Laser Remanufacturing Research Articles

Toward developing remanufactured Ti6Al4V alloys with high fatigue crack growth resistance by in-situ cooling during laser remanufacturing

The fatigue performance of remanufactured titanium alloy blade components has garnered significant attention in recent years. The repaired titanium alloy components using the direct energy deposition (DED) method exhibit structural differences, leading to an inhomogeneous microstructure that directly impacts the service life of the remanufactured component. The work presented here aimed to investigate novel approaches for enhancing the resistance to crack propagation and to gain a deeper insight into the fatigue crack propagation characteristics of the Ti6Al4V remanufactured interface with an inhomogeneous microstructure. The research focused on analyzing the microstructure evolution and fracture properties of remanufactured components using in-situ cooling. The results indicate that in-situ cooling has the potential to decrease the anisotropy of the repaired zone (RZ) and enhance the resistance to crack propagation in the heat-affected zone (HAZ) and base metal (BM). The high cooling rate associated with the in-situ cooling can elevate the presence of high-angle grain boundaries (HAGBs) in the RZ, diminish the phase transformation between the HAZ and BM, and decrease the size of the secondary α phase. The research contributes to a deeper comprehension of fatigue crack propagation in remanufactured components and provides a pathway for the improvement of fatigue performance of remanufactured titanium alloy.

Multi-Objective Optimization of Laser Remanufacturing Process Parameters for Steel Surface of Hydraulic Prop

Multi-Objective Optimization of Laser Remanufacturing Process Parameters for Steel Surface of Hydraulic Prop

A state-space model-based temperature control system for laser remanufacturing molten pool

ABSTRACT Laser remanufacturing is a key technology for remanufacturing, which has been widely used in aerospace, metallurgy, energy and other fields. However, the problem of shape control has been the bottleneck that restricts the scale and industrial application. In the laser remanufacturing process, the molten pool temperature is the critical to determine the shape and performance stability of remanufactured parts. Based on this, the paper proposes a real-time online control method for laser remanufacturing molten pool temperature based on state space model, which solves the problem of difficult to establish control mechanism model and multiple variable constraints. Develop a real-time online control system for molten pool temperature of laser remanufacturing process based on state space model and incremental integral separation PID control, which uses a single sampling point as temperature feedback, solving the problem of lag generated by traditional feedback cycle, realizing real-time online control of molten pool temperature of laser remanufacturing process. Finally, the experimental results show that the developed molten pool temperature control system can effectively eliminate the sudden and gradual temperature change in the deposition process and significantly improve the thermal accumulation phenomenon in the deposition process, thus improving the forming quality and performance stability of remanufactured parts.

PSO-BP-Based Morphology Prediction Method for DED Remanufactured Deposited Layers

Directed energy deposition is a typical laser remanufacturing technology, which can effectively repair failed parts and extend their service life, and has been widely used in aerospace, metallurgy, energy and other high-end equipment key parts remanufacturing. However, the repair quality and performance of the repaired parts have been limited by the morphological and quality control problems of the process because of the formation mechanism and process of the deposition. The main reason is that the coupling of multiple process parameters makes the deposited layer morphology and surface properties difficult to be accurately predicted, which makes it difficult to regulate the process. Thus, the deposited layer forming mechanism and morphological properties of directed energy deposition were systematically analyzed, the height and width of multilayer deposition layers were taken as prediction targets, and a PSO-BP-based model for predicting the morphology of directed energy deposited layers was settled. The weights and thresholds of Back Propagation (BP) neural networks were optimized using a Particle Swarm Optimization (PSO) algorithm, the predicted values of deposited layer morphology for different process parameters were obtained, and the problem of low accuracy of deposited layer morphology prediction due to slow convergence and poor uniformity of the solution set of traditional optimization models was addressed. Remanufacturing experiments were conducted, and the experimental results showed that the deposited layer morphology prediction model proposed in this paper has a high prediction accuracy, with an average prediction error of 1.329% for the layer height and 0.442% for the layer width. The research of the paper provided an effective way to control the morphology and properties of the directed energy deposition process. A valuable contribution is made to the field of laser remanufacturing technology, and significant implications are held for various industries such as aerospace, metallurgy, and energy.

An energy-efficient method of laser remanufacturing process

With the global energy shortages and the increasing concerns of environmental protection in various countries, energy consumption optimization in laser remanufacturing has attracted much attention. To address the problems of large energy consumption and high cost in the laser remanufacturing process, the energy consumption characteristics and mechanism of the laser remanufacturing process are analyzed in this work. Then an energy consumption model of the laser remanufacturing process is established. Moreover, an optimization model of laser remanufacturing process parameters with objectives of energy consumption, powder utilization rate, hardness and aspect ratio is formulated. A novel non-dominated sorting genetic algorithm-II (NSGA-II) based on adaptive crossover probability and multi-crossover operators is proposed to solve the model. In this way, the optimal process parameters are obtained by the improved Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) method. Finally, some remanufacturing experiments are carried out on the LDM4030 laser remanufacturing equipment. The results show that the model and algorithm presented in this work can effectively reduce energy consumption, improve powder utilization rate and ensure the quality of cladding. The research results of this work can provide an effective way for an energy-efficient laser remanufacturing process and give reference to the energy consumption optimization of other laser surface engineering technologies, such as laser shock strengthening and laser cleaning.

Research on trapezoidal shape optimization of laser remanufacturing heterogeneous interface under fatigue load

How to evaluate and improve the performance of heterogeneous interface was the key to ensure the reliability of laser remanufacturing products. Based on the analysis of stress eigenvalues at interface singularity, a fatigue life model and a trapezoidal interface shape optimization model were established. Thirteen different trapezoidal interface shapes were designed for static and fatigue experiments to verify the correctness. The results showed that the interface fatigue life prediction was accurate, and the optimized trapezoidal interface shape could significantly improve the interface mechanical properties. These provided a theoretical basis for the shape pretreatment of the damaged position in remanufacturing.

Research on Strengthening Process of Laser Additive Remanufacturing of Mill Housing

Based on the analysis of the wear mechanism of the mill housing, the results show that the main failure forms of the mill housing are corrosion wear and stress wear. Therefore, it is proposed to remanufacture and repair the housing to improve the hardness and impact resistance of the wear part of the housing. In order to strengthen the wear resistance of the wear part of the housing, Fe45+5%WC alloy powder was prepared to strengthen the wear resistance of the worn part of the housing. The sample of the alloy layer was produced by high power semi-conductor laser, the hardness, impact toughness and surface PT were tested, and the microstructure was observed by metallographic and EDS experiments. The results show that the alloy layer has high hardness and wear resistance, and the grains are fine and the alloy layer is metallurgical bonded to the substrate. The 3500mm reversing mill housing was repaired by laser re-manufacturing technology, and it was found that the alloy layer had good bonding and surface hardness was improved, thus strengthening the housing.

Influence of laser power on interface characteristics and cracking behavior during laser remanufacturing of nodular cast iron

Nodular cast iron shows poor weldability due to obvious crack tendency caused by chilled structure in interface region during welding and cladding process. However, chilled structure could be eliminated by controlling interface heat input during laser cladding process. In this paper, brazing interface characteristic with no chilled structure could be obtained by controlling the heat input of the interface, and the results showed that the brazing interface illustrated higher strength compared with the chilled structure interface. The results illustrated that the tensile strength of specimens with brazing and intermittent chilled structure characteristic could reach 564 MPa. However, tensile strength of specimens with continuous chilled structure characteristic was lower than 353 MPa. Cracks formed in the interface zone and extended to the ledeburite region. FEM method with the help of ANSYS software was adopted to determine the thermal cycles of the interface region during the cladding process, and the mechanism of the interface behavior was studied.

Multi-objective numerical simulation of geometrical characteristics of laser cladding of cobalt-based alloy based on response surface methodology

The objectives of this study are to optimize the key process parameters of laser cladding remanufacturing parts, improve the sealing quality of the hemispherical valve and prolong and improve its service life and reliability. A high-power fiber-coupled semiconductor laser was used to fabricate a single Co-based alloy cladding layer on the pump valve material ZG45 plate. The key process parameters of laser power, scanning speed and powder feeding rate in the process of laser remanufacturing are taken as optimization variables, and the coating width, coating height, coating depth, aspect ratio and dilution rate are taken as response indexes. Based on the response surface analysis method, the central compound experiment is designed using Design-Expert software. The variance analysis of the experimental results is performed, and the regression prediction model of the process parameters relative to the corresponding index is established. Through analysis of the established perturbation diagram and three-dimensional response surface, it is concluded that the main influence factors of melting width and penetration depth are laser power and positive effect, and the main influence factors of melting height are scanning speed and negative effect. The average error of each regression prediction model is lower than 10%. The above research work has important guiding significance for optimizing the process parameters and improving the cladding quality of cobalt-based alloy on ZG45.

Development of Laser Remanufacturing Technology and Application

Development of Laser Remanufacturing Technology and Application

Inconel 718覆层工艺用于K418叶片激光再制造立体成形

Inconel 718覆层工艺用于K418叶片激光再制造立体成形

Current status and development trend of laser remanufacturing of short stress path rolling mill

Current status and development trend of laser remanufacturing of short stress path rolling mill

Experimental and statistical analyses of geometry characteristics of Inconel 718 laser clad layer with response surface methodology

The process parameters of laser remanufacturing technology have significant effects on the geometric characteristics of the single clad layer in the laser remanufacturing process. In this study, the effects of laser power, laser scanning velocity, and powder feeding rate on the geometry characteristics of a clad layer are investigated by depositing Inconel 718 powder on Inconel 718 alloy via coaxial laser cladding. Based on the experimental results, the mathematical models of geometry characteristics are created using the response surface methodology and checked by the analysis of variance. The verification results indicate that the predicted values coincide with the measured ones, which confirms the reliability effectiveness of the models derived from the regression analysis. Finally, the relationship between the main process parameters and geometric characteristics is studied. The modeling results show that laser power has a positive effect on all the geometry characteristics, while the powder feeding rate has a positive effect on the clad height and a negative impact on the width, depth, W/H (the ratio of clad width to height), and dilution rate of the clad layer. The scanning velocity has a positive effect on the W/H and dilution rate of the clad layer and a negative effect on the width, depth, and height of the clad layer.

Influence of Organics Cladding Pretreatment on Microstructures and Properties of Austenitic Steel Coating via Laser Remanufacturing Technology

We report a new organics cladding pretreatment technique to fabricate the austenitic steel coating via the laser remanufacturing technology and demonstrate that the organics cladding pretreatment could refine the grains and alleviate defects of the coating remarkably, which consequently enhances significantly the mechanical property. In addition, a new synchronous lateral powder feeding device is employed to prevent the nozzle from being blocked by organics coated powder and also protect the surface of the molten pool from being oxidized. This new organics cladding pretreatment technique may be important for the technological improvement in the mechanical property of coating fabricated via laser remanufacturing method.

Effects of Carbon and Boron on Structure and Properties of Austenitic Stainless Steel Coatings Fabricated by Laser Remanufacturing

The coatings are fabricated using austenitic stainless steel powder with various contents of carbon and boron via laser remanufacturing technique. A new synchronous lateral powder feeding device is adopted to avoid surface oxidation of molten pool. The authors find that the strength can be increased but plasticity is decreased of with the rise of boron content due to the formation of lamellar borides phase structures, which are very brittle and have high hardness. In addition, the authors also find that the tensile strength and hardness are enhanced by increasing the content of carbon, while the plasticity is deteriorated due to the formed carbide in the grain of the austenitic stainless steel coating.

Surface remanufacturing of ductile cast iron by laser cladding Ni-Cu alloy coatings

Ductile cast iron is hard to be remanufactured without preheating and post heat treatment owing to the complicated phase evolution and a great tendency to form chilled structure during cladding process. Ni-Cu alloy shows great ability to obstruct the diffusion of carbon in the transition zone during the welding of cast iron due to the low solubility of carbon in nickel alloy. In the present study, different kinds of simulated grooves were devised to estimate the remanufacturing process of ductile cast iron by laser cladding. Ni-Cu alloy were used as the filling material. The microstructure and phase evolution in the transition zone were illustrated and mechanical properties have also been studied. Scanning electron microscopy (SEM), energy dispersive microanalysis (EDS), X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to identify the microstructure and phase types of the claddings and transition regions. The result illustrated that various microstructures were formed during laser remanufacturing. Circular groove and cross cladding procedure were conductive to reduce residual stress. Microhardness decreased obviously after multi thermal cycles. The specimen shows ultimate strength of 502 MPa no less than that of the substrate.

Laser re-manufacturing of failure 18Cr2Ni4WA gear in low-speed heavy-load mining machine transmission

This article investigated laser re-manufacturing technology application in mining industry. The research focused on green re-manufacturing of failure spur. Leave the main gear body stay intact after the dirty, rust, fatigue and injured part were removed completely before the green re-manufacturing procedure begin. The optimized laser operating parameters paved the road for excellent mechanical properties and comparatively neat shape which often means less post processing. The laser re-manufactured gear surface was systematically examined, including microstructure observation, and dry wear test at room temperature. The test results were compared with new gear surface and used but not broken gear surface. Finally, it proved that the green re-manufactured gear surface displayed best comprehensive mechanical properties, followed the new gear surface. The resistance of dry wear properties of used but not broken gear surface was the worst.

激光熔覆曲面零件再制造的机器人路径规划

激光熔覆曲面零件再制造的机器人路径规划

Investigate on the Properties of X80 Pipeline Steel Damaged by High Temperature

Remanufacturing engineering is an effective way to solve the waste of resource and the refurbishment of waste equipment. Laser remanufacturing technology mainly utilizes the laser cladding to repair the components and parts which were damaged or scrapped during their service life, and it has become an important part of the remanufacturing engineering. In order to evaluate the remanufacturing value of the workblank, a comprehensive study on the properties of the remanufacturing workblank is needed. The X80 high deformability pipeline steel are usually used as the oil and gas transmission pipeline and they can be damaged by high temperature during the service life. Properties of X80 high deformability pipeline steel damaged by high temperature were investigated in this paper. Different damage temperature and time were chosen to simulate the possible damage conditions. Then, the mechanical properties, hardness distribution, microstructure of the materials were systematically investigated by means of tensile testing machine, micro-hardness tester, optical microscopy. The results show that the properties of X80 pipeline steel are changed by the damage temperature and time . When the damage temperature is 1000 and the time is 12h, compared with the properties of base metal, the yield stress and the tensile stress is just about 44.5% and 64% of which, respectively. In addition, the mechanical performance of the materials will be decreased when the damage time is prolonged. This research can provide the reference for the laser cladding remanufacture of X80 pipeline steel.

Numerical Simulation of Temperature Field in Laser Remanufacturing

It plays an important role in guiding laser remanufacturing process and process control to research temperature field of laser remanufacturing. A numerical simulation method of temperature field based on MATLAB PDE Tool is proposed. Theoretical model of temperature field is presented. The temperature fields at different times are calculated and simulated with finite element method and MATLAB software with PDE Toolbox. The results show that this method can accurately calculate the temperature distribution of the laser remanufacturing process. The simulation results are helpful to optimize process parameters and to improve the quality of laser remanufacturing.