UNS S31653 (316LN) Forgings: Rolled Rings, Flanges, Bars, Shafts and Discs

Nitrogen-enhanced low-carbon 316 austenitic stainless steel, forged to ASTM A182 grade F316LN by Jiangyin Jiangnan Metal Co., Ltd.

1. Grade Designations and Equivalents

On 1.4406 and 1.4429: some mill datasheets give the DIN/EN number for 316LN as 1.4406, while EN cross-reference tables list X2CrNiMoN17-13-3 (1.4429) against S31653. 1.4406 is X2CrNiMoN17-11-2, the lower-molybdenum variant. State the required number on the order and it will be verified before melting.

2. Chemical Composition

Two columns are given because the limits differ slightly by product form. Forged flanges, fittings and valve parts are normally ordered to A182 F316LN, which is the basis used for certification here. A generic 316LN datasheet in wide circulation quotes nitrogen as high as 0.30 % and nickel from 10.0 %; that range does not meet A182 F316LN. If a drawing calls out A240, A479 or an EN grade instead, the applicable limits are confirmed at order entry.

3. Mechanical Properties

Fatigue data should be treated with care. Service results vary substantially because corrosive conditions, type of loading, mean stress and surface condition all affect fatigue behaviour, so no single endurance limit value represents all operating conditions. For heavy forgings, transverse elongation requirements differ from longitudinal, and the test-coupon location is agreed at order stage.

4. Selecting 316LN Rather Than 316 or 316L

5. Melting, Forging and Heat Treatment

Melting route

UNS S31653 is supplied from EAF plus VOD melted stock. ESR material is available where the specification or the end use calls for improved cleanliness and reduced segregation, for example nuclear, subsea or cryogenic duty.

Open-die forging and ring rolling

Billets are upset and drawn on open-die presses, or pierced and rolled into seamless rings. Forging reduction and finish-forging temperature are controlled to break down the as-cast structure so that grain flow follows the contour of the finished part.

Solution annealing

Austenitic stainless steels are supplied in the annealed condition ready for use. Heat treatment during or after fabrication may be needed to remove the effects of cold forming or to dissolve chromium carbides precipitated by thermal exposure. For 316LN the solution anneal is accomplished by heating in the 1040 to 1175 C (1900 to 2150 F) range followed by air cooling or a water quench, depending on section thickness. Plate practice to A240 is often run in a narrower window. The cycle actually used is set to the standard named on the order and recorded on the certificate.

Welding notes for fabrication

Austenitic stainless steels are considered the most weldable of the stainless steels and are routinely joined by all fusion and resistance welding processes. The two main concerns at the joint are avoiding solidification cracking and preserving the corrosion resistance of the weld and heat-affected zones. 316LN is often welded autogenously; where filler metal is required, low-carbon 316L is advisable. Contamination of the weld region with copper or zinc should be avoided, since these elements can form low-melting-point compounds that create weld cracking.

6. UNS S31653 Forged Products Manufactured

7. Industries and Service Conditions

UNS S31653 forgings are specified in chemical and petrochemical processing, nuclear plant, pulp and paper, rubber and plastics, pharmaceutical production and textile machinery, where a welded, corrosion-exposed structure needs low carbon together with molybdenum and nitrogen. In oil and gas the grade is used offshore and onshore, including subsea and deepwater production systems, wellhead and Christmas-tree components, industrial air compressors, power generators and nitrogen generators. Refinery duty includes fluid catalytic cracking units and polythionic-acid service, where resistance to sensitization is the deciding factor. Heat-transfer and energy equipment covers shell and tube heat exchangers, condensers, evaporators, preheaters, recuperators and waste-heat recovery, along with columns, towers, tanks, silos, crystallizer equipment and process modules. The alloy is also used for medical products such as trauma nails, orthopaedic and neurological devices and surgical instruments, although implant material is normally ordered to the dedicated implant specifications rather than to A182.

8. Testing, Inspection and Certification

Ultrasonic examination is carried out to the standard named on the order, including EN 10228-3, SEP 1921 and ASTM A388. Further testing available on request covers chemical analysis, room-temperature and low-temperature tensile and impact testing, hardness survey, grain size, intergranular corrosion testing to ASTM A262 practice E, ferrite measurement, positive material identification, dye-penetrant examination and dimensional reporting against the drawing. Certificates are issued to EN 10204 3.1, or to EN 10204 3.2 with witness and endorsement by a third-party body such as SGS, BV, TUV, DNV or Lloyd's.

9. Information Needed for a Quotation

A quotation can be prepared from the drawing or the finished dimensions plus machining allowance, the grade and governing specification such as ASTM A182 F316LN or EN 1.4429, the quantity and required delivery date, the delivery condition as forged or rough machined or finish machined, the level of non-destructive testing and certification, and any supplementary requirements covering melting route, test-coupon location, impact test temperature or marking. Drawings in PDF, STEP or DWG can be sent to sales@steelforgepieces.com and the reply will include weight, tooling approach and lead time.

10. Frequently Asked Questions

Related stainless steel forging grades

Data on this page is drawn from the ASTM A182/A182M F316LN grade tables, published 316LN (UNS S31653) mill datasheets for A240 and A479 product, and EN steel cross-reference tables. Figures are for guidance only; the governing purchase specification takes precedence. Last updated October 2026.