High-strength steels such as Dual Phase (DP), Transformation-Induced Plasticity (TRIP), and Twinning-Induced Plasticity (TWIP) steels have gained importance in automotive applications due to the potential for weight reduction and increased performance in crash tests. However, as resistance increases, there is also an increase in springback due to residual stresses after the forming process. This is mainly because of the greater elastic region of these materials and other factors associated with strain hardening, such as the Bauschinger effect, that brings theory of kinematic hardening to mathematical modeling. This means that finite element software must consider these properties so that the simulation can accurately predict the behavior. Currently, this knowledge is still not widespread since it has never been used in conventional materials. Additionally, engineers and researchers use the Forming Limit Diagram (FLD) curve in their studies. However, it does not fully represent the actual failure limit of materials, especially in high-strength materials. Based on this, the Fracture Forming Limit Diagram (FFLD) curve has emerged, which proposes to resolve these limitations. Thus, this review aims to focus on how finite element methods consider all these factors in their modeling, especially when it comes to the responses of high-strength steels.

There are 6 different types of equations that have been formulated to measure friction through the bending under tension test, however, there is no work to show whether these calculations actually represent what is happening in a sheet metal stamping process. This paper aims to make a direct comparison between the bending under tension test and the sheet metal forming of a test piece to see if the friction coefficient reported by the test is able to predict friction in a real part. Several sources of information were used such as computer simulations, bending under tension test with different sensors and sheet metal forming tests of a cylindrical geometry to evaluate the friction. The results indicate that the equations already developed are not able to accurately predict the friction at the sheet interface and, therefore, a new equation was developed for this that is simpler to measure and presented satisfactory results.

Friction between the interface workpiece and tooling has considerable importance in sheet metal forming operations; an accurate description of the friction is necessary to analyze and design new workpieces and tooling. This work suggests a methodology to determine and evaluate the mean coefficient of friction (COF) using the Finite Element Method (FEM) through Dynaform for the aluminum alloy AA1100. The results indicate that this methodology is consistent with reality. It is also observed that the software tends to diverge from the measured results because the software considers the COF to be constant along the process. Despite this trend, the greatest distance between the maximum drawing force given by the measurement and the numeric simulation was not high: it was approximately 6%. Workpiece strain measurements were collected to compare with the numerical simulation results, and it was observed that they are generally in agreement.

Boron-manganese steel 22MnB5 is extensively used in structural automotive components. Knowledge about its microstructural evolution during hot stamping and resistance spot welding (RSW) is extremely relevant to guarantee compliance with application requirements. Particularly, corrosion properties are critical to the application of uncoated sheet steels. However, microstructural studies are usually simplified to top-hat geometries, which might not be fully representative of the complex thermomechanical cycles locally faced by a real component. Therefore, the present work brings an extensive characterization of a hot-stamped 22MnB5 automotive B-pillar in terms of microstructure, hardness and corrosion resistance, which were correlated with a reverse engineering of the process using numerical simulation. Physical simulations of the subcritical heat affected zone (SCHAZ) of RSW were done to assess the influence of microstructure on martensite tempering. Results showed that the component undergoes a complex strain distribution along its body during hot stamping. Most heavily strained regions presented higher amounts of ferrite, leading to poorer corrosion resistance, since ferrite behaves as an anode. Physical simulations of the SCHAZ showed that the softening degree due to martensite tempering is solely affected by peak temperature, while other microstructural features appear to exert negligible or no influence.

Friction between the interface workpiece and tooling has considerable importance in sheet metal forming operations; an accurate description of the friction is necessary to analyze and design new workpieces and tooling. This work suggests a methodology to determine and evaluate the mean coefficient of friction (COF) using the Finite Element Method (FEM) through Dynaform for the aluminum alloy AA1100. The results indicate that this methodology is consistent with reality. It is also observed that the software tends to diverge from the measured results because the software considers the COF to be constant along the process. Despite this trend, the greatest distance between the maximum drawing force given by the measurement and the numeric simulation was not high: it was approximately 6%. Workpiece strain measurements were collected to compare with the numerical simulation results, and it was observed that they are generally in agreement.

The use of ultra-high-strength steels (UHSS) has been growing in recent years, mainly in the automotive industry. Since these steels have high strength and hardness, more applied stresses are required to deform them, probably also impacting friction behaviour. In this article, a variation in the process parameters commonly observed in sheet-metal forming, such as contact pressure, sliding speed, lubrication and working temperature was performed. The material used was TRIP1000. These process parameters were varied, aiming to investigate the friction-coefficient behaviour; however, it was observed that there were no significant variations, indicating that the steel hardness may have contributed to this. Another finding is that, even if the lubricant did not change the average value of the friction coefficient, it contributed to a more stable process, favouring the absence of premature wear of the tools.