FutureSteelVehicle: leading edge innovation for steel body structures

Abstract

WorldAutoSteel launched phase 2 of its FutureSteelVehicle programme with the aim to show automakers how latest and future steel grades and technologies can provide light body structures for electrified vehicles. The objective was to develop detailed design concepts and fully optimise a radically different steel body structure for a compact battery electric vehicle in production in the 2015-2020 timeframe. This article discloses the final outcomes of the phase 2 development, detailing steel body structure concepts for the aforementioned vehicles that achieved the aggressive mass target of 190 kg, while meeting 2015-2020 crash performance objectives as well as total life cycle greenhouse gas emissions targets, noise, vibration and harshness, and stiffness. This is achieved using advanced and ultra high strength steels, engineering design optimisation and advanced steel technologies.

Enhancing mechanical properties of medium Mn advanced high-strength steel by inter-critical annealing: elimination of austenizing and quenching steps

“…In recent years, medium Mn steels (3-10 wt-% Mn) have been considered new candidates for the third-generation advanced high-strength steels (AHSSs) [1][2][3][4][5]. Weight reduction [6][7][8], fuel efficiency [9], passengers' safety [10,11] and greenhouse gas emission reduction [12] are desired outcomes for the automotive industry, which can be achieved by improving the mechanical properties of the AHSSs [13][14][15][16][17].…”

Hydrogen Embrittlement of Automotive Ultra-High-Strength Steels: Mechanism and Minimisation

“…This however presents the drawback of a reduction in physical performance: thinner parts made from the same steels will have lower stiffness and toughness, both critical properties when talking about crash performance or passenger ride comfort. To address these issues, a variety of steel products have been developed with higher strengths and toughness than the mild steel or high-strength low-alloy steels (HSLA) typically utilised in automotive structures for the majority of the twentieth century [4,10]. These 'new' steels are typically referred to as 'advanced high-strength steels' (AHSS), and if they have ultimate tensile strength (UTS) over 980 MPa, 'ultra-high-strength steels' (UHSS) or 'giga-pascal steels'.…”

“…Despite this, steel is still the overwhelming choice of metallic material, accounting for around 60% of the total mass of an average vehicle, and being significantly cheaper to produce than competitor materials it is well placed to maintain a dominant position if the correct developments in steel technology are undertaken [2]. In current designs it can be seen that the amount of mild steel being utilised has been lowered to less than 3%, and it is clear that increasing use of advanced high-strength (AHSS) and ultra-high-strength steels (UHSS) (steels with ultimate tensile strength > 780 MPa [3]) is required to fulfil downgauging and crash protection requirements, particularly in 'anti-intrusive' crash protection structures or 'safety cage', in the face of increasing legislative and commercial pressure to reduce greenhouse gas emissions [4]. The significant drawback with using steels of increasing strength, either throughout the body or within chassis and suspension applications is that this makes them more susceptible to a phenomenon known as 'hydrogen embrittlement', whereby ingress into the steel of atomic hydrogen greatly lowers the strength, ductility, and toughness of the steel, causing it to fail under loads well below that expected when in service.…”