| Title |
Grain Boundary Crack Initiation and Propagation during Creep of Ni Base Superalloy RENE 80 |
| Authors |
조창용(Chang Yong Jo); 박용조(Yong Jo Park); 김승언(Seung Eon Kim); 김학민(Hak Min Kim); 이상래(Sang Lae Lee) |
| Abstract |
Two kinds of specimens with different microstructure were prepared by changing casting variables in vacuum investment casting. The effect of microstructural difference on the creep behavior, creep crack initiation and creep crack propagation was studied in Ni base superalloy RENE 80. The specimen having fine grained and uniformly distributed carbide exhibited superior creep properties to the large grained specimen tested at 760℃. However above 870℃, two kinds of specimens showed similar creep behavior. At higher temperature creep, crack initiation was principally caused by the reaction between the grain boundary exposed at the surface and the test atmosphere rather than the internal microstructural changes. The crack initiated at the surface propagated to the internal area and this kind of crack propagation leads to fracture of material. |