stages at which allotropic forms change

stages at which further heating does not increase temperature for some time

stages at which properties do not change with increase in temperature

there is nothing like points of arrest

room temperature

above melting point

between 1400°C and 1539°C

between 910°C and 1400°C

has a fixed structure under all conditions

exists in several crystal forms at different temperatures

responds to heat treatment

has its atoms distributed in a random pattern

below 10°K

above 100°K

around 0°C

around 100°C

austenite

pearlite

ferrite

cementite