Magnesium AZ31B-H24 vs. Plastic PBT GF30

Compare Magnesium AZ31B-H24 vs. Plastic PBT GF30 strength, stiffness, weight and thermal properties.

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Plastic PBT GF30Bulk polymer (molded or machined)

Mechanical
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Yield strength	220MPasourcetypical, H24, 0.5-6 mm, 0.2 % proof stress	not given (tensile used)
Ultimate tensile strength	290MPasourcetypical, H24, 0.5-6 mm	140MPasourcestress at break, 23 °C
Flexural strength	not sourced	210MPasourcetypical, 23 °C
Elongation at break	13%sourcetypical, H24, 0.5-6 mm, gauge 5.65√A	3%sourcestrain at break, 23 °C
Young's modulus (stiffness)	44.8GPasourcetypical (handbook physical constant)	9.8GPasourcetypical, 23 °C
Density	1,769kg/m³sourcenominal	1,530kg/m³sourcetypical
Strength to weight	124kN·m/kg36% higher	91.5kN·m/kg
Stiffness to weight	25.3MN·m/kg3.95x higher	6.41MN·m/kg
Poisson's ratio	0.35sourcetypical (handbook physical constant)	not sourced
Shear modulus	16.6GPa	not sourced
Bulk modulus	49.8GPa	not sourced
Speed of sound	5,032m/s	2,531m/s
Thermal
Thermal conductivity	76.9W/m·Ksourcetypical (temper/temperature not stated)	0.27W/m·Ksourcetypical (DIN 52612-1)
Thermal expansion	26.8µm/m·Ksourcetypical (temperature range not stated)	25µm/m·Ksourcelongitudinal (flow), mean 23-55 °C
100 mm part over a 50 °C swing	134µm growth	125µm growth7% less
Specific heat	1,040J/kg·Ksourcetypical	1,050J/kg·Ksourcetypical, 23 °C
Heats up and cools (diffusivity)	41.8mm²/s249x faster	0.168mm²/s
Thermal shock resistance	9,159W/m	not sourced
Melting point	not sourced	223°CsourceDSC (ISO 11357)
Max service temperature	149°Csourcestated application limit	205°CsourceHDT 1.8 MPa
Values for	AZ31B-H24 sheet 0.016-0.062 in., MIL-HDBK-5J Table 4.2.1.0(b) (AMS 4377); strengths are S-basis MINIMUMS	BASF Ultradur B 4300 G6 (PBT, 30% glass fibre), injection moulding grade; product information sheet 09/2026, typical values for uncoloured product at 23 °C.

Every value links to the document that states it. "Not sourced" means no citable source states it (or only a specification minimum); figures computed from it are left out too.

Questions

Is Magnesium AZ31B-H24 stronger than Plastic PBT GF30?

Magnesium AZ31B-H24 is stronger: its yield strength is 220 MPa against tensile strength 140 MPa for Plastic PBT GF30 (1.57x).

Which is lighter, Magnesium AZ31B-H24 or Plastic PBT GF30?

Plastic PBT GF30 is lighter: 1,530 kg/m³ against 1,769 kg/m³ for Magnesium AZ31B-H24.

Which is stiffer, Magnesium AZ31B-H24 or Plastic PBT GF30?

Magnesium AZ31B-H24 is stiffer: Young's modulus 44.8 GPa against 9.8 GPa for Plastic PBT GF30, so the same part in Magnesium AZ31B-H24 deflects less under the same load.

Which is lighter for the same job, Magnesium AZ31B-H24 or Plastic PBT GF30?

For the same stiffness or strength: Magnesium AZ31B-H24 is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.

Part that must be	Magnesium AZ31B-H24	Plastic PBT GF30
Stiff rod or tie (tension)	lighter	3.95x heavier
Stiff beam (bending)	lighter	1.85x heavier
Stiff panel or plate	lighter	44% heavier
Strong rod or tie	lighter	36% heavier
Strong beam	lighter	17% heavier
Strong panel or plate	lighter	8% heavier

For the same stiffness or strength, mass scales with density over stiffness (or strength) raised to a power set by how the part is loaded: 1 for a rod in tension, 1/2 for a beam in bending, 1/3 for a panel (the standard material-selection indices).

Which conducts heat better, Magnesium AZ31B-H24 or Plastic PBT GF30?

Magnesium AZ31B-H24 conducts heat better: 76.9 W/m·K against 0.27 W/m·K for Plastic PBT GF30.

Which expands less with temperature?

Plastic PBT GF30 expands less: 25 µm/m·K against 26.8 µm/m·K for Magnesium AZ31B-H24.

Among 72 materials

Stiffness against density

Strength against density