What is the effect of carbon content on the mechanical properties of steel? What is the effect of Mn, Si, S, P on the properties of steel?

What is the effect of carbon content on the mechanical properties of steel? What is the effect of Mn, Si, S, P on the properties of steel?

Carbon steel generally contains a small amount of silicon, manganese, sulfur and phosphorus in addition to carbon.
Effect of Monomanganese
Manganese is a kind of beneficial element in steelmaking by adding ferromanganese to deoxidize the steel. Manganese has a good deoxidizing ability, which can remove FeO from the steel and reduce the brittleness of the steel. Manganese can also form MnS with sulfur to reduce the harmful effect of sulfur. However, its content (Wmn) is generally not less than 0.8% in the presence of impurities, which has little effect on the properties of the steel.
Effect of disilicon
Silicon is a kind of useful element in steelmaking. The deoxidizing ability of silicon is stronger than that of manganese. At room temperature, silicon can dissolve into ferrite and improve the strength and hardness of steel. Therefore, silicon is also a beneficial element. However, its content (Wsi) is generally less than 0.4% in the presence of impurities.
Effect of trisulfide
Sulphur is brought into steel by ore and fuel during steelmaking. Sulphur forms compound FeS with iron in steel, and FeS and iron form eutectic with low melting point (985°C) distributed on austenite grain boundary. When steel is heated to 1100-1200°C for forging, eutectic on grain boundary has been melted, resulting in cracking of steel during forging, which is called "hot embrittlement ". MnS with high melting point (1620°C) can be formed by adding manganese into steel, and MnS is distributed in grain grain, and has certain plasticity at high temperature, so as to avoid hot embrittlement. Therefore, sulfur is a harmful element. Its content (Ws) should be strictly controlled below 0.03%-0.05%.
Effect of Tetraphosphorus
Phosphorus is introduced into steel from ore during steelmaking. Phosphorus can be completely dissolved in ferrite, resulting in strong solution strengthening, which increases the strength and hardness of steel, but decreases the plastic toughness significantly. This embrittlement phenomenon is more serious at low temperature, so it is called "cold embrittlement ". Phosphorus is easy to be segregated during crystallization, thus cold embrittlement occurs locally. Therefore, phosphorus is also a harmful element, and its content must be strictly controlled below 0.035%-0.045%.
However, when the content of sulfur and phosphorus is large, because of the high brittleness, the cutting is easy to break and form fracture chips, which improves the machinability of steel.

With the increase of carbon content place in the mechanical properties of Fe-C alloy with the increase of carbon content.... With the increase of carbon content, the mechanical properties of Fe - C alloy changed. In Fe-C alloy, with the increase of carbon content, what kind of mechanical properties change.... With the increase of carbon content, the mechanical properties of Fe - C alloy changed.

Carbon is the main element that determines the properties of steel, because the change of carbon content directly causes the change of crystal structure. With the increase of carbon content, the strength and hardness of steel increase, while the plasticity and toughness decrease. When the carbon content exceeds 1.0%, the strength of steel decreases. The increase of carbon content also reduces the weldability and corrosion resistance of steel, and increases the cold brittleness and aging tendency of steel.