HSLA steels usually have densities of around 7800 kg/m 3. HSLA steels are also more resistant to rust than most carbon steels because of their lack of pearlite – the fine layers of ferrite (almost pure iron) and cementite in pearlite. HSLA steel cross-sections and structures are usually 20 to 30% lighter than a carbon steel with the same strength. They are used in cars, trucks, cranes, bridges, roller coasters and other structures that are designed to handle large amounts of stress or need a good strength-to-weight ratio. This directional characteristic is substantially reduced in HSLA steels that have been treated for sulfide shape control. Bends that are parallel to the longitudinal grain are more likely to crack around the outer edge because it experiences tensile loads. Formability and impact strength can vary significantly when tested longitudinally and transversely to the grain. These are needed because most HSLA steels have directionally sensitive properties. Zirconium, calcium, and rare-earth elements are added for sulfide-inclusion shape control which increases formability. Ĭopper, silicon, nickel, chromium, and phosphorus are added to increase corrosion resistance. Because of their higher strength and toughness HSLA steels usually require 25 to 30% more power to form, as compared to carbon steels. Their yield strengths can be anywhere between 250–590 megapascals (36,000–86,000 psi). Precipitation strengthening plays a minor role, too. This eliminates the toughness-reducing effect of a pearlitic volume fraction yet maintains and increases the material's strength by refining the grain size, which in the case of ferrite increases yield strength by 50% for every halving of the mean grain diameter. These elements are intended to alter the microstructure of carbon steels, which is usually a ferrite- pearlite aggregate, to produce a very fine dispersion of alloy carbides in an almost pure ferrite matrix. Copper, titanium, vanadium, and niobium are added for strengthening purposes. Other alloying elements include up to 2.0% manganese and small quantities of copper, nickel, niobium, nitrogen, vanadium, chromium, molybdenum, titanium, calcium, rare-earth elements, or zirconium. They have a carbon content between 0.05 and 0.25% to retain formability and weldability. HSLA steels vary from other steels in that they are not made to meet a specific chemical composition but rather specific mechanical properties. High-strength low-alloy steel ( HSLA) is a type of alloy steel that provides better mechanical properties or greater resistance to corrosion than carbon steel.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |