Showing papers by "A. Karimi Taheri published in 2016"
TL;DR: In this paper, the failure of a reformer furnace tube was investigated due to a longitudinal crack developing in the circumferential weld joint close to the outlet end of the tube, where the mean wall temperature had reached the highest value during service.
19 citations
06 Apr 2016-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: The effect of tungsten and nitrogen on the as cast and the creep aged microstructures of heat resistant HP-Nb steel was studied in this article, where the steel was directionally solidified under two cooling rates of 31.2 and 7.6 Ksec−1.
Abstract: The effect of tungsten and nitrogen on the as cast and the creep aged microstructures of heat resistant HP-Nb steel was studied. The steel was directionally solidified under two cooling rates of 31.2 and 7.6 K sec−1. Creep rupture tests were performed at temperatures of 1150–1255 K on the specimens prepared from the cast ingots in transverse and longitudinal directions. It is shown that the addition of nitrogen significantly increases the eutectic temperature and thus refines the dendrites and alters the morphology of M7C3 eutectic carbide. Also, it is found that due to short time aging, nitrogen addition decreases the M7C3 carbide fragmentation, increases the secondary M23C6 precipitation density, and impedes the formation of Cr-rich M23C6 carbide on the primary Nb(C, N) carbide/matrix interface. These phenomena enhanced the creep resistance of the steel. The apparent activation energy and creep exponent of the steel containing both tungsten and nitrogen were determined as 210 ± 30 kJ mol−1 and 5.2, respectively, indicating that the grain boundary region plays a significant role in controlling the creep deformation of the steel.
15 citations
TL;DR: In this article, the grain refinement of copper strip is accelerated to ultrafine range by sandwiching it between two aluminum strips and then subjecting the three strips to ECAE process simultaneously.
10 citations
TL;DR: In this paper, the authors analyzed the flow behavior and workability of Ni-42Cu in cast and wrought conditions, and they performed hot deformation tests at temperatures and strain rates within the ranges of 900-1150 °C and 0.001-1 s −1, respectively.
2 citations