Surface Mechanical Treatment Research Articles

Research on surface modification of anodized aluminum alloy using piezoelectric machine hammer peening

Piezoelectric machine hammer peening (PEMHP) is a mechanical surface treatment method that hammers the workpiece surface by an oscillatory spherical tungsten carbide tool. The experiments have been conducted to investigate the surface modification of 6016 anodized aluminum alloy using PEMHP, including surface roughness, surface topography, and hardness. The experimental and simulation results indicated that PEMHP has better surface smoothing effect than milling and improves the surface integrity. The hardness of anodized aluminum alloy increases about 14–33% with different peening parameters. The influences of peening parameters on surface roughness, surface topography, and hardness are discussed. It is found out that peening parameters have strongly influenced surface integrity, especially line pitch. Therefore, PEMHP can be a subsequent machine process for aluminum alloy after anodic oxidation to improve surface integrity and hardness further.

Fatigue Strength Enhancement of Butt Welds by Means of Shot Peening and Clean Blasting

Shot peening is a mechanical surface treatment to improve the fatigue strength of metallic components. Similarities exist between regular shot peening and conventional industrial clean blasting. However, the main difference between these two processes is the peening media used and the lack of control and documentation of peening parameters. The clean blasting process is not yet qualified to optimize fatigue enhancement, although it holds a similar potential to regular shot peening. Clean blasting is frequently applied to welded components, with the purpose of surface preparation for application of corrosion protection. This article presents the results of regular shot peened double V-groove (DV) butt welds made from construction steels S355N and S960QL, as well as the high strength aluminum alloy Al-6082. The peening parameters are varied widely. Furthermore, the effect of coverage and intensity is investigated to test the robustness of the peening processes. The data is completed with industrially clean blasted welds, representing typical workshop conditions. The overall objective of this work is to derive minimum peening parameters that still allow significant fatigue strength benefits. The presented data show a high robustness of the fatigue results to peening parameters.

Comparative Analysis of Different Surface Modification Processes on AA 7075 T651

Modern industries turn into light weight high strength materials. Aluminum alloys are having such a great property, in which, AA 7075 T651 provides good strength than other alloys. Hence, hardness of aluminum alloys are poor there by improvement of surface hardness of aluminum alloy is necessitate. Shot peening, severe surface mechanical treatment (SSMT) and laser shock peening (LSP) are the surface property enhancement processes, which are used to improve the surface hardness of AA 7075 T651. This article deals with study the effect of shot peening, Severe surface modification process and laser shock peening on AA 7075 T 651. Among these two processes, LSP reveals better improvement in surface hardness. The Vickers micro hardness test is contacted on the specimens. 15%, 18% and 29% of harness improvements are obtain than unpeened specimen in shot peened specimen, SSMT specimen and Laser shock peened specimen respectively. The deformed layer thickness is 500 µm found in the laser shock peened specimen and 300 µm in the shot peened and SSMT treated specimens.

Recent Developments in the Application of Surface Mechanical Attrition Treatments for Improved Gradient Structures: Processing Parameters and Surface Reactivity

Recent Developments in the Application of Surface Mechanical Attrition Treatments for Improved Gradient Structures: Processing Parameters and Surface Reactivity

Adjustment of Lifetime-Increasing Surface Layer States by Complementary Machining∗

Abstract During manufacturing of metallic components, thermo-mechanical loadings induce surface layer states like topography or residual stresses, which influence the component properties like fatigue strength. In order to optimize the component properties, a mechanical surface treatment can be carried out after the machining process. In this work, the influence of the process parameters processing velocity and penetration depth on the resulting tool wear during external longitudinal turning of AISI 4140q&t by Complementary Machining is analyzed. The process strategy Complementary Machining (CM) combines machining and mechanical surface treatment using the cutting tool. The mechanical surface treatment takes place after the machining in the opposite machining direction. The results of this study show that the process variables have an influence on the tool wear and thus directly influence the resulting topography. The fatigue analysis shows that the fatigue strength after Complementary Machining is comparable to that of shot peening. Furthermore, the concept of local fatigue strength is used to show the extent that residual stress reduction as a result of cyclic loading affects the fatigue strength.

Slide burnishing—review and prospects

This review paper is devoted to the slide burnishing (SB) of metal components—state-of-the-art, achievements and perspectives. SB belongs to the group of static methods for mechanical surface treatment used largely in aerospace, automotive and other industries. By means of the plastic deformation of the surface layers, the surface integrity (SI) of the respective component is improved greatly in terms of minimum roughness, micro-hardness and introduced residual compressive stresses. As a result, fatigue crack resistance, crack corrosion resistance, wear resistance and corrosion resistance increase dramatically. The main feature of SB is the sliding friction contact between the deforming element and the surface being treated. Using the differential-morphological method, an integrated classification of the static methods is created and the area of SB is outlined. The proposed morphological matrix, which can be expanded and supplemented contains existing burnishing methods as well as combinations of elements and interactions that can be used to synthesize new burnishing methods and tools. In addition, a literature review of the publications devoted to SB has been conducted. Further, an analysis of the published studies on different criteria has been carried out and graphic visualizations of the statistical results have been made. On this basis, relevant conclusions have been made and the directions for future investigations of SB have been outlined.

Modeling thermal and mechanical cancellation of residual stress from hybrid additive manufacturing by laser peening

Additive manufacturing (AM) of metals often results in parts with unfavorable mechanical properties. Laser peening (LP) is a high strain rate mechanical surface treatment that hammers a workpiece and induces favorable mechanical properties. Peening strain hardens a surface and imparts compressive residual stresses improving the mechanical properties of a material. This work investigates the role of LP on layer-by-layer processing of 3D printed metals using finite element analysis. The objective is to understand temporal and spatial residual stress development after thermal and mechanical cancellation caused by cyclically coupling printing and peening. Results indicate layer peening frequency is a critical process parameter affecting residual stress redistribution and highly interdependent on the heat generated by the printing process. Optimum hybrid process conditions were found to exists that favorably enhance mechanical properties. With this study, hybrid-AM has ushered in the next evolutionary step in AM and has the potential to profoundly change the way high value metal goods are manufactured.

Adhesion behavior of conventional and high-translucent zirconia: Effect of surface conditioning methods and aging using an experimental methodology.

Evaluate the adhesive behavior of conventional and high-translucent zirconia after surface conditioning and hydrothermal aging. Conventional (ZrC) and high-translucent zirconia (ZrT) specimens were divided into six groups: without surface treatment (ZrC and ZrT), air-borne particle abrasion with 50-μm Al2 O3 sized particles (ZrC-AO and ZrT-AO), and tribochemical treatment with 30-μm silica modified Al2 O3 sized particles (ZrC-T and ZrT-T). Zirconia specimens were treated using an MDP-containing universal adhesive and bonded to two resins blocks with an adhesive luting cement. Microbar specimens with cross-sectioned areas of 1 mm2 were achieved. Half of the microbars were subjected to hydrothermal aging. Bond strength was evaluated by microtensile bond strength test and statistically evaluated by the Weibull analysis. Roughness of the ZrC-AO and ZrT-AO groups were statistically higher. Bond strength analysis revealed higher bond strength for ZrC-AO and ZrC-T groups compared to ZrT-AO and ZrT-T, respectively. Mixed failure was the most frequent for the mechanically treated groups, while no cohesive failures were obtained. Lower values of bond strength were obtained for the mechanically treated high-translucent zirconia groups when compared to their conventional zirconia counterparts. Mechanical surface treatment significantly improved the bond strength to conventional and high-translucent zirconia. Mechanical surface treatment (air-borne particle abrasion or tribochemical treatment) associated with the use of universal adhesives containing MDP could provide a durable bonding to conventional and high-translucent zirconia.

Comparison of Self-Etching Ceramic Primer and Conventional Silanization to Bond Strength in Cementation of Fiber Reinforced Composite Post.

Various mechanical and chemical surface treatments have been proposed to improve the retention of fiber-reinforced composite post (FRCP), but the results are still controversial. The bond strength and durability of a self-etching ceramic primer, which was recently released as an alternative to etching and silane, are not yet known. This study aimed to compare and evaluate the push-out bond strength of different surface treatments of FRCPs after an artificial aging procedure. Four groups (n = 10) were established to evaluated FRCP surface treatments (dentin adhesive bonding; silane and adhesive bonding; hydrofluoric acid, silane and adhesive bonding; and a self-etching ceramic primer). They were bonded with dual-curing rein cement (Multilink N) and stored in distilled water at 37 °C for 30 days, then thermal cycled for 7500 cycles. After being sectioned into 1 mm thickness, each coronal and apical part was evaluated for its the push-out bond strength by a universal testing machine. Each debonded specimen was observed by an optical microscope and divided according to the failure modes. The results showed that silane treatment significantly improved push-out bond strength, but the self-etching ceramic primer did not do so. Additional hydrofluoric acid treatment or the adhesive bonding agent alone did not significantly improve the retention of FRCPs. Cohesive failure of the luting material was found most frequently in all groups.

Accelerated biodegradation and improved mechanical performance of pure iron through surface grain refinement

Pure iron and its biocompatible and biodegradable alloys have a high potential to be used for temporary load bearing medical implants. Nevertheless, the formation of passive iron oxide and hydroxide layers, which lead to a considerably low degradation rate at the physiological environment, has highly restricted their application. Herein we used numerical and experimental methods to evaluate the effect of severe shot peening, as a scalable mechanical surface treatment, on adjusting the performance of pure iron for biomedical applications. The developed numerical model was used to identify the range of peening parameters that would promote grain refinement on the pure iron surface. Experimental tests were then performed to analyze the gradient structure and the characteristics of the interface free surface layer created on peened samples. The results indicated that severe shot peening could notably increase the surface roughness and wettability, induce remarkable surface deformation and grain refinement, enhance surface hardness and generate high in-depth compressive residual stresses. The increased surface roughness besides the high concentration of micro cracks and dislocation density in the grain refined top layer promoted pure iron’s degradation in the biologically simulated environment. Statement of SignificanceBiodegradable metallic materials with resorbable degradation products have a high potential to be used for temporary implants such as screws, pins, staples, etc. They can eliminate the need for implant retrieval surgery after the damaged tissue is healed, and result in reduced patient suffering besides lowered hospitalization costs.Pure iron is biodegradable and is an essential nutrient in human body; however, its application as biomedical implant is highly restricted by its slow degradation rate in physiological environment. We applied a scalable surface treatment able to induce grain refinement and increase surface roughness. This treatment enhances mechanical performance of pure iron and accelerates its degradation rate, paving the way for its broader applications for biomedical implants.

Enhancing the Structural Performance of Lightweight Metals by Shot Peening

Lightweight metals and metal alloys provide the opportunity to fulfill the exigent weight‐saving requirements for structural components. Mechanical surface treatments, in particular, shot peening and other varieties of impact‐based surface treatments are found to be able to significantly promote the structural application of lightweight metals through enhancing their mechanical performance. Moreover, these treatments have substantiated a notable prospect to modulate the surface–environment interaction of the treated material, bringing in original functionalities in multiple fields of application. Herein, the current state‐of‐the‐art in the implementation of shot peening‐based surface treatments is reviewed regarding lightweight metallic materials. The recent advancements are described focusing on the foremost characteristics of the major lightweight metals commonly used in aerospace, automotive, and biomedical sectors. Emergent applications and the existing challenges are highlighted. Lastly, future perspectives on tailoring the effects of shot peening‐based mechanical surface treatments to boost the appeal of lightweight metals as structural components are provided.

Theoretical and experimental analysis of compressive residual stress field on 6061 aluminum alloy after ultrasonic surface rolling process

Ultrasonic surface rolling process is a mechanical surface treatment used for improving fatigue life by introducing a compressive residual stress field into the surface of metallic components. This paper develops a simplified theoretical analysis model of compressive residual stress field induced by ultrasonic surface rolling process. Explicit dynamic solution in ABAQUS is used for calculating the plastic contact radius ap and velocity V0 of the tool tip. Afterward, compressive residual stress field is predicted by using MATLAB on the basis of this theoretical model. Additionally, ultrasonic surface rolling process experiments are conducted to verify the calculated results of compressive residual stress field. The influence of ultrasonic surface rolling process parameters on compressive residual stress field, such as static force F0, spindle speed n, vibration amplitude B, and ultrasonic frequency f, are examined by using theoretical analysis and experiments. The calculated results of compressive residual stress field are in relatively good agreement with the experimental results. Furthermore, ap essentially determines the distribution of compressive residual stress field. Other parameters indirectly affect the distribution of compressive residual stress field through changing ap. Finally, static force and vibration energy simultaneously applied to the tool tip can significantly affect the distribution of compressive residual stress field compared with only static force.

Effect of Mechanical Surface Treatments on Impact Strength for Low Carbon Steel AISI 1020

Objective of this paper is to study the influence of some mechanical surface treatments on impact strength stress for low carbon steel AISI 1020 AISI. Several specimens were subjected or encountered to for impact test were equipped agreeing to ASTM E23 and then were encounter to surface treatment Such as shot peening which was implemented on some specimens using steel balls having diameter of 1.25mm and hardness = 55HRC for (10,20,30) min. Some another’s specimens were treated with using laser peening pulse in notch zone of impact specimen at (5,10,15) laser CO2 pulse. and Plasma also used for surface treatment of impact specimens by using plasma beam for 2,5,10 sec. The results showed that the mechanical surface treatment contributed in improvements of toughness fracture for low carbon steel comparing with base metal. It was found that when increasing shot peening time finding decreasing in the impact strength decreased impact stress because of increase in hardness which generating from heat shot which generated residual stress and the best time was 10 min. and laser pulses and plasma beam were in contributed in increasing impact strength stress for the same reason above and the number of 5 pulse give gave the best result and also the plasma for 5 sec.

On the influence of ultrasonic surface rolling process on surface integrity and fatigue performance of Ti-6Al-4V alloy

An ultrasonic surface rolling process (USRP) is a novel mechanical surface treatment technique for enhancing the fatigue performance of metallic materials. In this work, USRP with different repeated processing numbers was employed for enhancing the fatigue performance of a Ti-6Al-4V alloy. The effect of USRP on their surface integrity (including microstructure, surface quality, microhardness, and residual stress) were investigated, which were characterized by means of scanning electron microscope, transmission electron microscope, confocal laser scanning microscope, microhardness tester, and X-ray diffraction residual stress tester. Especially, a refined microstructure (grain size: ~100–400 nm) was formed on the topmost surface of twelve-repeat USRP specimen. Subsequently, the fatigue behavior of the specimens was investigated via rotating-bending fatigue tests, and the results suggested that USRP could effectively enhance the fatigue performance of the Ti-6Al-4V alloy. The USRP-induced enhancement mechanism of the fatigue performance can be ascribed to the synergistic effect of the compressive residual stress, microstructure, work hardening, and improved surface quality. The best synergistic effect and, correspondingly, the greatest improvement in the fatigue performance were realized for the one-repeat USRP specimen.

Comparison of ultrasonically enhanced pulsating water jet erosion efficiency on mechanical surface treatment on the surface of aluminum alloy and stainless steel

Presented article is focused on the comparison of erosion efficiency on the surface treatment of ultrasonically enhanced PWJ (pulsating water jet) on different metal materials surfaces. Surfaces of EN X5CrNi18-10 stainless steel and EN-AW 6060 aluminum alloy were evaluated. Pulsating water jet technological factors were set to the following values: pressure was 70 MPa, circular nozzle diameter was 1.19 mm, traverse speed of cutting head was 100 mm s−1 (which is 200 impact for millimeter) for stainless steel and 660 mm s−1 (which is 30 impact per millimeter) for aluminum alloy. The evaluation was made based on the surface topography evaluation, evaluation of microstructure, and microhardness in the transverse cut. The results of the stainless steel surface evaluation show slight erosion of material, with creating microscopic craters. Subsurface deformation was found to a depth of a maximum of 200 μm. Hardness measurement shows 11% higher value of hardness under the affected area compared with a measurement in the center of the sample. From the findings, subsurface deformation strengthening of stainless steel with minimal influence of material surface can be assumed. Surface deformation of aluminum alloy is characterized by the formation of more pronounced depressions and less pronounced protrusions. Depressions were created by a combination of compression and tearing off material parts. A decrease in hardness value of 18% compared with a measurement in the center of the sample. In places of the first indent just below the disintegrated area (up to 600 μm deep), it is possible to assume the material plastic deformation, but the value of aluminum alloy tensile strength Rm is not exceeded. The experimental results from an aluminum alloy evaluation do not confirm the subsurface mechanical strengthening of the material.

The effect of material cyclic deformation properties on residual stress generation by laser shock processing

Laser shock processing (LSP) is a mechanical surface treatment to induce a compressive residual stress state into the near surface region of a metallic component. The effect of the cyclic deformation properties of ductile materials on the final residual stress fields obtained by LSP is analysed. Conventional modelling approaches either use simple tensile yield criteria, or isotropic hardening models if cyclic straining response is considered for the material during the peen processing. In LSP, the material is likely to be subject to cyclic loading because of reverse yielding after the initial plastic deformation. The combination of experiment and modelling shows that the incorporation of experimentally-determined cyclic stress-strain data, including mechanical hysteresis, into material deformation models is required to correctly reflect the cyclic deformation processes during LSP treatment and obtain accurate predictions of the induced residual stresses.

Effect of surface mechanical treatment on the oxidation behavior of FeAl-model alloy

Fe-based alloys are commonly used in almost every sector of human life. For different reasons, the surfaces of the real parts are prepared using different methods, e.g., mirror-like polishing, grit-blasting, etc. The purpose of the present work is to answer the question how the surface preparation influences the oxidation behavior of Fe-based alloys. To answer this question, a high-purity model alloy, Fe–5 wt%Al, was isothermally oxidized in a thermogravimetrical furnace. The post-exposure analysis included SEM/EDS (WDS) and XRD. The surface roughness was determined by a contact and laser profilometer. The obtained results demonstrate that the mechanical surface preparation influences oxidation kinetics as well as the microstructure of the oxide scale formed on the alloy at both studied temperatures. Namely, polishing and grinding caused local formation of Fe-rich nodules and sub-layer of protective Al2O3. In contrast, grit-blasting leads to the formation of a thick outer Fe-oxide and internal aluminum nitridation. A significant increase in the oxidation rate of the material after grit-blasting was attributed to grain refinement in the near-surface region, resulting in an increase in easy diffusion paths, namely grain boundaries.

Comparison of Adhesive Properties of Polyurethane Adhesive System and Wood-plastic Composites with Different Polymers after Mechanical, Chemical and Physical Surface Treatment.

The cost of most primary materials is increasing, therefore, finding innovative solutions for the re-use of residual waste has become a topic discussed more intensely in recent years. WPCs certainly meet some of these demands. The presented study is focused on an experimental analysis of the effect of surface treatment on the adhesive properties of selected WPCs. Bonding of polymer-based materials is a rather complicated phenomenon and modification of the bonded area in order to improve the adhesive properties is required. Two traditional types of surface treatments and one entirely new approach have been used: mechanical with sandpaper, chemical with 10 wt % NaOH solution and physical modification of the surface by means of a MHSDBD plasma source. For comparison purposes, two high-density polyethylene based products and one polyvinyl-chloride based product with different component ratios were tested. A bonded joint was made using a moisture-curing permanently elastic one-component polyurethane pre-polymer adhesive. Standardized tensile and shear test methods were performed after surface treatment. All tested surface treatments resulted in an improvement of adhesive properties and an increase in bond strength, however, the MHSDBD plasma treatment was proven to be a more suitable surface modification for all selected WPCs.

Deformation field interaction in sequential circular indentation of a strain hardening material

ABSTRACTAn experimental study was made to characterise and model the deformation field in sequential circular indentation of a model strain hardening material. Digital image correlation was used to measure the evolving subsurface deformation field in terms of displacement, strain rate and strain as a function of indentation spacing and depth. These measurements were used to validate a finite element model for complementary simulations. The results identify relationships between sequential indentation parameters and overlap of subsurface strain distributions, maximum subsurface strains and indentation loads. Maximum strain and the degree of strain field overlap in the deformed subsurface were maximised when the ratio of indentation spacing (S) to projected indentation contact length (L) was approximately S/L = [1.1, 1.2]. Also discussed are the implications for understanding process-scale considerations for indentation-based mechanical surface treatments, including energy dissipation and relationship of surface coverage measures to subsurface strain overlap. Relative differences in energy expended were found for conditions that produce similar levels of subsurface plastic strain and strain field overlap. Finally, the role of sequential indentation parameters on strain path changes and path reversals in the deformed subsurface is investigated and discussed in the context of heterogeneous mechanics and corresponding effects on subsurface microstructure evolution.

Burnishing of FSW Aluminum Al–Cu–Li Components

Ball-burnishing is presented herein as a mechanical surface treatment for improving mechanical properties after the friction stir welding process. Ball-burnishing provides good surface finish, high compressive residual stresses, and a hardness increase of the surface layer. These characteristics are key for the fatigue life improvement of the component, and for wear resistance due to the higher hardness. This work presents a complete analysis of surface and sub-surface hardness values focusing on the determination of each process parameter influence. Burnishing pressure, radial width, and burnishing direction influence were analyzed. The tested material was 2050 aluminum alloy with two different heat treatments (T3 and T8). The optimum parameters were established, and a complete analysis of the surface hardness was performed. Results show that burnishing is an economical and feasible mechanical treatment for the quality improvement of component surfaces.