The presence of chemical heterogeneities, called macrosegregation, and the variation of grain size are two main defects that are observed in large steel blocks. These defects greatly influence microstructure, especially the proportion of phases, which ultimately determines the severity of distortion of the final part as well as its mechanical properties. In order to reduce the rate of non-compliance in produced parts, it is important to quantify the impact of variations in chemical composition and grain size on the proportion of phases formed during quenching. In this project, the effect of variation in chemical composition and grain size on the evolution of microstructure during quenching of a large steel block has been predicted using finite element simulation software Forge® NxT 1.1. Currently, this kind of simulation is not well studied and is not applied to large ingots yet. A new method for simulation of large ingots with heterogeneous composition and different grain size is proposed. It is shown that macrosegregation and variation in grain size have a significant impact on start and end time of transformation as well as the volume fraction of phases. Validation of simulation results was performed on specimens taken from different zones (surface, quarter and core) of studied steel block. Dilatometry and X-ray diffraction tests were used to determine the volume fraction of martensite, bainite, and residual austenite for each experimental condition. The results of the simulation were compared and validated with experimental data.
| Date | 17 May 2018 |
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| Original language | French |
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| Awarding Institution | - École de technologie supérieure
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| Supervisor | Mohammad Jahazi (Supervisor) |
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Lyassami, M. (Author),
Jahazi (Supervisor),
17 May 2018Student thesis: Master's thesis › Master in Engineering: Engineering