ArcelorMittal - patented aluminium welding - Image shows the specimen

ArcelorMittal’s patented partial ablation technology was developed to ensure that hot stamped laser welded blanks (LWBs), made from the latest press hardenable steels (PHS), are as safe as possible. Although it was first used industrially in 2007, the patented partial ablation process is proving more popular than ever with carmakers. It is now used by numerous carmakers and has led to dramatic improvements in lightweighting and safety. By 2020, ArcelorMittal expects the technology will have been used to produce more than 70 million PHS LWBs using ablation technology at locations around the world.

PHS are typically supplied with an aluminum-silicon (AlSi) coating which protects the underlying steel during thermal treatments and prevents corrosion. ArcelorMittal’s patented partial ablation process removes a thin strip of the AlSi coating on the edge of the blanks before they are laser-welded together. If the coating is not removed before laser welding, the aluminum it contains can weaken the weld and cause the part to fail. Around 99 percent of the PHS LWBs made today utilize AlSi coated steels.

Laser Beam - AISi layer -Usibor- Untermetallic layer
Using ArcelorMittal’s patented ablation technology, a laser beam is used to remove the aluminum-silicon (AlSi) layer on the top of the press hardenable steel (PHS). The intermetallic layer is preserved during the operation to ensure corrosion resistance. After ablation, two or more blanks are welded together to form a single PHS laser welded blank (LWB). PHS LWBs are then hot stamped to form the part.
Remaining thin intermetallic layer - AISi Coating - allumium welding - Arcelor Mittal - aluminium welding
ArcelorMittal’s patented ablation technology removes the AlSi coating while preserving the intermetallic layers which sits between the coating and the underlying steel.
ArcelorMittal - patented aluminium welding - Image shows the specimen
Image shows the specimen – if the AlSi coating is not removed before welding, aluminum can pollute the weld and lead to part failure (left). Partial ablation ensures a strong and durable weld (right).

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