Recently the use of ultra high strength steels (UHSS) in structural and safety component is rapidly increasing in the automotive industry. For example, 1.5GPa grade hot stamping with die-quenching of boron steel 22MnB5 could apply crash-resistant parts such as bumpers and pillars. The development of laser welding process of hot stamping steels, fundamental bead-on-plate welding and lap joint welding test were carried out using 3kW Nd:YAG laser. Local hardening & HAZ softening occurred in hot stamping steel as a result of metallurgical change caused by the welding heat input in the Nd:YAG laser welding process. The size of soft zones in the hot stamping steel was related to the welding heat input, being smaller at high speeds which generated a smaller heat input. Also in the case of lap joint design structure, same welded characteristics were shown. The HAZ softening degree was controlled to ensure the joint strength.

Today, the most common process for generating Through Silicon Vias (TSVs) for 3D ICs is Deep Reactive Ion Etching (DRIE), which allows for high aspect ratio blind holes with low surface roughness. However, the DRIE process requires a vacuum environment and the use of expensive masks. The advantage of using lasers for TSV drilling is the higher flexibility they allow during manufacturing, because neither vacuum nor lithography or masks arc required and because lasers can be applied even to metal and to dielectric layers other than silicon. However, conventional nanosecond lasers have the disadvantage of causing heat affection around the target area. By contrast, the use of a picosecond laser enables the precise generation of TSVs with less heat affected zone. In this study, we conducted a comparison of thermalization effects around laser-drilled holes when using a picosecond laser set for a high pulse energy range and a low pulse energy range. Notably, the low pulse energy picosecond laser process reduced the experimentally recast layer, surface debris and melts around the hole better than the high pulse energy process.

Robot path generation and laser welding technology for manufacturing automotive body are studied. Laser welding and industrial robot systems are used with the robot based laser welding system. The laser system used in this study is 1.6kW Fiber laser, while the robot system is 6 axes Industrial robot (payload: 130kg). The robot based laser welding system is equipped with laser scanner system for remote laser welding. The laser source, robot and laser scanner system are used to increase the processing speed and to improve the process efficiency. The welding joints of steel plate are butt and lapped joints. The quality test of the laser welding are through the observation the shape of bead on plate and cross-section of welding part. The 3 dimensional laser welding for non-linear pipe welding line is performed. This paper introduces the robot based laser welding system to resolve the limited welding speed and accuracy of the conventional spot welding system.

Plasma electrolyte oxidation (PEO) surface treatment of magnesium alloy, an optical analysis method through reflection spectra were measured. As a result, the sample is formed on the membrane form of MgO or $Mg(OH)_2$ is in the form of oxide. The wavelength energy of surface treatment of magnesium alloy sample observed 0.23eV red shift. The measured reflectance spectra observed with the three different signals. This is due to $Mg(OH)_2$ oxide layer formed on porous hole.