FabDigit

SACM645 vs 38CrMoAlA and 2 more: properties

SACM64538CrMoAlA34CrAlMo5-1041CrAlMo7-10

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

207 GPa30 Msi
210 GPa30.5 Msi
210 GPa30.5 Msi
210 GPa30.5 Msi

Shear Modulus

80 GPa11.6 Msi
80 GPa11.6 Msi
81 GPa11.7 Msi
81 GPa11.7 Msi

Tensile Strength (Ultimate)

950 MPa138 ksi
1,030 MPa149 ksi
900 MPa131 ksi
1,050 MPa152 ksi

Yield Strength (0.2% offset)

780 MPa113 ksi
880 MPa128 ksi
720 MPa104 ksi
800 MPa116 ksi

Elongation at Break

17%
16%
14%
14%

Reduction in Area

55%
55%
48%
50%

Compressive Strength

790 MPa115 ksi
900 MPa131 ksi
730 MPa106 ksi
820 MPa119 ksi

Shear Strength

570 MPa82.7 ksi
640 MPa92.8 ksi
550 MPa79.8 ksi
630 MPa91.4 ksi

Fatigue Strength (Endurance Limit)

430 MPa62.4 ksi
470 MPa68.2 ksi
430 MPa62.4 ksi
480 MPa69.6 ksi

Fracture Toughness (K_IC)

70 MPa·√m63.7 ksi·√in
70 MPa·√m63.7 ksi·√in
75 MPa·√m68.3 ksi·√in
70 MPa·√m63.7 ksi·√in

Charpy V-Notch Impact (RT)

75 J55.3 ft·lbf
80 J59 ft·lbf
45 J33.2 ft·lbf
45 J33.2 ft·lbf

Hardness, Brinell

270 HB
310 HB
280 HB
320 HB

Hardness, Rockwell C

28 HRC
32 HRC
29 HRC
34 HRC

Hardness, Vickers

285 HV
325 HV
295 HV
335 HV

Same in both: Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29

Physical

Density and transition temperatures.

Density

7.8 g/cm³0.28 lb/in³
7.8 g/cm³0.28 lb/in³
7.8 g/cm³0.28 lb/in³
7.75 g/cm³0.28 lb/in³

Melting Point (Solidus)

1,425°C2,597 °F
1,420°C2,588 °F
1,420°C2,588 °F
1,420°C2,588 °F

Same in both: Liquidus Temperature 1,490°C2,714 °F

Thermal

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

Thermal Conductivity

36 W/m·K20.8 BTU/hr·ft·°F
33 W/m·K19.1 BTU/hr·ft·°F
34 W/m·K19.6 BTU/hr·ft·°F
34 W/m·K19.6 BTU/hr·ft·°F

Specific Heat Capacity

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

Thermal Expansion (CTE, 20–100 °C)

12.2 µm/m·K6.8 µin/in·°F
11.9 µm/m·K6.6 µin/in·°F
12.3 µm/m·K6.8 µin/in·°F
11.5 µm/m·K6.4 µin/in·°F

Latent Heat of Fusion

250 J/g107 BTU/lb
270 J/g116 BTU/lb
250 J/g107 BTU/lb
270 J/g116 BTU/lb

Max Service Temperature (continuous)

450°C842 °F
500°C932 °F
500°C932 °F
500°C932 °F

Same in both: Min Service Temperature -40°C-40 °F

Electrical

Conductivity and insulation.

Electrical Conductivity

7.5 % IACS
7.8 % IACS
8 % IACS

Electrical Resistivity

2.3×10⁻⁷ Ω·m9.06 µΩ·in
2.2×10⁻⁷ Ω·m8.66 µΩ·in
2.2×10⁻⁷ Ω·m8.66 µΩ·in
2.5×10⁻⁷ Ω·m9.84 µΩ·in

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Corrosion Resistance

15 / 100
12 / 100
12 / 100
15 / 100

Same in both: Galvanic Potential (seawater, vs SCE) -0.6 V

Manufacturability

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

Machinability

42 / 100
45 / 100
45 / 100
40 / 100

Machinability Rating (AISI 1212 = 100 %)

45%
55%
50%
45%

Weldability

18 / 100
20 / 100
20 / 100
15 / 100

Formability (cold)

25 / 100
20 / 100
25 / 100
15 / 100

Brazeability / Solderability

40 / 100
35 / 100
30 / 100

Polishability

60 / 100
70 / 100
65 / 100
65 / 100

Castability

25 / 100
20 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

34 MJ/kg14,617 BTU/lb
34 MJ/kg14,617 BTU/lb
31 MJ/kg13,328 BTU/lb
32 MJ/kg13,758 BTU/lb

Embodied Carbon (primary production)

2.5 kg CO₂/kg
2.3 kg CO₂/kg
2.2 kg CO₂/kg
2.3 kg CO₂/kg

Embodied Water

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

Typical Recycled Content

28%
30%
30%
30%

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

122 kN·m/kg
132 kN·m/kg
115 kN·m/kg
135 kN·m/kg

Specific Stiffness (E / density)

26.5 MN·m/kg
26.9 MN·m/kg
26.9 MN·m/kg
27.1 MN·m/kg

Modulus of Resilience

1,470 kJ/m³
1,844 kJ/m³
1,234 kJ/m³
1,524 kJ/m³

Thermal Diffusivity

9.9 mm²/s
9 mm²/s
9.5 mm²/s
9.5 mm²/s

Thermal Shock Resistance Index

14
14
12
15

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 scaleSACM64538CrMoAlA34CrAlMo5-1041CrAlMo7-10

Manufacturing and finishing

CapabilitySACM64538CrMoAlA34CrAlMo5-1041CrAlMo7-10
CNC machiningYesYes
Sheet metalYesYes
Default conditionQ&TQ&T
Relative cost$$ Standard$$ Standard$$ Standard$ Budget
Min. machined wall0.8 mm0.8 mm
Best machined surfaceRa 1.6 µmRa 1.6 µm
AlCrNYesYes
AlTiNYesYes
Black OxideYesYes
CVD Al2O3YesYes
CVD TiCNYesYes
CVD TiNYesYes
CerakoteYesYes
Chrome PlatingYesYes
CrNYesYes
DLCYesYes
E-CoatingYesYes
HVOF CoatingYesYes
Hot-Dip GalvanizingYesYes
MoS2YesYes
Multilayer CVDYesYes
Nickel PlatingYesYes
PTFE CoatingYesYes
PaintingYesYes

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

Ready to make it?

Upload a CAD file and FabDigit prices the part in SACM645 and 38CrMoAlA 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.