ASTM A266 is a specification covering forged carbon and alloy steel components used for pressure vessels, valves, flanges, and fittings in both high-temperature and high-pressure service conditions.
This steel grade is widely recognized for its strength, toughness, and structural integrity after heat treatment, ensuring safe and consistent performance in demanding industrial environments such as petrochemical plants, refineries, power stations, and pressure piping systems.
ASTM A266 defines four primary material classes—Grade 1, Grade 2, Grade 3, and Grade 4—each designed for specific strength and composition requirements. These grades differ in alloy content and mechanical performance to suit varied pressure service conditions.
Chemical Composition (Typical Ranges, %)
| Element | Carbon | Manganese | Phosphorus | Sulfur | Silicon | Chromium | Molybdenum | Nickel |
|---|---|---|---|---|---|---|---|---|
| Range | 0.25–0.50 | 0.60–1.00 | ≤ 0.035 | ≤ 0.040 | 0.15–0.35 | ≤ 1.00 | ≤ 0.30 | ≤ 0.50 |
Microalloying elements may be adjusted depending on grade and service condition to enhance toughness, strength, and creep resistance.
Mechanical Properties
| Property | Grade 2 (Typical) |
|---|---|
| Tensile Strength (MPa) | 485–655 |
| Yield Strength (MPa) | ≥ 250 |
| Elongation (%) | ≥ 22 |
| Reduction of Area (%) | ≥ 35 |
Heat treatment options include normalizing, quenching, and tempering, based on the specific grade and the end-use requirement. This ensures fine-grained microstructure, high fatigue strength, and stable performance at both ambient and elevated temperatures.
Key Features and Advantages
Excellent mechanical strength under high stress and pressure
Superior ductility and impact resistance
Good weldability and machinability in the normalized condition
Proven structural reliability in cyclic pressure applications
Fully compliant with ASME Boiler and Pressure Vessel Code (BPVC)
Common Applications
ASTM A266 steels are primarily used for forged components in pressure-retaining equipment. Typical applications include:
Pressure vessel flanges, valve bodies, and fittings
Forged shafts and couplings for turbine and power equipment
Bolting materials for pressure piping systems
High-pressure covers, rings, and discs in petrochemical and energy plants
These components often operate under severe temperature and stress variations, making ASTM A266 an industry-standard material for critical service environments.
Grades Overview
Grade 1: Carbon steel, normalized — good strength and weldability.
Grade 2: Carbon-manganese steel, improved toughness for general pressure service.
Grade 3: Molybdenum-alloy steel for elevated temperature resistance.
Grade 4: Chromium-molybdenum alloy steel — enhanced creep and fatigue resistance.
Each grade can be supplied in forged, machined, or heat-treated conditions according to the customer’s specification.
Reliable Supply from ChinaSpecSteel
ChinaSpecSteel provides ASTM A266 forged carbon and alloy steels produced by Jiyuan Iron & Steel Group, a well-established Chinese manufacturer specializing in special bar quality (SBQ) steels.
Jiyuan operates a long-process integrated production system—from ironmaking to steelmaking, rolling, and heat treatment—ensuring material uniformity, consistency, and full traceability.
Available Supply Forms:
Forged bars, billets, rings, and discs
Machined or rough-turned forgings
Normalized, quenched, or tempered conditions
Custom dimensions for OEM manufacturing
Supplied with mill test certificates (EN 10204/3.1) and third-party inspection (SGS, BV, TÜV) on request
Manufacturing Excellence — Jiyuan Iron & Steel
Jiyuan Iron & Steel is recognized as one of China’s major producers of high-quality special steels, equipped with advanced refining, forging, and rolling facilities.
The plant’s metallurgical control, ultrasonic testing, and mechanical inspection systems ensure that every product meets international standards for performance and reliability.
Its production covers a wide range of premium steels, including bearing steel, spring steel, gear steel, cold heading steel, alloy structural steel, carbon structural steel, and wear-resistant grades.
Deep-processed steel materials include precision wire, heat-treated bar, bright bar, and fasteners, supporting various industries such as power generation, petrochemical equipment, and heavy machinery.
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