Description (English)
Invar 36 (Fe-Ni36, UNS K93600, W.Nr. 1.3912, China grade 4J36) is a 36 % nickel-iron controlled-expansion alloy whose mean linear coefficient of thermal expansion is approximately one tenth that of carbon steel from cryogenic temperatures up to about 260 °C. The alloy retains good strength and impact toughness down to liquid-helium temperatures, is ferromagnetic below its Curie point (~230 °C), and is readily welded by TIG / MIG in the annealed condition. Supplied to ASTM B388, B753, B751, B829 and F1684 as sheet, plate, strip, bar, rod, wire, tube, pipe and forgings for cryogenic storage and transfer, length standards, optical benches, bi-metal thermostats, composite curing tools, satellite and missile electronic frames, shadow masks, and precision instrument components.
Size Range
- Sheet Thickness: 0.1–3.0 mm
- Sheet Width: 10–1,000 mm
- Sheet Length: 100–2,000 mm
- Plate Thickness: 4–130 mm
- Plate Width: 100–2,000 mm
- Plate Length: 100–6,000 mm
- Surface Condition: As supplied, annealed, or processed finish subject to availability
Grade Specification
| System | Value |
|---|---|
| 🇺🇸 ASTM | Invar 36, Alloy 36, UNS K93600 / K93601 / K93603 |
| DIN / Werkstoff | 1.3912, Vacodil 36 |
| SEW | SEW 385 |
| China (YB) | 4J36 (YB/T 5241) |
| Russia (GOST) | 26H, Fe-Ni36 |
| France (AFNOR) | NF A54-301 |
Chemical Composition
| Element | Value |
|---|---|
| Nickel (Ni) | 35.0–38.0% |
| Iron (Fe) | Balance |
| Carbon (C) | ≤ 0.10% |
| Manganese (Mn) | ≤ 0.60% |
| Silicon (Si) | ≤ 0.35% |
| Phosphorus (P) | ≤ 0.025% |
| Sulfur (S) | ≤ 0.025% |
| Chromium (Cr) | ≤ 0.50% |
| Molybdenum (Mo) | ≤ 0.50% |
| Cobalt (Co) | ≤ 1.00% |
Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength | ≥ 490 MPa |
| Yield Strength (0.2% Offset) | ≥ 240 MPa |
| Elongation | ≥ 42% |
| Hardness | ≤ 135 HB |
| Modulus of Elasticity | 141 GPa (Typical Value) |
Physical Properties
| Property | Unit | Value |
|---|---|---|
| Density | - | 8.05 g/cm³ |
| Specific Gravity | - | 8.05 |
| Thermal Conductivity (20 °C) | - | ~11 W/(m·K) |
| CTE 20 – 100 °C | - | ≤ 1.0 × 10⁻⁶ / °C |
| CTE 20 – 200 °C | - | ≤ 2.0 × 10⁻⁶ / °C |
| CTE 20 – 300 °C | - | ≤ 5.0 × 10⁻⁶ / °C |
| CTE 20 – 400 °C | - | ≤ 8.0 × 10⁻⁶ / °C |
| CTE 20 – 500 °C | - | ≤ 10.0 × 10⁻⁶ / °C |
Applications
- Cryogenic Systems — LNG, LIN and LHe storage tanks, transfer lines, pump housings, cryostat structures, valve bodies, fittings and flange hubs.
- Length Standards & Metrology — Reference standards, interferometer components, precision scales, gauge blocks.
- Optical & Laser Systems — Optical benches, mounts, laser cavities, mirror substrates, dimensionally stable housings.
- Bi-metal Thermostats — Low-expansion member of bi-metal strips paired with high-expansion alloys such as Invar 42.
- Aerospace — Composite curing moulds for aircraft wing skins, satellite and missile electronics frames, cryogenic fuel lines, low-drift antennae and waveguides.
- Electronics & Semiconductor — Shadow masks for CRT displays, lead-frame material, hard-drive dimensional components.
- Horology — Balance-wheel staff, hairspring wire, pendulum rods, precision clock components.
- Scientific Instrumentation — Particle-accelerator, mass-spectrometer and MRI cryostat structural components.