The material. Addition of manganese (Mn), nickel (Ni), molybdenum (Mo), or chromium (Cr) to steel lowers the critical quench rate and comes to create martensite, allowing thick sections to be hardened and then tempered. Adding some vanadium, V, as well creates a dispersion of carbides, giving strength while retaining toughness and ductility. Chrome-molybdenum steels such as AIS 4140 are used for aircraft tubing and other high-strength parts. Chrome-vanadium steels are used for crank and propeller shafts and high-quality tools. Steels alloyed for this purpose are called low alloy steels, and the property they have is called hardenability.
Composition
Fe/ < 1.0 C/ < 2.5 Cr/ < 2.5 Ni/ < 2.5 Mo/ < 2.5 V/
General properties
Density Price
Mechanical properties
Young’s modulus Yield strength (elastic limit)
Tensile strength Elongation Hardness—Vickers Fatigue strength at 107 cycles Fracture toughness
Thermal properties
Melting point
Maximum service temperature Thermal conductor or insulator?
Thermal conductivity Specific heat capacity Thermal expansion coefficient
Electrical properties
Electrical conductor or insulator?
Electrical resistivity
Low alloy chrome-molybdenum and chrome-vanadium steels are used for high-quality tools, bike frames, and automobile engine and transmission components.
Ecoproperties: processing
Casting energy Casting CO2 footprint Deformation processing energy Deformation processing CO2 footprint
Recycling
Embodied energy, recycling CO2 footprint, recycling Recycle fraction in current supply
Typical uses. Springs, tools, ball bearings, rollers; crankshafts, gears, connecting rods, knives and scissors, pressure vessels.
