Question

The intergranular failure of steels can be prevented by addition of

• A. Sulfur
• B. Manganese
• C. Silicon
• D. Phosphorous

Hint:

Manganese is added to steels mainly to counteract the harmful effects of sulfur by forming MnS.

Answer 1

The Correct Option is B

Step 1: Understanding intergranular failure.
Intergranular failure in steels occurs when fracture propagates along grain boundaries rather than through the grains. This type of failure is often caused by the presence of impurities such as sulfur at grain boundaries, which weaken them.
Step 2: Role of sulfur in steels.
Sulfur is a harmful impurity in steel. It forms iron sulfide (FeS), which segregates at grain boundaries and leads to hot shortness and intergranular cracking.
Step 3: Effect of manganese addition.
Manganese reacts preferentially with sulfur to form manganese sulfide (MnS), which is less harmful and remains distributed within the grains instead of accumulating at grain boundaries.
Step 4: Conclusion.
Thus, the addition of manganese prevents intergranular failure by neutralizing the adverse effects of sulfur.