ASTM A182 F62 Forgings UNS N08367 rings, flanges, shafts, discs and tube sheets, melted and forged in one works

Limits below are the requirements of ASTM A182/A182M for grade identification symbol F62, UNS N08367. Because the steel is melted here, chemistry is verified at the furnace with optical emission spectrometry rather than taken from a supplier certificate.

Heat analysis is reported on every certificate. Product analysis is available on request. Positive material identification with a handheld analyser can be added as a shipment check.

Pitting resistance and PREN

Project specifications often set a minimum PREN for 6 % molybdenum grades. Which formula applies matters, because the nitrogen coefficient differs between the published versions, so name the formula on the purchase order. One published guide treats a PREN above 40 as the working threshold for dependable seawater service at ambient to moderate temperatures. We report the full heat analysis, so you can calculate PREN by whichever formula your specification names rather than relying on a single quoted number.

Read these as acceptance minima, not as typical values. ASTM A182 calls for one tension test per heat on austenitic grades, and specimens are removed only after all heat treatment is finished. Test blanks get about the same amount of working as the finished forging and are heat treated with it.

Machining notes

F62 is ductile in the solution-annealed condition but work hardens fast and needs more power at the tool than plain carbon steel. Chips come off stringy and tough. As a starting point only, around 70 sfm for turning and milling and 50 sfm for drilling, with a rigid setup, positive feed and plenty of coolant. Tune these against your own tooling rather than copying them onto a process sheet.

After hot working, forgings are cooled below 1000 °F [538 °C] before heat treatment starts. Where the temperature straight after hot working has not dropped below the minimum solution annealing temperature, A182 also allows austenitic grades such as F62 to be rapid quenched individually from the forging heat. Three high-temperature car-bottom furnaces cover the solution temperature this grade needs, and two 15 m well-type furnaces allow long shafts to be quenched vertically.

How we melt it

F62 runs through the electric arc furnace, is refined in a ladle furnace and is decarburised under vacuum, which is the route that gives both the 0.030 % maximum carbon and the tight 0.18 to 0.25 % nitrogen band this grade depends on. Protective-atmosphere electroslag remelting is available where an order calls for it, and it is the route we use for nitrogen-alloyed grades that need extra cleanliness. Maximum heat size is 60 tonnes. A182 permits stainless grades to be melted by electric furnace with optional separate degassing and refining, by vacuum furnace, or by either route followed by vacuum or electroslag consumable remelting, so both of our routes meet the specification. Enough discard is taken to keep the material free of injurious piping and undue segregation.

This is an open-die forge and ring rolling mill, so parts are made to your drawing rather than picked off a shelf. In F62 we regularly produce seamless rolled rings and forged rings, weld neck, blind and slip-on flange blanks, round bars and billets, forged discs and disc blanks, hollow forgings, sleeves and bushings, shafts, spindles and eccentric shafts, tube sheets, nozzles, valve bodies, valve stems, seat rings and valve blocks, plus tube and pipe blanks bored from solid.

UNS N08367 was developed as a seawater-resistant material and has since been used across a wide range of corrosive service. Producer literature lists flue-gas desulphurisation scrubbers, reverse osmosis, distillation columns, offshore oil and gas, and heat exchangers, backed by more than 25 years of seawater service.

Our F62 forgings go into seawater, firewater and subsea pipework with the associated risers, manifolds, pressure vessels, valves and heat exchangers. Other regular end uses are desalination plant including high-pressure reverse osmosis trains and seawater piping, flue-gas desulphurisation and other pollution-control equipment in power generation, pulp and paper digesters, liquor tanks and paper machines, chemical and pharmaceutical reaction vessels, and mining, metallurgical and marine equipment. Forged rings, bars and spindles also serve as corrosion-resistant components in power transmission, gearboxes, turbines and gas compressors.

Where sour service governs rather than chloride pitting, tell us at enquiry, because NACE MR0175 and ISO 15156 bring their own hardness and heat-treatment constraints that sit on top of the A182 requirements.

The works holds CCS, BV, DNV, LR and NK classification society approvals and runs its own laboratory, so chemistry, tensile, impact and ultrasonic work is done in house rather than subcontracted.

ASTM A182 provides for intergranular attack testing to ASTM A262 practices on austenitic stainless steels where a purchaser specifies it as a supplementary requirement, which is why that row is worth naming on the order rather than assuming it. Certificates are issued to EN 10204 3.1, or to EN 10204 3.2 witnessed by BV, DNV, LR, SGS, TUV or your own inspector. Supporting records cover heat-treatment charts, NDT reports, dimensional reports and PMI results, and traceability runs from the melt number through forging, heat treatment and machining to shipment.

Composition and property limits for N08367 differ between the plate, pipe, bar and forging specifications, so confirm specification, edition and product form on the purchase order.

Related grades and product pages

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• Seamless rolled rings
• Forged discs
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