Carbon Steel A350 LF2 Round Bar
➡️ CS A350 LF2 | UNS K03011 | EN 1.0566 | ASTM A350 LF2
➡️ ASTM, EN, JIS & International Standards
➡️ Supply Conditions
➡️ Multiple Diameters & Supply Lengths
➡️ Global Export & International Delivery
Country of Origin:
Europe, Japan, USA
Material Type:
Carbon steel
UNS Number:
K03011
Wr. No.:
1.0566
MTC Available:
EN 10204 3.1
Product Description for Carbon Steel A350 LF2 Round Bar
ASTM A350 Grade LF2 is a low-alloy carbon steel produced to a low-temperature service specification originally written for forged and ring-rolled flanges, fittings, and valve bodies. Round bar supplied “to A350 LF2” is forging-quality or hot-rolled bar manufactured to the chemical composition, mechanical property, and Charpy V-notch toughness requirements of ASTM A350/A350M, and is stocked by distributors as raw material for machining or further forging into low-temperature piping components, rather than as a bar shape defined within the standard itself (ASTM A350 covers forgings; it does not specify bar dimensional tolerances).
The steel is fully killed and made to fine-grain practice, then supplied in the normalized, normalized-and-tempered, or quenched-and-tempered condition depending on section size and the class specified. LF2 carries a maximum carbon content of 0.30%, a manganese range of 0.60–1.35%, and small residual/alloying additions of Cr, Ni, Mo, Cu, V, and Nb that are individually capped and also limited in combination, keeping the carbon equivalent low enough for reliable field welding. Its defining characteristic is mandatory Charpy V-notch impact testing, qualifying the material down to -46°C (Class 1) or 0°C (Class 2), which distinguishes it from general-purpose grades such as A105 that are not routinely impact tested.
Mechanically, LF2 delivers a minimum yield strength of 250 MPa and a tensile strength of 485–655 MPa with 22% minimum elongation, placing it in ASME B16.5 pressure-temperature Group 1.2. It is used across oil and gas, petrochemical, LNG, and power-generation piping systems wherever equipment must tolerate low ambient or process temperatures, including cold-climate outdoor piping and autorefrigeration scenarios from depressurization. Typical end products machined from the bar include flanges, weldolets, valve bodies, and other pressure-retaining fittings built to ASME B16.5, B16.47, or API dimensional standards.
Buyers specifying this bar should confirm the required class (1 or 2), heat treatment condition, governing edition of ASTM A350/A350M, and whether supplementary requirements (such as vacuum carbon deoxidation, S4) apply, since these affect silicon content, impact test temperature, and certification requirements. The standard itself states this directly: “Although this specification covers some piping components machined from rolled bar and seamless tubular materials (see 5.3.3), it does not cover raw material produced in these product forms” (ASTM A350/A350M, Scope). This confirms that bar sold “to A350 LF2” is qualified to the grade’s chemistry, mechanical, and impact requirements as a matter of commercial practice, not because the standard itself certifies raw bar stock.
Common Applications of Carbon Steel A350 LF2 Round Bar
➡️ Machined shafts, spindles, valve stems, pump sleeves and pins for food, beverage, dairy and pharmaceutical equipment, where the passive chromium oxide film resists both product acids and caustic clean-in-place chemicals.
➡️ Fasteners, studs, bolts, threaded rod and anchor components produced from bar stock, chosen for corrosion resistance combined with the ductility needed for cold heading and thread rolling.
➡️ Chemical, water treatment and general process plant parts such as agitator shafts, flange blanks, nozzles and support components handling water, steam and mildly corrosive media free of significant chlorides.
➡️ Architectural and structural hardware including handrail stanchions, balustrade fittings, tension rods and bollards, where a bright ground or polished bar finish provides both appearance and low maintenance.
International Equivalent Grade for A350 LF2 Round Bar
Standard
Country / Region
Grade
ASTM / UNS
USA
A350 Grade LF2 / UNS K03011
JIS
Japan
JIS G3202 SFVQ1A
EN
Europe
EN 1.0566
BS
United Kingdom
BS EN 1.0566
GB / GB/T
China
-
KS
South Korea
-
Technical Specification for Carbon Steel A350 LF2 Round Bar
Specification
Value
Unit
Material
Carbon steel
-
Grade
LF2, UNS K03011
-
Standard
ASTM A350/A350M (ASME SA-350)
-
Product Form
Round bar
-
Diameter
Depends on mill/stockholder manufacturing range; verify availability with supplier
mm
Length
Random mill lengths or cut-to-size; depends on stockholder practice
mm / m
Manufacturing Process
Hot rolled and/or open-die forged bar; fully killed, fine-grain practice
-
Surface Finish
As-rolled/as-forged (black) or turned/peeled bright bar
-
Heat Treatment
Normalized, normalized and tempered, or quenched and tempered (per applicable class and section size)
-
Delivery Condition
Normalized (most common); state condition on order
-
Dimensional Tolerance
Per supplier's commercial round bar tolerance; not mandated by A350
mm
Straightness
Per supplier's commercial practice; not specified in A350
mm/m
Carbon Equivalent (CEV)
≤ 0.45
%
Density
~7.85
g/cm³
Magnetic Properties
Ferromagnetic
-
Corrosion Resistance
Not a corrosion-resistant grade; suited to general non-corrosive service; relies on coating/painting for atmospheric or corrosive-environment protection
-
Thermal Conductivity
~45–52
W/m·K
Electrical Resistivity / Conductivity
~0.15–0.20
µΩ·m
Specific Heat
~460
J/kg·K
Coefficient of Thermal Expansion
~11.5–12.5 (20–100°C)
×10⁻⁶/°C
Melting Range
~1420–1460
°C
Modulus of Elasticity
190–210
GPa
Technical Specifications
Get the key technical specifications for Carbon Steel A350 LF2 Round Bar
Grade identification for this bar rests on three linked elements: the ASTM A350/A350M standard, the LF2 grade designation, and the Class (1 or 2), which governs the mandatory Charpy V-notch test temperature and minimum absorbed energy rather than chemistry or strength: Class 1 and Class 2 share identical composition and tensile/yield requirements.
A350 is written for forgings, not bar stock, there is no bar-specific dimensional tolerance table in the standard itself; diameter and length tolerances, straightness, and surface finish are set by the rolling mill or stockholder’s commercial practice and should be confirmed at time of order, along with the applicable edition of ASTM A350/A350M, since impact-test and carbon-equivalent requirements have been revised across editions.
Heat treatment condition (normalized vs. normalized-and-tempered vs. quenched-and-tempered) affects both toughness and hardness and should be specified explicitly, as should any supplementary requirements such as S4 vacuum carbon-deoxidation, which caps silicon at 0.12% and is invoked only when the purchaser requests it.
Buyers intending to forge or heavily machine this bar into pressure-retaining components should also confirm whether the finished part must be re-certified to A350 after forging, since bar-stage certification does not automatically transfer to the forged/machined end product.
Chemical Composition for Carbon Steel A350 LF2 Round Bar
Element
Symbol
Min
Max
Unit
Carbon
C
-
0.30
%
Chromium
Cr
-
0.30
%
Nickel
Ni
-
0.40
%
Molybdenum
Mo
-
0.12
%
Manganese
Mn
0.60
1.35
%
Silicon
Si
0.15
0.30
%
Phosphorus
P
-
0.035
%
Sulfur
S
-
0.040
%
Iron
Fe
Balance
Balance
%
Copper
Cu
-
0.40
%
Vanadium
V
-
0.08
%
Niobium (Columbium)
Nb
-
0.02
%
Chemical Composition
View the chemical composition and applicable material limits for A350 LF2 Round Bar
LF2’s chemistry is built around a moderate carbon-manganese base with tightly capped residual alloying rather than deliberate alloy strengthening. The 0.30% carbon ceiling, lower than general-purpose A105 (0.35% max), reduces the risk of brittle fracture at low temperature by limiting the volume of hard carbide constituents in the microstructure.
Manganese (0.60–1.35%) is the primary strengthening and toughness-supporting element, refining grain size in combination with the mandated fine-grain melting practice. Phosphorus and sulfur are held to low ceilings (0.035% and 0.040%) to limit temper embrittlement and improve transverse toughness and weld-heat-affected-zone behavior.
Chromium, nickel, molybdenum, copper, vanadium, and niobium are all residual/trace-level elements individually capped at low percentages; their combined limits (Cu+Ni+Cr+V+Mo ≤ 1.00% and Cr+Mo ≤ 0.32%, both on heat analysis) exist specifically to keep the carbon equivalent (CE) low, which is what governs field weldability with standard carbon steel electrodes without heavy preheat.
Silicon (0.15–0.30%, or capped at 0.12% under Supplementary Requirement S4 vacuum carbon-deoxidation) affects deoxidation practice and, at the lower S4 level, is associated with improved low-temperature notch toughness. None of these elements are present at levels intended to provide meaningful corrosion resistance. This remains a plain carbon-alloy steel for mechanical/toughness performance, not a corrosion-resistant grade.
Mechanical Properties for Carbon Steel A350 LF2 Round Bar
Mechanical Property
Value
Unit
Tensile Strength
485–655
MPa
Yield Strength (min.)
250
MPa
Elongation (min.)
22
%
Reduction of Area (min.)
30
%
Hardness (max)
197
HB
Impact / Charpy V-notch
20 - 27
J
Proof Stress / 0.2% Proof Strength
250
MPa
Ultimate Tensile Strength
485–655
MPa
Mechanical Properties
Check the key mechanical properties and performance requirements of A350 LF2 Round Bar
The 250 MPa minimum yield strength and 485–655 MPa tensile range place this bar in a moderate-strength band suitable for standard pressure-class flanges, fittings, and valve bodies rather than high-yield structural applications; ASME B16.5 places LF2 in pressure-temperature Group 1.2, giving pressure ratings close to, but marginally higher than, general-purpose A105 (Group 1.1) at equivalent nominal pipe classes.
The 22% minimum elongation and 30% minimum reduction of area indicate good ductility, supporting cold forming and machining operations without excessive risk of cracking.
What distinguishes LF2 mechanically is the mandatory Charpy V-notch requirement: an average of 20 J across three specimens (Class 1, tested at -46°C) or 27 J (Class 2, tested at 0°C), with individual specimen minimums below the average, confirms the steel resists brittle, low-energy fracture at its rated minimum design temperature, which is critical for components that could otherwise fail suddenly under impact or thermal shock in cold service.
The maximum 197 HB hardness ceiling helps control weld heat-affected-zone hardness and supports NACE MR0175 sour-service compatibility when specified. Because toughness and hardness are heat-treatment-and-section-size dependent, actual mill certificates should be checked against the specific class and thickness ordered rather than assumed from nominal grade values alone.
Minor rounding variance appears across secondary sources on the metric-converted minima (e.g., 240 MPa vs. 250 MPa yield, 480 MPa vs. 485 MPa tensile, -45°C vs. -46°C test temperature). These stem from ksi/°F-to-metric conversion rounding in the “M” (metric) version of the standard and should not be read as conflicting requirements; the values in the table above (250 MPa / 485 MPa / -46°C) are the more consistently cited figures.
Dimension / Sizes for Carbon Steel A350 LF2 Round Bar
Dimension / Size
Value
Unit
Diameter
Depends on mill/stockholder manufacturing range; confirm with supplier
mm
Standard Length
Random mill length or supplier standard stock length; confirm with supplier
mm / m
Custom Length
Sawn/cut-to-length available from most stockholders
mm / m
Diameter Tolerance
Per supplier's commercial bar tolerance (not specified in ASTM A350)
mm
Length Tolerance
Per supplier's commercial practice
mm
Straightness Tolerance
Per supplier's commercial practice
mm/m
End Condition
Sawn/as-cut; machined ends by special request
-
Surface Finish
As-rolled/as-forged (black), or turned/peeled bright bar
-
Out-of-Roundness
Per supplier's commercial practice
mm
Ovality
Per supplier's commercial practice
mm
Dimensions & Sizes
Explore available diameters, lengths, and dimensional requirements for A350 LF2 Round Bar
Pricing for Carbon Steel A350 LF2 Round Bar
Round Bar Prices are generally quoted per kilograms or meters tonnes and can fluctuate with the global raw material and market prices. The final price will depend on a variety of factors, including the grade size, diameter, length, surface finish, the quantity and whether the bars are cut to length or in standard lengths.
For smaller quantities, we can also quote per metre or per piece basis once the required dimensions have been confirmed. Container-loads or orders that are larger in size are typically priced per tonne, based upon the specifications required and the supply conditions.
Please provide your desired dimensions, grades, length number, and end for a current quote including the lead time applicable and details for certification.
Pricing
Get current Carbon Steel A350 LF2 Round Bar pricing based on size, quantity, grade, finish, and delivery requirements.
Why Choose Us
Euro Steel Bars is an international distributor, stockist and exporter of stainless round steel bars that cover carbon, stainless alloy, special grades. We stock a variety of sizes and grades. We guarantee every order with mill test certificates as well as full quality-assurance documentation. Our name speaks to our roots: European-sourced materials that is backed by the certificates and rigor that buyers from Asia as well as the Gulf and Africa are looking for.
Each bar we deliver is accompanied by EN 10204 3.1 mill test certificates as well as complete documentation of quality, so what you receive corresponds to what’s written in the documents. We carry a selection of sizes and grades ready for transport, and cut length upon the request of customers, which results in quicker lead times, whether you’re ordering just a one-off spec or a complete project tonnage.
We operate an actual wholesale business that is that is supported with an internationally-operated supply chain therefore we are able to serve fabricators sourcing one grade the same way in the same way as an EPC contractor who is placing a large order. Our clients include manufacturers, fabricators EPC construction companies, engineers oil and gas projects as well as construction companies. we design our inventory as well as documentation to show what buyers need to bring projects forward.
Our customers trust us across Qatar, Oman, Bahrain, Kuwait, Jordan, Malaysia, Singapore, Thailand, Taiwan, Turkey, Italy and South Africa. If you’re looking to source an Gulf energy project, or a construction project within Southeast Asia, you get the same quality of certified material, the exact documentation, and the exact delivery procedure.
Frequently Asked Questions
What is ASTM A350 Grade LF2?
What is the difference between LF2 Class 1 and Class 2?
What is the UNS number for A350 LF2?
Is "A350 LF2 round bar" actually covered by the ASTM A350 standard?
What are the international equivalent grades for A350 LF2?
Is A350 LF2 weldable?
What corrosion resistance does A350 LF2 offer?
Can custom sizes or lengths be supplied?
How does A350 LF2 compare to A105?
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