NEWS
NEW WELDING METHOD TO EXPAND USE OF HIGH-STRENGTH STEEL
A new welding technique for advanced high-strength (AHS) steel used in automotive and aerospace applications has been developed by a researcher at the Brazilian Air Force Command’s Institute for Advanced Studies (IEAv). The new method, published in
the Welding Journal, addresses problems faced previously when welding AHS steels, namely brittle joints that would break when submitted to the hot stamping and forming featured in many manufacturing processes. AHS steels are characterised by
improved formability and collision resilience compared to conventional steel grades, making them ideal for use in critical safety locations in car body structures. Their tendency to become brittle when welded, however, hinders their application in industry. ‘This problem makes it
impossible to use AHS steel, not only in the automotive industry but also in other industries such as aerospace,’ said IEAv researcher Milton Sergio Fernandes de Lima. Lima’s technique consists of
heating sheets of 22MnB5 steel – the most promising AHS grade for hot stamping and forming – to approximately 450°C ten minutes
demonstrated improved resilience in the sheets containing bainite. ‘We succeeded in producing
tough weldments directly in the bainitic band without any need for additional heat treatment,’ said Lima, who explained that the technique can be applied in manufacturing to improve laser
producing tough weldments directly in the bainitic band
We succeeded in
welding of high-strength and ultra-high-strength steel. The automotive industry uses
The presence of bainite (indicated with B) in AHS steels is shown to produce tough and reliable weld joints
before laser welding, in order to equalise the temperatures involved. The sheets are then kept at a high temperature for another ten minutes after welding to produce a bainitic structure. Metallurgists have discovered
that bainite, a microconstituent that forms in steel under certain conditions, is the best candidate to produce tough and reliable weld
Laser cutting boosted by simulation software
Researchers at the Visual Interaction and Communications Technologies Center Foundation (Vicomtech) in Spain have developed software that can simulate the laser cutting process. The BeroSim 3D simulation software,
made in collaboration with manufacturing software firm Lantek, gives graphical representations of how heat sources affect sheet metal during laser and plasma cutting processes. The project, covered in the Journal of
Manufacturing Science Engineering, is anticipated to provide significant added value to the sheet metal cutting industry, according to the scientists, and represents progress in the digital
transformation of the sector towards Industry 4.0. The BeroSim software simulates the
impact and propagation of heat in laser and plasma sheet metal cutting, which reveals how the heat is distributed and the effect this has on the material. Users are then able to select the optimal sheet metal strategy and cutting order, while also anticipating and detecting potential unforeseen anomalies during the layout phase, such as material deformation. Engineers can also use the simulation to correct the cutting path and trajectory of the machine. ‘Understanding how heat sources affect sheet metal cutting processes is
joints. In particular, it displays high values for yield and tensile strengths. Analysis of the sheets welded at
this high temperature showed that they contained bainite and were far tougher than sheets welded at room temperature, which contained martensite, a microconstituent with lower yield and tensile strengths than bainite. Stress tests
laser welding to join steel blanks and stamped structural body parts such as pillars, beams, rails, frames, tunnels and bars faster and more reliably than with conventional welding. ‘Many materials developed by the
aerospace industry have never flown because they fail to meet the industry’s necessarily high-reliability requirements,’ said Lima. ‘But by-products of these materials may have applications and be easily introduced in other areas, such as the automotive industry.’
The simulation software shows how heat propagates through metal during laser cutting
essential in the design of efficient simulation tools,’ said Dr Aitor Moreno, a researcher and expert in industrial process simulation techniques at Vicomtech.
Simulating the cutting process also
means that the effects of cutting do not need to be tested on an actual machine, which saves time, materials and energy.
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LASER SYSTEMS EUROPE ISSUE 38 • SPRING 2018
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www.lasersystemseurope.com
Lima et al
Lantek
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