Surface Mechanical Treatment Research Articles

Effect of Shot Peening in Different Shot Distance and Shot Angle on Surface Morphology, Surface Roughness and Surface Hardness of 316L Biomaterial

Shot peening is a mechanical surface treatment with a beneficial effect to generate compressive residual stress caused by plastic deformation on the surface of material. This plastic deformation can improve the surface characteristics of metallic materials, such as modification of surface morphology, surface roughness, and surface hardness. The objective of this study is to investigate the effect of shot peening in different shot distance and shot angle on surface morphology, surface roughness, and surface hardness of 316L biomaterial. Shot distance was varied at 6, 8, 10, and 12 cm and shot angle at 30, 60, and 90°, working pressure at 7 kg/cm2, shot duration for 20 minutes, and using steel balls S-170 with diameter of 0.6 mm. The results present that the shot distance and shot angle of shot peening give the significant effect to improve the surface morphology, surface roughness, and surface hardness of 316 L biomaterial. Shot peening can increase the surface roughness by the increasing of shot distance and by the decreasing of shot angle. The nearest shot distance (6 cm) and the largest shot angle (90°) give the best results on the grain refinement with the surface roughness of 1.04 μm and surface hardness of 534 kg/mm2.

Influence of Complementary Machining on fatigue strength of AISI 4140

Mechanical surface treatment is an additional process step in the process chain of part manufacturing to enhance performance but increasing production time and costs. Hence, different hybrid processes have been developed including Complementary Machining, which does not need a complex tool. Investigations of orthogonal Complementary Machining indicates that optimized cutting edge microgeometries can induce useful surface layer states like nanocrystalline surfaces whilst minimizing tool wear. This paper analyzes the resulting surface layer states (roughness, residual stresses, grain refinement) and their influence on fatigue strength after turning and Complementary Machining for AISI4140q&t. Implementing these analyses a deeper process understanding is accomplished.

Characterization of Glass Laminate Aluminium Reinforced Epoxy- A Review

Due to present need of light weight and high performance structure, new hybrid materials are developed known as fiber metal laminates (FML). Fiber metal laminates comprises of alternate layers of composite and metals bonded together with appropriate adhesive technique. Mechanical and chemical surface treatment of 2024 aluminum alloy metal for obtaining strong interface bond between aluminum and composite layer. Due to decreased manufacturing cost and time, ease in forming, recyclability, thermoplastic composite are preferred in this study. Fiber metal laminates manufactured by press molding of one surface treated 2024 aluminum alloy as core material and two outer layers of glass fiber reinforced thermoplastic composite. This study investigates the mechanical properties of these fiber metal laminates by performing various tests such as tensile test, low velocity impact test, fire resistant test and flexural test. These results were further validated using analysis software.

Influence of the machine hammer peening technology on the surface near material structure of stainless steel X5CrNi18-10

Machine hammer peening (MHP) is a mechanical surface treatment process that leads to increased hardness and induces compressive residual stresses in surface-near layers of the peened workpiece. This fact, in combination with the possibility of phase transformation of the crystal lattice of a processed metastable austenitic to martensitic structure by the application of machine hammer peening, contains great potential. For this purpose, the present study deals with the investigation of the effects of plastic deformation in steel material according to increase the hardness as well as to influence the material structure in near-surface regions by the use of an electromagnetic hammer peening device. The deformation-induced processes of an austenitic stainless steel X5CrNi18-10 (1.4301) at room temperature were investigated.

Influence of Impact Force, Impact Angle, and Stroke Length in Machine Hammer Peening on the Surface Integrity of the Stainless Steel X3CrNiMo13-4

Industrial standard for introducing compressive residual stresses and improving the fatigue life of compressor blades in pumps, martensitic chromium-nickel stainless steel X3CrNiMo13-4 is surface treated by means of shot peening. Due to the process principle, the kinetic impact energy of the shot peening medium is lower and the resulting surface roughness is higher when compared with another mechanical surface treatment technology machine hammer peening. Machine hammer peening is an incremental, high-frequency surface treatment process that offers advantages over shot peening due to its deterministic process kinematics. However, the influence of the process parameters of machine hammer peening such as impact force, impact angle, and stroke length on the surface integrity of X3CrNiMo13-4 is unknown. Therefore, the objective of this work is to investigate the influence of peening strategies on the residual stresses and the surface roughness depending on various combinations of process parameters. Additionally, the surface layer state after machine hammer peening is compared to both, a milled and a shot peened surface. The results show that machine hammer peening leads to smoother surfaces accompanied by higher compressive residual stresses compared to an industrial shot peening reference.

Comparison between conventional shot peening and ultrasonic shot peening

Shot peening process is a mechanical surface treatment process widely used in the industry. Ultrasonic shot peening and conventional shot peening are two important mechanisms of this process. This work aims at studying and comparing the influence of conventional shot peening and ultrasonic shot peening on the surface characteristics (residual stresses, equivalent plastic deformations, and roughness). Three-dimensional models are established to simulate the two mechanisms by using the finite elements software ABAQUS/PYTHON. The residual stresses distributions, as well as the roughness and the equivalent plastic deformations of the AISI 2205 and the AISI 316L induced by both models, are predicted and compared.

Some insights on Combined Turning-Burnishing (CoTuB) process on workpiece surface integrity

This paper deals with a combined manufacturing process called Combined Turning-Burnishing (CoTuB) that performs turning and ball-burnishing simultaneously on the same machine tool. This innovative process aimed to enhance surface quality and integrity by exploiting rough turning conditions. Consequently, this implies an increase in productivity when compared to conventional surface treatment processes. For this reason, a device was manufactured in order to hold both commercial cutting and burnishing tools to carry out the removal material and the surface mechanical treatment processes simultaneously and under the same operation. As the design of CoTuB device sets the cutting tool ahead of the ball, turning is followed by burnishing operation along the manufactured surface. It has been depicted experimentally that a considerable improvement in surface quality could be achieved using the new combined process under suitable process parameters. Burnishing force, Ball burnishing diameter and depth of cut are independent parameters. In order to carry out a parametric process study, several experiments based on Taguchi method were performed. The aim is to identify the optimal turning/burnishing parameters when treating AISI 4140 steel. This helps to get a compromise between the optimal arithmetic surface roughness (Ra), the compressive residual stress state and the micro-hardness (μH).

Electrochemical Corrosion Characteristics of High Strength Low Alloy Domex 700 Steel After Mechanical Surface Treatment in Chloride Environment

Abstract Nowadays a large number of mechanical surface treatments of constructions materials is used in industry, mainly focusing on steel surface treatment. The aim of this study was to evaluate the effects of mechanical surface pre-treatment (grinding and shot peening) on corrosion resistance of high strength low alloy Domex 700 steel. Suitable mechanical surface treatment can by used for surface homogenization (eg. grinding) or for improvement of mechanical, strength and fatigue properties (shot peening). 0,1M NaCl solution of ambient temperature was used as an environment for electrochemical tests. Evaluation of the mechanical surface treatment effect on corrosion resistance of Domex 700 steel surface was realized by electrochemical tests: potentiodynamic polarization tests (using Tafel analysis) and electrochemical impedance spectroscopy (using equivalent circuit). From the obtained results it is possible to conclude, that the process of mechanical surface treatment by shot peening at choosen conditions has negative effect on corrosion resistance of Domex 700 steel.

Transverse strength of acrylic denture base resin repaired with different mechanical surface treatment methods

Amac: Bu calismanin amaci geleneksel isi ile polimerize olan akrilik rezinin tamirinde, tamir yuzeylerine uygulanan farkli mekanik yuzey islemlerinin akrilik rezinin transvers dayanimina etkisini arastirmaktir. Gerec ve Yontem : Ozel bir kalip yardimiyla dikdortgenler prizmasi seklinde 160 adet akrilik rezin ornek hazirlandi ve tamir yuzeylerine farkli islemler uygulamak uzere 4 farkli gruba ayrildi; Grup 1 islem uygulanmayan kontrol grubunu, Grup 2 kumlama uygulanan grubu, Grup 3 plazma uygulanan grubu ve Grup 4 Er:YAG lazer uygulanan grubu temsil etmektedir. Yuzey islemlerini takiben tamir yuzeyleri taramali elektron mikroskobu (SEM) ve enerji dagilimi spektroskopi (EDS) kullanilarak incelendi. Daha sonra ornekler otopolimerizan akrilik ile tamir edilerek yine dikdortgenler prizmasi seklinde (65×10×3.3 mm) toplam 80 adet ornek (n=20/grup) elde edildi. Tamir edilen orneklerin transvers dayanimi isisal dongu uygulandiktan sonra uc nokta bukme testi ile universal test cihazi kullanilarak olculdu. Sonuclarin istatistiksel analizi tek yonlu ANOVA ile yapildi ve sonrasinda Tukey HSD testi kullanilarak gruplara ait ortalamalar karsilastirildi. Sonuclar α =0.05 icin anlamli kabul edildi. Bulgular : Grup 2 (27.06 ± 5.02 MPa) ve Grup 4 (26.06 ± 3.44 MPa), kontrol grubuna (Grup 1; 18.26 ± 5.27 MPa) ve Grup 3’e (11.19 ± 2.73 MPa) gore istatistiksel olarak anlamli sekilde daha yuksek transvers dayaniklilik degerleri gosterdi (p<0.05), Grup 3 (11.19 ± 2.73 MPa) tum gruplardan istatistiksel olarak anlamli sekilde daha dusuk transvers dayaniklilik degerleri gosterdi (p<0.05). Sonuc : Geleneksel isi ile polimerize olan akrilik rezinin otopolimerizan akrilik rezin ile tamirinde, tamir yuzeylerine kumlama veya Er;YAG lazer uygulamasi akrilik rezinin transvers dayanimini arttirirken, plazma uygulamasi transvers dayanimi azaltti.

Effect of Ultrasonic Nanocrystal Surface Modification on residual stress, microstructure and fatigue behavior of ATI 718Plus alloy

Ultrasonic Nanocrystal Surface Modification (UNSM) is a mechanical surface treatment that induces large compressive residual stresses and near-surface microstructural changes in the material using repetitive impacts at ultrasonic frequencies with a WC tip. In this study, we investigate the use of UNSM to improve the fatigue life of ATI 718 Plus (718Plus). UNSM induced severe surface plastic deformation in 718Plus, which led to nano-sized crystallites, twins, and high dislocation density in the near surface regions, coupled with an increase in surface hardness by 2.3GPa and high magnitude of compressive residual stresses. These changes increased the endurance limit by ~ 13% (~ 100MPa) in room temperature fatigue tests. This improvement in fatigue life was attributed to near-surface microstructural changes, material hardening and high compressive residual stress induced by UNSM. The crack propagation rates were 66% lower for UNSM-treated 718Plus as compared with untreated material. The residual stress relaxation after cyclic loading indicates the effectiveness of UNSM in improving the fatigue life of 718Plus.

Corrosion behaviour of electropolished AISI 316L austenitic biomaterial in physiological solution

Due to suitable mechanical properties, satisfactory corrosion resistance and relatively low cost, austenitic stainless steels are important biomaterials for manufacture of implants and various medical instruments and devices. Their corrosion properties and biocompatibility are significantly affected by protective passive surface film quality, which depends on used mechanical and chemical surface treatment. This article deals with corrosion resistance of AISI 316L stainless steel, which is the most widely used Cr-Ni-Mo austenitic biomaterial. Corrosion behaviour of five various surfaces (original, electropolished, three surfaces with combined treatment finished by electropolishing) is evaluated on the bases of cyclic potentiodynamic polarization tests performed in physiological solution at the temperature of 37± 0.5 °C.

Effect of various surface preparation techniques on the delamination properties of vacuum infused Carbon fiber reinforced aluminum laminates (CARALL): Experimentation and numerical simulation

Carbon fiber reinforced aluminum laminates (CARALL) are one of the aluminum based Fiber metal laminates (FMLs) which, due to their high strength to weight ratio and good impact resistance are greatly replacing aluminum alloys in aircraft structures. In this research work, interlaminate shear strength of Vacuum assisted resin transfer molding (VARTM) manufactured CARALL has been investigated. Numerical simulation model incorporated with real time material data has been developed to predict the delamination behavior of CARALL laminates. Standard CARALL specimens with different surface morphologies were prepared by electric discharge machining, mechanical, chemical and electrochemical surface treatments. T-peel tests were carried out according to standard ASTM D1876-08 to find out inter laminate shear strength. FMLs made out of mechanically, chemically and electrochemically cleaned metal sheets depicted high interlaminate shear strength. SEM micrographs of failed surfaces verify the high adhesive strength of epoxy. Developed numerical simulation model accurately predicts the delamination behavior of CARALL as observed during experimentation.

Investigation on the effect of ball burnishing on fracture toughness in spiral API X70 pipeline steel

The present work is an investigation on the effect of mechanical surface treatment using ball burnishing technique on fracture toughness in spiral API X70 pipeline steel. The burnishing operation has been carried out on three series of impact API 5L 45 Ed specimens that have been prepared according to the location of the notch towards the weld bed: BM notched specimens, FZ notched specimens, and HAZ notched specimens. In the untreated specimens, the absorbed energy in BM specimens is higher than the energy found in FZ and HAZ through the testing temperature range of 50 to −40 °C. In surface-treated specimens, there has been a significant change in the three curves of absorbed energy versus temperature. This is observed when testing temperature decrease from 20 to −40 °C since the energy in BM specimens dropped drastically reaching values lower than that obtained for FZ and HAZ specimens. At the temperature range 50 to 20 °C, the absorbed energy in ball-burnished specimens is relatively higher. At lower testing temperatures below −40 °C, the absorbed energy converged to the same value. At room temperature, hardness tests indicate that where the absorbed energy is higher, hardness is lower.

Iron Plates Modified with ZrO2 Coatings by Surface Mechanical Attrition Alloy and Heat Treatment

Iron Plates Modified with ZrO₂ Coatings by Surface Mechanical Attrition Alloy and Heat Treatment

Experimental and statistical study of three adherence tests for an epoxy-amine/aluminum alloy system: Pull-Off, Single Lap Joint and Three-Point Bending tests

The mechanical resistance of a bonded joint depends on the adhesive interaction onto the substrate and the mechanical properties of the adhesive itself. Many existing tests can be useful for measuring the adherence or evaluating mechanical adhesive response. All these tests do not provide the same information: in particular, adherence measurements can be split into initiation tests and propagation ones. In this paper, three adherence tests have been considered for the evaluation of the fracture initiation between a poly-epoxide adhesive (a mixture of pure epoxy and amine) and an aluminum surface (AA 2024-T3), namely the Pull-Off, Single Lap Joint (SLJ) and Three-Point Bending tests. Various surface preparation protocols before bonding have been tested and optimized for aluminum substrates, including mechanical and chemical surface treatments, followed by the application of an appropriate primer before bonding. This study paves the way for the future development of adhesive systems as it provides reliable surface preparation protocols for aluminum surfaces and gives an insight into the choice of an adequate adherence test dedicated to high-performance adhesives. The load at break (FMax), the experimental error, the failure mode and statistical studies according to the Weibull model and Principal Component Analysis (PCA) were studied on each surface preparation configuration. It has been shown that the application of a primer, especially a sol-gel product increases the load at break and provides more reliable results. Then, this paper shows that the two tests can quantify the failure initiation and distinguish the different surface preparation efficiency, are the Single Lap Joint test (mode II or mode I + II) and the Three-Point Bending test (mode I), with an increase of the results reliability with the latter one. The Pull-Off test (mode I) is useful as a routine checking, and particularly interesting because its response does not depend on the substrate thickness, even though it cannot highlight the difference between all surface preparations.

Probabilistic methodology for predicting the dispersionof residual stresses and Almen intensity considering shot peening process uncertainties

To ensure a high fatigue life and a reduced weight of automotive suspension system components, compressive residual stresses are commonly induced near the surface using many mechanical surface treatments. Among the most preferred techniques, shot peening process presents a high efficiency and a relative low cost. Nevertheless, the employment of such process is generally affected by many sources of variability. Indeed, the experimental residual stress measurements exhibit a significant variation from one component to another and even from different positions on the same component. Therefore, error bars are commonly used to quantify the variability of experimental residual stress measurements. Nevertheless, the majority of predictive approaches of residual stresses induced by shot peening do not consider the effect of the variability of shot peening process parameters. In this study, a probabilistic methodology is applied to evaluate the variability of the induced residual stress profile and the Almen intensity, regarding the scattering of the most significant shot peening process parameters. Furthermore, iso-probabilistic residual stress profile can be utilized to predict the shot peening residual stress profile with a specified probability of appearance.

Effect of laser shock peening on elevated temperature residual stress, microstructure and fatigue behavior of ATI 718Plus alloy

Laser Shock Peening (LSP) is a mechanical surface treatment that induces large compressive residual stresses and microstructural changes in the material by using repetitive shocks from laser pulses. In this study, we investigate the use of LSP to improve the fatigue life of ATI 718 Plus (718Plus) at high temperature of 650°C. LSP led to severe surface plastic deformation, which, in turn, led to a high magnitude of surface compressive residual stresses and changes in the near-surface microstructure which caused high surface hardening. This change in the near-surface microstructure was in the form of high dislocation density forming dislocation entanglements and slip bands and formation of near-surface nanoscale sub-grains/crystallites that remained stable at elevated temperatures. In addition, LSP retained ∼−470MPa residual stress (68% of its initial residual stress) even after 140h exposure to 650°C. The retained residual stresses and the stable microstructure from the LSP increased the yield strength by ∼14% (∼140MPa) and endurance limit by ∼10% (∼90MPa) in corresponding tests at 650°C. This improvement in fatigue life was attributed to near-surface microstructure, hardening and high compressive residual stress. The estimated crack growth rates were 72% lower for LSP-treated 718Plus as compared with untreated material. The thermal-mechanical residual stress relaxation indicates the effectiveness of LSP in improving the fatigue life of 718Plus at 650°C.

Effect of Post-Curing Temperature and Mechanical Surface Treatment on Shear-Bond Strength of Asbestos-Free Brake Pad

Brake pad is the combination of lining and metallic components, e.g. steel backing plate (disc brake) and aluminum brake shoe (drum brake). Shear bond strength plays a major role to provide the safety and/or drive performances. This work aimed to study the processing factors affected the bonding strength. The molding temperature couple with post-curing temperature was simultaneously analyzed in order to optimize the processing temperature. The shear bond strengths of metallic plates were continually investigated with regard to the effect of different surface treatments. The obtained results indicated that the mechanical strength was increased as the molding temperature raised in ranges of 160°C to 180°C. Conversely, the deterioration of adhesive strength was progressively presented with rising post curing temperature. In comparing different backing plate, aluminum showed the higher shear bond strength than that of steel plate. In fact, the weakened property of aluminum in nature would be easily destroyed by mechanical treatments. From the shear tested results, an increase of surface roughness was inversely changed the shear bond strength. On the other hand, the contact angle of water droplet affected directly to adhesive strength. It was suggested that an adding surface roughness, commonly used in automotive industry, was inappropriate criteria, whist geometrical surface should be taken into account for improving the shear bond strength. Moreover, the contact angle and mechanical interlocking were recommended to use as a criteria of brake pad shear strength.

Surface texturing of rolling elements by hard ball-end milling and burnishing

Constant velocity joint shafts are machine elements within the driveshaft of cars. The tribological conditions within the raceways are characterized by mixed friction. To improve the lifetime of these machine elements, surface topography and surface integrity have to be adjusted. The positive effect of subsurface compressive residual stresses on the rolling fatigue strength for roller bearings is well known. Additionally, the positive effects of surface textures on tribological conditions in the mixed friction regime are known from cylinder liners. Within this paper, a novel approach to generate tribologically optimized surfaces by hard ball-end milling and an additional mechanical surface treatment by roller burnishing is tested and applied. First, the effects of both processes on the resulting surface topography are analyzed separately. In addition, the interactions between ball-end milling and burnishing are investigated. Concluding, this paper provides parameters to generate a plateau surface by the combination of ball-end milling and roller burnishing.

Uniaxial fatigue properties of closed die hot forged 42CrMo4 steel: Effect of flash and mechanical surface treatments

Uniaxial fatigue properties of 42CrMo4 steel, produced by closed die hot forging and then heat treated by conventional quenching and tempering treatment, are studied in the present work. The steel specimens underwent sand blasting. Successively, a set of samples was subjected to shot peening treatment, using 2 different intensities.Surface morphology and chemical composition as well as microstructure were investigated by scanning electron microscopy and stylus profilometry. Residual stresses were evaluated by X-ray Diffraction. The mechanical properties were studied by tensile tests and Vickers micro-hardness profiles. The fatigue limit was calculated with the Dixon Mood. In order to assess the causes of crack initiation, a simple model based on the local fatigue strength concept was adopted, considering the influence of residual stresses.The experimental findings showed that the surface treatments affect the fatigue properties. The crack nucleation site for the sand blasted specimens is close to the surface, while for the shot peened specimens the crack nucleation is linked to the activation of surface defects or to the presence of inclusions locally reducing the fatigue limit. The most probable crack nucleation region is in proximity of the flash.