22 November 2018 - Advanced engineering teams from ArcelorMittal and TRUMPF have presented the results of a collaborative study into laser trimming of press hardenable steels at the 2018 Erlanger Workshop. The study showed that the in-use properties of Usibor® 2000 were not affected if TRUMPF’s standard laser trimming parameters were used. The study also found that the resistance of Usibor® 2000 to stress corrosion cracking could be improved using optimized laser trimming parameters.
The study by ArcelorMittal and TRUMPF examined the impact of industrial laser trimming on the in-use properties of ArcelorMittal’s latest press hardenable steel, Usibor® 2000. The study provides valuable guidance to customers who want to get the most out of these highly advanced steel grades for automotive.
Laser trimming operation
ArcelorMittal is constantly developing innovative advanced steel grades for automotive applications to meet the changing needs of the global mobility industry. Since 2017, ArcelorMittal’s second generation of press hardenable steels (PHS), including Usibor® 2000, have been commercialized in Europe and in North America.
Optimized laser trimming for second generation PHS
Laser trimming is a standard technology which is already widely used to trim parts made from first generation PHS such as Usibor® 1500. The process must be used to trim Usibor® 2000 parts to limit the risk of hydrogen embrittlement. In collaboration with TRUMPF, a leading maker of machine tools and lasers for industrial manufacturing, ArcelorMittal investigated the impact of industrial laser trimming parameters on the in-use properties of Usibor® 2000.
Wide range of options considered
TRUMPF proposed several industrial laser trimming parameters for investigation. These included using different types of gas (air or nitrogen), different focus positions, and different speed and energy parameters. The results showed that the in-use properties of Usibor® 2000 were not affected if TRUMPF’s standard laser trimming parameters were used.
The study also found that the resistance of Usibor® 2000 to stress corrosion cracking could be improved using optimized laser trimming parameters. Tests showed that corroded parts, which had been trimmed with the optimized process, could withstand up to 80 percent of the force withstood before corrosion occurred.
Weight saving potential up to 10 percent
Using TRUMPF’s laser trimming parameters also ensure the cut edges of Usibor® 2000 parts meet expected fatigue and crash performance criteria. The high cycle-fatigue strength measured on the laser trimmed Usibor® 2000 specimens was not significantly impacted by variations in the parameters.
The fatigue performance of the Usibor® 2000 specimens was as good as the performance of Usibor® 1500. The low impact of laser trimming on the cut-edge crash performance of Usibor® 2000 specimens confirmed that weight savings of up to 10 percent are achievable compared to Usibor® 1500 which is trimmed using a standard industrial-laser process.
The authors of the study concluded that the industrial laser trimming conditions proposed by TRUMPF guarantee the optimum in-use properties of Usibor® 2000. They also provide OEMs with the opportunity to minimize the risk of stress-corrosion cracking.
Applications for Usibor® 2000 in the body-in-white of a C-segment vehicle are shown in red
ArcelorMittal’s range of press hardenable steels (PHS) already offer automotive designers a unique opportunity to create lighter and stronger solutions. But the introduction of two new products – Usibor® 2000 and Ductibor® 1000 – will allow OEMs even greater scope to lighten their vehicle fleet. And when Usibor® and Ductibor® are combined into a single laser welded blank (LWB), the properties of a part can be tailored to achieve additional cost-effective and lightweight solutions.
Click here to know more about ArcelorMittal's second generation of press hardenable steels.
TRUMPF is one of the market and technology leaders in machine tools and lasers for industrial production.
For more information, see: https://www.trumpf.com/