Product Code: ICAL06_P536

Experimental Study of Magnesium and Aluminium Alloys Absorption and Keyhole Evolution during Laser Interaction Nd:YAG Laser Interaction
Authors:
Nicolas Pierron, University of Bourgogne; Le Creusot France
Pierre Sallamand, University of Bourgogne; France
Simone Matteï, University of Bourgogne; France
Presented at ICALEO 2006

In the laser processes such as laser welding and heat surface treatment, the absorption factor of laser Nd: YAG by metals plays an important role. Its evolution depends on many parameters such as temperature or surface conditions. In this paper, we present a method based on the measurement of reflected energy during the laser process, carried out on two types of magnesium alloys (WE43 and RZ5) and aluminum alloy 1xxx. An integrating sphere coupled with a photodiode and a numerical oscilloscope is used. In a first part, the results are compared with measurements obtained with an isothermal differential micro-calorimeter CALVET. With this technique, we consider that the absorbed energy is transformed into calorific energy within the material. We use two types of coated substrates for RZ5: HAE treatment (anodizing process) and a conversion process (mordancage process). The aim of this chapter is to validate the experimental method. We use laser parameters which only allow having a molten pool without the formation of a keyhole. In the second part, different results for magnesium and aluminum alloys are presented. The laser parameters used allow the formation of a keyhole. A temporal evolution of absorption factor during the interaction is obtained. This information can be used for example to model the laser - material interaction, particularly the laser welding. Different stages during the interaction are observed. The solid- liquid transition and the beginning of the formation of the keyhole are brought to the fore. Metallographic analyses are used to confirm the different evolutions described from measure curves.