Beryllium

Silvery white, rigid medal that is lighter than  aluminum by approx. one third.

SymbolBe
Atomic number4
Atomic weight9.013
Specific weight at 20 °C1.85 g/cm3
Melting point1284 °C
Boiling point2400 °C
Melting heat1090 kJ/kg
Specific thermal capacity at 20 °C1.59 kJ/(kg·K)
Thermal conductivity201 kJ/(m·K)
Therm. coefficient for linear expansion Coefficient for linear expansion10.6·10-6/K


Beryllium in steel


Steel may contain up to approx 8 % of beryllium in solid solution at 1150 °C. At this temperature and with a content of 10 % Be, an eutectic of iron and the hexagonally crystallizing compound of FeBe2 is formed. Beryllium in iron, highly restricts the γ-region. The element is also found in steel in the form of carbide Be2C.

Addition of beryllium to steel increases the material’s hardenability. Steel with 1 % Be displays increased hardening after quenching. The tensile strength of this kind of steel is accordingly higher, however, its elongation at failure and impact resistance values are lower.

Beryllium is also used in case-hardening steel and usually added in the form of ferro-beryllium with a content of 80 % Be. A case-hardened layer with a thickness of 0.7 mm and a hardness of 554 HV was obtained for a beryllium-containing but otherwise unalloyed steel with 0.12 % C after a carburization period of ten hours at 1000 °C. Unusually large hardness values were achieved for beryllium steels with higher carbon contents after case hardening at 1100 °C.

Beryllium in cast iron

Due to toxicity of the metal vapors and the risk of people breathing these vapors during the casting process, addition of beryllium to cast iron is avoided. Similar to magnesium and calcium, beryllium has a strong affinity towards sulfur and thus would have a strongly desulfurizing effect if added to cast iron.

 


 

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