C 3/16 to 3/4 in. thick, steel 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 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 1136 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