Hydro has long been the leading supplier of extruded aluminium bumper beams to European automakers.

Hydro's competence in this area is embedded in its product and process engineering, which the company has developed continuously – and globally - for the past 40 years.

Crash management systems

The company's crash management systems – typically, bumper beams and crash boxes, but also rollover protection systems – are dominated by 6xxx and 7xxx-series extruded aluminium profiles. Most customers prefer the 7xxx-series family for bumper beam applications due to the higher yield strength.

High-strength aluminium (HSAlu, yield strength>300MPa) or ultra-high-strength aluminium (UHSAlu, yield strength>400MPa) is the normal choice for bumper beams. As long as compression buckling is avoided, the weight saving is approximately proportional to the yield strength of the alloy, thereby favoring the higher strength aluminium alloys.

The increased production cost of an UHSAlu 7xxx alloy can be offset by the need for less material. Moreover, reduced weight in automobiles also helps reduce energy consumption and greenhouse gas emissions.

Hydro's crash boxes are typically made with the 6060 alloy or the high-strength 7003 alloy. The 7003 has superior energy absorption characteristics combined with good ductility – both are needed in the compression folding of the box.

Making inroads

Statistics from the European Aluminium Association (EAA) show that HSAlu and UHSAlu alloys, originally from the aerospace sector, now further developed for volume extrusion, are making inroads into the automotive industry.

In fact, the EAA reports that these alloys were used in about nine million crash management systems produced last year in Europe, largely due to excellent strength-to-weight ratio and crash performance.

This performance is highly competitive with that of ultra-high-strength steel (UHSS) in crash management applications.

HSAlu and UHSAlu grades, when exploiting the design flexibility of an extruded profile, will allow weight savings of 30 percent compared to the UHSS solution in bumper beams, and 40-to-60 percent in crash boxes.

Hydro is the leading supplier of extruded aluminium bumper beams, delivering components to most of the world's largest producers of passenger vehicles.