Fast charger heating up the phone

[bhavstech]

the phone gets heated up to about 40-45 degrees Celsius if continuously kept on charging to charge 50-60% of the battery but once the phone reaches 70% the heat decreases and above 800% its cool is it normal for the phone/charger or i should get charger replaced?The charging pin also gets heated up ! Is it due to fast charger or i have a defective charging port?