ASTM A734 Low Alloy Steel Wire, Grade A

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

ASTM A734 Low Alloy Steel, Grade A Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: ASTM A734 Grade A Low-Alloy Steel for Low-Temperature Pressure Vessels** **ASTM A734 Grade A** is a high-strength, **heat-treated low-alloy steel** specifically designed for **welded pressure vessels and other critical applications operating at low temperatures down to -60°F (-51°C)**. It offers an excellent combination of strength, toughness, and weldability for demanding cryogenic and low-temperature service environments. The steel is typically supplied in the **quenched and tempered (Q&T) or normalized and tempered (N&T) condition**, with Q&T being the most common for optimal through-thickness properties. As a low-alloy steel, it provides superior mechanical properties compared to carbon steels while maintaining good fabricability, making it a preferred choice for liquefied gas storage, transportation, and processing equipment. --- ## **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 Feature:** This specification covers **heat-treated alloy and HSLA steels** where mechanical properties are a primary requirement. Chemistry can be adjusted by the manufacturer to achieve the specified properties. * **ASME Code Equivalent:** **SA-734 / SA-734M** in ASME Boiler and Pressure Vessel Code, Section II, Part A, for construction of ASME-stamped pressure equipment. * **Governing Standard:** ASTM A20/A20M provides the general requirements for delivery and testing of pressure vessel plates. --- ## **Chemical Composition (Weight %, typical ranges/maximums)** The composition for Grade A is reported by the manufacturer but is not rigidly specified; the focus is on achieving the required mechanical properties. The following represents a typical composition range for a 3.5% Ni low-alloy steel that would meet Grade A requirements. | Element | Typical Composition (%) | Role in Performance | | :--- | :--- | :--- | | **Carbon (C)** | 0.15 - 0.21 | Provides strength and hardenability. | | **Manganese (Mn)** | 0.70 - 1.00 | Enhances strength and hardenability. | | **Phosphorus (P)** | 0.025 max | Impurity, kept low for toughness. | | **Sulfur (S)** | 0.025 max | Impurity, kept low for weldability. | | **Silicon (Si)** | 0.15 - 0.40 | Deoxidizer and strengthener. | | **Nickel (Ni)** | **3.25 - 3.75** | **Critical element.** Dramatically improves low-temperature toughness and strength. | | **Chromium (Cr)** | 0.50 - 0.80 | Increases hardenability and strength. | | **Molybdenum (Mo)** | 0.20 - 0.30 | Enhances hardenability and strength, particularly at elevated temperatures. | | **Vanadium (V)** | ≤ 0.05 | Optional microalloy for grain refinement. | **Note:** The exact chemistry is proprietary to the steel producer and is optimized to meet the mechanical property guarantees, especially the impact toughness at -60°F. --- ## **Typical Physical & Mechanical Properties** Properties are for quenched and tempered plates. The exact values depend on the heat treatment and thickness. | Property | Value / Description | | :--- | :--- | | **Tensile Strength** | 585 - 760 MPa (85,000 - 110,000 psi) | | **Yield Strength (min)** | **450 MPa (65,000 psi)** | | **Elongation in 2-in (50 mm) (min)** | 18% | | **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:** **-60°F (-51°C)**. **Minimum Avg. for 3 Specimens:** **25 ft·lbf (34 J)**. This is a key performance criterion. | | **Brinell Hardness (typical)** | 200 - 240 HBW | --- ## **Product Applications** ASTM A734 Grade A is engineered for applications where high strength must be maintained in extremely cold environments. Its primary use is in the containment and processing of liquefied gases. **Primary Industries and Equipment:** 1. **Cryogenic Storage & Transportation:** * **Storage Tanks** for liquefied natural gas (LNG), liquefied ethylene (LEG), and liquid ammonia. * **Transportation Vessels:** ISO tanks, ship cargo tanks, and rail tank cars for cryogenic liquids. * **Vacuum-Jacketed Process Vessels** and inner shells. 2. **Petrochemical & Gas Processing:** * **Cold Boxes** and heat exchangers in air separation units (ASU) and natural gas liquefaction (LNG) trains. * **Separators, Knock-Out Drums, and Scrubbers** operating at low temperatures in gas processing plants. * **Pressure Vessels** for olefin production (ethylene, propylene). 3. **Industrial Gases:** * **Bulk Storage Tanks** for liquid oxygen, nitrogen, and argon. * **Process Vessels** within gas production and purification facilities. 4. **Specialized Applications:** * Components for polar and arctic offshore structures. * High-strength components for military and aerospace cryogenic systems. --- ## **Advantages and Fabrication Considerations** * **Advantages:** * **Exceptional Low-Temperature Toughness:** The nickel content guarantees excellent fracture resistance down to -60°F (-51°C), preventing brittle fracture. * **High Strength:** 65 ksi minimum yield strength provides a robust design margin for high-pressure low-temperature service. * **Good Weldability (with proper procedure):** Despite its alloy content, it can be successfully welded using low-hydrogen processes with appropriate preheat and post-weld heat treatment (PWHT). * **Critical Fabrication & Welding Considerations:** * **Strict Welding Protocols:** **Mandatory use of low-hydrogen electrodes and processes (e.g., SMAW with EXX15/18, SAW, GTAW).** Welding Procedure Specifications (WPS) must be qualified for the Q/T base metal. * **Preheat and Interpass Control:** Essential to prevent hydrogen-induced cracking (HIC) and to control cooling rates in the heat-affected zone (HAZ). Typical preheat is 200-300°F (95-150°C). * **Post-Weld Heat Treatment (PWHT):** Almost always required for pressure vessel fabrication to relieve residual stresses and temper the HAZ. The PWHT temperature must be below the original tempering temperature of the base plate. * **Thermal Cutting:** Oxy-fuel cutting requires preheat. Plasma or laser cutting is preferred for cleaner edges. **In summary, ASTM A734 Grade A is a premium, nickel-alloyed quenched and tempered steel that delivers an outstanding balance of high strength (65 ksi min yield) and guaranteed toughness at extremely low temperatures. It is an essential material for the safe and reliable design of pressure vessels and structures operating in the critical cryogenic and low-temperature regimes of the energy, industrial gas, and chemical processing industries.** -:- For detailed product information, please contact sales. -: ASTM A734 Low Alloy Steel, Grade A Specification Dimensions Size： Diameter 20-1000 mm Length <4521 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 A Properties -:- For detailed product information, please contact sales. -:

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

Packing of ASTM A734 Low Alloy Steel Wire, Grade A -:- 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 Wire 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 992 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