Study on the Deformation Control and Microstructures of Thin-Walled Parts Repaired by Laser Cladding

Abstract

To reduce the deformation and improve the quality of thin-walled parts repaired by laser cladding, a three-factor, three-level orthogonal experimental scheme was employed to clad Ni60 powder on thin-walled parts with a thickness of 3.5 mm. To measure the deformation of the thin-walled parts, a method of combining the meshing of the backs of the thin-walled parts and fixing one end of the parts during cladding was used. The effects of the powder feed rate, laser power, and scanning speed on the deformation of the thin-walled parts were studied via visual analysis and analysis of variance, and the process parameters that resulted in the minimum deformation were determined. The deformation process of the thin-walled parts and the causes of cladding stress were also studied, and the microstructure of the cladding layer with the minimum deformation was analyzed via scanning electron microscopy (SEM). The results reveal that the deformation of the thin-walled parts increased with the increase of laser power. The increases of the scanning speed and powder feed rate were found to reduce the deformation of thin-walled parts; the laser power was found to have a significant effect, and the powder feed rate was found to have no significant effect, on the deformation of thin-walled parts. The order of the influence of factors on the deformation of thin-walled parts from greatest to least was determined to be as follows: laser power > scanning speed > powder feed rate. The optimal parameters to obtain the minimum deformation and good metallurgical bonding of thin-walled parts were found to be a powder feed rate of 1.4 r/min, a laser power of 1100 W, and a scanning speed of 8 mm/s. From the bottom to the top, the crystal structure of the coating with the minimum deformation was found to be coarse dendrite, dendritic crystal, and equiaxed crystal.

Repair of Gear by Laser Cladding Ni60 Alloy Powder: Process, Microstructure and Mechanical Performance

“…Moreover, the heat released was limited, so grains in the transition zone are refined. After the cladding zone of precipitate-free dendritic structure adjacent substrate, three major morphologies of phases were recognizable in the BSE images: bulk-shaped (see Figure 15c,d), butterfly-or wing-shaped (see Figure 15i,j), and dendritic-shaped (see Figure 15h), the same precipitate having been reported in [30,42,43,46]. From Figure 15a-e, these precipitates have gone through processes from thin to coarse and from variable to less.…”

“…All peaks contain Cr-B-C, indicating that various Cr-B-C compounds exist in different lattices. Figure 15a-e As shown in Figure 15a, a white bright band presents at the interface, indicating metallurgical bonding was formed between the substrate and cladding layers [18,43]. After the white bright band, many layers of columnar dendrites are formed.…”

“…From Figure 15a-e, these precipitates have gone through processes from thin to coarse and from variable to less. As shown in Figure 15a, a white bright band presents at the interface, indicating metallurgical bonding was formed between the substrate and cladding layers [18,43]. After the white bright band, many layers of columnar dendrites are formed.…”

Prediction of Mechanical Properties of Thin-Walled Bar with Open Cross-Section under Restrained Torsion

“…In order to solve the torsion equation of the bar in Equation ( 4), the torsion problem can be compared with the deflection deformation of the membrane under uniform pressure. According to the membrane analogy theory [13][14][15], the deflection function of the membrane under the action of uniform pressure is mathematically similar to the stress function of torsion of the above-mentioned bar of equal sections.…”

Laser-assisted wire cladding using a retrofitted laser welding system

“…Laser cladding is a highly versatile technique that has found applications in part repair [1][2][3], surface protection or modification [4][5][6], and additive manufacturing [7] within industries that include power generation, aerospace, shipbuilding, oil, gas, and chemical processing. Several techniques exist for the delivery of material to the substrate surface, depending on the material's form as shown in Figure 1.…”