Experimental and numerical contribution to the study of transformation induced plasticity (TRIP)

Overview & Synopsis

This thesis has been created with the objective of providing a contribution to the study of transformation induced plasticity (TRIP) via experimental and numerical analyses. To do so, from the experimental point of view, an original experimental program on 35NCD16 steel observing the behaviors of austenite → martensite transformations were performed under different loading conditions. The results indicate that: (i) TRIP does not hold any significant memory effect, (ii) the material may present recovery from strain hardening during the martensite → austenite transformation, (iii) a dissymmetry between the TRIP responses under tension and compression were observed, (iv) the existence of TRIP backstress was revealed, (v) the amount of final TRIP may be considered proportional to the norm of the applied stress as long as the latter does not exceed the yield stress, and (vi) a slight physical orientation has however been observed when carrying out microstructural analyses on our material, which could suggest a small contribution of the Magee mechanism in TRIP. As for the numerical side, the predictive capabilities of the Leblond – Taleb – Sidoroff (LTS) model, and its updated version (U – LTS) are put to the test by simulating the experimental tests performed for this study. Our results show that: (i) the LTS model overestimates the experimental results, (ii) the LTS model fails in describing the dissymmetry between the TRIP responses under tension and compression, (iii) when using the U – LTS model, the comparative results show excellent capabilities in simulating the experimental data base performed in this work, especially compared to the LTS model. While our experimental results showed significant results, especially when put up against to the models observed in our study, further research considering other steels and other transformations is recommended.