A simple numerical model has been proposed for laser cladding. The model does not involve complex techniques such as cell addition, moving mesh, or prescribing a clad profile with a certain polynomial function. Instead, a mass function has been introduced to register the clad mass deposition on substrate, and from which the clad-track height can be estimated. The model takes several operational parameters, laser power, laser-head speed, and clad powder feeding rate, into consideration and predicts clad-track geometry, dilution, and substrate temperature. Experiments using two different combinations of substrate and clad powder materials to lay single and multiple clad tracks were conducted to provide data for model validation. The results show that the present model returns good agreement with experimental clad profiles for single and multiple tracks.

The FeMnCoCr high-entropy alloy/TiC/CaF2 self-lubricating coatings were successfully prepared on a Cu–Zr–Cr alloy for continuous casting mold by laser cladding for wear-resistance. The intriguing finding was that the laser-cladded FeMnCoCr is mainly composed of face-centered cubic and hexagonal close-packed solid solution phases. During the cladding process, the FeMnCoCr/TiC or the FeMnCoCr/TiC/CaF2 mixed sufficiently with Cu matrix, while FeMnCoCr exhibited a spherical shape owing to being insoluble in Cu. The average hardness of the FeMnCoCr/TiC/CaF2 self-lubricating high-entropy alloy (HEA) coatings was twice that of the pure FeMnCoCr HEA coating. By addition of TiC, the friction coefficient and wear rate were decreased from 0.35 and 3.68 × 10−15 mm3/m to 0.27 and 3.06 × 10−15 mm3/m, respectively. When CaF2 was added, the friction coefficients and wear rate were decreased to 0.16 and 2.16 × 10−15 mm3/m, respectively, which was 54% lower than the pure FeMnCoCr HEA coating. The main wear mechanism of the FeMnCoCr coating is abrasive wear while that of the FeMnCoCr/TiC coating is abrasive and adhesion wear. But adhesion wear is dominant for the FeMnCoCr/TiC/CaF2 coating.

To improve the high-temperature properties of tool steel, a microstructure-dense and crack-free Fe5Cr5Co5SiTiNbMoW high-entropy alloy (HEA) coating was successfully fabricated by laser cladding. And its microstructure and hardness evolution after various annealing temperatures of 800 °C, 850 °C, 950 °C, and 1050 °C for 4 h were carefully investigated by OM, scanning electron microscope, energy dispersion spectrum, X-ray diffraction, and microhardness tester, respectively. The experimental results show that the HEAcoating was mainly composed of body-centered cubic and (Nb, Ti)C plus few Laves phase. The high-temperature annealing processing has little influence on the phase composition. The dendrites and matrix are decomposed with the annealing temperature increasing. While annealing at 950 °C, a eutectic microstructure appeared in the coating. Moreover, the thickness of the diffusion layer of HEA coating increased with the increasing of annealing temperatures. Surprisingly, the HEA coating after annealing at 850 °C possessed ultra-high average hardness, about 1050 HV0.2, huge improvement compared with as-cladding HEA coating (∼780 HV0.2). Therefore, it might reveal that the HEA coating exhibits excellent annealing strengthening ability.

Cladding through laser metal deposition is a promising application of additive manufacturing. On the one hand, industrial robots are increasingly used in cladding because they provide wide wrist reorientation, which enables manufacturing of complex geometries. On the other hand, limitations in robot dynamics may prevent cladding of sharp edges and large objects. To overcome these issues, this paper aims at exploiting the residual degrees of freedom granted by the cladding process for the optimization of the deposition orientation. The proposed method optimizes the robot head orientation along a predefined path while coping with kino-dynamic constraints as well as process constraints. Experimental tests and results are reported and used to validate the approach.

The in situ synthesis of nickel-based composite coating reinforced with WC particle on mild steel has been investigated. Results show a planar crystal at the interface and some relatively coarse columnar dendrites on the side of the coating near the substrate. The synthesized WC particles homogenously distribute in the coating without cracks and pores. The maximum size, mean size, and volume fraction of the WC particle is 270 µm, 35 µm, and 71%, respectively. The microhardness value of the prepared coating can be up to a maximum of 755 HV2. The synthesized WC particles generally show a unique triangular prism shape, whose evolution rule and growth mechanism are investigated by Bravais–Friedel–Donnay–Harker theory. It is deduced that crystal structure and interface energy play important role in determining the shape of WC, which evolves from sphere to hexagonal prism and finally to triangular prism.

This work presented a study on the improvement of laser surface treatment on rolling contact fatigue resistance of gray cast iron. Sample surface covered with carbon powder was coupled with localized treatment by high-energy laser beam—a process defined as “laser cladding (LC).” With this method, the optimum precoating thickness was experimentally studied. Compared to the region treated by laser remelting, the crystal in LC region was finer, more compact, and uniform. Mechanical property testing showed not only high micro-hardness of LC region, but also improved tensile and compressive resistance of treated material. Fatigue wear tests and thorough analysis of fatigue detects suggested that LC treatment significantly improved fatigue wear resistance (FWR). Improved FWR was likely facilitated by delayed initiation and propagation of cracks, as well as the reduction of contact stress on substrate. Additionally, formations of fatigue defects on sample surface were thoroughly discussed.