Studies on microstructure and mechanical properties of keyhole mode Nd:YAG laser welded Inconel 625 and duplex stainless
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This article addresses the metallurgical and mechanical properties of Nd:YAG laser welded Inconel 625 and duplex stainless steel SAF 2205. Keyhole plasma mode laser welding was adopted to obtain the joints. Microstructure studies showed slight grain coarsening at the heat affected zone of Inconel 625. Line mapping and elemental mapping analysis were carried out at the weld interface and in the fusion zone to examine the elemental migration as well as the composition of the phases present in these regions. The fusion zone microstructure showed the presence of Nb, Mo rich Laves phase segregated at the interdendritic arms. Tensile studies corroborated that an average joint strength of 820 MPa has been displayed by these weldments, which was almost equal to one of the parent metals, SAF 2205. It is evident from the charpy v-notch studies that the impact toughness of these laser weldments was found to be 10 J and this low toughness could be reasoned out to the formation of Mo rich phases. The structure–property relationships of these weldments have been addressed in detail and the outcomes of the study will be highly useful for marine and geothermal applications.
Contributing Editor: Yang-T. Cheng a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2015.276
ERNiCrMo-3 fillers. The authors observed the formation of deleterious Laves phase and the Mo segregation at the fusion zone of ERNiCrMo-3 and ER2209 weldments, respectively. Due to the multi-pass welding, the fusion zone was subjected to reheating actions which severely affected the metallurgical and mechanical properties of the weldments. Laser welding of metals receives major attention in the industries due to several advantages such as reduced or nil heat affected zone (HAZ), faster cooling rates (reduces the segregation), lower distortion, narrow weld width, high penetration, higher productivity, and improved mechanical properties etc. There are two heating modes: conduction mode and keyhole mode attributing for melting of the metal during the laser welding. In conduction mode, the power density would be great enough to cause the metal to melt. Weld penetration was achieved by the heat of the laser conducting down into the metal from the surface. Thus conduction mode does not have high productivity and has a low aspect ratio. During keyhole mode welding the power density would be greater enough that the metal goes beyond just melting. It vaporizes. The vaporizing metal creates expanding gas that pushes outward. This creates a keyhole or tunnel from the surface down to the depths of the weld. The characteristics of keyhole laser welding mainly high penetration, high productivity, and high aspect ratio have led the industry to focus more on this mode. Janicki4 investigated the high power direct diode laser welding of 0.8 mm thick sheets of Inconel 625 by conduction mode. The authors reported that increasing
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Ó Materials Research Society 2015
I. INTRODUCTION
Dissimilar metal welds of Inconel 625 and duplex stainl
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