X1NiCrMoCu31-27-4 Forgings (EN 1.4563 / UNS N08028 / Alloy 28)

Designations and equivalent grades

The alloy appears under several names across national standards and mill catalogues. On forging orders, state the EN number 1.4563 or UNS N08028. Commercial names such as Sanicro 28 and Nicrofer 3127 LC belong to their respective producers and describe a proprietary product within this chemistry rather than a standard grade.

Chemical composition

The European and ISO chemistry windows are not identical. EN 1.4563 is the tighter of the two, with carbon at 0.020 % maximum and nickel held between 30.0 and 32.0 %, while ISO Alloy 28 and UNS N08028 allow carbon to 0.03 % and nickel to 34 %. Where a project calls for 1.4563, material is melted to the EN window.

Balance iron. The pitting resistance equivalent calculated from the nominal 27 Cr and 3.5 Mo analysis as PREN = %Cr + 3.3 x %Mo is approximately 38.6. Nitrogen is not credited because EN 1.4563 specifies a maximum only.

Mechanical properties

Solution annealed condition at 20 °C

R_p0.2 and R_p1.0 are the 0.2 % and 1.0 % offset proof strengths. Elongation A is based on a gauge length of 5.65 times the square root of the original cross-sectional area.

Impact toughness

The structure is fully austenitic, so toughness remains high down to cryogenic temperatures. Published forging values are KV above 100 J longitudinal and above 60 J transverse at +20 °C, with transverse KV above 60 J retained at -196 °C. The grade meets EN 13445-2 UFPV-2 at a minimum of 60 J at -270 °C and EN 10216-5 at a minimum of 60 J at -196 °C.

Strength at elevated temperature

Thinner sections carry higher minima, for example 200 MPa R_p0.2 at 50 °C. Approximate creep rupture strength is 186 MPa at 600 °C for 10 000 h and 146 MPa at 600 °C for 100 000 h.

Cold worked condition

High strength cold worked product for oil and gas service is a different delivery condition and should not be confused with annealed forgings. Published cold worked grades reach R_p0.2 of at least 760 MPa at a maximum of 35 HRC, and at least 860 MPa at a maximum of 37 HRC. Open-die forgings are normally supplied solution annealed, where hardness is 90 HRB maximum.

Physical properties

Two slightly different thermal conductivity figures are published for this grade. Both are given rather than averaged.

Corrosion performance

The alloy was developed for wet process phosphoric acid and remains a standard material for evaporator service in that duty. In laboratory testing in contaminated 95 % superphosphoric acid at 200 °C over 20 days the corrosion rate was 0.03 mm per year, matching Alloy G and well below Alloy 904L at 0.10 mm per year and UNS N08020 at 0.23 mm per year.

Limitations. For pure seawater duty superduplex 2507 is more resistant than this grade, and prolonged exposure above 600 °C causes intermetallic embrittlement. Both points are raised at enquiry stage where the service conditions make another grade the better choice.

Standards, approvals and certification

EN 10222-5 covers stainless steel forgings for pressure purposes in general. Confirm grade inclusion against the current edition of that standard for a specific project.

Forging, heat treatment and machining

Melting is by electric arc furnace with VOD refining, with ESR remelting available where cleanliness requirements call for it. Hot working runs from 1150 °C down to 850 °C. A solution anneal then restores corrosion resistance at 1100 to 1160 °C (2010 to 2120 °F) for 10 to 30 minutes followed by a water quench; an alternative solutioning range of 1050 to 1150 °C is also published. Because the grade is fully austenitic and work hardens readily, finish forging below 850 °C risks cracking and high residual stress, and omitting the post-forge solution anneal leaves the part open to intergranular attack in acid service.

Machining requires lower cutting speeds than standard austenitic grades. Compared with free-machining 316 and 316L, turning speed must be reduced by roughly 50 to 55 % with coated cemented carbide tooling, and a similar reduction applies to other operations. Feeds should be reduced only slightly and with care, since light feeds promote work hardening. Cold bending to small radii is possible without a subsequent anneal, though heat treatment after bending is advisable for service above 400 °C. For welding the grade falls in ISO welding group 8.2 and no preheat is required.

Forged products in 1.4563 / N08028

Production is open die and ring rolling to customer drawings or dimension lists rather than from a fixed catalogue. Typical items are seamless rolled rings and forged rings, flanges and blind flanges, round bars and billets, discs and blanks, sleeves and bushings, hollow shafts, spindles and eccentric shafts, tube sheets, nozzles, valve bodies, bonnets, seat rings and stems, pump and compressor parts, gear blanks and heat exchanger components.

Information needed for a quotation

Quoting requires the grade and standard, for example 1.4563 to EN 10250-4 or N08028 to ASTM B668 chemistry, a drawing or rough dimensions with machining allowance, the quantity, the required delivery condition and testing scope, and the certificate type. Where an end user specification or approved vendor requirement applies, send it with the enquiry, since it normally dictates the melt route, NDT class and third party involvement.

Frequently asked questions

Data sheet reviewed 9 October 2026 by the technical department, Jiangyin Jiangnan Metal Co., Ltd. Questions on this data: sales@steelforgepieces.com, +86-189-2135-9659. A plain text version of this page is available at X1NiCrMoCu31-27-4.md.