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Indexed by:Journal Papers

Date of Publication:2019-09-01

Journal:JOURNAL OF MANUFACTURING PROCESSES

Included Journals:EI、SCIE

Volume:45

Page Number:652-660

ISSN No.:1526-6125

Key Words:Water cooling assisted; Ni-based alloy; Laser dissimilar welding; Filler wire; Precipitated phase

Abstract:To clarify the effects of water cooling on solidification behavior of pulsed laser welding of Nickel-based alloy/austenitic stainless steel with filler wire, and to improve the mechanical properties of laser welded joints, the analyses of morphology, microstructure, anti-peel property and micro-hardness were carried out. The results indicated that adding water cooling increased cooling rate and temperature gradient of the weld. And the addition of water cooling made constitutional supercooling of the weld easier, so that the solidification rate increased with the increase of the temperature gradient. Therefore, the weld grain was refined by about 28%, and the average width of unmixed zone decreased by 35%, with a low volume fraction of Mo-rich precipitated phase consisting of p phase and mu phase. The mu phase was discovered in laser welding Nickel-based alloy/austenitic stainless. Both p phase and mu phase had a good coherent relationship with the matrix, which resulted in the low phase boundary energy between precipitated phase and matrix. The coherent relationship is described as [1 4 3] p // [5 3 1] gamma between the p phase and the matrix. And the coherent relationship is described as [1 2 0] mu // [2 2 1] gamma between the mu phase and the matrix. There are the stacking faults in the mu phase along the direction of [1 1 0], which is one of the slip system in mu phase. At the same time coherent relationship between p phase and matrix is better than that of mu phase. The micro-hardness, load capacity per length, and anti-peel stress were improved by 10.5%, 8.1%, and 11.8%, respectively.