Steel 4J36
GB 4J36 · UNS K93600
4J36 is the precision-alloy designation for the classic 36 % Ni-Fe Invar alloy (UNS K93600), the most widely stocked low-expansion grade.
Reference datasheet — 4J36 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the Annealed condition
4J36 tempers and conditions
4J36 is supplied in 5 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault solution/soft annealed, 830 °C water or air cooled | Standard stock condition for plate, sheet, bar and forgings; best ductility and lowest, most reproducible expansion after subsequent stabilizing. | 280 | 490 | 40 | 135 HB | — |
Hot rolled / hot forged, as-worked | Rough stock for thick plate, blocks and mould bases that will be machined and then stabilized. | 300 | 500 | 35 | 150 HB | 2.2 % IACS |
830 °C anneal + 315 °C stress relief + 95 °C ageing | Specify for gauge blocks, laser benches and metrology parts needing the lowest CTE and long-term dimensional stability (minimal creep/growth). | 300 | 500 | 35 | 140 HB | 2.2 % IACS |
Half hard | Intermediate strength strip, bar and tube where some springback and stiffness are wanted with usable ductility. | 450 | 620 | 20 | 12 HRC | 2.1 % IACS |
heavily cold worked bar, wire, strip, tube | Choose for maximum strength and straightness in wire, small bar and thin-wall tube; expansion is slightly reduced but internal stress must be relieved for precision parts. | 650 | 800 | 8 | 24 HRC | — |
What is 4J36?
4J36 is the precision-alloy designation for the classic 36 % Ni-Fe Invar alloy (UNS K93600), the most widely stocked low-expansion grade. It is used for tooling and instruments that must hold dimensions through temperature change, and is available as plate, bar, strip and tube in annealed, hot-rolled, half-hard, cold-drawn and stabilised conditions. Annealed properties are about 280 MPa yield, 490 MPa tensile, 40 % elongation and 135 HB (76 HRB), with weldability 75 and formability 85. Service is limited to 200 °C, machinability is low (30) and the alloy is not corrosion resistant; for a still lower expansion near ambient, 4J32 Super Invar is the alternative. 4J36 has a density of 8.1 g/cm³ (0.293 lb/in³), heavier than 97% of steel grades. It melts at 1,427°C (2,601 °F). 4J36 has a yield strength of 280 MPa (40.6 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 90% of steel grades. Elongation at break is 40% and the elastic modulus is 141 GPa (20.5 Msi).
What is 4J36 used for?
- precision molds/tooling
- measuring tapes and gauges
- bimetal strips
- cryogenic vessels
Advantages
- Ductile — tolerates forming and impact — 40%, better than 99% of steel grades
- Forms and bends easily — 85/100, better than 96% of steel grades
- Good corrosion resistance — 25/100, better than 92% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
- Readily welded — 75/100, better than 76% of steel grades
Limitations
- Poor heat conductor — 10.5 W/m·K (6.07 BTU/hr·ft·°F), worse than 100% of steel grades
- Low stiffness — 141 GPa (20.5 Msi), worse than 98% of steel grades
- Low electrical conductivity — 2.2 % IACS, worse than 98% of steel grades
- High embodied carbon — 5.5 kg CO₂/kg, worse than 97% of steel grades
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
4J36 properties
Typical room-temperature values for 4J36-Annealed; bars are the position among steel grades.
Physical3
4J36 has a density of 8.1 g/cm³ (0.293 lb/in³), heavier than 97% of steel grades. It melts at 1,427°C (2,601 °F).
Mechanical14
4J36 has a yield strength of 280 MPa (40.6 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 90% of steel grades. Elongation at break is 40% and the elastic modulus is 141 GPa (20.5 Msi).
Thermal6
4J36 is rated for continuous service to 200°C (392 °F). It conducts heat at 10.5 W/m·K (6.07 BTU/hr·ft·°F), worse than 100% of steel grades. Thermal expansion is 1.5 µm/m·K (0.833 µin/in·°F).
Electrical3
4J36 conducts electricity at 2.2 % IACS, worse than 98% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (25/100), better than 92% of steel grades.
Sustainability4
Producing a kilogram of 4J36 takes about 75 MJ of energy and emits 5.5 kg of CO₂ — more than 97% of steel grades. Typical recycled content is 30%.
Manufacturability8
4J36's machinability is poor (30/100, worse than 89% of steel grades); weldability very good (75/100); formability excellent (85/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. 4J36 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 4J36
Is 4J36 easy to machine?
Gummy and work-hardening: use sharp positive-rake carbide, rigid setup, low speed (20–35 m/min) with heavy constant feed and flood coolant; avoid dwelling to prevent glazing.
Can 4J36 be welded?
GTAW/EBW/laser with matching 36Ni filler and low heat input; keep interpass low and joints clean — sulfur, carbon or oil pickup causes hot cracking.
Can 4J36 be formed, bent or molded?
Excellent cold formability — deep drawing, bending and spinning are routine; anneal at 830 °C between heavy reductions.
4J36 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| NiInvar composition window; some standards allow 35.0–37.0 | 35 – 36.5 | 36 |
| C | ≤ 0.05 | 0.03 |
| Si | ≤ 0.3 | 0.15 |
| Mn | 0.2 – 0.6 | 0.4 |
| P | ≤ 0.02 | |
| S | ≤ 0.02 | |
| Crresidual | ≤ 0.15 | |
| Curesidual | ≤ 0.2 | |
| Coresidual; Co is deliberately added only in 4J32 Super-Invar | ≤ 0.5 | |
| Fe | balance |
What surface finishes work on 4J36?
Not corrosion resistant — protect with electroless nickel, chrome plating, passivation or paint; polishes reasonably well but must be stabilized after machining to hold dimensions.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel 4J36 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- K93600
How much does 4J36 cost?
4J36 is a high-cost steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
4J36 — frequently asked
What is 4J36 used for?
4J36 is typically used for precision molds/tooling, measuring tapes and gauges, bimetal strips and cryogenic vessels. In short: classic Invar 36 grade; most widely stocked low-expansion alloy; cryogenic-capable.
What is the yield strength of 4J36?
4J36 has a typical yield strength of 280 MPa (40.6 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 90% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is 4J36 easy to machine?
Not especially — machinability is rated poor (30/100, worse than 89% of steel grades). Gummy and work-hardening: use sharp positive-rake carbide, rigid setup, low speed (20–35 m/min) with heavy constant feed and flood coolant; avoid dwelling to prevent glazing.
Can 4J36 be welded?
Yes — weldability is rated very good (75/100). GTAW/EBW/laser with matching 36Ni filler and low heat input; keep interpass low and joints clean — sulfur, carbon or oil pickup causes hot cracking.
What surface finishes work on 4J36?
Not corrosion resistant — protect with electroless nickel, chrome plating, passivation or paint; polishes reasonably well but must be stabilized after machining to hold dimensions.
Can 4J36 be formed, bent or molded?
Excellent cold formability — deep drawing, bending and spinning are routine; anneal at 830 °C between heavy reductions.
What is the maximum service temperature of 4J36?
4J36 is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 4J36 cost?
4J36 is a high-cost steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM F1684 Standard Specification for Iron-Nickel and Iron-Nickel-Cobalt Alloys for Low Thermal Expansion Applications — ASTM (2020)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Low-Expansion Alloys) — ASM International (1990)
- Invar 36 / Pernifer 36 alloy datasheet — specialty alloy producers (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.