| Title |
Effect of Microstructure on Fracture Toughness of High Cr White Iron hardfaced Layers |
| Authors |
이성학(Sung Hak Lee); 추성훈(Seong Hun Choo); 백응율(Eung Ryul Baek); 안상호(Sang Ho Ahn); 김낙준(Nack J . Kim) |
| Abstract |
This study aims at investigating the effect of matrix microstructure of high Cr white iron hardfacing alloys on fracture toughness and abrasion resistance. The hardfacing alloys were deposited twice on a mild steel plate using self-shielding flux cored arc welding method. In order to examine the matrix effect, different matrices such as pearlite, austenite, and mixture of pearlite and austenite were employed by changing the ratio of Mn/Si, while the total volume fraction of carbides was fixed. As the volume fraction of austenite in the matrix was increased, hardness and abrasion resistance were nearly constant, but fracture toughness was increased. In-situ observation of fracture process showed that cracks initiated at large primary M_7C₃ carbides tended to be blocked at the austenitic matrix, whereas they propagated through the pearlitic matrix. It could be concluded that abrasion resistance was controlled mainly by the volume fraction of primary carbides, while fracture toughness was controlled mainly by the amount of austenite in the matrix. Considering both abrasion resistance and fracture toughness, thus, the austenitic matrix was preferred for the high Cr white iron hardfacing alloys. |