Product Code: ICAL09_1604

Laser Absorption in CO2 Laser Welding of Medium, High and Ultra High Strength Steels
Authors:
Azim Ahmad, Lappeenranta University of Technology; Lappeenranta Finland
Veli Kujanpää, Lappeenranta University of Technology; Lappeenranta Finland
Presented at ICALEO 2009

Absorption varies quite a lot in laser welding. Accurate measurement of absorption in laser welding is also a challenging problem. Usually a calorimeter is commonly employed for measuring absorption. In this paper an alternative approach is presented for measuring absorption in laser welding of lean duplex LDX2101 and austenitic stainless steels of type 301 LN and 316 L based on the temperature distribution in the heat affected zone. The location for microstructural changes observed in real laser welds are identified and matched with those taken from Gleeble thermal simulation. The temperature corresponding to those microstructural changes observed in simulation are used for the prediction of absorption. The distance between the two specific microstructural changes are measured from real weld micrographs and then a modified analytical equation for heat flow is implemented for calculating absorption values. The adopted method is valid and particularly suitable for lean duplex and austenitic stainless that do not show very clear and evident phase transformations in the heat affected zone, as is the case in ordinary low-carbon steels.