Chromium in steel

The correct answer is Option B: Refines grain size and produces less tendency to carburisation, improves corrosion and heat resistant properties
Here's why:
Chromium is a very important element added to steel to change its properties.
Option A is incorrect because while chromium does improve wear resistance, it doesn't significantly improve cutting ability and toughness on its own. Other elements are more important for those properties.
Option B is correct. Chromium significantly improves the steel's ability to resist corrosion (rust) and oxidation at high temperatures (heat resistance). It also helps in refining the grain size of the steel, making it stronger and tougher. Finally, it reduces the tendency for the steel to absorb carbon during heat treatment (carburization).
Option C is incorrect because chromium typically *increases* hardenability, not reduces it. And it does not mainly improve cutting ability.
Option D is partially correct, it mentions anti-corrosion properties, which is true for chromium. However, chromium alone does not primarily give ductility or toughness in steel. Other elements, like nickel, are more important for that. Also, while it contributes to tensile strength, it's not the main element responsible. So, Option D is not the *best* answer.
Therefore, Option B most accurately describes the primary effects of chromium in steel.