Nickel Alloy 36 Bars, Invar 36 Rods, UNS K93603 Round Bars, Invar 36 Round Bar, Invar 1.3912 Bar, Werkstoff Nr. 1.3912 Bars Manufacturer in India
Jade Alloys supplies Alloy 36 (Invar 36) round bars, a nickel-iron alloy known for its uniquely low coefficient of thermal expansion. Invar 36 round bar (Alloy 36) is a nickel-iron alloy made of approximately 36% nickel and 64% iron (UNS K93600 / K93603, Werkstoff Nr. 1.3912, ASTM F1684). Its defining property is an extremely low coefficient of thermal expansion, about 1.3 µm/m·°C between 20 and 100 °C, roughly one-tenth that of carbon steel, so precision parts keep their dimensions as temperature changes.
Jade Alloys stocks and exports Invar 36 round bars from 3 mm to 800 mm diameter in cold drawn, bright, centreless ground, peeled, polished and forged finishes, supplied with test certificates (EN 10204 3.1 on request) from Mumbai, India to customers worldwide. Also available as hex, square, flat, hollow and threaded bar.
Quick Section Links
- Invar 36 Round Bar at a Glance
- Why Choose Invar 36? Thermal Expansion Compared
- Alloy 36 / Invar 36 Round Bar Specifications
- Surface finish codes
- Equivalent Grades & Designations of Alloy 36 Round Bars
- Chemical Composition (%) of Alloy Invar 36 Round Bars
- Mechanical & Physical Properties of Invar 36 Round Bars
- Invar 36 Bar Forms in Stock
- Applications of Invar 36 Round Bars
- Invar 36 vs Invar 42 vs Kovar vs Super Invar
- Machining & Fabrication Tips
- Frequently Asked Questions
Invar 36 Round Bar at a Glance
| Common names | Invar 36, Alloy 36, Nilo 36, FeNi36, 4J36, Invar 1.3912 |
|---|---|
| UNS | K93600 / K93603 |
| Werkstoff Nr. / DIN | 1.3912 / Ni36 (DIN 17745) |
| Specification | ASTM F1684 (Fe-Ni controlled-expansion alloys) |
| Nominal composition | Ni 36%, Fe balance |
| Thermal expansion (20–100 °C) | Approx. 1.3 × 10⁻⁶ /°C [VERIFY against lab/MTC data] |
| Density | Approx. 8.1 g/cm³ |
| Melting point | Approx. 1430 °C (2606 °F) |
| Round bar sizes | 3 mm – 800 mm diameter |
| Condition | Annealed, cold drawn, hot rolled, forged |
| Certification | Mill Test Certificate; EN 10204 3.1 on request [VERIFY] |
| Supply | Ex-stock Mumbai; worldwide export; cut-to-size |
Why Choose Invar 36? Thermal Expansion Compared
Most metals grow noticeably when heated. Invar 36 does not within its useful range (up to roughly 200 °C), because its magnetic behaviour offsets normal lattice expansion. That is why it is specified wherever a few microns of drift can ruin accuracy.
| Material | Approx. CTE (µm/m·°C, room temp. to ~100 °C) |
|---|---|
| Invar 36 / Alloy 36 | ~1.3 |
| Invar 42 / Alloy 42 | ~4–5 |
| Kovar (Alloy 29-17) | ~5–6 |
| Carbon steel | ~12 |
| Stainless steel 304 | ~17 |
| Aluminium | ~23 |
Alloy 36 / Invar 36 Round Bar Specifications
| Item | Details |
|---|---|
| Standards | EN, DIN, JIS, ASTM, BS, ASME, AISI |
| Round bar size | Diameter 3 – 800 mm |
| Hex bar size | 2 – 100 mm A/F |
| Flat bar size | Thickness 2 – 100 mm; width 10 – 500 mm |
| Square bar size | 4 – 100 mm |
| Angle bar size | 3×20×20 mm to 12×100×100 mm |
| Rectangular section | 3.0 – 12.0 mm thickness; sizes 33×30 mm to 295×1066 mm |
| Channel bar | 80×40 mm to 150×75 mm section; 5.0 – 6.0 mm thickness |
| Hollow bar | 32 mm OD × 16 mm ID to 250 mm OD × 200 mm ID |
| Threaded bar / billet size | 1/2″ to 495 mm diameter (see our threaded rod weight chart) |
| Finish | Cold (bright) drawn, centreless ground, hot rolled, smooth turned, peeled, slit rolled edge, hot rolled annealed, rough turned, polished, black |
| Tolerance | h8, h9, h10, h11, h12, h13, k9, k10, k11, k12 or as per customer requirement |
| Surface | Bright, hot rolled pickled, cold drawn, sand blasted, polished, hairline |
| Condition | Annealed, cold drawn, stress-relieved |
| Technique | Hot rolled, cold drawn, cold rolled, forged |
| Processing | Cut-to-size on request [VERIFY max cutting size] |
| Forms | Round, rod, hex (A/F), square, flat, hollow, threaded, half-round, triangle, rectangle, T-bar, channel, precision ground, billet, ingot, rings, blocks, forgings |
Surface finish codes
| Code | Meaning | Code | Meaning |
|---|---|---|---|
| CD | Cold drawn | P | Polished |
| BD | Bright drawn | SRE | Slit rolled edge |
| CG | Centreless ground | HF | Hot finished |
| CF | Cold finished | HRAP | Hot rolled annealed & pickled |
| P&T | Peeled and turned | RT | Rough turned/peeled |
| ST | Smooth turned | PR | Peeled and reeled |
Equivalent Grades & Designations of Alloy 36 Round Bars
| System | Designation |
|---|---|
| Trade names | Invar 36®, Alloy 36, Nilo 36, FeNi36 |
| UNS | K93600, K93603 |
| Werkstoff Nr. | 1.3912 |
| ASTM | ASTM F1684 |
| DIN | DIN 17745 – Ni36 |
| China (GB) | 4J36 |
Chemical Composition (%) of Alloy Invar 36 Round Bars
| C | Mn | P | S | Si | Ni | Cr | Fe | Co |
|---|---|---|---|---|---|---|---|---|
| 0.15 max | 0.60 max | 0.006 max | 0.004 max | 0.40 max | 36.0 nom | 0.25 max | Bal | 0.50 max |
Mechanical & Physical Properties of Invar 36 Round Bars
| Property | Typical value |
|---|---|
| Tensile strength | 75 ksi (518 MPa) [VERIFY – competitors list 71 ksi / 490 MPa annealed] |
| Yield strength | 40 ksi (276 MPa) [VERIFY] |
| Elongation (2 in.) | 34% [VERIFY] |
| Hardness (annealed) | HRB 80 [VERIFY] |
| Modulus of elasticity | 20.5 Mpsi (141 GPa) [VERIFY] |
| Density | ~8.1 g/cm³ |
| Melting point | ~1430 °C |
| Curie temperature | ~230 °C (ferromagnetic below this) |
Invar 36 Bar Forms in Stock
Round bar (cold drawn, bright, ground, peeled, forged) • Hex bar 2–100 mm A/F • Square bar 4–100 mm • Flat bar • Hollow bar • Threaded bar • Half-round • Triangle • Rings & forgings • Cut-to-size blanks.
Need the weight of a cut length? Use our metal weight calculator.
Alloy 36 / Invar 36 Hex Bar
Alloy 36 / Invar 36 Square Bar
Alloy 36 / Invar 36 Bright Bar
Alloy 36 / Invar 36 Threaded Bar
Alloy 36 / Invar 36 Flat Bar
Alloy 36 / Invar 36 Rectangular Bar
“Contact Jade Special Metals today with your requirement for Alloy 36 Round Bars and Invar 36 Rods. We assure you of the best quote.
Applications of Invar 36 Round Bars
- Precision instruments & metrology: measuring rods, calibration standards, spacers, supports
- Optical & laser systems: lens mounts, optical benches, alignment rods
- Aerospace tooling: moulds, dies and fixtures for carbon-fibre composite layup
- Cryogenic & LNG equipment: instrument supports and low-temperature components
- Electronics & semiconductor equipment: frames, stages, mask parts
- Thermostats & bimetal devices: low-expansion element paired with a high-expansion metal
- Radio, radar & satellite hardware: dimensionally stable structures
Invar 36 vs Invar 42 vs Kovar vs Super Invar
Invar 36 is one of several controlled-expansion and specialty grades. For a wider view of the family, read our guide to nickel alloys in industrial applications.
| Alloy | Best for | Trade-off |
|---|---|---|
| Invar 36 (Alloy 36) | Lowest expansion near room temperature; precision, optics, tooling | Limited corrosion resistance; moderate strength |
| Invar 42 (Alloy 42) | Glass/ceramic sealing, lead frames | Higher expansion than Invar 36 |
| Kovar (Alloy 29-17) | Glass-to-metal and ceramic-to-metal seals | Not chosen for lowest room-temp. expansion |
| Super Invar (32-5) | Ultra-precision needing even lower expansion over a narrow range | Specialised; narrower useful temperature range |
Machining & Fabrication Tips
- Invar 36 machines gummy and work-hardens: use rigid set-ups, sharp positive-rake tools, steady feeds and plenty of coolant; avoid light rubbing passes.
- Rough machine first, then stress-relieve, then finish machine or grind to hold final dimensions.
- Weldable and brazeable with qualified procedures; control heat input to limit distortion.
- Moderate corrosion resistance only: oil, plate or coat finished parts exposed to humidity.
Quality, Testing & Certification
Every lot is traceable to its heat number. Available on request: Mill Test Certificate (EN 10204 3.1), chemical analysis, PMI, mechanical test reports, ultrasonic testing, third-party inspection and thermal-expansion (CTE) test reports [VERIFY each item]. Export packing in wooden cases/pallets with VCI protection. See our Quality and Certificate pages.
Related Invar 36 Round Bars
Frequently Asked Questions
Invar 36 round bar is solid cylindrical stock of a nickel-iron alloy containing about 36% nickel and 64% iron. It is also called Alloy 36, FeNi36 or 1.3912 (UNS K93600). Its very low thermal expansion keeps machined parts dimensionally stable across temperature changes.
Invar 36 expands about 1.3 µm/m·°C between 20 and 100 °C, roughly one-tenth of carbon steel. The low-expansion range extends to about 200 °C, after which expansion rises near the Curie temperature (~230 °C).
It is used for precision instruments, optical and laser mounts, aerospace composite tooling, cryogenic and LNG components, electronics equipment, calibration standards and thermostat elements, wherever dimensional change from temperature must be minimised.
They all refer to approximately 36% nickel low-expansion alloys and are commonly treated as equivalents. Chemistry limits, CTE requirements and delivery conditions can differ by standard, so confirm the governing specification (for example ASTM F1684) before substituting.
We maintain ready stock of: ASTM A193 B7, B8, B8M, B16; ASTM A194 Grade 2H, 4, 7, 8, 8M; ASTM A320 L7, L7A (cryogenic); ASTM A307; ASTM A325; and ASTM A453 Grade 660. All grades are available with EN 10204 3.1 Mill Test Certificates. Cryogenic grade certifications are available for LNG facility applications at Ras Laffan.
Invar 36 has only moderate atmospheric corrosion resistance and can rust in humid or salty environments. Finished parts are usually oiled, plated or coated; it is not a substitute for stainless steel where corrosion resistance is the main need.
It is gummy and work-hardens, so it needs sharp tools, rigid set-ups and coolant. For tight tolerances, rough machine, stress relief, then finish machine or grind.
Jade Special Metals supplies Invar 36 round bars from 3 mm to 800 mm diameter in cold drawn, bright, ground, peeled, polished and forged finishes, cut to your required length, with test certificates and worldwide export packing.
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