D18 vs D24

D24 and D18 are about equally stiff. Their densities are about the same. Per unit mass they are about equally stiff (16.67 and 17.24 MJ/kg). Strength: f_m,k = 18 MPa for D18, f_m,k = 24 MPa for D24.

D18 EN 338:2016 D24 EN 338:2016

Side by side

ratio = D24 / D18 · log scale

Property	D18	D24	Unit	Ratio
E₁ Modulus, direction 1	9.5	10	GPa	1.05×
E₂ Modulus, direction 2	0.63	0.67	GPa	1.06×
E₃ Modulus, direction 3	0.63	0.67	GPa	1.06×
G₁₂ Shear modulus 1-2	0.59	0.63	GPa	1.07×
G₁₃ Shear modulus 1-3	0.59	0.63	GPa	1.07×
E₀,₀₅ Modulus parallel to grain, 5 % fractile	8	8.4	GPa	1.05×
ρ Density	570	580	kg/m³	1.02×
ρ_k Density, characteristic (5 % fractile)	475	485	kg/m³	1.02×
f_m,k Bending strength	18	24	MPa	1.33×
f_t,0,k Tension parallel to grain	11	14	MPa	1.27×
f_t,90,k Tension perpendicular to grain	0.6	0.6	MPa	1×
f_c,0,k Compression parallel to grain	18	21	MPa	1.17×
f_c,90,k Compression perpendicular to grain	4.8	4.9	MPa	1.02×
f_v,k Shear strength	3.5	3.7	MPa	1.06×
E/ρ Specific stiffness E/ρ · derived	16.67	17.24	MJ/kg	1.03×
c₀ Bar wave speed √(E/ρ) · derived	4082	4152	m/s	1.02×
f/ρ Specific strength f/ρ · derived	31.58	41.38	kJ/kg	1.31×

Values at the first thickness band or product form of each material (EN 338:2016; EN 338:2016). A minimum and a characteristic value are not the same kind of number — read the ratio as a guide. Each material's page lists every band and every source.