Nickel-based Superalloy GH4169 Research Articles

Study on the cutting performance of AlTiN/AlTiSiN composite coating tool in deep-hole pull boring tool of GH4169

As one kind of difficult-to-cut material, when deep-hole machining Nickel-based superalloy GH4169, there are server adhesive wear, poor tool wear resistance and multiple surface defects, which limits its improvement of processing efficiency and processing quality. The comparative studies on the tool wear mechanism and the workpiece surface morphology characteristic are carried out during deep-hole pull boring GH4169 with AlCrN and AlTiN/ AlTiSiN composite coating tool. The results show that the flank and rake wear is mainly adhesive wear and abrasive wear, accompanied by coating shedding, micro-tipping, built-up edge and burn blackening. Compared with AlCrN, the AlTiN/ AlTiSiN composite coating tool has better wear resistance and slight adhesive wear. With the increase of feeding speed and boring depth, it is more likely to produce the built-up edges on the rake face and occur the vibration wrinkles on the flank face. But there is the smaller scale of the narrow wear groove mark on the minor flank face at a higher feed speed. Feed groove marks, material adhesion, rolling traces and the surface defects such as pits and micro-hole are the main features of the machined inner surface. Within the range of boring deepth 50mm~1060mm, the machined surface roughness basically fluctuates between 1.130 μm and 1.940 μm which is smaller at the initial cutting edge. The higher the feed speed, the larger scale of the residual feed marks, and the rougher the machined surface of inner hole.

Experimental study of picosecond laser-assisted grinding of GH4169 nickel-based superalloy

The nickel-based superalloy GH4169 exhibits excellent thermal stability and fatigue resistance, making it widely utilized in the aerospace and marine manufacturing industries. However, the high mechanical strength of the nickel-based superalloy GH4169 leads to issues such as high grinding forces during grinding and poor surface morphology of the material after grinding. To improve the processing quality of GH4169, this study employs ultrafast pulse laser texturing to create two distinct biomimetic structures on its surface. The study explores the impact of laser parameters on both the recast layer and surface hardness. Subsequently, grinding experiments are conducted on both structured and non-structured workpieces. The grinding forces and surface roughness during grinding are analyzed, and the surface morphology of the workpiece after grinding and the corrosion resistance of the material are also tested. According to the test results, the grinding forces of the fishbone-like and nacre-like structure workpieces are reduced compared with those of the non-structured workpieces, and the maximum tangential grinding forces are reduced by 38.54 % and 35.98 %, and the maximum normal grinding forces are reduced by 30.24 % and 29.6 %, respectively. In addition, the corrosion resistance of the surface of the structured workpieces after grinding is better compared to the non-structured workpieces, and the best corrosion resistance is obtained for the fishbone-like structure.

Experimental research on turning nickel-based superalloy GH4169 under cryogenic cooling mixed lubrication jets

Abstract GH4169 nickel-based superalloy is the material of choice in industries such as aerospace due to its exceptionally high strength, corrosion resistance, and stability under high temperatures. However, GH4169 has relatively poor thermal conductivity, limiting the effective heat dissipation during the cutting process. This causes elevated temperature in the machining area, adversely affecting both the quality of machining and the life of cutting tools, and there are no mature processing techniques currently available to address these challenges. This paper explores a machining method with cryogenic cooling mixed lubrication for turning on GH4169, compared to traditional cutting fluids and only liquid nitrogen cooling. The results show that compared to conventional emulsion machining, techniques using liquid nitrogen cooling and a combination of liquid nitrogen and emulsion significantly reduce tool wear rates and temperature, and improve surface quality, thereby enhancing machining efficiency. These findings offer a new perspective and solution for the machining processes of GH4169 nickel-based alloy.

Investigation on the thermal-mechanical coupling effect on wear mechanism of high-speed cutting nickel-based superalloy GH4169 with cermet cutting tools

Investigation on the thermal-mechanical coupling effect on wear mechanism of high-speed cutting nickel-based superalloy GH4169 with cermet cutting tools

Investigation of High-Speed Rubbing Behavior of GH4169 Superalloy with SiC/SiC Composites

The silicon carbide fiber-reinforced silicon carbide matrix (SiC/SiC), ceramic matrix composite (CMC) and nickel-based superalloy GH4169 can be utilized in high-temperature applications due to their high-temperature performance. The SiC/SiC composites are commonly used in turbine outer rings, where they encounter friction and wear against the turbine blades. This high-speed rubbing occurs frequently in aircraft engines and steam turbines. To investigate the tribological behavior of these materials, rubbing experiments were conducted between the SiC/SiC and the GH4169 superalloy. The experiments involved varying the blade tip speeds ranging from 100 m/s to 350 m/s and incursion rates from 5 μm/s to 50 μm/s at room temperature. Additionally, experiments were conducted at high temperatures to compare the tribological behavior under ambient conditions. The results indicated that the GH4169 superalloy exhibited abrasive furrow wear during rubbing at both room temperature and high temperature. Furthermore, at elevated temperatures, some of the GH4169 superalloy adhered to the surface of the SiC/SiC. The analysis of the experiments conducted at ambient temperatures revealed that the friction coefficient increased with higher blade tip velocities (100~350 m/s). However, the coefficient was lower at high temperatures compared to room temperature. Furthermore, significant temperature increases were observed during rubbing at room temperature, whereas minimal temperature changes were detected on the rubbing surface at high temperatures.

Evidence of microstructural evolution linked to non-monotonic distribution of micromechanical properties induced by shot peening

The residual stress field induced by surface strengthening processes such as mechanical shot peening and other forms of plastic deformation does not generally exhibit a simple “monotonic” distribution trend. Some researchers have analyzed this fact from a mechanical perspective based on Hertz theory. However, the micro/nano-scale microstructural changes corresponding to the distribution of residual stress fields still appear to be lacking. In this study, we focused on a widely used material in aviation manufacturing, namely nickel-based superalloy GH4169, as our experimental material. We subjected GH4169 alloy to mechanical strengthening treatment using a shot peening intensity of 0.25 mmA, followed by quantitative testing of micromechanical performance indicators such as microhardness and residual stress. To thoroughly investigate the relationship between micromechanical properties and microstructure changes, we utilized transmission electron microscopy (TEM) to observe and analyze shot-peened materials at different depths. Our findings revealed that the most severe microstructural distortion induced by mechanical shot peening in GH4169 alloy was likely to occur within a depth range of 25 to 75 μm. This observation aligns with the actual phenomenon that the maximum microhardness and maximum residual compressive stress did not manifest on the outermost surface of the material. By presenting a detailed analysis of deformation defects such as dislocations, stacking faults, and twinning in different depths of mechanically strengthened layers, our study contributes to a deeper understanding and practical application of post-processing technologies based on plastic deformation.

Automatic crack tip localization in enormous DIC images to in-situ characterize high-temperature fatigue crack growth behavior

Digital Image Correlation (DIC), with its advantages of full-field, non-contact and applicability to extreme environments, is a powerful deformation measurement technique to in-situ monitor the high-temperature fatigue crack propagation behavior. For the DIC-based fracture mechanics analyses of cracking, crack tip position in DIC images, which is usually determined visually and manually, plays a significant role. However, the long-term fatigue-DIC experiment at both room-and high-temperatures poses a real challenge due to the huge amount of DIC images, lower image quality at high-temperature, and even the invisibility of cracks. In this paper, a fully automated algorithm for localizing the crack tip is proposed based on the crack tip displacement field and the immune algorithm. Compared to traditional algorithms, it does not necessitate iterative initial values of crack tip location, and permits precise and fast determination of critical fracture mechanics parameters, such as the Stress Intensity Factors (SIFs). The algorithm reliability is validated by both numerical simulation and fatigue testing of nickel-based superalloy GH4169 at room temperature and 650℃. It is shown that crack tip position and SIF values can be precisely and automatically determined within 7 s per image using an ordinary low-cost computer, which significantly improves the analyzing efficiency.

Thermodynamic Entropy-Based Fatigue Life Assessment Method for Nickel-Based Superalloy GH4169 at Elevated Temperature Considering Cyclic Viscoplasticity.

This paper develops a thermodynamic entropy-based life prediction model to estimate the low-cycle fatigue (LCF) life of the nickel-based superalloy GH4169 at elevated temperature (650 °C). The gauge section of the specimen was chosen as the thermodynamic system for modeling entropy generation within the framework of the Chaboche viscoplasticity constitutive theory. Furthermore, an explicitly numerical integration algorithm was compiled to calculate the cyclic stress-strain responses and thermodynamic entropy generation for establishing the framework for fatigue life assessment. A thermodynamic entropy-based life prediction model is proposed with a damage parameter based on entropy generation considering the influence of loading ratio. Fatigue lives for GH4169 at 650 °C under various loading conditions were estimated utilizing the proposed model, and the results showed good consistency with the experimental results. Finally, compared to the existing classical models, such as Manson-Coffin, Ostergren, Walker strain, and SWT, the thermodynamic entropy-based life prediction model provided significantly better life prediction results.

A Novel Method for Predicting Residual Stress in GH4169 Machined Surfaces through Micro-Hardness Measurement

The presence of residual stress seriously affects the mechanical performance and reliability of engineering components. Here, the authors propose a novel method to determine corresponding residual stress through micro-hardness measurements of machined surfaces. In this study, a mathematical model with equal biaxial stress indentation is established. Then, the correlation of micro-hardness with indentation and residual stress is used to determine the prediction equation of residual stress. The material applied in this study is the nickel-based Superalloy GH4169. The residual stress prediction formula for Superalloy GH4169 is ultimately determined through the finite element method by subjecting the indentation to residual stress and fitting the experimental test data. The relationship between the indentation modulus and indentation depth is given quantitatively. The relationship between residual stress and hardness is given quantitatively. The prediction results show that the compressive residual stress can enhance the material hardness and make the contact deformation only require a low indentation depth to achieve complete plastic deformation. Conversely, the tensile residual stress can result in a deeper depth and less hardness at the initial stage of the fully plastic state. For the materials that yield more easily (small ratio of elastic modulus to yield strength), the effect is more evident. The model presented in this paper can accurately forecast corresponding residual stress through measurements of the micro-hardness of machined surfaces.

Experimental study on the machining performance of nickel-based superalloy GH4169 milled by AWJ

Experimental study on the machining performance of nickel-based superalloy GH4169 milled by AWJ

Creep deformation and damage characteristics of nickel-based superalloy GH4169

To further understand the creep behavior of nickel-based superalloys, creep deformation and damage characteristics of nickel-based superalloy GH4169 were investigated systematically by using SEM, EBSD and TEM characterizations in this study. Creep tests were conducted at 650 °C under 820 MPa.The results indicated that the fractions of low-, high-angle, and twin grain boundaries changed significantly after creep. Due to the grain rotation mechanism, the overall microstructure changed from random to preferred crystallographic orientation. <110>//loading direction (LD) oriented grains were rotated to <100>//LD and <111>//LD fibers, resulting in the decrease of <110> fiber, and the increase of <100> and <111> fibers. Cases of <110> oriented grains rotating into <100> and <111> orientations were also provided. Deformation twin and stacking faults were determined as the main deformation mechanisms. The failure of the specimen was induced by intergranular brittle fracture. The grain boundaries with special characteristics, namely high Schmid factor m and low Schmid factor mismatch Δm of neighbouring grains, and low geometric compatibility factor m’, exhibited high susceptibility to cracking.

Wear and Life of K40 Carbide Tool for Plunge Milling GH4169

In order to solve the problems of serious tool wear and poor durability during plunge milling of nickel base superalloy GH4169, the design test obtains the wear morphology process of the tool through K40 carbide tool insertion and milling GH4169. The experiment analyzed the impact and sensitivity of cutting parameters on tool life. The experiment and analysis show that when the K40 carbide tool is the plunge milling GH4169, the service life of the tool decreases rapidly with the increase of cutting speed, feed rate per tooth, and radial cutting depth; The tool life is most sensitive to changes in cutting speed, followed by the feed rate per tooth, and least sensitive to radial cutting depth.

Fretting fatigue life improvement of nickel-based superalloy GH4169 dovetail slots by deflecting abrasive waterjet peening process

The proposed deflecting abrasive waterjet peening (DAWJP) process can be used for surface strengthening of metallic parts with confined space features, which has great potential to improve the surface integrity and fretting fatigue (FF) life of dovetail slots in turbine discs. In this paper, the nickel-based superalloy GH4169 dovetail slot is strengthened by DAWJP and shot peening (SP), and the effects of DAWJP and SP on surface integrity and FF performance of the dovetail slot are investigated. First, the DAWJP with three different processes (water pressure of 205 MPa, traverse speed of 5 mm/s, standoff distance of 2 mm, and path interval of 0.05, 0.1, and 0.15 mm) and the SP with one process (peening intensity of 0.25 mmA with coverage of 100%) were conducted on the contour surface of the dovetail slot. The surface integrity of the dovetail slot before and after the DAWJP and SP treatment was investigated, including microstructure, surface roughness and microscopic morphology, microhardness, and residual stress. Results showed that the dovetail slot treated by the DAWJP with different path intervals formed a plastic deformation layer with a thickness of 22–43 μm and surface roughness Ra and Sa of 0.391–0.501 μm and 0.763–0.907 μm. The surface microhardness and CRS of the DAWJP-treated dovetail slot were approximately 541–591 HV and 1005–1169 MPa, 16%–27% and 178%–224% times higher than the as-received dovetail slot. The SP-treated dovetail slot produced relatively large surface roughness, slight plastic deformation, and low microhardness and CRS compared with the DAWJP-treated dovetail slot. Finally, FF tests were carried out to study the FF behavior of the dovetail slot before and after DAWJP and SP treatment. The FF lives of the dovetail slot treated by DAWJP were 4.82 and 3.91 times that of the as-received dovetail slot at room temperature and a high temperature of 650 °C. In contrast, the FF lives of the SP-treated dovetail slot were 2.96 and 1.96 times that of the as-received specimen at room temperature and a high temperature of 650 °C, which verified that DAWJP has a more significant effect on improving the FF life of dovetail slots than the SP treatment used for comparison. The FF fracture and fretting contact surface and its cross-sectional microstructure were examined, and the results showed that the extreme grain refinement, large CRS, and high work-hardening induced by DAWJP could be the key to greatly improving the FF life of dovetail slots. This work takes the lead in the surface treatment of dovetail slots through the proposed DAWJP process, which provides a feasible reference plan for effectively and economically improving the FF resistance of dovetail slots in turbine discs.

Analysis of Tool Wear in GH4169 Material Milling Process

Nickel-based superalloy GH4169 is a material with strong mechanical properties and is difficult to process. In order to reduce tool wear during material processing and improve the workpiece surface processing quality, based on the finite element simulation software DEFORM, the influence of n, ap, and fz parameters on tool wear during carbide tool milling GH4169 was studied, and a simulation of an orthogonal experimental model was established. The prediction model of tool wear was obtained. The ultrasonic vibration milling was compared with ordinary milling, and the improvement degree of different coating materials on carbide tool wear was explored. The results showed that the ultrasonic vibration signal is helpful to reduce tool wear, improve the surface quality of the workpiece, and improve the stability of the milling process. TiAlN/TiN (WC)-composite-coated tools have good cutting performance, help to reduce tool temperature, reduce tool wear, and improve tool life.

Molecular dynamics study of the effect of rolling process on subsurface strengthening of nickel-based superalloy GH4169 plastic deformation

In this paper, the molecular dynamics (MD) method is used to establish a rolling model at the nanoscale, the same depth of rolling is rolled, and three rolling methods are used, namely, one time, two times and three times respectively. The effects of three rolling methods on the workpiece are studied, and the evolution of dislocation and defect atoms, subsurface damage, surface quality and subsurface micro-strengthening mechanism of the rolled workpiece are mainly analyzed. The results show that the dislocation density increases most significantly by one rolling, and the difficulty of material deformation is reduced by multiple rolling, with the increase of rolling times, the surface roughness increases. We found that the rolling process has a directional effect on the micro-strengthening of nickel-based single crystal alloys, and the strengthening effect is most significant in the normal direction. The subsurface strengthening effect of rolled workpiece is positively correlated with dislocation density and rolling force. Compared with the previous macro rolling test research, we observed the strengthening effect of dislocation density on rolling plastic deformation of nickel-based single crystal alloy from the microscopic level, which can provide a reference for understanding the strengthening mechanism of rolling process on nickel-based single crystal alloy and the optimization of rolling parameters.

Investigation on White Layer Formation in Dry High-Speed Milling of Nickel-Based Superalloy GH4169

To investigate the formation mechanism of the white layer on the machined surface during high-speed milling of nickel-based superalloy GH4169, several cutting parameters were selected for milling experiments. Energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and electron backscattered diffraction (EBSD) were employed to characterize element distribution, phase transformation, and microstructure changes in the machined surface of the superalloy and then reveal the formation mechanism of the white layer on the machined surface. The results show that the white layer appears on the machined surface of GH4169, which is dense and has no obvious structural features. The total amount of elements in the white layer remains unchanged, but the distribution of elements such as C, N, O, Fe, and Ni changes due to phase change. The formation mechanism of the white layer is due to the dynamic recovery and dynamic recrystallization caused by the heat–force coupling effect, which leads to the grain refinement of the material and thus forms the white layer. This investigation can provide theoretical support to improve the service life of the parts in actual machining.

Molecular dynamics study on the effects of nanorolling processes on the properties of nickel-based superalloy GH4169

Rolling is a process that can improve the performance and roughness of machined parts and has a special economic value; therefore, the optimization of rolling process parameters is crucial to workpiece performance. In this paper, three rolling methods are used in molecular dynamics (MD) rolling simulations to study their effects on the surface of nickel-based superalloy GH4169 at the nanoscale. The surface and subsurface of the workpiece after rolling with the three different rolling methods are studied separately; in particular, a comparative analysis of the dislocation generation and movement on the subsurface, crystal defect evolution, and surface roughness was performed. The results show that the increase in subsurface dislocation density by average rolling has a significant influence on the work hardening effect, and the average roughness of the rolled groove surface is the lowest. This is an important reference for the optimization of the parameters of actual rolling processes.

Dynamic plastic evolution mechanism in cutting zone of nickel-based superalloy GH4169

In the cutting process of GH4169 at high speed, the chips are mostly serrated. Serrated chips have an important impact on cutting force, surface integrity and tool wear. According to the microstructure of GH4169, the micro-deformation mechanism of GH4169 during cutting is studied. Through in-depth study of dislocation-stress-strain evolution mechanism, the influence of dislocation on work hardening and flow stress is analyzed from the microscopic viewpoint, and the relationship between shear angle and strain gradient is established. A constitutive model was established to characterize the effects of parameters such as strain rate, dislocation density, steady-state stress and cutting temperature on cutting deformation. The average relative error of the model was 4.26%. When cutting GH4169, the matrix phase mainly undergoes plastic deformation, and the reinforced phase mainly undergoes elastic deformation, and the reinforced phase is the main fracture source. The crack propagation of the reinforced phase will promote the further plastic deformation of the matrix phase. By studying the interaction between two phases in cutting, the generated process of sawtooth chip was revealed, and the mechanism of cutting deformation was explained from the microscopic view.

Molecular dynamics study on defect evolution during the plastic deformation of nickel-based superalloy GH4169 single crystal under different rolling temperatures.

Nickel-based superalloy GH4169 is widely used as an important material in the aviation field. The rolling forming process can improve its surface quality and performance. Therefore, conducting an extensive investigation into the microscopic plastic deformation defect evolution process of nickel-based single crystal alloys during the rolling process is crucial. This study can offer valuable insights for optimizing rolling parameters. In this paper, a nickel-based superalloy GH4169 single crystal alloy was rolled at different temperatures from the atomic scale using the molecular dynamics (MD) method. The crystal plastic deformation law, dislocation evolution and defect atomic phase transition under different temperature rolling were studied. The results show that the dislocation density of nickel-based single crystal alloys increases as the temperature increases. When the temperature continues to increase, it is accompanied by an increase in vacancy clusters. When the rolling temperature is below 500 K, the atomic phase transition of the subsurface defects of the workpiece is mainly a Close-Packed Hexagonal (HCP) structure; when the temperature continues to increase, the amorphous structure begins to increase, and when the temperature reaches 900 K, the amorphous structure increases significantly. This calculation result is expected to provide a theoretical reference for the optimization of rolling parameters in actual production.

Machine Learning Method for Fatigue Strength Prediction of Nickel-Based Superalloy with Various Influencing Factors.

The accurate prediction of fatigue performance is of great engineering significance for the safe and reliable service of components. However, due to the complexity of influencing factors on fatigue behavior and the incomplete understanding of the fatigue failure mechanism, it is difficult to correlate well the influence of various factors on fatigue performance. Machine learning could be used to deal with the association or influence of complex factors due to its good nonlinear approximation and multi-variable learning ability. In this paper, the gradient boosting regression tree model, the long short-term memory model and the polynomial regression model with ridge regularization in machine learning are used to predict the fatigue strength of a nickel-based superalloy GH4169 under different temperatures, stress ratios and fatigue life in the literature. By dividing different training and testing sets, the influence of the composition of data in the training set on the predictive ability of the machine learning method is investigated. The results indicate that the machine learning method shows great potential in the fatigue strength prediction through learning and training limited data, which could provide a new means for the prediction of fatigue performance incorporating complex influencing factors. However, the predicted results are closely related to the data in the training set. More abundant data in the training set is necessary to achieve a better predictive capability of the machine learning model. For example, it is hard to give good predictions for the anomalous data if the anomalous data are absent in the training set.