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Steel A369 FP91 vs AR500

Steel · grade comparison

Steel A369 FP91 and AR500 are both steel grades. AR500 is the stronger of the two: yield strength 1,350 MPa (196 ksi) against 500 MPa (72.5 ksi) for A369 FP91, about 170% more; tensile strength follows at 1,650 MPa (239 ksi) vs 660 MPa (95.7 ksi). In exchange, A369 FP91 is the more ductile: elongation 23% versus 9% for AR500, and AR500 is harder (500 HB vs 210 HB). A369 FP91 is stiffer (218 GPa vs 205 GPa) and A369 FP91 runs hotter in service (600°C vs 250°C continuous). On the shop floor, A369 FP91 machines more easily (fair vs not recommended) and A369 FP91 sits in a lower cost tier (standard, $$) than AR500 (high, $$$$).

A369 FP91Choose it when the part is bent, formed or impact-loaded, or when the part sees heat.

AR500Choose it when strength drives the design.

A369 FP91 vs AR500: properties

A369 FP91AR500

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

218 GPa31.6 Msi
205 GPa29.7 Msi

Shear Modulus

84 GPa12.2 Msi
80 GPa11.6 Msi

Bulk Modulus

180 GPa26.1 Msi
160 GPa23.2 Msi

Poisson's Ratio

0.3
0.29

Tensile Strength (Ultimate)

660 MPa95.7 ksi
1,650 MPa239 ksi

Yield Strength (0.2% offset)

500 MPa72.5 ksi
1,350 MPa196 ksi

Elongation at Break

23%
9%

Reduction in Area

62%
30%

Compressive Strength

510 MPa74 ksi
1,400 MPa203 ksi

Shear Strength

400 MPa58 ksi
1,000 MPa145 ksi

Fatigue Strength (Endurance Limit)

300 MPa43.5 ksi
700 MPa102 ksi

Fracture Toughness (K_IC)

110 MPa·√m100 ksi·√in
50 MPa·√m45.5 ksi·√in

Charpy V-Notch Impact (RT)

130 J95.9 ft·lbf
35 J25.8 ft·lbf

Hardness, Brinell

210 HB
500 HB

Hardness, Rockwell C

18 HRC
50 HRC

Hardness, Vickers

220 HV
525 HV

Physical

Density and transition temperatures.

Density

7.77 g/cm³0.28 lb/in³
7.85 g/cm³0.28 lb/in³

Melting Point (Solidus)

1,450°C2,642 °F
1,420°C2,588 °F

Same in both: Liquidus Temperature 1,500°C2,732 °F

Thermal

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

Thermal Conductivity

26 W/m·K15 BTU/hr·ft·°F
40 W/m·K23.1 BTU/hr·ft·°F

Specific Heat Capacity

480 J/kg·K0.11 BTU/lb·°F
470 J/kg·K0.11 BTU/lb·°F

Thermal Expansion (CTE, 20–100 °C)

10.8 µm/m·K6 µin/in·°F
12 µm/m·K6.7 µin/in·°F

Max Service Temperature (continuous)

600°C1,112 °F
250°C482 °F

Min Service Temperature

-30°C-22 °F
-40°C-40 °F

Same in both: Latent Heat of Fusion 270 J/g116 BTU/lb

Electrical

Conductivity and insulation.

Electrical Conductivity

2.9 % IACS
7.5 % IACS

Electrical Resistivity

6×10⁻⁷ Ω·m23.6 µΩ·in
2.3×10⁻⁷ Ω·m9.06 µΩ·in

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Galvanic Potential (seawater, vs SCE)

-0.58 V
-0.62 V

Corrosion Resistance

30 / 100
13 / 100

Manufacturability

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

Machinability

45 / 100
12 / 100

Machinability Rating (AISI 1212 = 100 %)

45%
10%

Weldability

40 / 100
45 / 100

Formability (cold)

30 / 100
15 / 100

Castability

45 / 100
—

Brazeability / Solderability

35 / 100
—

Polishability

60 / 100
55 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

34 MJ/kg14,617 BTU/lb
30 MJ/kg12,898 BTU/lb

Embodied Carbon (primary production)

2.5 kg CO₂/kg
2.3 kg CO₂/kg

Embodied Water

60 L/kg7.2 gal/lb
55 L/kg6.6 gal/lb

Same in both: Typical Recycled Content 25%

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

85 kN·m/kg
210 kN·m/kg

Specific Stiffness (E / density)

28.1 MN·m/kg
26.1 MN·m/kg

Modulus of Resilience

573 kJ/m³
4,445 kJ/m³

Thermal Diffusivity

7 mm²/s
10.8 mm²/s

Thermal Shock Resistance Index

7
27

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 scaleAR500A369 FP91

Manufacturing and finishing

CapabilityA369 FP91AR500
CNC machining—Yes
Sheet metal—Yes
Default condition—Q&T
Relative cost$$ Standard$$$$ High
Min. machined wall—0.8 mm
Best machined surface—Ra 1.6 µm
AlCrN—Yes
AlTiN—Yes
Black Oxide—Yes
CVD Al2O3—Yes
CVD TiCN—Yes
CVD TiN—Yes
Cerakote—Yes
Chrome Plating—Yes
CrN—Yes
DLC—Yes
E-Coating—Yes
HVOF Coating—Yes
Hot-Dip Galvanizing—Yes
MoS2—Yes
Multilayer CVD—Yes
Nickel Plating—Yes
PTFE Coating—Yes
Painting—Yes

They share 9 finishes: Copper Plating, Electroless Nickel (EN), Epoxy Coating, Gold Plating, Hard Chrome Plating, Manganese Phosphate, Plasma Spray, Silver Plating, Zinc Phosphate.

A369 FP91 vs AR500 — frequently asked

Is AR500 stronger than A369 FP91?

Yes. AR500 has a typical yield strength of 1,350 MPa (196 ksi) against 500 MPa (72.5 ksi) for A369 FP91 — about 170% more. Tensile strength is 1,650 MPa (239 ksi) vs 660 MPa (95.7 ksi).

Which is cheaper, A369 FP91 or AR500?

A369 FP91 is the lower-cost material: it sits in the standard tier ($$) while AR500 is high ($$$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.

Which is easier to machine, A369 FP91 or AR500?

A369 FP91. Its machinability rates fair (45/100) against not recommended (12/100) for AR500; for welding the order is AR500 first (fair, 45/100) then A369 FP91 (fair, 40/100).

Ready to make it?

Upload a CAD file and FabDigit prices the part in A369 FP91 and AR500 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.