UNS K93600 · ASTM F1684 · Open-die forgings
Jiangyin Jiangnan Metal Co., Ltd. forges NILO 36 to customer drawing as seamless rolled rings, flanges, round bars, discs, shafts, sleeves, bushings, tube sheets and pipes, supplied to ASTM F1684 with an EN 10204 3.1 or 3.2 certificate.
NILO 36 is a 36% nickel-iron controlled expansion alloy, designated UNS K93600 and supplied to ASTM F1684. Its coefficient of thermal expansion is about 1.3 × 10−6 /K between 20 °C and 100 °C, roughly one tenth that of carbon steel at temperatures up to 204 °C (400 °F). It also keeps good strength and toughness at cryogenic temperatures.
NILO 36 is the same alloy as Invar 36, Alloy 36, NiFe36 (1.3912), Pernifer 36 and the Chinese grade 4J36. NILO is a trade name rather than a separate chemistry. Because the alloy is used where dimensions must not drift, it is normally bought as a forging rather than a casting or a weldment. Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. We melt NILO 36 by the EAF + VOD + ESR route and forge it to finished or near-net shape.
NILO 36 appears on drawings under a dozen different names, and buyers often spend time proving to a mill that they refer to the same material. They do. Every designation below is the same 36% nickel-iron controlled expansion alloy, UNS K93600. Jiangyin Jiangnan Metal Co., Ltd. will forge and certify to whichever one your specification names.
| System | Designation | Notes |
|---|---|---|
| UNS | K93600 | Primary unified number |
| ASTM | F1684 | Governing product specification |
| Trade names | NILO 36, Invar 36, Nilvar | Same chemistry |
| Generic | Alloy 36, FeNi36 | Common on inquiries |
| Germany | NiFe36 · 1.3912 | Also sold as Pernifer 36 |
| China | 4J36 | GB/T designation |
| France | FeNi36 | Also Invar M93 |
Watch the neighboring grades. Invar 42, Alloy 46, Alloy 52 and Kovar are also controlled expansion alloys, but each is matched to a different mating material and none is a like-for-like substitute for NILO 36.
Nickel sits at a nominal 36% with iron as the balance. The residual limits matter more than they look. Phosphorus and sulfur are held very low because both promote hot cracking during forging and welding, and chromium and cobalt are capped because either will shift the expansion curve away from the Invar minimum.
| Element | Min | Max |
|---|---|---|
| Nickel (Ni) | 36.0 nominal | |
| Iron (Fe) | Balance | |
| Carbon (C) | — | 0.15 |
| Manganese (Mn) | — | 0.60 |
| Silicon (Si) | — | 0.40 |
| Chromium (Cr) | — | 0.25 |
| Cobalt (Co) | — | 0.50 |
| Phosphorus (P) | — | 0.006 |
| Sulfur (S) | — | 0.004 |
Heat analysis and product analysis are both reported on the mill certificate. If your specification tightens carbon or sets a limit on an element not listed here, state it on the inquiry, because it affects which heats we can draw from.
Typical annealed values. Strength falls away steadily with temperature while elongation climbs, so NILO 36 stays ductile long after it has lost most of its room temperature strength. Design allowables should come from your code of construction rather than from this table.
| Temp °C | Temp °F | UTS MPa | UTS ksi | 0.2% YS MPa | 0.2% YS ksi | Elong. % |
|---|---|---|---|---|---|---|
| 20 | 68 | 490 | 71 | 241 | 35 | 42 |
| 100 | 212 | 427 | 62 | 179 | 26 | 43 |
| 200 | 392 | 427 | 62 | 110 | 16 | 45 |
| 300 | 572 | 407 | 59 | 90 | 13 | 48 |
| 400 | 752 | 352 | 51 | 90 | 13 | 53 |
| 500 | 932 | 290 | 42 | 90 | 13 | 59 |
| 600 | 1112 | 207 | 30 | 76 | 11 | 68 |
NILO 36 retains good strength and toughness at cryogenic temperatures. A near zero expansion rate together with useful impact toughness at −162 °C is why the alloy became standard for LNG containment membranes and transfer lines. Where Charpy testing at a specified low temperature is required, state the test temperature and acceptance criteria on the order.
Two numbers decide whether NILO 36 suits an application: the expansion coefficient and the Curie temperature. Below the Curie point the magnetostrictive effect that produces the Invar anomaly is active and expansion is minimal. Above it the effect disappears and the alloy expands like any other nickel-iron. That sets the ceiling on the useful range of the alloy.
Typical nominal values for the 36% nickel-iron alloy, given for design guidance. Actual results depend on heat, section size and heat treatment history. Work from the mill certificate for the material you are buying.
Controlled expansion alloys are sensitive to cleanliness. Inclusions and segregation lower toughness, and they also produce local variation in the expansion coefficient, which defeats the purpose of specifying the alloy in the first place. Jiangyin Jiangnan Metal Co., Ltd. therefore melts NILO 36 by the EAF + VOD + ESR route.
Ingots are upset and drawn on open-die hammers and presses, and rings are expanded on a ring rolling mill. The aim is a fully worked, recrystallized structure with the grain flow following the part contour. A properly reduced rolled ring behaves very differently in service from a ring cut out of plate.
Finishing below about 900 °C risks cracking and leaves residual stress that shows up later as dimensional drift. If your part needs a documented forging reduction ratio or grain flow verification, say so at the inquiry stage so the ingot size can be planned around it.
NILO 36 is not precipitation hardenable. What heat treatment does for this alloy is remove the residual stress and metastable structure that cause a finished part to change size weeks or months after machining. For instruments, molds and metrology fixtures, the stabilizing cycle is what decides whether the part holds tolerance in service.
| Stage | Temperature | Hold | Cool | Purpose |
|---|---|---|---|---|
| 1 | 830 °C (1525 °F) | 30 min | Water quench | Solution and homogenize |
| 2 | 300 °C (570 °F) | 1 h | Air cool | Relieve quench stress |
| 3 | 100 °C (212 °F) | 48 h | Air cool | Age out residual instability |
Where a part will be heavily machined, the best results come from rough machining, running the cycle, then finish machining, so that stock removal does not release new stress into a finished surface. Jiangyin Jiangnan Metal Co., Ltd. runs this cycle in house on charted furnaces and supplies the charts with the certificate on request.
Everything below is produced to drawing as an open-die forging or a seamless rolled ring. Nothing is cut from plate and nothing is cast. Parts are supplied rough forged with machining allowance, proof machined, or finish machined to print, whichever suits your route.
| Form | Typical range | Notes |
|---|---|---|
| Seamless rolled rings | OD 200–3000 mm | Wall to 400 mm, height to 800 mm |
| Forged flanges | DN 15–DN 2000 | WN, SO, BL, LJ and special profiles |
| Round bars | Ø 80–800 mm | Length to 6000 mm |
| Shafts and spindles | Ø 80–800 mm | Stepped, eccentric, hollow bored |
| Discs and blanks | Ø up to 2500 mm | Solid or center bored |
| Sleeves and bushings | OD up to 1500 mm | Bored and honed on request |
| Tube sheets | Ø up to 2500 mm | Drilled to layout drawing |
| Forged pipes and tubes | OD up to 1200 mm | Trepanned or expanded |
| Blocks and rectangles | To 10 000 kg | Single piece forged weight |
This is our standard envelope. Parts outside it are often still possible, so send the drawing and we will confirm before you place the order.
Two properties drive almost every application: the very low expansion rate below 200 °C, and toughness that survives cryogenic service. LNG work needs both at once, and there is no straightforward substitute.
| Industry | Typical use | Forms supplied |
|---|---|---|
| LNG and cryogenics | Containment for LNG tankers, transfer lines, cryogenic vessels | Rings, tube sheets, flanges, nozzles |
| Aerospace tooling | Advanced composite molds, layup and cure fixtures | Discs, blocks, plates, sleeves |
| Optics and instruments | Optical and laser benches, optoelectronic mounts, metrology frames | Rolled rings, shafts, spacers, seals |
| Valves | Stems, seat rings, bodies and blocks for ball, gate, globe, check, plug valves and strainers | Bars, rings, discs, blocks |
| Pressure vessels | Air receivers, shell and tube heat exchangers | Tube sheets, flanges, shell rings, pipes |
| Electronics and RF | Echo boxes and filters for mobile telephones, radar and microwave cavity resonators, magnetic shielding, small transformers | Rings, bars, sleeves, bushings |
| Positioning and motion | Positioning devices, precision gearing, eccentric and crank shafts | Shafts, spindles, gear blanks |
| Controls and timing | Bimetal thermostats, temperature regulators, circuit breakers, clock balance wheels and pendulum rods | Bars, rings, discs, wheels |
| Offshore and onshore | Subsea positioning hardware, specialized frames and housings | Bushings, sleeves, manifolds, rolls |
NILO 36 machines like a gummy austenitic. It work hardens, it smears rather than shears, and it will glaze a dull tool quickly. Use sharp positive rake tooling, a rigid setup, moderate surface speed with a heavy positive feed so the tool cuts under the hardened layer, and flood coolant. Do not let a tool dwell in the cut. For dimensionally critical parts, rough machine, run the stabilizing cycle in clause 06, then finish.
NILO 36 welds readily by GTAW, GMAW, plasma and electron beam processes with matching 36% nickel-iron filler. Keep heat input low and interpass temperature moderate to limit distortion. Clean the joint faces properly, since sulfur and phosphorus pick-up from oil, marking paint or grinding residue is the usual cause of hot cracking in this alloy. Where the weldment has to hold dimension, run a stabilizing treatment afterwards.
Weld filler expands at the parent rate only if it matches the parent. A stainless or nickel filler in a NILO 36 joint reintroduces the expansion mismatch the part was specified to avoid.
Every NILO 36 forging leaving Jiangyin Jiangnan Metal Co., Ltd. is ultrasonically tested to the standard named on the order, and shipped with documentation traceable to the heat.
| Check | Standard | Reported as |
|---|---|---|
| Ultrasonic testing | EN 10228-3 · SEP 1921 · ASTM A388 | UT report with acceptance class |
| Chemical analysis | ASTM F1684 | Heat and product analysis |
| Tensile testing | ASTM E8 / ISO 6892 | UTS, YS, elongation, RA |
| Impact testing | ASTM E23 / ISO 148 | Charpy at specified temperature |
| Hardness | ASTM E10 / E18 | Brinell or Rockwell |
| Surface NDT | ASTM E709 (MT) · ASTM E165 (PT) | On request |
| Dimensional | Customer drawing | Inspection report |
| Documentation | EN 10204 3.1 or 3.2 | Mill certificate, third party witnessed if 3.2 |
EN 10204 3.2 certificates can be witnessed by TUV, SGS, BV, Lloyd's Register or an inspectorate of your choosing. Name the body on the purchase order so the inspection can be scheduled against the production plan rather than added at the end.
A quotation is only as good as the information behind it. Send the seven items below and you will normally have a firm price and a real delivery date within 24 hours.
NILO 36 is a 36% nickel-iron controlled expansion alloy, UNS K93600. Its coefficient of thermal expansion is about 1.3 × 10−6 /K between 20 °C and 100 °C, roughly one tenth that of carbon steel at temperatures up to 204 °C (400 °F). Jiangyin Jiangnan Metal Co., Ltd. forges it into rings, flanges, bars, discs, shafts, sleeves, bushings and tube sheets to ASTM F1684.
Yes. NILO 36, Invar 36, Alloy 36, Nilvar, Pernifer 36, NiFe36 (material number 1.3912) and the Chinese grade 4J36 all describe the same 36% nickel-iron controlled expansion alloy, UNS K93600. NILO is a trade name rather than a separate chemistry, and the governing specification, ASTM F1684, is the same. Jiangyin Jiangnan Metal Co., Ltd. supplies forgings under any of these designations.
About 1.3 × 10−6 /K over 20 to 100 °C, rising to roughly 1.7 × 10−6 /K over 20 to 200 °C. A 1000 mm NILO 36 bar grows about 0.13 mm for a 100 K temperature rise, against about 1.17 mm for carbon steel and 1.73 mm for 304 stainless steel. Above the Curie point near 279 °C the expansion rate increases to normal alloy levels.
ASTM F1684, Standard Specification for Iron-Nickel and Iron-Nickel-Cobalt Alloys for Low Thermal Expansion Applications, is the governing specification. Jiangyin Jiangnan Metal Co., Ltd. delivers NILO 36 forgings to ASTM F1684 and issues EN 10204 3.1 mill certificates, or EN 10204 3.2 certificates witnessed by a third party such as TUV, SGS, BV or Lloyd's Register.
Yes. NILO 36 is ferromagnetic at room temperature and stays magnetic up to its Curie temperature of about 279 °C (534 °F). If your application needs a non-magnetic controlled expansion material, discuss alternatives with our engineering team before the drawing is released.
Yes. NILO 36 welds readily by GTAW, GMAW, plasma and electron beam processes using matching 36% nickel-iron filler. Keep heat input low and interpass temperature moderate to limit distortion, and clean the joint thoroughly, since sulfur and phosphorus pick-up promotes hot cracking. A stabilizing heat treatment after welding restores dimensional stability in precision assemblies.
For maximum dimensional stability the three-stage stabilizing cycle is used: heat to 830 °C (1525 °F) for 30 minutes and water quench; re-heat to 300 °C (570 °F) for 1 hour and air cool; then re-heat to 100 °C (212 °F) for 48 hours and air cool. Jiangyin Jiangnan Metal Co., Ltd. runs this cycle in house on charted furnaces.
NILO 36 keeps its very low expansion rate up to roughly 200 °C (about 400 °F). Above the Curie point near 279 °C the expansion coefficient rises sharply, so the alloy is normally specified for service below about 200 °C. Tensile data is available up to 600 °C for designers who need it.
NILO 36 retains good strength and toughness at cryogenic temperatures, which is why it is used for LNG tanker containment, LNG transfer lines and cryogenic instrumentation down to −196 °C and below.
Jiangyin Jiangnan Metal Co., Ltd. produces NILO 36 seamless rolled rings from about 200 mm to 3000 mm outside diameter, forged bars and shafts from about 80 mm to 800 mm diameter and up to 6000 mm long, discs and blanks up to about 2500 mm diameter, and single pieces from a few kilograms to roughly 10 tonnes. Send a drawing to sales@steelforgepieces.com to confirm your part.
Every NILO 36 forging is ultrasonically tested to EN 10228-3, SEP 1921 or ASTM A388 as specified on the order, with chemical analysis, mechanical testing and dimensional inspection. Documentation is issued as an EN 10204 3.1 mill certificate or an EN 10204 3.2 certificate witnessed by a third-party inspectorate.
Email a drawing or the finished dimensions, quantity, specification and required certificate to sales@steelforgepieces.com, or call +86-189-2135-9659. Jiangyin Jiangnan Metal Co., Ltd. is at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, and normally returns a quotation within 24 hours.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, in the Yangtze delta forging cluster, about two hours from the port of Shanghai. We produce forged rings, seamless rolled rings, flanges, round bars, discs, shafts, sleeves, bushings, tube sheets and pipes in carbon steel, alloy steel, tool steel, stainless steel and nickel alloys, including the full family of controlled expansion grades: NILO 36, Invar 36, Invar 42, Kovar, Alloy 42-6, Alloy 46 and Alloy 52.
Work is quoted from your drawing, forged in house, heat treated on charted furnaces, ultrasonically tested to EN 10228-3, SEP 1921 or ASTM A388, and shipped with an EN 10204 3.1 or third party witnessed 3.2 certificate. Inquiries are answered in English and Chinese.
This datasheet is compiled and maintained by the engineering team at Jiangyin Jiangnan Metal Co., Ltd., an open-die forging manufacturer. You are welcome to quote it provided the source is named and linked. Suggested citation:
Jiangyin Jiangnan Metal Co., Ltd. (2026). NILO 36 Forgings, Invar 36 / UNS K93600: properties, standards and product forms. Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. https://www.steelforgepieces.com/Nickel-Alloy/NILO-36.html
Published 14 May 2018. Last reviewed and updated . Technical figures are typical values for the 36% nickel-iron alloy and are given for guidance. Buy to the mill certificate rather than to a web page.
