Index of content:
Volume 29, Issue 1, February 2017
- Technical Articles
Advantages of laser beam oscillation for remote welding of aluminum closely above the deep-penetration welding threshold29(2017); http://dx.doi.org/10.2351/1.4963399View Description Hide Description
Laser beam welding of aluminum has been developed into a widely used process in modern car body manufacturing. Following the trend of recent lightweight designs and the use of high strength materials, the application of thinner aluminum sheets is increasing. Due to the stepwise increase of the welding depth at the transition from heat-conduction welding to keyhole welding, the usability of the laser beam as a tool has some limitations. This work has investigated the penetration depth when keyhole welding close to the deep-penetration welding threshold can be reduced in a controlled manner by means of laser beam oscillation.
29(2017); http://dx.doi.org/10.2351/1.4963270View Description Hide Description
A pulsed laser beam from an excimer laser was used to ablate a solid tin target immersed in water in the presence of an external electric field. High fluence resulted in the formation of an overheated melt at the target surface resulting in homogeneous nucleation and phase explosion. The ablation products were studied with transmission electron microscopy. It was found that with no external field the size distribution of particles has peaks at ∼1 and ∼10 nm and that externally applied electric fields resulted in a decrease of particle size. A model based on Rayleigh instability and polarization effects was proposed to explain the observations. This work demonstrates a possible approach for controlling nanoparticle size.