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It is studied stress relaxation at microstructure modeling, in particular percentage of
rolling reduction and relaxation time at forming microstructure. For the specimen ingot is given a
stress in hot-rolling method at temperature of 250 œC. The variable parameter is 1, 2 and 3% bulk
reduction during rolling; loading duration is 0.5 - 3.5 s. Tensile test is used to measure the tensile
strength. Knowing the initial time of grain formation, we state the initial and final moments of
precipitate during recrystallization. The microstructure analysis is performed by using Scanning
Electron Microscopy (SEM). The research results show that in the case of 1% bulk reduction
during rolling, there is a microstructure recovery in the first 0.5 s, then recrystallization begins
via 1 sec, the beginning of precipitation takes place after 1.5 s, and grain growth begins after
2.5 s. Corresponding results for 2% bulk reduction during rolling: recrystallization begins via
0,5 s, the beginning of precipitation takes place after 1 sec, and grain growth begins after 2.5 s.
The results for 3% bulk reduction during rolling: the beginning of precipitation takes place after
0.5 sec, and grain growth begins after 1.5 s.
Keywords: microstructure modeling; stress relaxation; Scanning Electron Microscopy (SEM). |
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