Cracking in dissimilar laser welding of tantalum to molybdenum. (June 2018)

• Record Type: Journal Article
• Authors: Zhou, Xingwen; Huang, Yongde; Hao, Kun; Chen, Yuhua
• Is Part Of: Optics & laser technology. Volume 102(2018)
• Page Start: 54
• Page End: 59
• Publication Date: 2018-06
• Subjects: Tantalum -- Molybdenum -- Dissimilar laser welding -- Cracking; Optics -- Periodicals; Lasers -- Periodicals; Electronic journals; 621.366
• DOI: 10.1016/j.optlastec.2017.12.026
• Languages: English
• ISSNs: 0030-3992

Abstract

Highlights: Transgranular and intergranular cracks were found in the fusion zone of dissimilar laser welded joint of Ta to Mo. Solidification cracking tendency of Mo is a main reason for crack initiation in the Ta/Mo joint. Low ductility feature of the fusion zone promoted the transgranular propagation of cracking. Abstract: Dissimilar joining of tantalum (Ta) to molybdenum (Mo) is of great interest in high temperature structural component applications. However, few reports were found about joining of these two hard-to-weld metals. The objective of this experimental study was to assess the weldability of laser butt joining of 0.2 mm-thick Ta and Mo. In order to study cracking mechanism in Ta/Mo joint, similar Ta/Ta and Mo/Mo joints were compared under the same welding conditions. An optical microscope observation revealed presence of intergranular cracks in the Mo/Mo joint, while both transgranular and intergranular cracks were observed in Ta/Mo joint. The cracking mechanism of the Ta/Mo joint was investigated further by micro-hardness testing, micro X-ray diffraction and scanning electron microscopy. The results showed that solidification cracking tendency of Mo is a main reason for crack initiation in the Ta/Mo joint. Low ductility feature in fusion zone most certainly played a role in the transgranular propagation of cracking.