Targeted AHSS Properties
The Need for 3rd Generation Advanced High Strength Steels
The automotive industry has identified the need for a new generation of Advanced High Strength Steels (AHSS) with greater ductility to enable the design of lighter weight vehicle structures. These steels have an availability target of 2017 for integration into design and production.
Achieving the combination of both high strength and high ductility in the same steel has long been elusive and has opened the door for alternative materials in automotive lightweighting. Existing advanced high strength steels require that customers make a tradeoff between high strength parts that are designed using more limited geometries or using more expensive production methods such as hot stamping. Both of these approaches are less than optimal and have the effect of hindering the usage of these steels.
The existing pattern in strength and ductility relationships in steel alloys used in automobiles is demonstrated by the well-known “Banana plot” from World Auto Steel shown in the tabs below.
The conventional steels, in green, are currently used in most automotive applications and demonstrate high formability, which allows them to be inexpensively shaped. The known AHSS, shown in orange, trade much of that formability for increased strength. The exceptions to this are Twinning Induced Plasticity (TWIP) steels, which have high ductility but whose use has been limited due to multiple factors including delayed fracture, and austenitic stainless steels which are prohibitively expensive for automotive body structures.
Given this, automakers established properties for 3rd Generation AHSS to meet the needs of the industry. NanoSteel sheet steel is designed to meet and exceed these targets.