Thank You ! :)

Hi Sankar, based on my knowledge, inter-granular fracture is one which is caused by the crack which follows the grain boundaries, which means the crack is restricted to one particular grain e.g stress cracking ; however trans-granular fracture is caused by crack which does not follow grain boundaries and hence transcends from one grain to another grain e.g fatigue crack..

Regards,

Arvind

Hello Sankar,

I agree with Arvind. Intergranular fracture: crack follows the grain boundaries whereas, transgranular it passes from one to another. 

I would like to add a discussion about how hydrogen change the fracture mode: Generally in high-Mn steels hydrogen changes the fracture mode from intergranular to quasi-cleavage.

Please also see:

https://www.jstage.jst.go.jp/article/isijinternational1989/34/2/34_2_211/_article

http://www.sciencedirect.com/science/article/pii/S0010938X1200114X 

Generally at higher T grain boundary weak-intergranular fracture. e.g.-Creep- required less Grain boundary hence coarse or single grain is preffered .However, at lower T grains are weak, fracture across the grain.

equicohesive Temperature- transition temperature @ TF become IF