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X40MnCr18 / 1.3817 Forgings: Rings, Bars, Flanges and Shafts

Austenitic non-magnetizable Mn-Cr steel to SEW 390, open-die forged to drawing by Jiangyin Jiangnan Metal Co., Ltd.

Designation

X40MnCr18

Material No.

1.3817

Standard

SEW 390

Structure

Austenitic, non-magnetizable

Permeability

below 1.01

Melting

EAF + VOD / ESR

1. What the grade is and where it is used

X40MnCr18 belongs to the family of non-magnetizable steels whose delivery conditions are set out in SEW 390. Manganese at 17 to 19 percent holds the structure fully austenitic at room temperature, so the steel does not turn ferromagnetic and does not distort a magnetic field around it. The published remark on 1.3817 states both the strength and the limit of the grade: it is used for construction components that place no high demand on corrosion resistance, and if the component is exposed to corrosive loading, electro-chemical protection is required.

Two fabrication points affect the design of the forging. 1.3817 has good flame-cutting properties and is weldable using standard welding procedures. Machinability, on the other hand, is poor, which on forged blanks argues for generous rough-turning stock, rigid set-ups and conservative feeds.

Typical applications for non-magnetizable Mn-Cr forgings

• Structural and clamping components in and around electrical machines, where a ferromagnetic part would distort flux or heat up through induced currents.
• Housings, collars and support rings for instruments that have to read a magnetic field undisturbed. The same reasoning lies behind non-magnetic drill collars, which were developed so that magnetic surveying instruments inside the drill string can read the well trajectory.
• End plates, pressure rings, wedges and fasteners in generator and transformer construction.

Point to check before you order: generator retaining rings were historically forged from an 18Mn-5Cr steel of broadly this type and cold-expanded to raise the yield strength. That application has since moved to the 18Mn-18Cr composition, which is now the only composition satisfying ASTM A289, because the older 18Mn-5Cr rings proved susceptible to stress-corrosion cracking in relatively mild, moist environments. X40MnCr18 should not be treated as a drop-in retaining-ring material against current ASTM A289. Ask us about 18Mn-18Cr for that job.

2. Chemical composition of X40MnCr18 (1.3817)

Published ranges for this grade are not consistent between sources. Several European stockist sheets quote C 0.35 to 0.45 percent, Si 0.40 to 0.80 percent and a lower chromium band of 1.50 to 3.00 percent, against the SEW 390 band of 3.00 to 5.00 percent. If your drawing or your end customer fixes the chromium window, state it on the enquiry and we will melt to that window and evidence it on the EN 10204 certificate. A web table is not a purchase specification.

3. Mechanical properties

Mechanical properties of 1.3817 depend on section size, delivery condition and any cold work, and the figures circulating on data aggregator sites for this grade contradict each other. Instead of republishing doubtful numbers, we issue the tested values for your heat and your section, covering proof strength Rp0.2, tensile strength Rm, elongation A, reduction of area Z and impact energy KV, on the EN 10204 3.1 or 3.2 certificate that travels with the forgings. Send us the acceptance criteria you have to meet and we will confirm feasibility for the section before accepting the order.

Magnetic acceptance is usually the governing criterion for this grade. Relative permeability for 1.3817 is below 1.01. If your specification sets a tighter limit or calls for permeability measurement on each piece, state it at enquiry stage.

4. Forged product range in X40MnCr18

Manufacturing and quality route

• Melting: EAF plus VOD as standard, with ESR available where a cleaner and more homogeneous ingot is required.
• Forming: open-die forging and ring rolling, with the forging ratio agreed to suit the section.
• Heat treatment: solution annealing to restore the fully austenitic, non-magnetizable condition after hot work.
• Non-destructive testing: ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388, to the acceptance class you nominate.
• Documentation: EN 10204 3.1 works certificate, or 3.2 countersigned by a third-party inspectorate such as TUV, SGS, BV or Lloyd's on request.

5. Other names for 1.3817

If you are checking an old drawing or a European mill certificate, the same SEW 390 composition appears under several proprietary names: AMANOX 3817 from Deutsche Edelstahlwerke Specialty Steel, BGH 3817 from BGH Edelstahl Siegen, RemAM 3817 from Remystahl and SIDUR 3817 from SIJ. Other suppliers list it simply as 1.3817 or X40MnCr18. Nitrogen-strengthened austenitic grades such as Nitronic 32 are separate alloys with different chromium and nitrogen levels, not substitutes, so confirm with us before cross-substituting.

6. Frequently asked questions

Related forged grades

Maintained by the technical sales department of Jiangyin Jiangnan Metal Co., Ltd. Last updated 10 October 2026. Property data is summarised from the SEW 390 and 1.3817 material datasheets and mill literature. Values are indicative and do not replace an order-specific mill certificate.