If a steel having ASTM grain size number 5 have transition temperature equal to 20 degrees. For the same steel having ASTM grain size 10, the DBTT will be equal to __________
Correct Answer: -50
As the ASTM grain size number increases, effectively the grain diameter decreases. Also, it is known that if the grain size is smaller, the ductile to brittle transition temperature will be lower; the DBTT temperature will be less than 20 degrees Celsius.