Boron Steels for Mechanical Fasteners

The metallurgical effects of boron additions to carbon steel are reviewed. Mechanical property data for low carbon-boron steel fasteners is presented and is compared with similar properties for higher carbon steel fasteners. Mechanical property comparisons include data on tensile strength, ductility, toughness, fatigue strength and heat resistance. Mechanical properties of low carbon-boron steel fasteners are shown to be generally equivalent to mechanical properties of higher carbon steel fasteners with two notable exceptions: The ductility of the low carbon steel fasteners is higher than that of the higher carbon steel fasteners at all strength levels, and the heat resistance of the low carbon-boron steels is considerably lower than that of the higher carbon steels.