Micro Laser Welding of AISI 430 Ferritic Stainless Steel: Mechanical Properties, Magnetic Characterization and Texture Evolution

In the present work, a high power Nd:YAG laser has been employed to weld AISI 430 ferritic stainless steel thin sheets. Optical microscopy was used to study the microstructural evolutions during laser welding. Tensile test and microhardness measurement were employed in order to investigate the mechanical behaviors of welds. Also, vibrational sample magnetometry was used for characterizing magnetic properties. Texture evolution during laser welding of AISI 430 stainless steel was also studied and a correlation was made between texture evolution and magnetic properties of welded samples. The effects of welding cycle on the mechanical properties of the laser welds in terms of fracture strength and microhardness profile are discussed. It was found that the magnetic properties of welded samples experiences significant decrease due to the formation of large grains in the fusion zone which are oriented in an unfavorable direction. The results showed that the grain size of base metal increase from 17 μm up to 92 μm after laser welding. Also, base metal had a dominant -fiber, some α-fiber components and also rotated cube texture component. But after laser welding, the cube texture however has been diminished when α and -fiber completely disappears. These phenomena also led to decrease in fracture strength of welded samples.