ASTM A734 Low Alloy Steel Foil/Strip, Grade B

ASTM A734 Low Alloy Steel Foil, Grade B Product Information -:- For detailed product information, please contact sales. -: ASTM A734 Low Alloy Steel Foil, Grade B Synonyms -:- For detailed product information, please contact sales. -:

ASTM A734 Low Alloy Steel, Grade B Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: ASTM A734 Grade B Low-Alloy Steel for Elevated Strength and Low-Temperature Service** **ASTM A734 Grade B** is a high-performance, **quenched and tempered low-alloy steel** designed for **welded pressure vessels and critical structural components requiring superior strength combined with excellent low-temperature toughness**. It represents a higher strength grade within the A734 specification, offering enhanced mechanical properties for demanding applications in cryogenic, petrochemical, and power generation industries. The steel achieves its optimal characteristics through precise **quenching and tempering (Q&T) heat treatment**, resulting in a fine-grained microstructure that provides exceptional strength-toughness balance at temperatures as low as **-60°F (-51°C)**. --- ## **International Standard & Key Specifications** * **Primary Standard:** **ASTM A734 / A734M** - Standard Specification for Pressure Vessel Plates, Alloy Steel and High-Strength Low-Alloy Steel, Quenched-and-Tempered, for Pressure Vessels. * **Key Distinction:** Unlike specifications with fixed chemistries, A734 emphasizes **achievement of specified mechanical properties** through heat treatment, allowing manufacturers flexibility in composition optimization. * **ASME Code Equivalent:** **SA-734 / SA-734M** in ASME Boiler and Pressure Vessel Code, Section II, Part A, mandatory for ASME-stamped pressure equipment fabrication. * **Governing Standard:** **ASTM A20/A20M** - Provides general requirements for testing, inspection, tolerances, and certification of pressure vessel plates. --- ## **Chemical Composition (Weight %, typical ranges/maximums)** The exact composition is proprietary to the steel manufacturer and is engineered to meet the mechanical property guarantees. Grade B typically features a modified alloy content compared to Grade A to achieve higher strength levels. The following represents a typical composition profile: | Element | Typical Composition (%) | Role in Performance | | :--- | :--- | :--- | | **Carbon (C)** | 0.18 - 0.23 | Primary contributor to strength and hardenability; carefully balanced for weldability. | | **Manganese (Mn)** | 0.80 - 1.20 | Enhances strength and hardenability while maintaining good toughness. | | **Phosphorus (P)** | 0.025 max | Impurity, kept at minimum levels to preserve notch toughness. | | **Sulfur (S)** | 0.025 max | Impurity, minimized to ensure optimal weldability and through-thickness properties. | | **Silicon (Si)** | 0.15 - 0.50 | Deoxidizer and solid solution strengthener. | | **Nickel (Ni)** | **2.75 - 3.25** | **Critical alloying element** that significantly enhances low-temperature toughness and strength. | | **Chromium (Cr)** | 1.00 - 1.50 | Increases hardenability, strength, and provides some corrosion resistance. | | **Molybdenum (Mo)** | 0.40 - 0.60 | Enhances hardenability, strength, and creep resistance at moderate temperatures. | | **Vanadium (V)** | 0.03 - 0.08 | Optional microalloy addition for grain refinement and precipitation strengthening. | **Note:** The specific Ni-Cr-Mo balance is optimized by steelmakers to achieve the required 75 ksi yield strength while maintaining exceptional impact properties at low temperatures. --- ## **Typical Physical & Mechanical Properties** All properties are guaranteed for quenched and tempered plates. Values may vary slightly based on manufacturing process and plate thickness. | Property | Value / Description | | :--- | :--- | | **Tensile Strength** | 620 - 795 MPa (90,000 - 115,000 psi) | | **Yield Strength (min)** | **515 MPa (75,000 psi)** | | **Elongation in 2-in (50 mm) (min)** | 17% | | **Reduction of Area (min)** | 45% | | **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:** **-60°F (-51°C)**. **Minimum Avg. for 3 Specimens:** **25 ft·lbf (34 J)**. This stringent requirement ensures fracture safety in cryogenic service. | | **Brinell Hardness (typical)** | 210 - 250 HBW | | **Maximum Allowable Stress Values (ASME Sec. VIII Div. 1)** | Significantly higher than carbon steels, enabling more efficient (thinner) designs for given pressure ratings. | --- ## **Product Applications** ASTM A734 Grade B is specified for critical applications where both high strength and reliable low-temperature performance are non-negotiable requirements. **Primary Industries and Equipment:** 1. **Cryogenic & LNG Infrastructure:** * **Primary Containment Vessels** in LNG storage tanks and transport ships (membrane and spherical tank designs). * **Cold Boxes** and pressure vessels in natural gas liquefaction plants. * **High-Pressure Cryogenic Pumps and Separators.** 2. **Petrochemical Processing:** * **Reactor Vessels** for low-temperature chemical synthesis processes. * **High-Pressure Heat Exchangers** in ethylene and propylene production facilities. * **Hydrogenation Reactors** operating at low to moderate temperatures. 3. **Power Generation:** * **Hydrogen Cooler Shells** and associated high-pressure vessels in turbine-generator systems. * **Feedwater Heaters** for advanced high-pressure boiler systems. 4. **Industrial Gases:** * **Bulk Storage Tanks** for liquid oxygen, nitrogen, and argon requiring high design pressures. * **Inner Vessels** of vacuum-insulated cryogenic containers. 5. **Specialized Engineering:** * Components for arctic and offshore structures subjected to low ambient temperatures. * Pressure vessels for aerospace and defense applications requiring weight savings. --- ## **Advantages and Critical Fabrication Considerations** * **Advantages:** * **Exceptional Strength-Toughness Combination:** 75 ksi minimum yield strength with guaranteed toughness at -60°F provides an outstanding performance envelope. * **Weight Reduction Potential:** Higher strength allows for thinner wall sections, reducing material weight and transportation costs for large vessels. * **Superior Low-Temperature Performance:** The Ni-Cr-Mo alloy system ensures reliable operation in cryogenic environments where carbon steels would be unsuitable. * **Critical Fabrication & Welding Considerations:** * **Stringent Welding Controls:** **Mandatory use of ultra-low hydrogen welding processes and consumables.** Welding Procedure Specifications (WPS) must be rigorously qualified, often requiring impact testing of weld metal and heat-affected zone (HAZ). * **Preheat and Interpass Temperature Management:** Essential to prevent hydrogen-induced cracking (HIC). Typical preheat ranges from **250°F to 400°F (120°C to 205°C)** depending on thickness. * **Mandatory Post-Weld Heat Treatment (PWHT):** Required for virtually all pressure vessel applications to relieve fabrication stresses and temper the HAZ. The PWHT temperature must be carefully controlled to avoid overtempering the base metal. * **Thermal Cutting Requirements:** Preheating is necessary for flame cutting. Machining or abrasive cutting is often preferred for critical edges. * **Non-Destructive Testing (NDT):** Extensive ultrasonic testing (UT) of base plates and radiography (RT) of welds are standard requirements. **In summary, ASTM A734 Grade B is a premium, heat-treated low-alloy steel that delivers an optimal balance of high strength (75 ksi min yield) and exceptional low-temperature toughness. Its use enables the design of lighter, more efficient pressure vessels for the most demanding cryogenic and high-pressure applications in the energy and chemical processing sectors, though it demands sophisticated fabrication expertise and strict quality control throughout the manufacturing process.** -:- For detailed product information, please contact sales. -: ASTM A734 Low Alloy Steel, Grade B Specification Dimensions Size： Diameter 20-1000 mm Length <4522 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 A734 Low Alloy Steel, Grade B Properties -:- For detailed product information, please contact sales. -:

Applications of ASTM A734 Low Alloy Steel Foil, Grade B -:- For detailed product information, please contact sales. -: Chemical Identifiers ASTM A734 Low Alloy Steel Foil, Grade B -:- For detailed product information, please contact sales. -:

Packing of ASTM A734 Low Alloy Steel Foil/Strip, Grade B -:- 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 Foil/Strip 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 993 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