ABSTRACT
This chapter discusses the characteristics of engineering materials and components. For example, ductile wrought metallic materials are usually isotropic while brittle materials are stronger in compression than in tension. The stiffness of a component may be increased by increasing the second moment of area of its cross section or by selecting a higher modulus material for its manufacture. When weight is important, the specific strength (strength/density) and specific stiffness (modulus of elasticity/density) may be used as the selection criteria. Increasing the strength of a material usually reduces its toughness. Decreasing the operating temperature of carbon and low-alloy steels causes a decrease in toughness. The fatigue strength of metallic materials generally increases with increasing tensile strength. However, the higher the strength, the higher the notch sensitivity and the greater is the need to have homogeneous structure. Fine dispersion of stable second-phase particles may be used to improve the creep strength. Corrosion resistance of metals depends on their composition and processing history and can be further protected by coatings. Plastics and glasses are resistant to most chemicals except organic solvents and HF respectively. Hard-surface coatings and surface hardening may be used to improve wear resistance.
