ASTM A736 Low Alloy Steel Sheet,Plate, Grade C, Class 3

ASTM A736 Low Alloy Steel Sheet/Plate, Grade C, Class 3 Product Information -:- For detailed product information, please contact sales. -: ASTM A736 Low Alloy Steel Sheet/Plate, Grade C, Class 3 Synonyms -:- For detailed product information, please contact sales. -:

ASTM A736 Low Alloy Steel, Grade C, Class 3 Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: ASTM A736/A736M Grade C, Class 3 Precipitation-Strengthened Alloy Steel** **ASTM A736/A736M Grade C, Class 3** represents the premium tier within the Grade C classification of this specification, designed for **welded pressure vessels requiring the highest combination of strength and toughness in low-temperature service**. This advanced material leverages a **low-carbon, age-hardening nickel-copper-chromium-molybdenum-columbium alloy system** to achieve exceptional mechanical properties through sophisticated **heat treatment processes**, typically involving quenching and tempering with precise precipitation control. Class 3 denotes **enhanced toughness requirements at lower temperatures** compared to Class 1 or 2, making it suitable for critical applications where fracture resistance under severe conditions is paramount. --- ## **International Standard & Key Specifications** * **Primary Standard:** **ASTM A736/A736M** - Standard Specification for Pressure Vessel Plates, Low-Carbon Age-Hardening Nickel-Copper-Chromium-Molybdenum-Columbium Alloy Steel. * **Grade & Class Distinction:** **Grade C** specifies higher minimum tensile and yield strength requirements than Grade A. **Class 3** designates enhanced impact toughness at lower test temperatures within Grade C. * **ASME Code Equivalent:** **SA-736/SA-736M** in ASME Boiler and Pressure Vessel Code, Section II, Part A. Mandatory for ASME-stamped pressure equipment. * **Governing Standard:** **ASTM A20/A20M** - Standard Specification for General Requirements for Steel Plates for Pressure Vessels. * **Key Design Philosophy:** Achieves ultra-high strength through precipitation hardening while maintaining excellent weldability and fracture toughness, enabling efficient, high-performance pressure vessel designs. --- ## **Chemical Composition (Weight %, max unless range is specified)** The chemical composition follows the same ranges as other Grade C materials but is produced with tighter controls and optimized processing to achieve Class 3 performance levels. The ultra-low carbon content is fundamental to its weldability and toughness. | Element | Composition Range (%) | Role in Performance for Class 3 | | :--- | :--- | :--- | | **Carbon (C)** | 0.07 max | **Ultra-low** – Ensures exceptional weldability and base toughness; essential for the precipitation-hardening mechanism without compromising ductility. | | **Manganese (Mn)** | 0.40 - 0.70 | Solid solution strengthener; optimized to balance strength and hardenability. | | **Phosphorus (P)** | 0.025 max | Impurity – Kept at absolute minimum to prevent temper embrittlement. | | **Sulfur (S)** | 0.025 max | Impurity – Tightly controlled for optimal weldability and ductility. | | **Silicon (Si)** | 0.15 - 0.50 | Deoxidizer; controlled to avoid excessive HAZ hardness. | | **Nickel (Ni)** | 0.70 - 1.00 | Enhances toughness and hardenability; critical for microstructural stability at low temperatures. | | **Chromium (Cr)** | 0.40 - 0.65 | Improves hardenability and provides moderate oxidation resistance. | | **Molybdenum (Mo)** | 0.20 - 0.30 | **Critical element** – Provides solid solution strengthening, improves elevated temperature strength, and significantly reduces susceptibility to temper embrittlement. | | **Copper (Cu)** | 1.00 - 1.30 | **Primary precipitation-hardening element** – Forms fine, coherent Cu-rich precipitates during aging/tempering, providing major strength contribution. | | **Columbium (Cb/Nb)** | 0.02 - 0.10 | **Key microalloy** – Provides grain refinement through Nb(CN) precipitates and contributes to precipitation strengthening; controls austenite grain growth. | | **Vanadium (V)** | 0.03 - 0.08 | Secondary precipitation strengthener; complements Nb's effect. | | **Aluminum (Al)** | 0.06 max | Grain refining deoxidizer. | --- ## **Typical Physical & Mechanical Properties (Grade C, Class 3)** Properties are achieved through optimized quenching and tempering heat treatments designed to maximize both strength and toughness. Note: Specific property values for Class 3 should be verified with the material producer, as they may be subject to supplementary requirements. | Property | Value / Description | | :--- | :--- | | **Tensile Strength** | **725 - 895 MPa (105,000 - 130,000 psi)** | | **Yield Strength (min)** | **620 MPa (90,000 psi)** | | **Elongation in 2-in (50 mm) (min)** | 18% | | **Reduction of Area (min)** | 50% | | **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:** **Typically -60°F (-50°C) or lower** (subject to Supplementary Requirement S9 or purchaser specification). **Minimum Avg. for 3 Specimens:** **35-45 ft·lbf (47-61 J) range or higher**. | | **Brinell Hardness (typical)** | 240 - 300 HBW | | **Elevated Temperature Strength** | Maintains a higher percentage of room temperature strength at moderate temperatures (up to ~650°F / 345°C) compared to conventional steels. | --- ## **Product Applications** ASTM A736 Grade C, Class 3 is specified for the most demanding applications where ultra-high strength must be combined with reliable low-temperature fracture toughness. **Primary Industries and Equipment:** 1. **Advanced Power Generation:** * **High-Pressure Components in Supercritical/Ultra-Supercritical Power Plants** (e.g., feedwater heaters, steam drums). * **Hydrogen Coolers and Associated High-Pressure Vessels** in turbine systems. * **Nuclear Plant Components** requiring high strength and toughness (where code-approved). 2. **Petrochemical & High-Pressure Processing:** * **Thick-Walled Reactors** for high-pressure hydrogen service (hydroprocessing). * **High-Pressure Heat Exchangers and Separators** in refining and chemical synthesis. * **Process Vessels** in ethylene, methanol, and ammonia plants. 3. **Energy Transition & Gas Infrastructure:** * **High-Pressure Hydrogen Storage Vessels** (for stationary storage or transportation). * **Components in Carbon Capture and Storage (CCS) Systems**. * **High-Pressure Natural Gas Equipment**. 4. **Specialized High-Performance Applications:** * **Aerospace and Defense Pressure Vessels**. * **High-Pressure Accumulators** for heavy industrial machinery. * **Components for Offshore and Subsea Applications**. --- ## **Advantages and Critical Fabrication Considerations** * **Advantages:** * **Exceptional Strength-Toughness Combination:** 90 ksi minimum yield strength coupled with enhanced impact toughness at low temperatures. * **Excellent Resistance to Temper Embrittlement:** Optimized alloying (particularly Mo) ensures toughness stability over long-term service. * **Superior Weldability for its Strength Class:** The ultra-low carbon content (<0.07%) results in a very low carbon equivalent, minimizing susceptibility to hydrogen-induced cracking. * **High Strength-to-Weight Ratio:** Enables significant weight and material savings in pressure vessel design. * **Critical Fabrication & Welding Considerations:** * **Precise Heat Treatment Control:** Final mechanical properties are highly dependent on exact tempering/aging parameters. Unauthorized thermal exposure can degrade properties. * **Stringent Welding Procedures:** **Mandatory use of ultra-low hydrogen welding processes** with strict control over heat input. Welding consumables must be carefully selected to match both strength and toughness. * **Comprehensive WPS Qualification:** Welding Procedure Specifications require extensive qualification testing, including impact tests on weld metal and HAZ at the design temperature. * **Strict Preheat/Interpass Temperature Control:** Typically **250°F - 400°F (120°C - 205°C)**, depending on thickness, with continuous monitoring. * **Post-Weld Heat Treatment (PWHT):** Essential but must be carefully controlled to avoid over-aging. PWHT parameters should be developed in consultation with material specialists. * **Advanced Non-Destructive Testing:** Typically requires 100% volumetric examination (UT) of welds plus surface examination (MT/PT). Radiographic testing (RT) may also be specified. **In summary, ASTM A736 Grade C, Class 3 is a premium, precipitation-hardened low-alloy steel that delivers an outstanding combination of ultra-high strength (90 ksi min yield) and enhanced low-temperature toughness. It is engineered for the most critical pressure vessel applications where performance, reliability, and weight efficiency are paramount. Its successful application demands sophisticated metallurgical understanding, precise fabrication control, and adherence to stringent quality assurance protocols throughout the manufacturing process.** -:- For detailed product information, please contact sales. -: ASTM A736 Low Alloy Steel, Grade C, Class 3 Specification Dimensions Size： Diameter 20-1000 mm Length <4531 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 A736 Low Alloy Steel, Grade C, Class 3 Properties -:- For detailed product information, please contact sales. -:

Applications of ASTM A736 Low Alloy Steel Sheet,Plate, Grade C, Class 3 -:- For detailed product information, please contact sales. -: Chemical Identifiers ASTM A736 Low Alloy Steel Sheet,Plate, Grade C, Class 3 -:- For detailed product information, please contact sales. -:

Packing of ASTM A736 Low Alloy Steel Sheet/Plate, Grade C, Class 3 -:- 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 1002 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