More than fifty years ago Frank proposed that a dislocation with a Burgers vector larger than a critical value would have an open core. Since then, there has been controversy as to whether micropipes in SiC are examples of open core screw dislocations. In this work open core dislocations in 4H-SiC material are investigated by AFM. The results are interpreted on the basis of Frank’s theory and the surface energy of SiC is estimated from the critical value of Burgers vector. Finally, the extracted surface energy is compared with the results of other research.