Resumen

SIAS-CHACON, A.; COVARRUBIAS-ALVARADO, O.  y  PEREZ-UNZUETA, A.. Mechanical properties assessment of a high strength automotive steel processed via Quenching and Partitioning. RIIIT. Rev. int. investig. innov. tecnol. [online]. 2020, vol.8, n.43, pp.1-17.  Epub 05-Feb-2021. ISSN 2007-9753.

The emphasis of the automotive industry in manufacturing vehicles of reduced weight has led to an increase in the usage of hot stamped steel components. However, improving the formability is still a challenge for these steels. The new Quenching and Partitioning (Q&P) process offers a good alternative to produce high strength and at the same time, formable steels based on the development of a microstructure consisting of martensite and retained austenite.

This research is focused on the enhancement of formability while maintaining a high mechanical strength using the feature of the microstructure developed after Q&P treatments for a commercially produced CSiMn steel. The investigated steel was fully austenitized with subsequent quenching to a temperature below the martensite start temperature (Ms), followed by isothermal holding at the same temperature (one-step) and by reheating to higher temperature (two-step). Formability was on the one hand characterized by using the common description in terms of uniform and total elongation from tensile tests and on the other hand, by using a maximum achievable bending angle determined from three-point bending tests. The outcomes indicated that the enhancement of the formability is higher with partitioning at 440 °C for 100 seconds, suggesting a strong Transformation Induced Plasticity (TRIP) effect due to larger fractions of stable austenite. Whereas at lower partitioning temperatures the reduced amounts of retained austenite and the consequently lower formability can be explained by carbides precipitation which suppress the stabilization of retained austenite.

Palabras llave : Ductility; High strength; Martensite; Partitioning; Retained austenite.

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