A Review on Hot Stamping of Advanced High-Strength Steels: Technological-Metallurgical Aspects and Numerical Simulation

Abstract

The production of ultra-high strength automotive components requires a multi-directional approach. Hot stamping combines both forming and heat treatment processes to obtain a usually martensitic structure of complicated shaped automotive parts. The preparation for production using hot stamping must involve the latest methods of numerical analysis of both temperature changes and forming, which are applied for an increasing range of materials used. In this paper, the current state of knowledge about the basics of hot stamping, used technological lines, and the current state of material used with applied heat treatments and possible coatings have been reviewed. Moreover, the numerical modeling process has been described. The most important aspects of process automation, including the use of digital twins for simulation and optimization of operational kinetics of the robots accomplishing the production process, analysis and minimization of time of production cycles, and searching for weak operational points of the control systems and for real time visualization of operation of complete line, are considered. The digital twins and corresponding numerical models enable the symmetrical design of real production lines. The details of heat treatment profiles with so called tailored zone heat treatment are provided. Hot stamping is a dynamically developing technology as evidenced by the increasing range of materials used, also from the 3rd generation of advanced high strength (AHSS) steels. It starts to combine forming of symmetric or asymmetric elements with more complex heat treatment processes as required for dual phase (DP) stainless steels or the newest generation of high-strength and ductile medium-manganese steels.

Analysis of Transition Zone on a Hot‐Stamped Part with Tailored Tool Tempering Approach by Numerical and Physical Simulation

“…[ 1,4 ] Martensitic steels have high strength levels but show very low formability. Finally, the press‐hardened steels are typically carbon–manganese–boron alloyed steels, [ 5 ] which are generally adopted in the press hardening (PH) process where the unformed blank is heated in a furnace up to the complete austenitization temperature, formed in the hot condition and finally quenched in the die. These steels are typically delivered in ferritic‐pearlitic conditions and have, at the end of the PH process, almost doubled resistance levels due to the transformation into the martensitic phase due to the quenching phase.…”

“…These steels are typically delivered in ferritic‐pearlitic conditions and have, at the end of the PH process, almost doubled resistance levels due to the transformation into the martensitic phase due to the quenching phase. Among the PHS, the most common one is the 22MnB5; [ 5 ] however, other steel grades with higher carbon content are recently proposed to be used in the PH process. [ 6–8 ] PHS combined with the PH process allow to satisfy at the same time the requirements related to safety and those related to vehicle weight reduction, [ 9 ] therefore they are increasingly adopted in anti‐intrusion applications of automotive structures (bumpers, doors, bodies‐in‐white).…”

Crashworthiness evaluation of press hardened steels with different lath-like microstructures.

“…In the direct method, a hot blank is transferred to a press where forming and cooling takes place, while in the indirect method, a cold-formed blank is heated and then transferred to a cooled tool for final forming and cooling of the shape. The resulting component can have tensile strength values ranging from 1500 to 2000 MPa, allowing the production of parts with different mechanical properties [7].…”

Effects of the Intermediate Precooling Parameters on the Mechanical Properties of a Tailored Press‐Hardened Component in Advanced High‐Strength Steel

“…[ 11 ] This is a forming process in which the blanks are heated up to the complete austenitization temperature, held at this temperature for a few minutes, and then transferred to a press equipped with a water‐cooled die where the forming and the quenching of the final component occur. [ 12,13 ] During this last quenching phase, the material undergoes a martensitic transformation, giving the component high mechanical strength. [ 13–15 ] This allows to adopt thinner blanks to reduce the overall weight of the vehicle.…”