ASTM A350 LF5
ASTM A350 LF5 Flanges / Forged Components
ASTM A350 LF5 is a low-temperature carbon steel forging material alloyed with nickel and chromium to enhance its strength, ductility, and notch toughness in sub-zero environments. This grade is specifically designed for low-temperature service applications, such as pipelines, pressure vessels, and cryogenic process equipment in the oil & gas, petrochemical, and power generation industries.
Key Features
Excellent impact toughness at low temperatures
Good weldability and machinability
Suitable for cryogenic and sub-zero applications
High strength-to-weight ratio
Uniform grain structure ensuring durability
Excellent resistance to brittle fracture
Specification
| Standard | Details |
|---|---|
| Specification | ASTM A350 / ASME SA350 |
| Grade | LF5 |
| Product Forms | Flanges, Forged Fittings, Round Bars, Forged Rings, Valves |
| Forging Type | Open Die, Closed Die, Rolled, or Press Forged |
| Heat Treatment | Normalized, Quenched, and Tempered |
| Testing | Charpy V-Notch Impact Test, Hardness Test, Tensile Test |
| Manufacturing Standard | ASME B16.5, B16.47, MSS SP-44, API 6A, DIN, EN, JIS |
Equivalent Grades
| Standard | Equivalent Grade |
|---|---|
| ASTM | A350 LF5 |
| ASME | SA350 LF5 |
| EN | 1.5670 |
| UNS | K11562 |
| BS | 1503-660-490 |
| DIN | Ck15Ni5 |
Available Sizes
| Form | Size Range |
|---|---|
| Flanges | ½” to 48” (DN15 to DN1200) |
| Forged Fittings | ⅛” to 4” (Socket Weld & Threaded) |
| Round Bars | 10 mm to 600 mm Diameter |
| Custom Forgings | As per customer drawing or 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 |
| Phosphorus (P) | 0.035 max |
| Sulfur (S) | 0.040 max |
Mechanical Properties
| Property | Unit | Value |
|---|---|---|
| Tensile Strength | MPa | 485 min |
| Yield Strength | MPa | 250 min |
| Elongation | % | 22 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 | 1425 – 1540°C |
| Modulus of Elasticity | 205 GPa |
| Thermal Conductivity | 45 W/m·K |
| Specific Heat Capacity | 480 J/kg·K |
Type of ASTM A350 LF5 Flanges
Corrosion Resistance
ASTM A350 LF5 exhibits moderate corrosion resistance in atmospheric and mildly corrosive environments. It is suitable for oil & gas pipelines, cryogenic lines, and industrial cooling systems. For enhanced corrosion resistance, it is often coated, galvanized, or clad with stainless steel or nickel alloys.
Heat Resistance
Performs efficiently up to 400°C (750°F)
Loses strength beyond prolonged high-temperature exposure
Primarily recommended for low-temperature service, not high-temperature conditions
Heat Treatment
Normalizing: 870°C – 940°C, followed by air cooling
Quenching & Tempering: To refine grain and improve toughness
Stress Relieving: Post-weld heat treatment to relieve residual stresses
Welding
ASTM A350 LF5 offers good weldability using standard carbon steel welding techniques such as MIG, TIG, or SMAW.
Preheating before welding is recommended (120–150°C)
Post-weld heat treatment enhances ductility and toughness
Fabrication
Easily machined, forged, drilled, and formed
Hot working temperature range: 900°C – 1200°C
Cold working can be performed with appropriate stress relief
Applications
Cryogenic and Low-Temperature Piping Systems
Pressure Vessels and Heat Exchangers
Valves and Flanges in Oil & Gas Plants
Petrochemical Processing Units
Offshore Platforms and Refineries
Power Generation and LNG Terminals