(1) Carbon; the higher the carbon content, the higher the hardness, but the worse its plasticity and toughness.
(2) Sulfur; it is a harmful impurity in steel. When steel with high sulfur content is subjected to pressure processing at high temperature, it is easy to be brittle and is usually called hot brittleness.
(3) Phosphorus; can significantly reduce the plasticity and toughness of steel, especially at low temperatures, this phenomenon is called cold brittleness. In high quality steel, sulfur and phosphorus should be strictly controlled. However, from another point of view, the inclusion of higher sulfur and phosphorus in low carbon steel can make it easy to cut, which is beneficial to improve the machinability of steel.
(4) Manganese; can improve the strength of steel, can weaken and eliminate the adverse effects of sulfur, and can improve the hardenability of steel, high alloy steel (high manganese steel) with high manganese content has good wear resistance And other physical properties.
(5) Silicon; it can increase the hardness of steel, but the plasticity and toughness decrease. The steel used in electrical engineering contains a certain amount of silicon, which can improve the soft magnetic properties.
(6) Tungsten; can improve the red hardness and heat strength of steel, and can improve the wear resistance of steel.
(7) Chromium; can improve the hardenability and wear resistance of steel, and can improve the corrosion resistance and oxidation resistance of steel.
In order to improve the corrosion resistance of steel pipes, general steel pipes (black pipes) are galvanized. Galvanized steel pipes
are divided into hot-dip galvanizing and electric steel zinc. The hot-dip galvanizing galvanized layer is thick, and the cost of electro-galvanizing is low, so there is a galvanized steel pipe.