Transition temperature is one at which a material gain or lose some particular properties. Factors affecting the transition temperature are as follow.
1. Grain size : material grain size have huge effect on the transition temperature, with the increase in grain size the transition temperature increase and with the decrease in grain size transition temperature decrease.
2. Interstitial atoms: interstitial atoms are one which is added or already naturally present inside the material for example alloys. These atoms and increase or decrease the transition temperature of the material for example increasing the carbon atom in a material will increase its transition temperature of ductility means material will be ductile at higher temperature.
3. Thickness: specimen thickness represents its transition temperature. Greater the thickness high will be the transition temperature, smaller the thickness lower will be the transition temperature.
4. Crystalline structure: crystalline structure represents the temperature required by material to change from ductile to brittle. Only BCC structure materials experience ductile to brittle transition temperature so be careful to select the service temperature. This is due to limited active slip systems operating at low temperature. they have very low plastic deformation.