A study of laser cladding NiCrBSi/Mo composite coatings

Abstract

Laser cladding Ni-based composite coating was fabricated on the surface of 42CrMo steel using 6 kW fibre laser. By the addition of Mo powder, a well-formed and crack-free laser cladding composite coating was obtained. The morphology, composition, microhardness and wear resistance of composite coatings were studied using a scanning electron microscopy, an energy-dispersive spectroscopy, an X-ray diffraction spectrum, a microhardness tester and a wear tester. The results show that the cladding layer has metallurgical bonding with the substrate. The main phases of Ni45 + 10%Mo laser cladding layer are (Fe, Ni), Cr23C6, Cr3C2, Mo2FeB2 and Cr2B3. After the addition of Mo powder, the size of the microstructure of composite coatings is finer than that of Ni45 cladding layer. Stubby-rod carbides are displayed in the interdendritic interface. The molybdenum and chromium are rich in the grain boundaries. The distribution of hardness is uniform in Ni-based cladding layer, and its microhardness is significantly higher than that of the substrate. Ni45 + 10%Mo composite coating has the best wear resistance. Its wear resistance reaches 1.734 times of Ni45 coating and 2.367 times of 42CrMo steel.

Tensile Fracture Behavior and Failure Mechanism of Additively-Manufactured AISI 4140 Low Alloy Steel by Laser Engineered Net Shaping

“…Moreover, there also exists an increased industrial demand for all the components with higher performance and durability [ 11 ]. Therefore, it is imperative to repair and reconstruct the worn and damaged components in order to extend the life span and minimize waste of expensive materials, economic losses, downtime, and embodied energy, thereby increasing the industrial competitiveness [ 12 , 13 ].…”

Microstructure and Wear Behavior of Laser Cladded Ni45 + High-Carbon Ferrochrome Composite Coatings

“…Figure 4 demonstrates the EDS mapping of the laser cladded Ni45 + 40 wt.% high-carbon ferrochrome coating, which exhibits that the concentrations of Cr and C were higher in the lath-shaped structures. As known, nickel alloys with chromium, boron, and silicon contents represent a type of hard facing alloys by means of the formation of nickel, chromium borides and complex carbides as dominant primary hard phases [13,14]. In this paper, high-carbon ferrochrome was added to the Ni45 alloy, and as a result more chromium carbides could form due to the high Cr content of high-carbon ferrochrome.…”

Properties of Curved Parts Laser Cladding Based on Controlling Spot Size

“…It was found that a good metallurgical bonding was formed between the substrate and the cladding layer; additionally, there were few pores and cracks, which indicated the rationality of the method. Because the growth of the crystal morphology during solidification mainly depends on the value of G/R [9], where 'G' means the temperature gradient of the liquid phase and 'R' is the solidification rate of solid phase, the instantaneous value of G/R changes with the distance to the solidification interface. The cladding layer is divided into three parts: bottom, middle and top, each having a different micro-morphology [24,25].…”

“…At present, Fe-based [1][2][3], Ni-based [4,5], and Co-based [6,7] self-fluxing alloy powders are widely used to repair and strengthen the surface performance in laser cladding. The mechanical properties of coatings are analyzed through microhardness, wear resistance and microstructure properties, and the results shows that coatings can be equal to, or even superior to those of the alloys fabricated by die-casting or forging [8,9]. The repair and recycle industries are therefore greatly enhanced by the advances in laser cladding technology, and have widespread applications in many fields, such as petroleum, chemical, and military [10][11][12].…”