By means of thermal dilatation a AISI 4340 steel was austenitized at some different temperatures in a range from 900 to 1150°C to obtain different austenite grain sizes (AGS), then rapidly cooled to room temperature to obtain martensitic structures. The transmission electron microscopy (TEM) including electron diffraction and microanalysis was used to describe the microstructures. It was found that both AGS and A1N exert a great effect on the martensite transformation kinetics. The larger the AGS, the higher the starting temperature of martensite transformation (tms). Within different austenitizing temperature ranges, there are different kinds of compound precipitates found, affecting the nucleation of martensites. At and below 1000°C, since the particles of AlN play an important role during the martensite transformation, tms increased rapidly. However at and above 1050°C, tms still increases with AGS. This fact may be due to the precipitation of relatively higher dissolution temperature, such as TiC, on the boundary of austenite.
|Number of pages||4|
|Journal||Dongbei Daxue Xuebao/Journal of Northeastern University|
|Publication status||Published - 2006 Jun 1|
All Science Journal Classification (ASJC) codes
- Computer Science Applications
- Applied Mathematics