Multiphase steels with customized characteristics - xpand® and xtend® guarantee stable production processes

In addition to the classic representatives of multiphase steels in the strength range from 450 MPa to 980 MPa, Salzgitter Flachstahl GmbH (SZFG) is now also offering its customers specialized versions. These have been developed in intense cooperation involving customers, Salzgitter Mannesmann Forschung GmbH (SZMF), and SZFG Technical Customer Services.

Photo of a hole expansion samplehole expansion sample with superimposed simulation of the material stress — Example hole expansion sample to describe the xpand® steels with superimposed simulation of the material stress

The first version has the term xpand^® added to its name. The term xpand^®stands for the material's guaranteed increased hole expansion capacity. This describes how far a hole punched into a sample can be widened without leading to material failure at the cut edge. The hole expansion capacity is described by the hole expansion ratio λ, which describes the ratio of the original hole size to that of the expanded hole. The higher the hole expansion ratio λ, the more resistant the material is to edge cracks. The standardized hole expansion test described in DIN ISO 16630 is used to determine λ.

Photo of car trailing arm with collared hole. — Example of a car trailing arm with collared hole. Fulfillment of the requirement for a reliable depiction with low tendency to form edge cracks in the material thanks to use of xpand® steels

xpand^® steels are used in applications that place higher demands on the material's formability characteristics in shear-cut areas. One example is trimmed and consequently work-hardened areas of a plate from which collars or bent portions are to be formed in a later stage of the component manufacture.

Photo of a complex body part — Example of a complex body part with the requirement for higher material elongation as a possible application for xtend® steels

The use of xpand^®steels not only broadens the range of components thanks to the shear-cut component's edge improved formability, it also allows a reliable and stable process.

The second improved material versions are steels with xtend^® added to their name. The brand name xtend^® stands for the steel's improved elongation. The optimized characteristics feature an increased value for the elongation at break in the single-axis tensile test. SZFG is currently offering its customers its first xtend^®steel, grade CR440Y780T-DH (named in accordance with the VDA239-100 standard) in a hot- dipped zinc-coated version.

Unlike xpand^®steels, xtend steels^®are used in situations that place comprehensively higher demands on the material's formability characteristics in shear-cut areas. This particularly occurs in the manufacture of highly complex deep-drawn components for vehicle bodies, such as gusset plates or pillar reinforcements.

Both of these versions of the enhanced multiphase steels with xpand^®or xtend^®characteristics are excellent choices for the manufacture of elements with extremely high demands on their complexity. In addition, significant improvements in the process reliability and process stability are possible.

If you have any questions, your contact from Sales and the Technical Customer Services would be happy to help.