As fast cooling in the spot inherent in hardened steel hard and brittle martensite when the organization will be larger in the stress cracks. In order to eliminate quenching to improve the joint performance, usually tempered after welding0 electrode double pulse spot welding consumable , which the first current pulse to pulse welding, the second pulse for the tempering, the use of this method should note two points:
(1) the time interval between the two pulses must be cooled to ensure that the spot temperature below the martensitic transformation point Ms;
(2) tempering current pulse amplitude should be appropriate to avoid the welding area of ??the metal back more than Austenite caused by secondary quenching.
At present, some research institutions and industrial enterprises are developing new Low Alloy Steel Electrode. The sand of the new transistor laser pulse (Diodengepumpte Scheibenlaser) is one such example. Stuttgart Institute of Laser Tools (IFSW) to point out: The new sand this is a new laser technology, laser technology transistor solid program, which has a high laser efficiency and good performance of the laser focus.
Lasing medium is a thin reflective film, the thickness of a few per cent to two per cent in a few microns. Compact pulsed laser beam by multiple refraction refractor system, and finally by the crystal injection. Despite the small size of reflector thickness, but its high reflectivity, the total efficiency is very high. Mr Hügel that: The set of CO2 laser technology, laser technology and the Nd: YAG solid laser technique has the advantage in one, in the future can open up many new application areas.
The use of laser welding is growing, the German VW Touran car company is a good example. In this new sedan, the laser spot to the 1400 number, total length of the weld 70m. In a comfortable, beautiful open-top production cars, VW's technical staff and experts in Austria Fronius welding companies developed a hybrid laser welding technology. Senior Convertible car at the door, the length of the laser hybrid welding seam reach 3570mm, is a pure laser welding seam length of 3 times.