ASTM A738 Carbon Steel Sheet,Plate, Grade C

ASTM A738 Carbon Steel Sheet/Plate, Grade C Product Information -:- For detailed product information, please contact sales. -: ASTM A738 Carbon Steel Sheet/Plate, Grade C Synonyms -:- For detailed product information, please contact sales. -:

ASTM A738 Carbon Steel, Grade C Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: ASTM A738 Grade C Heat-Treated Carbon Steel** **ASTM A738 Grade C** is a premium **heat-treated carbon-manganese-silicon steel plate** designed for **welded pressure vessels requiring maximum strength combined with assured low-temperature toughness**. As the highest strength grade in the A738 specification, it offers a **minimum yield strength of 70 ksi (485 MPa)** while maintaining mandatory Charpy V-notch impact properties. This grade is supplied exclusively in the **quenched and tempered (Q&T) condition**, developing a fine-grained tempered martensitic or bainitic microstructure that provides an exceptional strength-toughness balance for demanding low-temperature service. The controlled chemistry and rigorous heat treatment make it suitable for critical applications where both high pressure and low temperature present concurrent challenges. --- ## **International Standard & Key Specifications** * **Primary Standard:** **ASTM A738/A738M** - Standard Specification for Pressure Vessel Plates, Heat-Treated, Carbon-Manganese-Silicon Steel, for Moderate and Lower Temperature Service. * **Heat Treatment Requirement:** Grade C plates **must be quenched and tempered** - distinguishing it from Grades A and B which may be normalized or normalized and tempered. * **ASME Code Equivalent:** **SA-738/SA-738M** in ASME Boiler and Pressure Vessel Code, Section II, Part A. Required for ASME-stamped pressure equipment. * **Governing Standard:** **ASTM A20/A20M** - Standard Specification for General Requirements for Steel Plates for Pressure Vessels. * **Mandatory Testing:** All plates undergo **tensile testing and Charpy V-notch impact testing** at specified low temperatures as a fundamental requirement. --- ## **Chemical Composition (Weight %, max unless range is specified)** The chemistry is carefully balanced to achieve maximum hardenability for quenching while maintaining adequate weldability and toughness after tempering. | Element | Composition (%) | Role in Performance | | :--- | :--- | :--- | | **Carbon (C)** | 0.30 max | Provides strength and hardenability; controlled at upper limit for quench response. | | **Manganese (Mn)** | 1.15 - 1.70 | Enhances strength and hardenability; critical for achieving full quench effect. | | **Phosphorus (P)** | 0.035 max | Impurity, minimized to prevent embrittlement. | | **Sulfur (S)** | 0.040 max | Impurity, tightly controlled for weldability and ductility. | | **Silicon (Si)** | 0.15 - 0.40 | Deoxidizer and solid solution strengthener. | | **Nickel (Ni)** | **0.40 max (optional)** | Strongly recommended for enhanced low-temperature toughness in Q&T condition. | | **Copper (Cu)** | 0.35 max | Residual element. | | **Vanadium (V)** | 0.05 max | May be present for grain refinement. | | **Carbon Equivalent (CE)** | Typically ≤ 0.52 | Calculated value indicates need for careful welding procedure development. | **Key Distinction:** The higher carbon and manganese limits compared to Grades A and B provide the necessary hardenability for quenching to achieve 70 ksi yield strength, while optional nickel addition significantly improves toughness in this high-strength condition. --- ## **Typical Physical & Mechanical Properties** Properties are guaranteed for quenched and tempered plates after final heat treatment. | Property | Value / Description | | :--- | :--- | | **Tensile Strength** | **620 - 795 MPa (90,000 - 115,000 psi)** | | **Yield Strength (min)** | **485 MPa (70,000 psi)** | | **Elongation in 2-in (50 mm) (min)** | 17% | | **Reduction of Area (min)** | 40% | | **Modulus of Elasticity** | ~200 GPa (29 x 10⁶ psi) | | **Density** | ~7.85 g/cm³ (0.284 lb/in³) | | **Charpy V-Notch Impact Toughness** | **Test Temperature:** **-50°F (-45°C)**. **Minimum Avg. for 3 Specimens:** **20 ft·lbf (27 J)**. **Minimum Single Value:** 15 ft·lbf (20 J). | | **Brinell Hardness (typical)** | 210 - 270 HBW | | **Design Advantage:** Approximately 40% higher allowable stress values compared to Grade A in ASME Code applications. | --- ## **Product Applications** ASTM A738 Grade C is specified for the most demanding pressure vessel applications where maximum strength is required without compromising low-temperature toughness, enabling highly efficient, thin-walled designs for severe service conditions. **Primary Industries and Equipment:** 1. **High-Pressure Gas Processing:** * **High-Pressure Separators** in natural gas and synthesis gas processing. * **Gas Compression System Pressure Vessels**. * **Sour Gas Service Equipment** (with appropriate corrosion allowance). 2. **Petrochemical & Refining:** * **Moderate Temperature Hydroprocessing Reactors**. * **High-Pressure Heat Exchangers** and **Separators**. * **Process Vessels** in methanol and ammonia plants. 3. **Power Generation:** * **High-Pressure Feedwater Heaters** in supercritical power plants. * **Steam Drums** and **Moisture Separators**. * **Hydrogen Cooler Shells** for large turbine generators. 4. **Specialized Industrial Applications:** * **High-Pressure Accumulators** for hydraulic systems. * **Gas Storage Vessels** for industrial and medical gases. * **Process Reactors** in chemical and pharmaceutical industries. 5. **Transportation:** * **High-Pressure Gas Transport Tubes** (for specialized applications). * **Marine and Offshore Pressure Vessels**. --- ## **Advantages and Critical Fabrication Considerations** * **Advantages:** * **Maximum Strength with Guaranteed Toughness:** 70 ksi yield strength with mandatory impact testing provides an exceptional performance envelope. * **Superior Strength-to-Weight Ratio:** Enables significant reductions in wall thickness and vessel weight. * **Fine-Grained Microstructure:** Quenching and tempering produces uniform, refined microstructure with excellent through-thickness properties. * **Cost Efficiency:** Provides high-strength performance at lower cost than low-alloy steels in many applications. * **Critical Fabrication & Welding Considerations:** * **Welding Challenges:** High carbon equivalent requires **extremely careful welding procedure development**. **Ultra-low hydrogen processes are mandatory.** * **Stringent Preheat Requirements:** Essential to prevent hydrogen-induced cracking. Typical range: 250-350°F (120-175°C) depending on thickness. * **Post-Weld Heat Treatment (PWHT):** Required for all pressure vessel welds. **Critical** - PWHT temperature must be below the original tempering temperature to avoid overtempering and strength loss. * **Welding Consumable Selection:** Filler metals should match base metal strength; often requires high-toughness, low-hydrogen electrodes (E10018, E11018 types). * **Comprehensive WPS Qualification:** Welding procedures must be qualified with mechanical testing including impact tests on weld metal and HAZ. * **Thermal Cutting:** Requires preheat; plasma or laser cutting is preferred over flame cutting for critical edges. * **Thickness Limitations:** Maximum thickness is limited by quench effectiveness; typically 4 inches (100 mm) maximum for guaranteed properties. * **Nickel Addition Importance:** For applications below -20°F (-29°C), nickel addition is strongly recommended to maintain adequate toughness. **In summary, ASTM A738 Grade C represents the pinnacle of heat-treated carbon steel for pressure vessel applications, offering 70 ksi minimum yield strength with guaranteed impact toughness at -50°F. Its quenched and tempered condition provides the optimal microstructure for demanding high-pressure, low-temperature service, enabling highly efficient vessel designs. While offering significant performance advantages, successful application requires sophisticated welding expertise, precise thermal control during fabrication, and rigorous quality assurance to fully realize its potential in critical pressure containment systems.** -:- For detailed product information, please contact sales. -: ASTM A738 Carbon Steel, Grade C Specification Dimensions Size： Diameter 20-1000 mm Length <4536 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. -: ASTM A738 Carbon Steel, Grade C Properties -:- For detailed product information, please contact sales. -:

Applications of ASTM A738 Carbon Steel Sheet,Plate, Grade C -:- For detailed product information, please contact sales. -: Chemical Identifiers ASTM A738 Carbon Steel Sheet,Plate, Grade C -:- For detailed product information, please contact sales. -:

Packing of ASTM A738 Carbon Steel Sheet/Plate, Grade C -:- 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 Sheet/Plate 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 1007 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