Steel 4J32
GB 4J32 · UNS K93601 · JIS Super Invar
4J32 is the Super Invar type Fe-32Ni-Co low-expansion alloy (UNS K93601), formulated to give an even lower expansion coefficient than 36 % Ni Invar around room temperature.
Reference datasheet — 4J32 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 M condition
4J32 tempers and conditions
4J32 is supplied in 5 conditions, soft to hard. M 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 |
|---|---|---|---|---|---|---|
MDefault Thermomechanically controlled processed | Default annealed delivery state from an 830 °C anneal with slow cooling: lowest expansion coefficient and highest ductility for later cold forming and finish machining. | 280 | 490 | 35 | 140 HB | — |
Annealed plus dimensional stabilization | Pick annealed plus stabilization (≈315 °C hold, slow cool) after rough machining for metrology instruments and optical bases needing long-term dimensional stability. | 300 | 500 | 33 | 150 HB | 2.2 % IACS |
Cold drawn | Choose cold drawn bar or wire for good size accuracy and surface quality with medium strength at 450 MPa yield, suited to parts machined directly from stock. | 450 | 620 | 20 | 11 HRC | 2.1 % IACS |
Half hard, cold rolled/drawn ≈20–30 % reduction | Use half-hard material cold worked about 20–30 % for strip and elastic supports that need 560 MPa yield while retaining some forming capability. | 560 | 700 | 12 | 20 HRC | 2.2 % IACS |
Hard, cold rolled ≥50 % reduction | Pick hard strip cold rolled ≥50 % for thin springs needing maximum strength and stiffness at 730 MPa yield; expansion rises slightly and stabilizing is required to restore it. | 730 | 830 | 5 | 27 HRC | 2.2 % IACS |
What is 4J32?
4J32 is the Super Invar type Fe-32Ni-Co low-expansion alloy (UNS K93601), formulated to give an even lower expansion coefficient than 36 % Ni Invar around room temperature. It is used for high-precision instrument and optical structures and is supplied as bar, plate and strip in annealed (M), annealed plus stabilised (M+ST), cold-drawn, half-hard (Y2) and hard (Y) conditions. Typical values are 280 MPa yield, 490 MPa tensile, 35 % elongation and 140 HB (78 HRB), with a 200 °C service limit. Machinability is low (30), corrosion resistance is poor, and the low expansion is lost above roughly 100–200 °C, where 4J36 Invar is the broader-range option. 4J32 has a density of 8.15 g/cm³ (0.294 lb/in³), heavier than 97% of steel grades. It melts at 1,425°C (2,597 °F). 4J32 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 35% and the elastic modulus is 145 GPa (21 Msi).
What is 4J32 used for?
- precision instrument frames
- optical benches
- measuring standards
Advantages
- Ductile — tolerates forming and impact — 35%, better than 97% of steel grades
- Good corrosion resistance — 28/100, better than 94% of steel grades
- Forms and bends easily — 80/100, better than 93% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Poor heat conductor — 11 W/m·K (6.36 BTU/hr·ft·°F), worse than 99% of steel grades
- High embodied carbon — 8.5 kg CO₂/kg, worse than 99% of steel grades
- Low stiffness — 145 GPa (21 Msi), worse than 98% of steel grades
- Low electrical conductivity — 2.2 % IACS, worse than 98% of steel grades
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
4J32 properties
Typical room-temperature values for 4J32-M; bars are the position among steel grades.
Physical3
4J32 has a density of 8.15 g/cm³ (0.294 lb/in³), heavier than 97% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical14
4J32 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 35% and the elastic modulus is 145 GPa (21 Msi).
Thermal6
4J32 is rated for continuous service to 200°C (392 °F). It conducts heat at 11 W/m·K (6.36 BTU/hr·ft·°F), worse than 99% of steel grades. Thermal expansion is 0.6 µm/m·K (0.333 µin/in·°F).
Electrical3
4J32 conducts electricity at 2.2 % IACS, worse than 98% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (28/100), better than 94% of steel grades.
Sustainability4
Producing a kilogram of 4J32 takes about 115 MJ of energy and emits 8.5 kg of CO₂ — more than 100% of steel grades. Typical recycled content is 25%.
Manufacturability8
4J32's machinability is poor (30/100, worse than 89% of steel grades); weldability very good (70/100); formability very good (80/100).
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. 4J32 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 4J32
Is 4J32 easy to machine?
Sticky and strongly work-hardening: use sharp positive-rake tooling, low speed with heavy feed and plentiful emulsion coolant. Stress-relieve after roughing and before finishing to hold dimensional stability.
Can 4J32 be welded?
TIG, electron-beam and laser welding are all usable with matching-composition filler, low heat input and no carbon contamination; anneal and stabilise after welding to restore low expansion and dimensional stability.
Can 4J32 be formed, bent or molded?
Ductility is excellent in the soft condition — deep drawing, bending and cold rolling to thin strip are routine; heavy cold work raises the expansion coefficient, so recrystallisation anneal to restore it.
4J32 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 |
|---|---|---|
| Nimain element controlling low thermal expansion | 31.5 – 32.5 | 32 |
| Coshifts the expansion minimum to room temperature | 3.2 – 4.2 | 3.7 |
| C | ≤ 0.05 | 0.03 |
| Si | ≤ 0.3 | 0.15 |
| Mn | ≤ 0.6 | 0.35 |
| P | ≤ 0.02 | |
| S | ≤ 0.02 | |
| Fe | balance |
What surface finishes work on 4J32?
Corrosion resistance is poor — protect with electroless nickel, chrome plating or paint; optical parts are usually nickel plated then polished. Cannot be anodised.
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 4J32 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- K93601
- JIS
- Super Invar
How much does 4J32 cost?
4J32 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.
4J32 — frequently asked
What is 4J32 used for?
4J32 is typically used for precision instrument frames, optical benches and measuring standards. In short: lowest room-temperature expansion; super Invar equivalent; optical-bench stability grade.
What is the yield strength of 4J32?
4J32 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 4J32 easy to machine?
Not especially — machinability is rated poor (30/100, worse than 89% of steel grades). Sticky and strongly work-hardening: use sharp positive-rake tooling, low speed with heavy feed and plentiful emulsion coolant. Stress-relieve after roughing and before finishing to hold dimensional stability.
Can 4J32 be welded?
Yes — weldability is rated very good (70/100). TIG, electron-beam and laser welding are all usable with matching-composition filler, low heat input and no carbon contamination; anneal and stabilise after welding to restore low expansion and dimensional stability.
What surface finishes work on 4J32?
Corrosion resistance is poor — protect with electroless nickel, chrome plating or paint; optical parts are usually nickel plated then polished. Cannot be anodised.
Can 4J32 be formed, bent or molded?
Ductility is excellent in the soft condition — deep drawing, bending and cold rolling to thin strip are routine; heavy cold work raises the expansion coefficient, so recrystallisation anneal to restore it.
What is the maximum service temperature of 4J32?
4J32 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.
What is the difference between 4J32-M and 4J32-Y?
M is the default condition — default annealed delivery state from an 830 °C anneal with slow cooling: lowest expansion coefficient and highest ductility for later cold forming and finish machining. Y: pick hard strip cold rolled ≥50 % for thin springs needing maximum strength and stiffness at 730 MPa yield; expansion rises slightly and stabilizing is required to restore it. Yield strength is 280 MPa in M versus 730 MPa in Y.
How much does 4J32 cost?
4J32 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
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Low-Expansion Alloys) — ASM International (1990)
- Super Invar 32-5 Alloy Technical Datasheet — Carpenter Technology (2020)
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.