The Effects of Average Power and Pulse Duration on Weld Characteristics, Microstructure, Mechanical Properties and Corrosion Resistance of a Laser Welded 21% Cr Ferritic Stainless Steel
L.L. Liu, S.S. Hu, J.Q. Shen, L. Ma and Y. Li
This study investigated the effects of average power and pulse duration of pulsed laser welding on weld dimensions, microstructure, microhardness pitting corrosion resistance of 21% Cr ferritic stainless steel. Optical microscopy and scanning electron microscopy (SEM) were used to observe the microstructure of the fusion zone. Microhardness tests and electrochemical measurements were carried out to study the mechanical and pitting corrosion properties, respectively. Results show that the depth of welds dropped firstly and then increased with the pulse duration. The grain size in the fusion zone and heat-affected zone (HAZ), and the width of HAZ all increased with the average power, but changed little with the pulse duration. The microhardness of welds decreased with the average power but almost kept constant when the pulse duration was lower than 5 ms. The pitting corrosion resistance of welded joints was weakened with increase of pulse duration.
Keywords: Nd:YAG laser, pulsed laser welding, ferritic stainless steel, microstructure; microhardness, pitting corrosion resistance, fusion zone, heat-affected zone (HAZ)