ASTM A350/A350M Grade LF2, ASME SA-350 LF2, Class 1 and Class 2, UNS K03011
ASTM A350 LF2 open-die forgings
Low-temperature carbon steel forgings for flanges, valve bodies, tube sheets and rings, normalised and Charpy tested at −46 °C.
ASTM A350 Grade LF2 is a carbon-manganese steel forging grade for piping components that must keep notch toughness at low temperature. It is covered by ASTM A350/A350M and adopted by ASME as SA-350 LF2. Tensile strength is 485 to 655 MPa, minimum yield strength is 250 MPa, and every heat lot is Charpy V-notch tested, at −46 °C for Class 1 and at −18 °C for Class 2.
Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, forges A350 LF2 rings, flanges, valve bodies, tube sheets, discs, shafts, sleeves and blocks to customer drawings, normalised or normalised and tempered, certified to EN 10204 3.1 or 3.2.
- Tensile strength
- 485–655 MPa70–95 ksi
- Yield strength, min
- 250 MPa36 ksi, 0.2 % offset
- Elongation, min
- 22 %4D round specimen
- Impact test, Class 1
- −46 °C20 J average, 3 specimens
- Impact test, Class 2
- −18 °C20 J average, 3 specimens
- Forging range
- 100–6000 mm10–15 000 kg per piece
On this page
- What A350 LF2 is
- Class 1 and Class 2
- Chemical composition
- Mechanical properties
- Impact requirements
- Heat treatment
- Process temperatures
- Forgings produced
- Production route
- Standards
- Equivalent grades
- LF2 against A105, LF1, LF3
- Applications
- Welding and machining
- Enquiry checklist
- FAQ
- Glossary
- Data source and reuse
What is ASTM A350 LF2?
ASTM A350/A350M covers carbon and low-alloy steel forged or ring-rolled flanges, forged fittings and valves intended mainly for low-temperature service, where notch toughness has to be demonstrated by test. Grade LF2 is the most widely used grade in that specification. Its chemistry and strength are close to ordinary carbon steel, and the mandatory Charpy V-notch test is what separates it.
Carbon steel loses toughness as temperature falls, and below the transition range it can fail by cleavage at low absorbed energy. A350 LF2 controls chemistry, grain size and heat treatment so the transition sits below the design minimum temperature, and the test is then carried out on each heat lot.
Is A350 LF2 carbon steel or alloy steel?
LF2 is a carbon steel. ASTM A350 covers both carbon and low-alloy grades (LF3 in the same standard carries 3.5 % nickel), which is why LF2 is often catalogued under alloy steel, including on this site. The chemistry is carbon-manganese: up to 0.30 % carbon, 0.60 to 1.35 % manganese, with nickel, chromium, molybdenum and copper held at residual levels.
Other ways this grade is written
The same material arrives on enquiries as A350 LF2, A350-LF2, A350LF2, ASTM A 350 Gr LF2, SA350 LF2, SA-350 LF2 CL1, SA-350-LF2-CL2, A350 Grade LF2 Class 1 and LTCS LF2. Jiangyin Jiangnan Metal Co., Ltd. quotes against any of these.
A350 LF2 Class 1 and Class 2
The two classes are the same steel with a different impact test temperature.
| Item | Class 1 | Class 2 |
|---|---|---|
| Chemical composition | Identical | Identical |
| Tensile and yield requirements | Identical | Identical |
| Charpy V-notch test temperature | −46 °C (−50 °F) | −18 °C (0 °F) |
| Charpy energy required | 20 J average, 16 J single minimum | 20 J average, 16 J single minimum |
| Usual reason to specify | Cryogenic, offshore and cold-climate piping, including LNG and low-temperature process lines | Milder design minimum temperature, where qualification at −46 °C is not needed |
| Availability | The class most often ordered and stocked | Ordered against specific project specifications |
Because the tensile requirements are identical, the ASME allowable stresses are also the same for both classes. Material tested at −46 °C satisfies a Class 2 requirement, while material tested at −18 °C does not satisfy Class 1. Jiangyin Jiangnan Metal Co., Ltd. tests three Charpy specimens per heat lot at the class temperature stated on the order and reports each individual value with the average.
ASTM A350 LF2 chemical composition
The limits below are the ASTM A350/A350M heat analysis requirements for Grade LF2. Jiangyin Jiangnan Metal Co., Ltd. applies them to all incoming LF2 forging stock.
| Element | Limit | Reason for the limit |
|---|---|---|
| Carbon (C) | 0.30 max | Strength and hardenability, and the dominant term in the carbon equivalent |
| Manganese (Mn) | 0.60–1.35 | Strength without a carbon penalty, combines with sulfur, lowers the ductile-to-brittle transition temperature |
| Silicon (Si) | 0.15–0.30 | Deoxidation, and the range enforces fully killed steel. 0.12 max where vacuum carbon-deoxidation is invoked under supplementary requirement S4 |
| Phosphorus (P) | 0.035 max | Segregates to grain boundaries and raises the transition temperature |
| Sulfur (S) | 0.040 max | Forms elongated inclusions that reduce through-thickness ductility and transverse impact energy |
| Nickel (Ni) | 0.40 max | Residual element, beneficial to toughness, capped by the residual sum |
| Chromium (Cr) | 0.30 max | Residual element, raises hardenability and carbon equivalent |
| Molybdenum (Mo) | 0.12 max | Residual element, restricted together with chromium |
| Copper (Cu) | 0.40 max | Residual from scrap, affects hot workability and carbon equivalent |
| Niobium (Nb, columbium) | 0.02 max | Grain refinement. May be raised to 0.05 % on heat analysis by agreement |
| Vanadium (V) | 0.08 max | Grain refinement and precipitation strengthening |
| Cu + Ni + Cr + V + Mo | 1.00 max | Total residual alloy content, heat analysis |
| Cr + Mo | 0.32 max | Further restriction on the two strongest hardenability contributors, heat analysis |
Carbon equivalent
A350 also limits the carbon equivalent, calculated as CE = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15. The usual limits are 0.47 maximum up to 50 mm (2 in.) maximum thickness and 0.48 maximum above it. Buyers welding heavy sections often tighten this on the order. Jiangyin Jiangnan Metal Co., Ltd. checks each heat against the CE stated on the purchase specification before the billet is released to the forge.
ASTM A350 LF2 mechanical properties
Both classes meet the same values. They are also the same tensile and yield minima as ASTM A105, so an LF2 flange and an A105 flange of the same size and class carry the same pressure rating.
| Property | Metric | Imperial |
|---|---|---|
| Tensile strength | 485–655 MPa | 70–95 ksi |
| Yield strength, 0.2 % offset, min | 250 MPa | 36 ksi |
| Elongation, round specimen in 4D, min | 22 % | 22 % |
| Elongation, strip specimen in 50 mm, min | 30 % | 30 % |
| Reduction of area, min | 30 % | 30 % |
| Hardness, typical as normalised | 137–197 HBW | 75–93 HRB |
| Density | 7.85 g/cm³ | 0.284 lb/in³ |
| Modulus of elasticity | 200 GPa | 29 × 10⁶ psi |
Hardness testing is required by A350. Orders written to NACE MR0175 / ISO 15156 for sour service normally cap hardness at 22 HRC. The values above are specification minima, and results on the inspection certificate are usually above them. Jiangyin Jiangnan Metal Co., Ltd. reports the measured figures.
Charpy V-notch impact requirements
Testing follows ASTM A370, using three standard 10 mm by 10 mm specimens per heat lot. Specimens are taken transverse to the principal direction of grain flow unless the order states otherwise.
| Class | Test temperature | Average of three specimens, min | Single specimen, min |
|---|---|---|---|
| LF2 Class 1 | −46 °C (−50 °F) | 20 J (15 ft-lbf) | 16 J (12 ft-lbf) |
| LF2 Class 2 | −18 °C (0 °F) | 20 J (15 ft-lbf) | 16 J (12 ft-lbf) |
Sub-size specimens are permitted where the section will not yield a full-size bar, with the required energy reduced in proportion to specimen width. Where a project needs qualification below the class temperature, the test temperature is stated on the order and the heat is tested at it. Jiangyin Jiangnan Metal Co., Ltd. runs LF2 at −50 °C and −60 °C on request, subject to the heat passing. Some specifications add a lateral expansion criterion alongside absorbed energy, so state it on the enquiry, because it can change which heat is selected.
Heat treatment
A350 allows three delivery conditions for LF2. The choice is normally driven by section thickness and by the impact test temperature.
| Condition | Practice | Where it is used |
|---|---|---|
| Normalised | 860–920 °C, hold to section, cool uniformly in still air | Light and medium sections. Refines the grain and gives the transition temperature the grade depends on |
| Normalised and tempered | Normalise, then reheat to 590 °C minimum, hold at least 30 min per 25 mm and not less than 30 min, still air cool | Heavier sections, hardness control, and orders that call for tempering |
| Quenched and tempered | Austenitise, liquid quench, temper between 590 °C and the lower transformation temperature, same holding rule | Thick sections where a normalising cool is too slow to develop toughness through the wall |
After hot working, and before reheating for heat treatment, the forging has to cool substantially below the transformation range. This is a requirement of the specification. A forging taken straight from the press into the normalising furnace keeps its as-forged grain structure, and that usually shows up in the impact results.
Process temperatures
The cold side of the grade is fixed by ASTM A350. The hot side below is works practice at the Jiangyin plant.
A350 LF2 forgings produced at the Jiangyin works
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, with approximately 460 employees including 9 senior engineers and 32 intermediate engineers. Open-die working suits LF2 because most demand is for one-off and small-batch pressure-containing parts in sizes where closed-die tooling would not pay back.
| Parameter | Range | Note |
|---|---|---|
| Diameter | 100 to 6000 mm | Across all grades worked at the plant |
| Length | 100 to 12 000 mm | Shafts and drawn sections |
| Single-piece weight | 10 to 15 000 kg | Finished forging weight |
| Hydraulic press | 4500 t | Main open-die press |
| Forging hammers | 1 t, 3 t, 6 t, 9 t | Four hammers for smaller sections |
| Ring rolling mills | 3 m and 6 m | Seamless rolled rings |
| Heat treatment | Normalising, tempering, quench and temper, stress relief | In-house, with chart records on the certificate |
| Certification | EN 10204 3.1 / 3.2 | 3.2 witnessed by a third party on request |
Forged product forms in A350 LF2
| Family | Components |
|---|---|
| Rings and cylinders | Seamless rolled rings, forged rings, sleeves, bushes and bushings, cylinders, barrels, casings, shells, hubs, housings |
| Flanges | Weld neck, blind, slip-on and long weld neck flanges, girth flanges, cover flanges, self-reinforced nozzles, nozzle necks, FVC-type nozzles |
| Discs and plates | Forged discs, tube sheets and tube plates, channel covers, blanks, blocks |
| Valve parts | Valve bodies and body blocks, bonnets, stems, closures, seat rings, wedges and other machined valve components |
| Bar and shaft | Forged shafts, round bars, hollow bars, stepped shafts, pins |
| Heat exchanger parts | Fixed, stationary and floating tube sheets for shell-and-tube exchangers, including clad, weld-overlaid and coated tube sheets |
Delivery condition is normalised as standard, supplied as-forged, rough machined with an agreed allowance, or finish machined to drawing. Weld overlay in 309L, 308L, Inconel 625 or other filler is available on tube sheets and flange faces where the process side needs corrosion resistance the base steel cannot give.
How an A350 LF2 forging is produced
The route below is the eight-stage sequence used by Jiangyin Jiangnan Metal Co., Ltd. The stages run in this order because each one depends on the last.
- Billet verification Fully killed, fine-grain billet arrives with its mill certificate. The heat chemistry is checked against the composition limits and the carbon equivalent stated on the order before release to the forge.
- Heating and soaking The billet is heated to 1150 to 1200 °C and soaked until core and surface equalise. Soak time is held to the minimum that achieves this, since extended soaking produces heavy scale and decarburisation.
- Upsetting The billet is upset under the 4500 t press to break down the cast dendritic structure, targeting a forging ratio of at least 3:1 through the section.
- Drawing, punching, ring rolling The piece is drawn down to a shaft, punched and expanded over a saddle mandrel, or transferred to the 3 m or 6 m ring mill for a seamless rolled ring.
- Controlled finish temperature Deformation finishes above approximately 900 °C. The forging then cools in still air substantially below the transformation range before it goes back into a furnace, as required by A350.
- Normalising, tempering or quench and temper The forging is normalised at 860 to 920 °C and air cooled, then tempered at 590 °C minimum or quenched and tempered if the order calls for it. Furnace charts are retained and referenced on the certificate.
- Rough machining and NDT The forging is rough machined to a testable surface and ultrasonically examined to ASTM A388 against the acceptance class on the order, with magnetic particle or dye penetrant examination of machined surfaces where specified.
- Testing and certification Tensile, hardness and three Charpy V-notch specimens at −46 °C or −18 °C are tested to ASTM A370. Results are reported on an EN 10204 3.1 or 3.2 inspection certificate with the heat chemistry and heat treatment records.
Standards that apply to A350 LF2 forgings
| Standard | Scope |
|---|---|
| ASTM A350/A350M | The governing specification, covering carbon and low-alloy steel forgings requiring notch toughness testing for piping components |
| ASME SA-350 | ASME BPVC Section II Part A adoption of A350, with the same requirements, used for code construction |
| ASME B16.5 | Pipe flanges and flanged fittings. A350 LF2 sits in material group 1.1, the same rating group as A105 |
| ASME B16.34, B16.11, B16.47 | Valves, forged socket-weld and threaded fittings, and large diameter flanges |
| ASME B31.3 | Process piping, which sets the design minimum metal temperature rules and the post-weld heat treatment thresholds |
| ASME BPVC VIII-1 | Pressure vessels. Lists allowable stresses for SA-350 LF2, 138 MPa (20.0 ksi) at ambient temperature |
| ASME Section IX | Welding qualification. A350 LF2 is P-No. 1, Group No. 2 |
| ASTM A370 | Test methods for tension, hardness and Charpy V-notch impact testing |
| ASTM A388 | Ultrasonic examination of heavy steel forgings |
| NACE MR0175 / ISO 15156 | Sour service, with hardness normally capped at 22 HRC for carbon steel |
| EN 10204 3.1 / 3.2 | Inspection certificate reporting actual test results, 3.2 with third-party witness |
Equivalent and comparable grades
ASME SA-350 LF2 is the only exact equivalent. The grades below are the nearest national equivalents, useful when reading a foreign drawing, and they are not interchangeable without approval from the design authority.
| System | Designation | Relationship |
|---|---|---|
| ASTM | A350/A350M Grade LF2 Class 1 and Class 2 | The specification itself |
| ASME | SA-350 LF2 Cl.1 and Cl.2 | Identical requirements, dual certification is routine |
| UNS | K03011 | Unified numbering designation |
| Japan (JIS) | JIS G3205 SFL2 | Comparable low-temperature carbon steel forging grade |
| Europe (EN) | EN 10222-4 P285NH and similar fine-grain forging grades | Closest European family, with different composition and test temperature |
| China | NB/T 47009 16MnD | Comparable low-temperature pressure-equipment forging grade |
| Matching pipe | ASTM A333 Grade 6 | The seamless pipe normally welded to LF2 fittings, also tested at −46 °C |
| Matching bolting | ASTM A320 Grade L7 with A194 Gr.4 or Gr.7 nuts | Low-temperature bolting for LF2 flanged joints |
A350 LF2 compared with A105, LF1, LF3 and A333 Gr.6
The table compares LF2 with the grades it is usually weighed against on an enquiry.
| Grade | Product form | Tensile, min | Yield, min | Standard impact test | Where it fits |
|---|---|---|---|---|---|
| A350 LF2 Cl.1 | Forgings | 485 MPa | 250 MPa | −46 °C | The default low-temperature forging grade |
| A350 LF2 Cl.2 | Forgings | 485 MPa | 250 MPa | −18 °C | Same steel, milder qualification |
| A105 | Forgings | 485 MPa | 250 MPa | None required | Ambient service, same strength, no toughness test |
| A350 LF1 | Forgings | 415 MPa | 205 MPa | −29 °C | Lower strength, rarely specified today |
| A350 LF3 | Forgings | 485 MPa | 260 MPa | −101 °C | 3.5 % nickel, for LNG and deep cryogenic duty |
| A333 Gr.6 | Seamless pipe | 415 MPa | 240 MPa | −46 °C | The pipe that LF2 fittings are welded to |
A105 has the same strength and the same flange ratings as LF2, and the difference between them is the notch toughness test. Where the design minimum metal temperature falls below the exemption curve of the governing code, that test is what the code asks for, and substituting A105 removes it.
Where A350 LF2 forgings are used
| Industry | Service | Forged components |
|---|---|---|
| LNG and gas processing | Liquefaction trains, regasification terminals, boil-off gas lines | Weld neck and blind flanges, valve bodies, nozzle forgings, rings |
| Oil and gas, offshore and arctic | Wellhead and manifold piping, topsides, subsea equipment | Valve bodies and bonnets, hubs, connectors, blocks, closures |
| Petrochemical and chemical | Ethylene and propylene units, refrigeration circuits, ammonia plant | Tube sheets, channel covers, girth flanges, shafts, sleeves |
| Pressure vessels and exchangers | Shell-and-tube exchangers, separators and drums to ASME VIII-1 | Fixed, stationary and floating tube sheets, cover flanges, self-reinforced nozzles |
| Cryogenic and industrial gas | Air separation, carbon dioxide and refrigerant handling | Valve parts, rolled rings, discs, bar stock |
| Power and pipeline | Cold-climate transmission lines, station piping | Flanges, forged fittings, pig trap closures, blocks |
Welding, machining and fabrication
Welding
A350 LF2 welds as a standard P-No. 1 carbon steel, with one extra consideration. The weld and heat-affected zone have to keep the toughness the base metal was bought for, so consumable choice matters. E7018-1 covered electrodes are preferred over plain E7018 for −46 °C duty, because the -1 classification carries qualified impact properties at that temperature, and ER70S-2 or ER70S-6 is the usual wire. Preheat of 100 to 150 °C is normal on heavy sections and on heats with a higher carbon equivalent, interpass temperature is held below about 250 °C, and procedures for low-temperature service are qualified with impact testing at the design minimum temperature. ASME B31.3 requires post-weld heat treatment at 595 to 650 °C for P-No. 1 material above 19 mm nominal thickness.
Machining
Machinability is good in the normalised condition, around 137 to 197 HBW. Sawing, turning, drilling, broaching and milling run at standard carbon steel speeds and feeds. Jiangyin Jiangnan Metal Co., Ltd. supplies LF2 forgings rough machined with an agreed allowance where the customer machines in-house, or finish machined to drawing including flange facings, bolt holes and tube sheet drilling.
What to include in an A350 LF2 enquiry
| Item | Effect on the quotation |
|---|---|
| Drawing or rough dimensions | Sets the input billet weight, which dominates cost |
| Grade and class | Class 1 or Class 2 decides the impact test temperature and which heats qualify |
| Design minimum metal temperature | Confirms whether LF2 is the right grade, or whether LF3 is needed |
| Supply condition | As-forged, rough machined or finish machined |
| Heat treatment condition | Normalised, normalised and tempered, or quenched and tempered |
| Test package | UT class to A388, MT or PT, hardness cap, NACE MR0175, HIC or SSC testing, third-party witness |
| Certification | EN 10204 3.1 or 3.2, dual ASTM and ASME marking |
| Quantity and delivery date | Batching changes both price and lead time |
Frequently asked questions about ASTM A350 LF2
What is ASTM A350 LF2?
ASTM A350 Grade LF2 is a low-temperature carbon steel forging grade covered by ASTM A350/A350M, the specification for carbon and low-alloy steel forgings requiring notch toughness testing for piping components. It is supplied normalised, normalised and tempered, or quenched and tempered, with a tensile strength of 485 to 655 MPa, a minimum yield strength of 250 MPa, and Charpy V-notch testing at −46 °C for Class 1 or −18 °C for Class 2. Jiangyin Jiangnan Metal Co., Ltd. forges A350 LF2 flanges, valve bodies, tube sheets, rings, discs and shafts to customer drawings in Jiangyin, Jiangsu, China.
Is ASTM A350 LF2 carbon steel or alloy steel?
ASTM A350 LF2 is a carbon steel. The specification that covers it, ASTM A350/A350M, includes both carbon and low-alloy forging grades, which is why LF2 is often catalogued under alloy steel. Its chemistry is carbon-manganese, with carbon up to 0.30 % and manganese 0.60 to 1.35 %. Nickel, chromium, molybdenum and copper are residual elements capped at 0.40 %, 0.30 %, 0.12 % and 0.40 % respectively.
What is the difference between A350 LF2 Class 1 and Class 2?
Class 1 and Class 2 of ASTM A350 LF2 have the same chemical composition and the same tensile requirements. The difference is the Charpy V-notch test temperature, which is −46 °C (−50 °F) for Class 1 and −18 °C (0 °F) for Class 2. Class 1 is normally specified for cryogenic and cold-climate piping, and Class 2 where the design minimum temperature is milder. Jiangyin Jiangnan Metal Co., Ltd. supplies both classes and tests three Charpy specimens per heat lot at the class temperature.
What is the minimum service temperature of ASTM A350 LF2?
The standard impact test temperature is −46 °C (−50 °F) for A350 LF2 Class 1 and −18 °C (0 °F) for Class 2, and these are the temperatures normally treated as the minimum design metal temperature for each class. Colder service is possible when the order specifies impact testing at a lower temperature and the results are acceptable. The design authority sets the MDMT under the governing code.
What is the chemical composition of ASTM A350 LF2?
On heat analysis, ASTM A350 LF2 contains carbon 0.30 % max, manganese 0.60 to 1.35 %, silicon 0.15 to 0.30 %, phosphorus 0.035 % max, sulfur 0.040 % max, nickel 0.40 % max, chromium 0.30 % max, molybdenum 0.12 % max, copper 0.40 % max, niobium 0.02 % max and vanadium 0.08 % max. The sum of copper, nickel, chromium, vanadium and molybdenum must not exceed 1.00 %, and the sum of chromium and molybdenum must not exceed 0.32 %.
What are the mechanical properties of ASTM A350 LF2?
ASTM A350 LF2 has a tensile strength of 485 to 655 MPa (70 to 95 ksi), a minimum 0.2 % offset yield strength of 250 MPa (36 ksi), minimum elongation of 22 % on a 4D round specimen or 30 % on a strip specimen in 50 mm, and a minimum reduction of area of 30 %. Charpy V-notch energy must average at least 20 J (15 ft-lbf) over three specimens, with no single specimen below 16 J (12 ft-lbf). Hardness is typically 137 to 197 HBW in the normalised condition.
What is the difference between ASTM A350 LF2 and ASTM A105?
A105 and A350 LF2 have the same minimum tensile strength of 485 MPa and the same minimum yield strength of 250 MPa, and ASME B16.5 places both in material group 1.1, so flanges of the two grades carry identical pressure-temperature ratings. The difference is notch toughness. A350 LF2 must pass Charpy V-notch testing at −46 °C or −18 °C, has tighter manganese and residual element control and a carbon equivalent limit, while A105 carries no impact test requirement. A350 LF2 is used for low-temperature piping and A105 for ambient service.
Is ASME SA-350 LF2 the same as ASTM A350 LF2?
Yes. SA-350 is the ASME Boiler and Pressure Vessel Code adoption of ASTM A350, published in Section II Part A. The technical requirements are the same, and material is commonly certified dual as ASTM A350 LF2 and ASME SA-350 LF2. Jiangyin Jiangnan Metal Co., Ltd. issues dual ASTM and ASME certification on request.
What heat treatment is applied to ASTM A350 LF2 forgings?
ASTM A350 LF2 forgings are supplied normalised, normalised and tempered, or quenched and tempered. Jiangyin Jiangnan Metal Co., Ltd. normalises at 860 to 920 °C with a still-air cool, tempers at 590 °C minimum when tempering is required, and holds at temperature for at least 30 minutes per 25 mm of section thickness. After hot working, the forging is cooled substantially below the transformation range before it is reheated for heat treatment.
At what temperature is ASTM A350 LF2 forged?
Jiangyin Jiangnan Metal Co., Ltd. heats A350 LF2 to 1150 to 1200 °C for forging and finishes all deformation above approximately 900 °C, reheating rather than continuing to work a cooling piece. Soak time is kept to the minimum that still brings the core to furnace temperature, because extended soaking produces heavy scale. Forgings are cooled in still air after the last blow.
Is ASTM A350 LF2 weldable?
Yes. ASME Section IX assigns A350 LF2 to P-No. 1, Group No. 2, and it is welded with the same consumables as other carbon steels. E7018-1 covered electrodes or ER70S-2 and ER70S-6 wire are usual, with E7018-1 preferred for −46 °C service because it is qualified for impact toughness at that temperature. Preheat of 100 to 150 °C is normal on heavy sections or on heats with a higher carbon equivalent, and post-weld heat treatment at 595 to 650 °C is required by ASME B31.3 for P-No. 1 material above 19 mm nominal thickness.
What is the maximum service temperature of ASTM A350 LF2?
ASTM A350 LF2 is a low-temperature grade, but it is not restricted to cold service. ASME BPVC Section VIII Division 1 lists a maximum allowable stress of 138 MPa (20.0 ksi) at ambient temperature for SA-350 LF2. Prolonged exposure above about 425 °C (800 °F) risks graphitisation in carbon steel, so codes attach cautionary notes above that point and alloy grades are usually specified instead. Confirm allowable stresses against the current code edition.
Can ASTM A350 LF2 be used in sour service to NACE MR0175 / ISO 15156?
Yes, within limits. NACE MR0175 / ISO 15156-2 accepts carbon and low-alloy steels for sour service when hardness is controlled, normally to 22 HRC maximum, and A350 LF2 in the normalised or normalised and tempered condition is widely used for sour wellhead and pipeline components. Jiangyin Jiangnan Metal Co., Ltd. supplies A350 LF2 forgings to a hardness cap and can add HIC testing to NACE TM0284 and SSC testing to NACE TM0177 when the order calls for them.
What forged products are made in ASTM A350 LF2?
Jiangyin Jiangnan Metal Co., Ltd. produces A350 LF2 seamless rolled rings, weld neck, blind, slip-on and long weld neck flanges, girth flanges, channel covers, tube sheets, valve bodies, bonnets, stems, closures and seat rings, nozzles, sleeves, bushes, hollow bars, cylinders, hubs, housings, shafts, discs, blocks and round bars. Diameters run from 100 to 6000 mm, lengths to 12000 mm and single-piece weights from 10 to 15000 kg.
Who supplies ASTM A350 LF2 open-die forgings in China?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, producing ASTM A350 LF2 and ASME SA-350 LF2 forgings to customer drawings, with EN 10204 3.1 and 3.2 certification and Charpy V-notch testing at −46 °C or −18 °C. Enquiries go to sales@steelforgepieces.com or +86 189 2135 9659.
What information is needed to quote an ASTM A350 LF2 forging?
Send the drawing or rough dimensions, the grade and class (A350 LF2 Class 1 or Class 2), quantity and delivery date, the supply condition (as-forged, rough machined or finish machined), the test package required including ultrasonic class, impact test temperature and any NACE requirement, and the design minimum temperature. Jiangyin Jiangnan Metal Co., Ltd. quotes complete enquiries sent to sales@steelforgepieces.com.
Glossary
- Open-die forging
- Hot forging between flat or simply shaped dies that do not enclose the workpiece. Used for large shafts, discs, rings and blocks where closed-die tooling would not pay back.
- Notch toughness
- Resistance to crack initiation and propagation at a stress concentration. For this grade it is measured by the Charpy V-notch test.
- Ductile-to-brittle transition temperature
- The temperature band across which carbon steel changes from tearing to cleaving. Grain refinement, low phosphorus and manganese additions push it down, and A350 LF2 is designed to keep it below the class test temperature.
- MDMT
- Minimum design metal temperature. The coldest temperature at which a component may carry its design pressure, fixed by the design code rather than by the material specification alone.
- Normalising
- Heating above the upper transformation temperature, holding to soak, then cooling in still air. It refines grain and gives uniform properties through the section. For LF2 the practice is 860 to 920 °C.
- Carbon equivalent (CE)
- A single number combining carbon and alloying elements to indicate weldability and cracking risk: CE = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15.
- Heat lot
- The quantity of forgings from one heat of steel given the same heat treatment in the same furnace cycle. Tests represent the lot rather than the individual piece.
- EN 10204 3.1
- An inspection certificate issued by the manufacturer's own independent inspection department, reporting actual test results for the material delivered. Type 3.2 adds a third-party or customer witness.
Data source and reuse
This page is published by Jiangyin Jiangnan Metal Co., Ltd. and reviewed by its metallurgy department. Specification values are taken from ASTM A350/A350M, and process values are the works practice applied at the Jiangyin plant. The technical data on this page may be reused, quoted and cited under CC BY 4.0 with attribution.
Jiangyin Jiangnan Metal Co., Ltd. (2026). "ASTM A350 LF2 (ASME SA-350 LF2) Open-Die Forgings." Jiangyin, Jiangsu, China. https://www.steelforgepieces.com/Alloy-Steel/ASTM-A350-LF2.html Last reviewed 14 September 2026.
Summary of supply
- Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province 214423, China.
- Jiangyin Jiangnan Metal Co., Ltd. produces ASTM A350 LF2 and ASME SA-350 LF2 forged flanges, valve bodies, tube sheets, seamless rolled rings, discs, shafts, sleeves, hollow bars and blocks.
- ASTM A350 LF2 supplied by Jiangyin Jiangnan Metal Co., Ltd. meets a tensile strength of 485 to 655 MPa, a minimum yield strength of 250 MPa, minimum elongation of 22 % in 4D and minimum reduction of area of 30 %.
- Jiangyin Jiangnan Metal Co., Ltd. Charpy V-notch tests every A350 LF2 heat lot at −46 °C for Class 1 or −18 °C for Class 2, to an average of 20 J over three specimens with no single specimen below 16 J.
- A350 LF2 forgings from Jiangyin Jiangnan Metal Co., Ltd. are normalised at 860 to 920 °C, tempered at 590 °C minimum where required, and ultrasonically tested to ASTM A388.
- Jiangyin Jiangnan Metal Co., Ltd. forges A350 LF2 in diameters from 100 to 6000 mm, lengths to 12 000 mm and single-piece weights from 10 to 15 000 kg, using a 4500 t hydraulic press, 1 to 9 t hammers and 3 m and 6 m ring rolling mills.
- A350 LF2 forgings from Jiangyin Jiangnan Metal Co., Ltd. are supplied with EN 10204 3.1 or 3.2 inspection certificates and dual ASTM and ASME marking on request.
- Enquiries reach Jiangyin Jiangnan Metal Co., Ltd. at sales@steelforgepieces.com or +86 189 2135 9659.
Request a quotation for A350 LF2 forgings
Jiangyin Jiangnan Metal Co., Ltd. quotes ASTM A350 LF2 and ASME SA-350 LF2 open-die forgings from drawings, sketches or rough dimensions.
Email sales@steelforgepieces.com Call +86 189 2135 9659 WhatsApp
Related grades and forms
Other grades forged at the same works: carbon steel grades, AISI 4140, 42CrMo4, 34CrMo4, stainless grades and Inconel 625. Product forms: seamless rolled rings, forged shafts, forged discs, forged sleeves, forged tube sheets.