In this research, the microstructure of Inconel 625 cladded layer on ASTM A575 steel has been investigated. By examining different parameters, the optimal single-pass sample with the least amount of dilution, porosity and fusion and suitable wetting angle was determined. Then Cladding process with the optimal parameter was performed. The microstructure of the Cladding layer was evaluated from the base metal to the top. Due to different cooling rates, dendritic morphologies were observed at different distances. Also, the Cladding layer was free of any cavities, porosity and cracks and its thickness was 0. 9 mm (900 micrometers). The results of (XRD) and (EDS) analyzes indicate thatthe γphase is formed and there is a relatively uniform distribution of elements in the Cladding layer. These results also indicate that no change in the chemical composition of the substrate surface was achieved near the interface. The hardness test results also show that the hardness starts from 450 VHN at the top surface and reaches to 135 VHN in the base metal with a gentle slope. This slope of hardness can be attributed to the cooling or heating rates of the substrate.

The aim of this work was to synthesize TiC reinforced coating on carbon steel via reduction of ilmenite powder. A mixture of ilmenite and graphite was pre-placed on AISI 1020 steel surface. The effect of the addition of excess graphite amounts on the progress of the synthesis of carbide particles was studied. The evolution of phases in different coatings was analyzed via X-ray diffraction and scanning electron microscopy. Then, the initial powder mixtures were mechanically activated for various durations, to accelerate the reactions in the transient melt pool. Finally, the Fe-TiC hard coating was successfully synthesized by carbothermic reduction of ilmenite through Laser surface treatment. Moreover, it is proved that combination of mechanical activation with additive Laser melting effectively improves the level of ilmenite reduction, besides enhancing the distribution of hard particles and the hardness of the coatings to more than 1300 HV.

In coaxial Laser Cladding, the quality and property of deposition products are greatly influenced by the powder flow, which is responsible to transport additive materials to the deposition point on a substrate precisely. The metallic powder flow in coaxial Laser Cladding is simulated by a numerical model based on the gas-solid flow theory. The characteristics of powder concentration distribution between coaxial nozzle and deposition point for a kind of nickel based alloy powder are studied by the proposed model. The relationship between the process parameters and powder flow characteristics, such as focus distance from the nozzle exit and maximum powder concentration, is analyzed to optimize the powder feeding process. In addition, the influence of substrate with different surface shapes on the powder flow is investigated. The results can be used as a guideline for the location of the substrate and the selection of proper processing parameters for coaxial Laser Cladding.

Laser shock welding process has recently attracted the attention of many researchers. Similar to explosive and magnetic welding, this process may also be used for impact welding using solid state welding principle. Impact welding is based on the influence of high-velocity collision of two base metals and generation of metallurgical atomic bonding in the solid phase at the contact area at ambient temperature. This process is also used to clad a sheet metal with a thin layer of other metal, named flyer plate. The base metal is serrated with certain angle and depth and the flyer plate is moved rapidly to collide with the base plate to generate bonding. The energy required to move the flyer plate, is produced by plasma pressure created by Laser impact on the surface of the flyer plate. The main advantage of this connection is its capability to attach two dissimilar metals in order to enhance physical, chemical, or mechanical properties on one side of a cheaper metal. Same as other welding methods, it is very important to forecast and optimize the weld quality obtained by this process. Hence, finite element method using ABAQUS software, was employed to simulate the Laser welding or Cladding process in this research and verified by experimental data. Impact speed, serration angle and depth are the main affecting parameters on weld quality. Therefore, multi-objective particle swarm optimization (MOPSO) algorithm for a certain thickness of the flyer plate was utilized to maximize the welded area of two plates and minimize the cost of machining the base plate for making serration using the data generated by finite element analysis, linked to MATLAB for optimization of these objectives. The optimization results indicate an increase in joined area at the connection point as well as reduced number of grooves which leads to decrease in manufacturing cost.

Laser Cladding technology has received much attention in recent years. Injection of powder by carrier gas through the nozzles plays an important role in the quality and control of the Laser Cladding process, so it is important to be studied. In this study, a two-phase flow of gas-powder metal from the nozzle in a Laser-Cladding process is numerically simulated and compared with the results of an experimental study of the nozzle output to confirm the numerical simulation. The three-dimensional simulation was carried out steadily by Ansys CFX software. Experimental study is carried out by the visualization of powder flow. The results of the experimental study and the numerical simulation are in good agreement. In the next section, the effects of various parameters such as particle flow rate, carrier gas flow rate and shielding gas flow rate on particle concentration are investigated. The simulation results showed that by decreasing the carrier gas flow rate, the maximum concentration of particles increases and the particles concentration location gets closer to the nozzle outlet. Also, increasing the powder flow rate only increases the concentration of the particles and has no effect on the other parameters of the powder flow. The change in the shield gas flow rate also has no effect on the powder flow behavior.

Synthesis of a hard layer on the surface of mild steel is a proper way to rise its performance. Titanium carbide is among the preferred wear-resistant materials. In this research, the carbothermal synthesis of TiC via pulsed Laser is studied. Ilmenite is used, as an economic raw material, for in-situ synthesis of TiC. However, the conversion of FeTiO3 to TiC in the short period of Laser processing is challenging. Therefore two solutions were accompanied: the applied carbon content was more than the stoichiometry of reduction, while the blended ilmenite and graphite powders were mechanically activated. The increase of activation time to 200 hours was investigated via X-ray diffraction analysis. Afterward, a layer of the powder was preplaced on the substrate and the Laser Cladding was conducted. The effect of mechanical activation on the formation of the dispersed particles is studied, especially considering the transformation of oxides to TiC. SEM with EDS analyzer and XRD analysis were applied for this aim. The morphology of TiC particles and the microstructure of the matrix were also deliberated. The characteristic microstructure of directional solidification with equiaxed, cellular, dendritic and eutectic regions was observed. Otherwise, the Vickers microhardness measurements represented a gradual increase from the substrate toward the surface, which has reached to 1600 HV. It is confirmed that the synthesis of a composite layer with gradual dispersion of TiC particles via Laser reduction of ilmenite is a feasible process.

The aim of this project is to fabricated an aluminium-copper bimetal through the fusion method and examine its performance. An aluminium-copper-aluminium bimetal was built by the Laser Cladding method. The Laser power as well as the annealing time effects on its interfacial properties of the bonding’s formed through the Laser Cladding were investigated. To fabricate the multilayer bimetal, the Laser beam characteristic including the beam radios, and Transverse Electromagnetic Mode (TEM), and focusing conditions were considered in a heat source model. The model was, next, integrated within ANSYS package to predict the temperature distribution and clad bead profile during the Laser Cladding of the pre-placed copper powder layer on the aluminium substrate. After preparation of the samples, the intermetallic compounds formed at the joints were explored through the Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) processes. Based on the experimental results, a Laser power increase from 1100 W to 1150 W increased the intermetallic compound width, while an increase of 1150 W to 1200 W does not have much effect on the width. Also, increasing the annealing time results, increases the intermetallic compound thickness. In addition, based on experimental results obtained, four specimens are detected at the bimetal interface, one of which has 73.4 % copper and 26.1 % aluminium. The results also indicate that, with increasing both the Laser power and annealing time, the electrical resistance of the samples decreases.

Precipitation-hardened nickel based superalloys are very difficult to weld in a defect-free manner due to the formation of hot cracks in the weld metal as well as liquation cracks in the heat affected zone. Laser Cladding has been recognized as the one of the most attractive and promising state of the art welding to improve weld quality and repair high cost components such as industrial turbine blades. In this study, IN625 used as the filler was deposited on IN738LC mechanical samples by Laser. The microstructure and metallurgical defects such as oxide phases, porosities and cracks were investigated by optical microscope and scanning electron microscope. The low oxide phase and porosity were observed at the deposited layer. Furthermore, the hardness and tensile properties of the base metal and the deposited samples were evaluated at room temperature. The results have shown that the yield stress and tensile strength of the deposited samples campare well with base material (1. 2%, 3. 2%, respectively) while the average values of Hardness and ductility decreased significantly (11. 0%, 33. 3%, respectively).

Laser Cladding is one of the advanced surface modification techniques. In this process, a narrow layer of the material was deposited on the surface of the parts. In this research, Laser Cladding of 17-4 steel was performed by using 316L powder and 400 W pulsed Nd:YAG Laser. Laser frequency, pulse width, and scanning speed were considered as the input variables. The geometry of the deposited beads (width, height, and clad angle), dilution ratio, and hardness were considered as the output responses. The effect of input variables on the output responses was investigated and the suitable parameters were selected for Laser Cladding. The results showed that by increasing the Laser frequency and pulse width, the bead height and hardness decreased while the bead width, clad angle, and dilution ratio increased. By increasing the Laser scanning speed, the bead height and hardness increased while the bead width, clad angle, and dilution ratio decreased. The Laser frequency of 10 Hz, pulse width of 10 ms, and Laser scanning speed of 5 mm/s were found to be the suitable parameters over the ranges investigated in this work. The average hardness value of the suitable sample was approximately 590 Hv, about 1.3 times the value of the substrate. The hardness value increased by increasing the distance from the substrate to the clad zone. The hardness value decreased near the clad-substrate interface. This can be attributed to a higher proportion of columnar grains formed near the clad-substrate interface.

This experimental-statistical study investigates the influence of Laser Cladding parameters—Laser power (700–900 W), scanning speed (6–8 mm/s), and wire feed rate (70–80 mm/min)—on the geometric characteristics of single-pass coatings of 2507 duplex stainless steel on a VCN200 substrate. Experimental data were analyzed using Response Surface Methodology (RSM) with a three-factor, four-level design matrix. Measurements including clad width (W), height (H), penetration depth (b), wettability angle (Z), and dilution percentage (D) were obtained via ImageJ software. Results indicated that increasing Laser power from 700 to 900 W led to a 14% increase in clad width (from 1417 to 1744 µm), a 33% rise in clad height (from 450 to 594 µm), a 6% increase in penetration depth (from 88 to 93 µm), and a 3% improvement in wettability angle (from 71° to 69°). In contrast, increasing scanning speed from 6 to 8 mm/s reduced clad width by 12% (from 1513 to 1787 µm), clad height by 31% (from 650 to 573 µm), and wettability angle by 15% (from 67° to 78°), while enhancing penetration depth by 4% (from 85 to 84 µm) and dilution by 19% (from 58% to 53%). Moreover, raising the wire feed rate from 70 to 80 mm/min increased clad height by 13% (from 502 to 747 µm) and wettability angle by 4% (from 75° to 78°), but decreased dilution by 19% (from 59% to 48%).