I don’t know how you have been cleaning a burnt iron. But whether your iron got burnt with a cloth or not, using it for a long time without adequate cleaning would definitely change its surface.

In Rajgarh, Madhya Pradesh, a 32-year-old ASHA worker was brutally assaulted by her in-laws after a neighbor allegedly ...

Bhopal: In a horrific and heartbreaking incident, a woman in Madhya Pradesh's Rajgarh district was brutally tortured by her in-laws for ‘bringing dishonour to the family’ after their neighbour tried ...

There may well be some iron inside each burnt strand, but it can’t react because no oxygen can get to it there. This effect of surface area effect is actually a very general principle.