Effect of pulse energy on microstructure and properties of laser lap-welding Hastelloy C-276 and 304 stainless steel dissimilar metals

• Published in: Optics and laser technology 2021-10, Vol.142, p.107236, Article 107236
• Main Authors: Zhou, Siyu, Wang, Baoxing, Wu, Dongjiang, Ma, Guangyi, Yang, Guang, Wei, Wenyi
• Format: Article
• Language: English
• Subjects: Base metal; Corrosion resistance; Depletion; Dilution; Dissimilar metals; Element distribution; Energy; Grain size; Hastelloy (trademark); Laser beam welding; Laser welding; Mechanical property; Microhardness; Microstructure; Molybdenum; Morphology; Neodymium lasers; Nickel; Penetration depth; Pulse energy; Pulsed lasers; Shear properties; Solid phases; Stainless steel; Stainless steels; Weld metal; Welded joints; YAG lasers
• ISSN: 0030-3992; 1879-2545
• DOI: 10.1016/j.optlastec.2021.107236

•The relation between laser pulse energy and dilution level was built.•The influence mechanism of dilution level on segregation and precipitation was revealed.•The higher pulse energy leads to the reduction of mechanical and corrosion resistance properties.•The width of unmixed zone was reduced with the increase of pulse energy.•The maximum tensile-shear load capacity was achieved at a pulse energy of 4.0 J. Nd:YAG pulsed laser lap-welding of Hastelloy C-276 and 304 stainless steel was conducted. The effect of pulse energy on weld morphology, element distribution, microstructure, phase structure, tensile-shear property and corrosion property of weld joint was analyzed. The results indicated that, with the increase of pulse energy, both the penetration depth and bead width of weld metal (WM) and dilution level of 304 base metal (BM) were linearly increased. Unmixed zone between WM and 304 BM was reduced, however, the grains sizes in WM became coarser. The precipitated phase with higher content of Mo and W is mainly p phase, with the increase of pulse energy, segregation potential of Mo element was increased, however, the amount of precipitated phase was decreased due to a decline in Mo element in WM. The fracture mode of weld joint transferred from interfacial fracture to tensile fracture with the increase of bead width, and the maximum load capacity of which was achieved at a pulse energy of 4.0 J. The average micro-hardness value of WM was decreased with the increase of pulse energy due to the depletion of Mo and W strengthening elements and the coarser grain size in WM. The corrosion resistance of WM was weakened with the increase of pulse energy ascribed to the reduce of Ni and Mo elements.