ASTM A350 LF9
ASTM A350 LF9 Flanges / Forged Components
ASTM A350 LF9 is a low-temperature carbon steel alloy containing nickel, chromium, and molybdenum, designed to deliver superior strength, toughness, and impact resistance at sub-zero temperatures. This alloy provides an excellent balance of mechanical performance, weldability, and corrosion resistance, making it ideal for cryogenic and low-temperature pressure systems.
At Emirerri Steel, we manufacture and export high-quality ASTM A350 LF9 flanges, forged fittings, and bars, conforming to ASTM, ASME, and international standards. These products are widely used in LNG facilities, oil & gas pipelines, refineries, and power plants, where both strength and ductility under low temperatures are critical.
Key Features
Excellent toughness and strength at low temperatures
Enhanced corrosion and oxidation resistance due to Cr-Mo-Ni composition
Good weldability and machinability
Suitable for cryogenic and sub-zero service
Available in multiple Classes (Class 1 & 2)
Complies with ASTM A350 / ASME SA350 standards
Consistent microstructure ensuring high impact performance
Specification
| Standard | Details |
|---|---|
| Specification | ASTM A350 / ASME SA350 |
| Grade | LF9 |
| Product Forms | Flanges, Forged Fittings, Bars, Rings, Shafts, Valves |
| Manufacturing Type | Forged / Rolled / Heat Treated |
| Heat Treatment | Normalized, Quenched, and Tempered |
| Testing | Charpy V-Notch Impact, Hardness, Tensile Tests |
| Applicable Standards | ASME B16.5, B16.47, MSS SP-44, API 6A, DIN, EN, JIS |
Equivalent Grades
| Standard | Equivalent Grade |
|---|---|
| ASTM | A350 LF9 |
| ASME | SA350 LF9 |
| UNS | K90941 |
| EN | 1.7362 |
| BS | 1503-622-510 |
| DIN | 13CrMo44 |
Available Sizes
| Form | Size Range |
|---|---|
| Flanges | ½” to 48” (DN15 to DN1200) |
| Forged Fittings | ⅛” to 4” (SW / NPT / BSP) |
| Round Bars | 10 mm to 600 mm Diameter |
| Custom Forgings | As per drawing or project specification |
Chemical Composition
| Element | % (Max/Min) |
|---|---|
| Carbon (C) | 0.15 – 0.25 |
| Manganese (Mn) | 0.30 – 0.60 |
| Silicon (Si) | 0.15 – 0.35 |
| Nickel (Ni) | 8.00 – 10.00 |
| Chromium (Cr) | 8.00 – 10.00 |
| Molybdenum (Mo) | 0.90 – 1.10 |
| Phosphorus (P) | 0.035 max |
| Sulfur (S) | 0.040 max |
Mechanical Properties
| Property | Unit | Value |
|---|---|---|
| Tensile Strength | MPa | 585 min |
| Yield Strength | MPa | 275 min |
| Elongation | % | 20 min |
| Impact Energy (Charpy V-Notch @ -46°C) | Joule | 27 min |
| Hardness | HB | 197 max |
Physical Properties
| Property | Value |
|---|---|
| Density | 7.85 g/cm³ |
| Melting Point | 1370 – 1400°C |
| Modulus of Elasticity | 205 GPa |
| Thermal Conductivity | 25 W/m·K |
| Specific Heat | 460 J/kg·K |
Type of ASTM A350 LF9 Flanges
Corrosion Resistance
The Cr-Ni-Mo alloy composition provides superior resistance to oxidation, scaling, and moderate corrosion in atmospheric and chemical environments. ASTM A350 LF9 is ideal for use in wet gas, steam, and mildly acidic media. For enhanced corrosion resistance, additional surface coatings or overlays can be applied.
Heat Resistance
Maintains mechanical integrity up to 500°C (932°F)
Good resistance to thermal fatigue and scaling
Not recommended for continuous use above 550°C
Designed primarily for low to medium temperature applications
Heat Treatment
Normalizing: 900°C – 950°C, air cooled
Quenching & Tempering: To refine microstructure and enhance mechanical properties
Stress Relieving: Post-weld to improve ductility and toughness
Welding
ASTM A350 LF9 provides excellent weldability using conventional methods such as GTAW (TIG), SMAW (Stick), and GMAW (MIG).
Preheating at 200–300°C recommended before welding
Post-weld heat treatment enhances joint performance
Use of low hydrogen electrodes is essential to avoid cracking
Fabrication
Highly forgeable and machinable
Hot working temperature range: 900°C – 1200°C
Can be drilled, cut, and turned with standard machining practices
Offers excellent dimensional stability during fabrication
Applications
Low-Temperature Pressure Vessels
Cryogenic and Sub-Zero Piping Systems
Valves, Flanges, and Fittings in LNG Terminals
Oil & Gas Refining Equipment
Heat Exchangers and Reactors
Power Generation & Steam Systems
Petrochemical Process Units