The "Fe" in Fe-550 stands for iron, while the "550" refers to the minimum yield strength of the steel measured in megapascals (MPa). In other words, Fe-550 bars can withstand a minimum load of 550 MPa before they start to deform.
Fe-550 bars are commonly used in reinforced concrete structures, such as bridges, high-rise buildings, and dams, where high strength and durability are essential. These bars are manufactured by hot rolling process and then subjected to controlled cooling. This process gives the bars their characteristic deformed shape, which provides a better grip and bonding with the surrounding concrete.
It is important to note that Fe-550 bars should only be used under the guidance of a professional engineer or architect who has experience with steel reinforcement design. They should also be sourced from reputable manufacturers who adhere to quality standards and have a track record of producing high-quality products.