Product Code: ICAL05_P565

Surface Treatment of Welded Duplex Stainless Steels by Diode Laser
Authors:
Barbara Previtali, Politecnico Di Milano Dipartimento Di Meccanica; Milano Italy
Edoardo Capello, Politecnico Di Milano Dipartimento Di Meccanica; Milano Italy
Maurizio Vedani, Politecnico Di Milano Dipartimento Di Meccanica; Milano Italy
Moreno Castelnuovo, Politecnico Di Milano Dipartimento Di Meccanica; Milano Italy
Presented at ICALEO 2005

In this paper the recovery of the laser welded microstructure of Duplex Stainless Steel (DSS) by means of diode laser treatment is investigated. The goal of the laser surface treatment is to obtain a well balanced austenite-ferrite structure in the weld and heat affected zone. The temperature distribution in a workpiece treated by a diode laser beam is firstly determined by a thermal model, which allowed reproducing the main features of the diode laser treatment. Then, the thermal analysis of the heat treatment process is performed under various power and feed rate conditions, showing that the peak temperature and the cooling rate play a prominent role on the treated maximum width. The metallurgical conditions to obtain the desired microstructure by the laser treatment are pointed out and used to identify the operability region. It is found that the process window for the diode laser treatment is quite narrow and therefore imposes an accurate parameter selection. Moreover, there is an intrinsic limit in the laser treatment speed which could affect the process productivity. Corrosion tests, performed on the best treated conditions, show that the diode laser heat treatment could be a valid alternative to the more traditional DDS recovery processes.