With the addition of certain alloys, low-alloy steels have chemical compositions that contribute better mechanical properties than most conventional mild or carbon steels. These alloys make up about 1 per cent to 5 per cent of the overall composition of the steel, and depending on the alloy, they provide certain attributes, such as improving strength, adding toughness and increasing temperature strength. It's important to know exactly what type of low-alloy steel you have for welding and for selecting the proper filler metal.
HY 80, HY 90 and HY 100
Low-alloy steels beginning with HY 80, HY 90 and HY 100 are used for building ship hulls, bridges, submarines and off-highway vehicles. They contain nickel, molybdenum and chromium. These elements add notch toughness and yield strength, and they also make the material easier to weld.
High-strength, low-alloy steel, or HSLA, differs from other low-alloy steels in that each has been created with the intention to meet specific mechanical requirements rather than given a chemical composition. High-strength, low-alloy steel is used for warships and structural steel for the increased strength.
ASTM A514, A517 and T1
ASTM A514, A517 and T1 steels are designed for strength and toughness at low temperatures. These steels are quenched and tempered and used for heavy equipment manufacturing and boiler and pressure vessel production.
ASTM A242, A588 and A709 Grade 50W
ASTM A242, A588 and A709 Grade 50W are weathering steels that require certain alloys to create a protective layer to resist corrosion. The layer also gives a weathered appearance to the steel. This low-alloy steel is popular in art, bridges and as facing material on some buildings.