نوع مقاله : مقاله پژوهشی
1 استادیار، مرکزتحقیقات مهندسی مواد، دانشگاه صنعتی مالک اشتر تهران،
2 دانشجوی کارشناسی ارشد، دانشکده مهندسی و فناوری های نوین، دانشگاه صنایع و معادن ایران،
عنوان مقاله [English]
In this research effect of pouring temprature on the microstructure charactristics and hot tensile properties of an experimental Ni-Fe based superalloy N-155 has been investigated. the the melt was made in induction furnece by vacuum melting . All samples were poured in the preheated ceramic mould in different pouring temprature include of 1420, 1460, 1500, 1540 and 1580 °C and cooled down to room temprature in insolated conditions. The microstructure charactristics was analised by SEM and EDS tecniques. The hot mechanical properties was caried out in 816°C for each casting condition. The results show that the main microstructure consist of austenite as only dominate phase and the secand perciptation phase concist of MCN carbunitride as shown in continuse films precipteted in a long of grain boundries. A fine equiaxed / cellural structure can be shown in pouring temprature less than 1460°C due to initial dissolved carbids. The microstructure was modified to coarse dendritic structure inlongated in heat transpher direction at higher pouring temprature around of 1500 °C. The SE images showed that the carbides morphology are blocy and short script-like in matrix respectivly was preciptated in lower superheat while in higher temprature that change to the thin and non-continouse films which preciptated around of grains boundries. The hot UTS strength reached to 310 Mpa in 1500 °C due to modified structure and reduced to 245 Mpa because of enlarged grains and also elongation increases as pouring temprature rises.