High-Strength Low-Alloy Steel

In most instances, corrosion test methods for plain carbon steels, high-strength low-alloy steels, and alloy steels do not differ greatly. Therefore, these steels are grouped together for the purposes of this chapter. (Alloy steels here refers to heat treatable constructional and automotive steels, and does not include the stainless steels or other high alloys.) There are some differences in the corrosion test methods used for different mill products of this group of steels, and these will be discussed. The steels covered in this chapter are defined below. 

Steels for structural use are classified as carbon steels, high-strength low-alloy steels, and alloy steels. For design purposes, these steels can be assumed to have a density of 7.85 g/cm, a modulus of elasticity of 210 GPa, and a Poisson s ratio of 0.3. Carbon steels are classified based on the percentage of carbon. Mild carbon steels (0.15-0.29 % C) with yield points in the range of 220-250 MPa and tensile strengths of 400-500 MPa are the most common structural carbon steels. Typically, an increase in carbon percent raises the yield point and increases hardness, but reduces ductility and makes welding more difficult. These drawbacks can be minimized by heat treatments. 

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