Third generation of advanced high-strength steels: Processing routes and properties

Abstract

The automobile industry is presently focusing on processing of advanced steels with superior strength-ductility combination and lesser weight as compared to conventional high-strength steels. Advanced high-strength steels are a new class of materials to meet the need of high specific strength while maintaining the high formability required for processing, and that too at reasonably low cost. First and second generation of advanced high-strength steels suffered from some limitations. First generation had high strength but low formability while second generation possessed both strength and ductility but was not cost effective. Amongst the different types of advanced high-strength steels grades, dual-phase steels, transformation-induced plasticity steels, and complex phase steels are considered as very good options for being extended into third generation advanced high-strength steels. The present review presents the various processing routes for these grades developed and discussed by different authors. A novel processing route known as quenching and partitioning route is also discussed. The review also discusses the resulting microstructures and mechanical properties achieved under various processing conditions. Finally, the key findings with regards to further research required for the processing of advanced high-strength steels of third generation have been discussed.

Development of Lightweight Steels for Automotive Applications

“…Since then, due to the continuous pressure on material development, several new high strength steel grades appeared and reached already the everyday industrial application. Systematic analysis of these developments can be found in several papers from various authors in the literature [3][4][5][6][7]. In the next sections, a systematic classification of these developments will be summarized.…”

“…The microstructure of these steels consists of a high strength phase (e.g., nano/ultrafine-grained ferrite, martensite, or bainite) combined with a further phase or constituent that provides substantial ductility and work hardening (e.g., austenite). With this development concepts, very high strength steels in the GPa range with even though remarkable formability can be produced [7].…”

Enabling sustainable transportation through joining of dissimilar lightweight materials

“…Third-generation AHSS alloys have been introduced in the last decade with tensile strengths comparable to those of UHSS while maintaining the ductility of DP and TRIP steels, allowing for increased formability and ease of manufacturing. 6 As the push for greater fuel economy continues, the automotive industry is also looking at lower density materials options, including aluminum alloys, carbon fiber composites, and magnesium alloys. Carbon fiber composites were introduced into the automotive industry in 1981 in McLaren's MP4/1 Formula 1 car.…”

“…In 2015, a research team from Magna International and Ford Motor Company published the results of their Multimaterial Lightweight Vehicle design that weighed 23.3% less than the baseline vehicle, a 2013 Ford Fusion, while also meeting safety and performance targets. 6 Table I shows how the mass reductions were applied across the major subsystems of the vehicle. 10 The design relied on commercially available materials and production processes; it was aluminum intensive, with steel, carbon fiber composite, and magnesium components as seen in Figure 2.…”

Mechanical Properties Characterization of Welded Automotive Steels

“…RSW and LBW are the most commonly-used joining methods for DP steels in the automotive industry [5]. However, the characterization of the mechanical properties of the weld metal remains a critical concern to analyze the safety of automotive products [6]. Various investigations, therefore, deal with the fracture behavior of resistance spot-welded steel [7].…”