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Steel GX5NiS36 vs Super Invar

Steel · grade comparison

Steel GX5NiS36 and Super Invar are both steel grades. Super Invar is the stronger of the two: yield strength 300 MPa (43.5 ksi) against 200 MPa (29 ksi) for GX5NiS36, about 50% more; tensile strength follows at 500 MPa (72.5 ksi) vs 420 MPa (60.9 ksi). Super Invar is the more ductile: elongation 35% versus 12% for GX5NiS36, and Super Invar is harder (150 HB vs 135 HB). GX5NiS36 runs hotter in service (200°C vs 150°C continuous). On the shop floor, GX5NiS36 machines more easily (fair vs poor) and Super Invar welds better (very good vs poor).

GX5NiS36Choose it when the part sees heat, or when the part is machined in volume.

Super InvarChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.

GX5NiS36 vs Super Invar: properties

GX5NiS36Super Invar

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

140 GPa20.3 Msi
145 GPa21 Msi

Shear Modulus

55 GPa8 Msi
57 GPa8.3 Msi

Bulk Modulus

105 GPa15.2 Msi
110 GPa16 Msi

Poisson's Ratio

0.29
0.28

Tensile Strength (Ultimate)

420 MPa60.9 ksi
500 MPa72.5 ksi

Yield Strength (0.2% offset)

200 MPa29 ksi
300 MPa43.5 ksi

Elongation at Break

12%
35%

Reduction in Area

20%
60%

Compressive Strength

430 MPa62.4 ksi
310 MPa45 ksi

Shear Strength

300 MPa43.5 ksi
340 MPa49.3 ksi

Fatigue Strength (Endurance Limit)

160 MPa23.2 ksi
250 MPa36.3 ksi

Fracture Toughness (K_IC)

58 MPa·√m52.8 ksi·√in
100 MPa·√m91 ksi·√in

Charpy V-Notch Impact (RT)

20 J14.8 ft·lbf
130 J95.9 ft·lbf

Hardness, Brinell

135 HB
150 HB

Hardness, Rockwell B

75 HRB
80 HRB

Hardness, Vickers

142 HV
155 HV

Physical

Density and transition temperatures.

Density

8.1 g/cm³0.29 lb/in³
8.15 g/cm³0.29 lb/in³

Same in both: Melting Point (Solidus) 1,425°C2,597 °F · Liquidus Temperature 1,450°C2,642 °F

Thermal

How each material carries heat and how hot it can run.

Thermal Conductivity

11.5 W/m·K6.6 BTU/hr·ft·°F
10.5 W/m·K6.1 BTU/hr·ft·°F

Thermal Expansion (CTE, 20–100 °C)

3 µm/m·K1.7 µin/in·°F
0.5 µm/m·K0.28 µin/in·°F

Latent Heat of Fusion

275 J/g118 BTU/lb
—

Max Service Temperature (continuous)

200°C392 °F
150°C302 °F

Min Service Temperature

-150°C-238 °F
-50°C-58 °F

Same in both: Specific Heat Capacity 515 J/kg·K0.12 BTU/lb·°F

Electrical

Conductivity and insulation.

Electrical Conductivity

2.1 % IACS
2.2 % IACS

Electrical Resistivity

8.2×10⁻⁷ Ω·m32.3 µΩ·in
8×10⁻⁷ Ω·m31.5 µΩ·in

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Corrosion Resistance

30 / 100
28 / 100

Galvanic Potential (seawater, vs SCE)

—
-0.6 V

Manufacturability

FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.

Machinability

40 / 100
30 / 100

Machinability Rating (AISI 1212 = 100 %)

35%
30%

Weldability

25 / 100
70 / 100

Formability (cold)

10 / 100
75 / 100

Castability

60 / 100
—

Brazeability / Solderability

55 / 100
70 / 100

Polishability

45 / 100
65 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

110 MJ/kg47,292 BTU/lb
75 MJ/kg32,244 BTU/lb

Embodied Carbon (primary production)

8.5 kg CO₂/kg
5.5 kg CO₂/kg

Embodied Water

300 L/kg35.9 gal/lb
130 L/kg15.6 gal/lb

Typical Recycled Content

35%
25%

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

52 kN·m/kg
61 kN·m/kg

Specific Stiffness (E / density)

17.3 MN·m/kg
17.8 MN·m/kg

Modulus of Resilience

143 kJ/m³
310 kJ/m³

Thermal Diffusivity

2.8 mm²/s
2.5 mm²/s

Thermal Shock Resistance Index

12
72

Strength versus weight

Yield strength against density for every steel grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.

2005001,0002,0007.588.5Density (g/cm³)Yield strength (MPa) — log scaleGX5NiS36Super Invar

Manufacturing and finishing

CapabilityGX5NiS36Super Invar
Default condition——
Relative cost$$$$ High$$$$ High
Min. machined wall——
Best machined surface——

Both take the same 9 finishes: Copper Plating, Electroless Nickel (EN), Epoxy Coating, Gold Plating, Hard Chrome Plating, Manganese Phosphate, Plasma Spray, Silver Plating, Zinc Phosphate.

GX5NiS36 vs Super Invar — frequently asked

Is Super Invar stronger than GX5NiS36?

Yes. Super Invar has a typical yield strength of 300 MPa (43.5 ksi) against 200 MPa (29 ksi) for GX5NiS36 — about 50% more. Tensile strength is 500 MPa (72.5 ksi) vs 420 MPa (60.9 ksi).

Which is cheaper, GX5NiS36 or Super Invar?

Both sit in the same relative cost tier ($$$$, high); the part price will be decided by machining time, tolerance and quantity rather than by the material.

Which is easier to machine, GX5NiS36 or Super Invar?

GX5NiS36. Its machinability rates fair (40/100) against poor (30/100) for Super Invar; for welding the order is Super Invar first (very good, 70/100) then GX5NiS36 (poor, 25/100).

Ready to make it?

Upload a CAD file and FabDigit prices the part in GX5NiS36 and Super Invar side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.

Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.