Showing papers by "Ming Gao published in 2015"
TL;DR: In this paper, the relative density, metallurgical bonding mechanisms, microstructure and mechanical properties of 1Cr18Ni9Ti stainless steel samples with 60-150μm powder layers are presented.
155 citations
TL;DR: In this article, the effects of beam oscillating parameters on weld morphologies were investigated, and it was shown that the difference in cross-section width from the top to the lower gradually reduced to disappear with the increase of oscillating frequency.
84 citations
TL;DR: In this article, the effects of laser power on the characteristics of fiber laser induced plasma plume were studied by emission spectroscopic analysis firstly, and the results indicated that the plasma shielding effect is dominated by inverse bremsstrahlung linear absorption coefficient.
57 citations
TL;DR: In this article, laser-arc hybrid welding with Cu3Si filler wire was employed to join dissimilar Ti6Al4V titanium alloy and AISI316 stainless steel (316SS).
Abstract: Laser-arc hybrid welding with Cu3Si filler wire was employed to join dissimilar Ti6Al4V titanium alloy and AISI316 stainless steel (316SS). The effects of welding parameters on bead shape, microstructure, mechanical properties, and fracture behavior were investigated in detail. The results show that cross-weld tensile strength of the joints is up to 212 MPa. In the joint, obvious nonuniformity of the microstructure is found in the fusion zone (FZ) and at the interfaces from the top to the bottom, which could be improved by increasing heat input. For the homogeneous joint, the FZ is characterized by Fe67−x
Si
x
Ti33 dendrites spreading on α-Cu matrix, and the two interfaces of 316SS/FZ and FZ/Ti6Al4V are characterized by a bamboo-like 316SS layer and a CuTi2 layer, respectively. All the tensile samples fractured in the hardest CuTi2 layer at Ti6Al4V side of the joints. The fracture surface is characterized by river pattern revealing brittle cleavage fracture. The bead formation mechanisms were discussed according to the melt flow and the thermodynamic calculation.
38 citations
TL;DR: In this paper, the structure, interdendritic, and intergranular segregation, and precipitates of an Alloy 690 electro-slag remelting (ESR) ingot in commercial scale (3t) were investigated by the optical microscopy, electroprobe microanalysis, scanning electron microscopy (TEM) techniques.
Abstract: The structure, interdendritic, and intergranular segregation, and precipitates of an Alloy 690 electro-slag remelting (ESR) ingot in commercial scale (3t) were investigated by the optical microscopy, electroprobe microanalysis, scanning electron microscopy, and transmission electron microscopy (TEM) techniques. The results indicate that the central longitudinal section of the ESR ingot comprised the ramp-up, steady-state, and hot-top regions, which could be easily distinguished from each other through the macrostructures of them. In the interdendritic area, Cr and Ti were enriched, while Ni and Fe were depleted, and the nominal segregation indexes (ζ
i = C
0
i
/C
interdendritic
i
) of Ti, Cr, and Ni were 0.40, 0.91, and 1.04, respectively, in the hot-top region where suffered the severest segregation. Nitrides, principally precipitated between dendrites, were identified as TiN by TEM and EDS. The morphology, size distribution, and volume fraction of them were determined as well. In terms of the intergranular area, Cr and C coexisted, while Ni and Fe were depleted. And the dendrite-like carbides continuously distributed on the interface between grains, which were identified as M23C6 by the selected area diffraction pattern.
12 citations