ahss high-ductility stands for “advanced high strength steels high-ductility”.voestalpine developed these high-strength, cold-rolled steels as an enhancement to the classic AHSS steels (dual-phase, complex-phase, and TRIP steels with minimum tensile strengths up to
1200 MPa). ahss high-ductility steels offer a previously unattained balance among the following properties:
- top forming
- good weldability
- excellent crash behavior
Asian trend. Asian automakers rely heavily on high-quality cold-formed steels for safety-relevant parts. Although European OEMs are focusing more on press-hardened steels, in Asia there is an increasing demand for highest-strength cold-formed steels. voestalpine’s AHSS developments were industrially implemented in the mid-90s, and this solid know-how edge paid off during the development of high-ductility steels. These steels have since been certified by many European and Asian OEMs, and accordingly major orders have been booked. The keen interest is reflected in the many ongoing certifications. Typical applications for high-ductility steels are the classic crash-relevant components in the passenger compartment as well as seat tracks and profile applications.
Coatings and portfolio. Proven metallic coatings protect these steels from corrosion. voestalpine offers the usual automotive coatings—galvanized and electrolytic. The portfolio includes:
- ahss high-ductility complex-phase steels with unbeatable bending properties for a yield strength with minimum tensile strengths of 980 and 1180 MPa
- ahss high-ductility dual-phase steels with outstanding drawing properties and excellent crash behavior with minimum tensile strengths of 590, 780, 980, 1180 MPa
The “deep” secret of success. These excellent properties are achieved based on a modified microstructure design unlike that of “classic AHSS steels”. The key is increasing the bainite content in the matrix structure, and sometimes using tempered martensite for highest-strength steels. The extraordinary characteristics result from a suitable alloy design and complex temperature control that prevents the separation of iron carbides both during bainite formation and when tempering the martensite.