The laser based processing of copper components with blue lasers with 450nm wavelength gained significance in the last years due to the increasing demand in eMobility applications. The high absorption level allows new process approaches, which were formerly however restricted by the limited power level of blue laser systems. With the availability of multi-kilowatt blue laser systems with 450 nm wavelength, a further step has been achieved to extend the application range of laser technology. Process stages from heat conduction welding to keyhole welding can be precisely adjusted. The properties of these process stages however vary from the conventional behavior known from IR laser sources. In this contribution, the behavior of materials while processed with multi-kilowatt blue laser are investigated. This is achieved by an evaluation of the process stages by high speed videography and an investigation of the resulting melting efficiency. Furthermore, we will review the latest application results regarding blue laser welding. Even though the overall research and process development with the blue laser is concentrated on copper processing, other metals, alloys or non-metal materials also indicate a change of interaction at 450 nm compared to IR wavelength. In order to assess these properties, experiments regarding non-copper applications conclude the contribution.