FabDigitFabDigit

Steel 15B35 vs SMnB443H

Steel · grade comparison

Steel 15B35 and SMnB443H are both steel grades. SMnB443H is the stronger of the two: yield strength 780 MPa (113 ksi) against 620 MPa (89.9 ksi) for 15B35, about 26% more; tensile strength follows at 950 MPa (138 ksi) vs 730 MPa (106 ksi). SMnB443H is harder — 293 HB against 217 HB for 15B35 — which matters for wear surfaces and threads. SMnB443H runs hotter in service (400°C vs 350°C continuous) and 15B35 conducts electricity better (9.5 % IACS vs 7.8 % IACS). On the shop floor, 15B35 welds better (fair vs poor) and 15B35 forms better (good vs poor).

15B35Choose it when it will be welded.

SMnB443HChoose it when strength drives the design, or when surface hardness matters.

15B35 vs SMnB443H: properties

15B35SMnB443H

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Tensile Strength (Ultimate)

730 MPa106 ksi
950 MPa138 ksi

Yield Strength (0.2% offset)

620 MPa89.9 ksi
780 MPa113 ksi

Elongation at Break

13%
14%

Reduction in Area

40%
45%

Compressive Strength

620 MPa89.9 ksi
790 MPa115 ksi

Shear Strength

440 MPa63.8 ksi
570 MPa82.7 ksi

Fatigue Strength (Endurance Limit)

330 MPa47.9 ksi
430 MPa62.4 ksi

Charpy V-Notch Impact (RT)

25 J18.4 ft·lbf
40 J29.5 ft·lbf

Hardness, Brinell

217 HB
293 HB

Hardness, Rockwell B

96 HRB
—

Fracture Toughness (K_IC)

—
70 MPa·√m63.7 ksi·√in

Hardness, Rockwell C

—
30 HRC

Hardness, Vickers

—
305 HV

Same in both: Elastic (Young's) Modulus 205 GPa29.7 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29

Physical

Density and transition temperatures.

Melting Point (Solidus)

1,425°C2,597 °F
1,420°C2,588 °F

Liquidus Temperature

1,495°C2,723 °F
1,490°C2,714 °F

Same in both: Density 7.85 g/cm³0.28 lb/in³

Thermal

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

Thermal Conductivity

46 W/m·K26.6 BTU/hr·ft·°F
43 W/m·K24.8 BTU/hr·ft·°F

Specific Heat Capacity

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

Thermal Expansion (CTE, 20–100 °C)

11.9 µm/m·K6.6 µin/in·°F
12.2 µm/m·K6.8 µin/in·°F

Latent Heat of Fusion

247 J/g106 BTU/lb
250 J/g107 BTU/lb

Max Service Temperature (continuous)

350°C662 °F
400°C752 °F

Min Service Temperature

-30°C-22 °F
-40°C-40 °F

Electrical

Conductivity and insulation.

Electrical Conductivity

9.5 % IACS
7.8 % IACS

Electrical Resistivity

1.8×10⁻⁷ Ω·m7.09 µΩ·in
2.2×10⁻⁷ Ω·m8.66 µΩ·in

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Galvanic Potential (seawater, vs SCE)

-0.61 V
-0.65 V

Corrosion Resistance

10 / 100
11 / 100

Manufacturability

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

Machinability

55 / 100
48 / 100

Machinability Rating (AISI 1212 = 100 %)

65%
55%

Weldability

40 / 100
30 / 100

Formability (cold)

55 / 100
30 / 100

Brazeability / Solderability

60 / 100
50 / 100

Polishability

55 / 100
60 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

25 MJ/kg10,748 BTU/lb
26 MJ/kg11,178 BTU/lb

Embodied Water

40 L/kg4.8 gal/lb
45 L/kg5.4 gal/lb

Same in both: Embodied Carbon (primary production) 1.9 kg CO₂/kg · Typical Recycled Content 30%

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

93 kN·m/kg
121 kN·m/kg

Modulus of Resilience

938 kJ/m³
1,484 kJ/m³

Thermal Diffusivity

12.3 mm²/s
11.7 mm²/s

Thermal Shock Resistance Index

14
16

Same in both: Specific Stiffness (E / density) 26.1 MN·m/kg

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 scale15B35SMnB443H

Manufacturing and finishing

Capability15B35SMnB443H
Default condition——
Relative cost$ Budget$ Budget
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.

15B35 vs SMnB443H — frequently asked

Is SMnB443H stronger than 15B35?

Yes. SMnB443H has a typical yield strength of 780 MPa (113 ksi) against 620 MPa (89.9 ksi) for 15B35 — about 26% more. Tensile strength is 950 MPa (138 ksi) vs 730 MPa (106 ksi).

Which is cheaper, 15B35 or SMnB443H?

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

Which is easier to machine, 15B35 or SMnB443H?

15B35. Its machinability rates good (55/100) against fair (48/100) for SMnB443H; for welding the order is 15B35 first (fair, 40/100) then SMnB443H (poor, 30/100).

Ready to make it?

Upload a CAD file and FabDigit prices the part in 15B35 and SMnB443H 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.