Question

write a chemical equation to illustrate the use of aluminium for joining cracked railway line

Answer 1

here is your answer friend
fe2o3 + AL - Al2o3 + fe
which is used in joing the cracked railway and machine parts. This process is know as thermit procsss
if you like this answer mark as brainlist

Answer 2

Basically for this a mixture of iron (III) oxide and aluminium powder is ignited with a burning magnesium ribbon.

The intention is that aluminium reduces iron oxide to produce molten iron metal with the evolution of  heat.

Fe2O3(s) + 2Al(s) → 2Fe(l) + Al2O3(s) + Heat

The molten iron produced is then poured between the broken iron pieces to weld them.