PERSPECTIVES ON COATED ADVANCED HIGH STRENGTH STEELS FOR AUTOMOTIVE APPLICATIONS(IL23)

摘要

Advanced High Strength Steels (AHSS) is the fastest growing segment of sheet products in theautomotive industry. Coated (galvanized or galvannealed) AHSS are the most important of this classof steels. AHSS includes various families of steels, major among them being dual-phase, multi-phaseor complex-phase, TRIP and martensitic steels. Recently, Twin Induced Plasticity (TWIP) andQuenching and Partitioning (QP) steels are also becoming popular. Finally, press-hardened steels(PHS) are increasingly becoming a material of choice for many automotive manufacturers. Inaddition to tensile and yield strength properties, many of these steels are also required to possessother functionalities such as total and uniform elongation, sheared-edge stretch- flangeability,bendability and weldabilty. To achieve the combination of properties, most of these steels containsignificant amounts of various alloying elements. Presence of both the alloying elements as well asthe complex microstructures poses a challenge for coatability. These multi-faceted aspects of coatedAHSS and their metallurgical challenges will be discussed in this paper. Mechanisms to explaincoating behavior will be included as appropriate. Finally, new coatings for improved functionalitiesand future breakthrough products for automotive applications will also be briefly discussed.