| Title |
The Effect of Heat Treating Temperatures on the Creep - Rupture Properties |
| Authors |
조현기(Hyun Kee Cho); 정인상(In Sang Chung); 이동희(Dong Hee Lee) |
| Abstract |
In recent years, manufacturing processes for the Fe-25Cr-20Ni-0.4C heat resistant alloy such as hot rolling and hot extrusion, were tried to improve the shape and surface quality of the centrifugally casted product although these hot worked ones have poor creep-rupture properties. So heat treatment and addition of alloying element were needed to improve the poor creep-rupture properties of the hot worked product. The effects of heat treating temperatures and addition of Ti on the creep-rupture properties of the hot worked alloy were investigated. The results obtained are as follows : 1) The times to rupture of the alloy heat treated at 1250℃ were greatly increased than those of hot worked one due to the change of grain size and distrubution of M_(23)C_6 at the grain boundary. 2) Heat treating at 1290℃ was more effective to increasing of the rupture time than those at 1250`C due to the formation of M_7C₃ carbide at the grain boundary besides M_(23)C_6. 3) The fracture modes of hot worked and solution treated alloy at 1250℃ were mixture of transgranular and intergranular. But those of solution treated alloy at 12901℃ were intergranular. 4)Titanium is a useful element to increase the rupture time of the alloy due to the formation of TiC at the grain boundary. |