The influence of Martensite Volume Fraction (MVF) on fracture mechanisms in a Dual Phase steel with two different grain sizes was studied in this work. Ferrite-Martensite microstructure was obtained by an intercritical heat treatment for both groups of grain sizes. The results show a direct relationship between a higher temperature during the intercritical heat treatment and the increase of the MVF. The fine microstructure with higher MVF presents a high tensile strength and a good ductility. Furthermore, in relation to the material behavior under impact conditions, grain refinement and higher values of MVF promote ductile fracture by typical microvoid coalescence. High values of impact energy refer to the presence of low-carbon martensite formed at higher temperatures, which is more ductile than high carbon martensite formed at lower temperatures. Additionally, fine-grained materials have a better ability to dissipate impact energy. It was shown that an increase of 10.0% in MVF allows fine grain microstructures to improve their capacity to dissipate impact energy by 11.4%. This behavior may be explained because of the low carbon content of the as-received material, and the mechanical properties of the martensite obtained by the intercritical heat treatment.

Currently, the steel manufacturing industry faces significant challenges in meeting the necessary processing requirements to develop low-weight and high-strength materials through efficient and clean production routes. For example, in the transportation and automotive manufacturing industries, lightweight structural materials that enhance the autonomy versus fuel consumption ratio, improve passenger safety, and optimize processing costs, are increasingly a mandatory requirement in the research and development of recent manufacturing projects. [1] In this sense, the development of advanced high-strength steels (AHSS), particularly dual-phase steels (DP), has enabled the improvement of automotive engineering safety through the use of sheet metal members (safety cage components, roof rails, and rear shock reinforcements) with thin walls to improve crashworthiness. [2,3] Low-carbon dual-phase steels consist of a ferrite matrix and a second phase of distributed martensite. The two phases combined, usually produced by intercritical heat treatments (IHT) and water quenching, are responsible for the plastic flow mechanism observed in these steels. [4,5] Shear stresses are generated along grain boundaries due to the austenite to martensite transformation during the quenching process. Therefore, due to these microstructure volume changes, dislocation density increases. [6,7] As a result, a pile-up of sliding unanchored dislocations reduces yield stress and interacts to produce a high work-hardening rate. [8] Hence, the continuous plastic flow behavior evidenced by dual-phase steel results from the above-mentioned factors. [9] The deformation process of

The influence of Martensite Volume Fraction (MVF) on fracture mechanisms in a Dual Phase steel with two different grain sizes was studied in this work. Ferrite-Martensite microstructure was obtained by an intercritical heat treatment for both groups of grain sizes. The results show a direct relationship between a higher temperature during the intercritical heat treatment and the increase of the MVF. The fine microstructure with higher MVF presents a high tensile strength and a good ductility. Furthermore, in relation to the material behavior under impact conditions, grain refinement and higher values of MVF promote ductile fracture by typical microvoid coalescence. High values of impact energy refer to the presence of low-carbon martensite formed at higher temperatures, which is more ductile than high carbon martensite formed at lower temperatures. Additionally, fine-grained materials have a better ability to dissipate impact energy. It was shown that an increase of 10.0% in MVF allows fine grain microstructures to improve their capacity to dissipate impact energy by 11.4%. This behavior may be explained because of the low carbon content of the as-received material, and the mechanical properties of the martensite obtained by the intercritical heat treatment.

The present study proposes the design, simulation, and finite element analysis (FEA) of a mechanical press to test coining tools that contain nanostructured coatings. The designed mechanical testing press has a nominal force capacity of 800 kN with a ram stroke of 100 mm. CAD modeling of components, assemblies, and press structure is developed. The validation of the safety factor of the stress of the press is implemented by FEA analysis. Axisymmetric 2D FEA simulation is applied to determine the nanostructured coating behavior when subjected to high loads, the results are promising for future simulation studies on coatings. A displacement mechanism was designed for the test sheet, offering versatility and a variety of options for testing the coining tools as often as necessary under different load conditions. The final results of the machine operation simulation are satisfactory.