ASTM A350 LF6
ASTM A350 LF6 Flanges / Forged Components
ASTM A350 Grade LF6 is a low-temperature carbon steel forging material containing nickel and chromium to enhance strength, ductility, and notch toughness under sub-zero conditions. It is primarily used in the manufacturing of flanges, forged fittings, valves, and piping components that operate at low temperatures down to –46°C.
This grade is suitable for pressure systems, oil & gas pipelines, LNG facilities, and cryogenic equipment, where reliable toughness and impact resistance are essential.
At Emirerri Steel, we manufacture and export ASTM A350 LF6 Class 1 and Class 2 forgings conforming to ASTM, ASME, and international standards, ensuring performance and durability in the most demanding environments.
Key Features
Excellent low-temperature impact toughness
Good strength and ductility
Reliable weldability and machinability
Suitable for cryogenic and sub-zero applications
Available in Class 1 and Class 2 (varied mechanical requirements)
Manufactured to ASTM A350 / ASME SA350 standards
Ideal for pressure and pipeline applications
ASTM A350 LF6 Specification
| Standard | Description |
|---|---|
| Specification | ASTM A350 / ASME SA350 |
| Grade | LF6 |
| Class | Class 1 & Class 2 |
| Product Forms | Flanges, Forged Fittings, Bars, Rings, Shafts, Valves |
| Manufacturing Process | Forged / Rolled / Heat Treated |
| Heat Treatment | Normalized, Quenched, and Tempered |
| Testing | Charpy V-Notch Impact Test, Tensile Test, Hardness Test |
| Applicable Standards | ASME B16.5, B16.47, MSS SP-44, API 6A, DIN, EN, JIS |
ASTM A350 LF6 Equivalent Material
| Standard | Equivalent Grade |
|---|---|
| ASTM | A350 LF6 |
| ASME | SA350 LF6 |
| UNS | K03011 |
| EN | 1.0566 |
| BS | 1503-660-490 |
| DIN | Ck15NiCrMo6 |
Available Sizes
| Product 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) | 0.30 max |
| Manganese (Mn) | 0.40 – 1.35 |
| Silicon (Si) | 0.15 – 0.30 |
| Nickel (Ni) | 3.25 – 3.75 |
| Chromium (Cr) | 0.40 – 0.80 |
| Molybdenum (Mo) | 0.15 – 0.25 |
| Phosphorus (P) | 0.035 max |
| Sulfur (S) | 0.040 max |
Mechanical Properties
| Property | Class 1 | Class 2 |
|---|---|---|
| Tensile Strength (MPa) | 485 min | 550 min |
| Yield Strength (MPa) | 250 min | 345 min |
| Elongation (%) | 22 min | 20 min |
| Impact Energy (J @ -46°C) | 27 min | 27 min |
| Hardness (HB) | 197 max | 197 max |
Physical Properties
| Property | Value |
|---|---|
| Density | 7.85 g/cm³ |
| Melting Point | 1425 – 1540°C |
| Modulus of Elasticity | 205 GPa |
| Thermal Conductivity | 45 W/m·K |
| Specific Heat | 480 J/kg·K |
Type of ASTM A350 LF6 Flanges
Corrosion Resistance
ASTM A350 LF6 provides moderate corrosion resistance against atmospheric and mild industrial environments. For harsh chemical or marine exposure, components may be coated, galvanized, or cladded with corrosion-resistant materials such as stainless steel or nickel alloys.
Heat Resistance
Performs effectively up to 400°C (752°F)
Designed primarily for low-temperature service, not for prolonged high-temperature exposure
Excellent thermal stability and structural integrity
Heat Treatment
Normalizing: 870°C – 940°C, air cooled
Quenching & Tempering: To improve grain structure and mechanical strength
Stress Relieving: After welding to reduce residual stress
Welding
ASTM A350 LF6 offers good weldability using standard methods like MIG, TIG, and SMAW.
Preheating at 120–150°C recommended before welding
Post-weld heat treatment enhances toughness and ductility
Low hydrogen electrodes should be used to prevent cracking
Fabrication
Excellent machinability and forgeability
Hot working temperature: 900°C – 1200°C
Cold working possible with suitable stress relieving
Can be drilled, cut, and machined to custom dimensions
Applications
Low-Temperature Pressure Vessels
Cryogenic Piping Systems
Valves and Flanges in LNG Plants
Offshore and Marine Engineering
Oil & Gas Refineries
Power Generation Equipment
Heat Exchangers and Chemical Processing Units