ASTM A182 F5 – UNS K41545
Forged 5Cr-½Mo steel for high temperature and sulfidizing media
Cr-Mo steel with 4–6% Cr and 0.5% Mo, forged to ASTM A182 for flanges, fittings and valves in refineries. Chromium gives resistance to oxidation and sulfur corrosion at high temperature, and Mo gives creep resistance. The higher-strength variant F5a (C ≤ 0.25%) also exists.
Designations and equivalents
| System | Designation |
|---|---|
| UNS | K41545 |
| W.Nr./EN | X16CrMo5-1 – 1.7366 (EN 10222-2); ≈ X12CrMo5 – 1.7362 |
| DIN | 12CrMo19-5 (old) |
| JIS | SFVAF5B (JIS G3203) |
| Trade names | 5Cr-½Mo, F5 |
| Others | Pipe A335 P5; plate A387 Gr 5; fittings A234 WP5; casting A217 C5 |
Standards by product form
| Form | Standard |
|---|---|
| Forging (flanges, fittings, valves) | ASTM A182/A182M F5 / F5a; ASME SA-182 |
| Bar/larger forgings | ASTM A336 F5 |
| Pipe/tube | ASTM A335 P5 / A213 T5 |
| Plate | ASTM A387 Gr 5 |
| Butt-welding fittings | ASTM A234 WP5 |
| Casting | ASTM A217 C5 |
Tolerances and HS codes
- Forged bars (round and square): machining allowance from 2 mm (Ø 6–16 mm) to 24 mm (Ø 400–500 mm) on the diameter. E.g. Ø 100–125 mm finished: +7 mm, tolerance +6 / −0 (length up to 3,500 mm).
- Forged discs: allowance of 4 to 9 mm on the diameter and 3 to 11 mm on the height, plus-only tolerance.
- Cutting and machining: band saw −0 / +5 to +15 mm on length; waterjet +10 % of thickness on the diameter (min. 2 mm); machined parts −0 / +2 to +5 mm on the diameter. See the full tables (INF 002 and INF 003, the same for every alloy).
| Form | NCM (Brazil, 8 digits) | HS (international, 6 digits) | HTS (USA, 10 digits)* | CN (European Union, 8 digits)* |
|---|---|---|---|---|
| Forged bar | 7228.40.00 | 7228.40 | 7228.40.0000 | 7228 40 90 |
| Hot-rolled bar | 7228.30.00 | 7228.30 | 7228.30.8041 | 7228 30 61 |
| Plate (> 10 mm, width ≥ 600 mm) | 7225.40.90 | 7225.40 | 7225.40.3050 | 7225 40 40 |
| Seamless pipe | 7304.19.00 | 7304.19 | 7304.19.5050 | 7304 19 10 |
| Welded pipe | 7306.19.00 | 7306.19 | 7306.19.5150 | 7306 19 00 |
| Flange and fitting | 7307.91.00 | 7307.91 | 7307.91.5030 | 7307 91 00 |
Tariff class: alloy steel (by chemical composition, under the Chapter 72 Notes and Section XV Note 5).
Pipe: 7304.19 and 7306.19 are line pipe for oil and gas pipelines; boiler, heat exchanger or process tubes go under 7304.39/7304.59 (seamless) and 7306.30/7306.50 (welded).
*: US and EU codes for reference. NCM per current legislation (General Rules of Interpretation, Notes to Chapters 72, 74 and 75 and Section XV Note 5). Confirm the final code with your customs broker according to the item size and finish. HS = first 6 digits of the NCM.
Chemical composition (%)
ASTM A182/A182M – F5
| Element | Range (%) |
|---|---|
| C | ≤ 0.15 |
| Mn | 0.30 – 0.60 |
| P | ≤ 0.030 |
| S | ≤ 0.030 |
| Si | ≤ 0.50 |
| Ni | ≤ 0.50 |
| Cr | 4.0 – 6.0 |
| Mo | 0.44 – 0.65 |
Mechanical properties
Annealed or normalized + tempered – ASTM A182 F5
| Property | Value |
|---|---|
| Yield strength (0.2%) | ≥ 275 MPa |
| Tensile strength | ≥ 485 MPa |
| Elongation | ≥ 20% |
| Reduction of area | ≥ 35% |
| Hardness | 143 – 217 HBW |
| F5a (reference) | YS ≥ 450 / UTS ≥ 620 MPa; 187–248 HBW |
Typical physical properties
| Property | Value |
|---|---|
| Density | 7.80 g/cm³ (typical) |
| Modulus of elasticity | ≈ 210 GPa (typical) |
| Thermal conductivity (20 °C) | ≈ 36 W/m·K (typical) |
| Thermal expansion (20–100 °C) | ≈ 11.0 µm/m·K (typical) |
Heat treatment, welding and machining
| Item | Usual practice |
|---|---|
| Service temperature | Up to ≈ 600–650 °C (ASME allows up to 649 °C); oxidation limit ≈ 620 °C. |
| Heat treatment | Full annealing or normalizing (≈ 900–950 °C) + subcritical tempering ≥ 675 °C. |
| Welding | Air hardening: preheat 200–300 °C, controlled interpass, consumable AWS E8018-B6 / E8015-B6 (A5.5), ER80S-B6 (A5.28); PWHT mandatory ≈ 705–760 °C. CE (IIW) ≈ 1.3 is not a useful indicator for 5Cr; follow ASME B31.3/VIII. |
| Machining | Good in the annealed condition; similar to low-alloy Cr-Mo steels. |
Filler metal for welding
The wire composition is usually not identical to the material: each page explains why.
Typical applications
- Refinery furnace and transfer line flanges and fittings
- Cracking and distillation of sulfur-bearing crude
- Valves for hot sulfidizing oil
- Coker and visbreaker furnace piping
- High-temperature heat exchangers
Alternatives: F9 for more severe sulfur/temperature; F22 when the medium is less sulfidizing; F91 for high pressure and creep; 316/317L stainless when naphthenic acid is present; 321/347 for severe H2/H2S.
ASTM A182 F5: complete guide
What ASTM A182 F5 steel is
F5 belongs to the family of Cr-Mo alloy steels for high temperature, between F22 (2¼Cr-1Mo) and F9 (9Cr-1Mo). It is the forged version of A335 P5 pipe. With 4 – 6% chromium, its advantage over the lower-alloy grades is resistance to sulfidation and oxidation, which is why it is the classic material for furnaces and lines carrying heavy sulfur-bearing fractions.
Chemical composition and role of the elements
Chromium forms a stable oxide layer that protects the steel from air and hot H2S; molybdenum increases creep resistance. With 5% chromium the steel already hardens in air after forging or welding, which explains the requirement for preheating and post-weld heat treatment.
Mechanical properties
In the annealed or normalized and tempered condition the standard requires a minimum yield strength of 275 MPa, minimum tensile strength of 485 MPa, minimum elongation of 20%, minimum reduction of area of 35% and hardness between 143 and 217 HBW. Grade F5a, with higher carbon, reaches YS ≥ 450 MPa and UTS ≥ 620 MPa.
Heat treatment
Annealing or normalizing and tempering, with a minimum tempering temperature of 675 °C. Dustre performs the cycle in its own furnaces, with temperature records, as part of its heat treatment service.
Applications
Refinery furnaces, distillation, hydrotreating and cracking units, piping and valves carrying sulfur-bearing hydrocarbons above 300 °C, heat exchangers. Not indicated for aqueous corrosion: in those cases use stainless steel.
Supply forms and Dustre services
Round bars and blocks forged in open die, cut to size on a band saw, with rough or finish machining, heat treatment in our own furnaces and hardness, tensile and impact testing. All material is supplied with a 3.1 inspection certificate and heat traceability.
Frequently asked questions
What is the chemical composition of ASTM A182 F5?
Per ASTM A182/A182M – F5: C ≤ 0.15; Mn 0.30 – 0.60; P ≤ 0.030; S ≤ 0.030; Si ≤ 0.50; Ni ≤ 0.50.
Which standards cover ASTM A182 F5?
Forging (flanges, fittings, valves): ASTM A182/A182M F5 / F5a; ASME SA-182. Bar/larger forgings: ASTM A336 F5. Pipe/tube: ASTM A335 P5 / A213 T5. Plate: ASTM A387 Gr 5. Butt-welding fittings: ASTM A234 WP5. Casting: ASTM A217 C5.
Up to what temperature can ASTM A182 F5 be used?
Up to ≈ 600–650 °C (ASME allows up to 649 °C); oxidation limit ≈ 620 °C.
Which materials can replace ASTM A182 F5?
F9 for more severe sulfur/temperature; F22 when the medium is less sulfidizing; F91 for high pressure and creep; 316/317L stainless when naphthenic acid is present; 321/347 for severe H2/H2S.
