ANS:B - Nickel

Nickel is an alloying element commonly used in steel production due to its beneficial effects on the properties and performance of steel. One of the significant advantages of nickel is its ability to reduce the formation of iron sulfide (FeS) in steel. Iron sulfide is a detrimental inclusion in steel that can lead to various issues such as hot cracking, reduced ductility, and decreased toughness. When nickel is added to steel, it forms nickel sulfide (NiS) instead of iron sulfide. Nickel sulfide has a higher melting point compared to iron sulfide, which means it remains solid at higher temperatures during steel processing. This property prevents the formation of liquid nickel sulfide inclusions, which are known to cause hot cracking during solidification of the steel. By reducing the formation of iron sulfide and promoting the formation of nickel sulfide, nickel helps improve the cleanliness and quality of the steel. Clean steel with minimal inclusions tends to have better mechanical properties, such as increased toughness, ductility, and fatigue resistance. Furthermore, nickel also contributes to other desirable properties of steel, including increased strength, corrosion resistance, and high-temperature performance. It forms solid solutions with iron and other alloying elements, enhancing the overall microstructure and mechanical behavior of the steel. In summary, the addition of nickel to steel reduces the formation of iron sulfide inclusions, thereby improving the cleanliness and quality of the steel. This results in steel with superior mechanical properties and performance, making nickel a valuable alloying element in steel production.