**6. Conclusions**

In this article, the derived crystal plasticity simulation of 3D local stress and strain has been successfully obtained from the 2D simulation result. The difference in the local stress and strain distributions in 2D and 3D simulations of the same surface is significant. There are three different parameter series, including total grain numbers, strain levels, and volume fractions. After identifying the difference in the local distributions, the alternative error and least square methods are used to transform the 2D results to match with 3D observations. It is shown that using the presented proposed iterative technique, the 3D distribution can be quickly derived from the 2D result in a ferrite matrix of DP steel. It can be concluded that the desired transformation can be achieved in the fourth iterative step by using the identified iterative constants for each phase. For the iterative constants, almost similar values regardless of total grain numbers and volume fractions are displayed. The accuracy of the developed method is demonstrated by visual and statistical analysis, and the proposed numerical approach can be regarded as effective and efficient. In the future, this method can be applied to forecast 3D distributions of stress and strain in other multiphase materials, such as spheroidized steels and particle-based metal composites.

**Author Contributions:** Conceptualization, S.T. and F.Q.; methodology, S.T. and F.Q.; software, S.T. and F.Q.; validation, S.T. and F.Q.; formal analysis, S.T. and F.Q.; investigation, S.T. and F.Q.; resources, S.G.; data curation, S.T. and F.Q.; writing–original draft preparation, S.T. and F.Q.; writing–review and editing, S.T. and F.Q.; visualization, S.T., F.Q. and C.C.; supervision, S.G., C.C. and U.P.; project administration, U.P. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable. **Data Availability Statement:** The simulation data are not publicly available but can be shared upon request.

**Acknowledgments:** The authors acknowledge the DAAD/MOST scholarship (Sandwich program) for doctoral candidates from Taiwan, 110-2927-I-011-505, for funding for sponsoring the stay of Shao-Chen Tseng at the IMF TU Freiberg. The authors acknowledge the DAAD Faculty Development for Candidates (Balochistan), 2016 (57245990)-HRDI-UESTP's/UET's funding scheme in cooperation with the Higher Education Commission of Pakistan (HEC) for sponsoring the stay of Faisal Qayyum at thr IMF TU Freiberg. The authors also acknowledge the support of Martin Diehl and Franz Roters (MPIE, Düsseldorf) for their help regarding the functionality of DAMASK.

**Conflicts of Interest:** The authors declare no conflict of interest.
