Effect Of Shot Peening Research Articles

Tribological behavior of shot peened/austempered AISI 5160 steel

In order to enhance component performance, material sustainability, and service life, this study presents the tribological behavior of different austempered AISI 5160 steel specimens with shot peening. All the specimens were austempered for 2 h, then followed by shot peening to study the effect of shot peening and bainite morphologies on the wear and friction behavior. The microstructures, hardness, and residual stress of specimens were studied by optical microscopy, scanning electron microscopy, Vickers micro-hardness, 3D-profiler, and X-ray diffraction. Shot peening produced higher hardness on soft austempered specimens, rather than on hard austempered specimens. Compared with non-shot peened austempered disk specimens, the wear reduction of disk specimens with shot peening is up to 73%.

Fatigue Limit of Custom 465 with Surface Strengthening Treatment.

In order to study the effect of nitriding or shot peening on the surface modification and fatigue properties of martensitic stainless-steel Custom 465, the residual stress and micro-hardness of the strengthened layer are determined by X-ray and micro-hardness tester, respectively. The up-and-down method is used to measure the rotational bending fatigue strength at 1 × 107 cycles, and the fatigue fracture characteristic is observed by scanning electron microscopy. The relationship between surface residual stress and internal fatigue limit of surface strengthening treatment is discussed. Results show that nitriding or shot peening surface strengthening layer forms a certain depth of compressive residual stress, where in the surface compressive residual stress of the nitrided specimens is greater than the shot peened specimens. The micro-hardness of the nitrided or shot peened surface strengthening layer is significantly improved, where in the surface micro-hardness of nitriding specimens are higher than shot peening specimens. The nitriding or shot peening surface strengthening can significantly improve the fatigue limit of Custom 465, wherein the fatigue limits of nitrided and shot peened surface strengthened specimens are 50.09% and 50.66% higher than that of the un-surface strengthened specimens, respectively. That is, the effect of the two strengthening methods on fatigue limit is not very different. The fracture characteristics show that the fatigue crack of the un-surface strengthened specimens originates from the surface, while the fatigue crack of surface strengthened specimens originates from the subsurface layer under the strengthened layer. The relationship between the internal fatigue limit and the surface residual stress of the surface strengthened specimen can be used as a method for predicting the fatigue limit of the surface strengthened specimens.

Effect of ultrasonic shot peening on strain controlled fatigue behaviour of low nickel austenitic stainless steel

In the present investigation effect of Ultrasonic shot peening (USP) treatment on strain controlled fatigue behavior of low nickel austenitic stainless steel (Low Ni ASS) was studied at room temperature. The gauge section of fatigue samples were USPed with 2 mm diameter hard steel shots for 3 min. Microstructural characterization of the USP treated samples were carried out using XRD, SEM and TEM techniques. Refinement of grains in the surface region was observed and grain size was found to be ≈17 nm from quantitative analysis of XRD patterns. Strain controlled fatigue tests were carried out at different total strain amplitudes (Δεt/2) ranging from ±0.4% to ±0.8%. Fatigue life was increased significantly by 200% at lowest Δεt/2 of ±0.4% whereas it was reduced at highest Δεt/2 of ±0.8% by 50%. Fracture surfaces were characterized using SEM.

Effect of Shot Peening Operation on the Microstructure and Wear Behavior of AZ31 Magnesium Alloy

Shot peening is a treatment used to increase surface hardness and wear resistance. In this study, the effect of shot peening on the microstructure, hardness and wear resistance of AZ31 magnesium alloy was investigated. For this purpose, specimens were exposed to shot peening operation using steel pellets for periods of 20, 40, 60, and 80 min. Microstructures were investigated using a scanning electron microscope (SEM) and X-Ray diffraction (XRD). In addition, the Vickers method and the pin on disk method were used to measure the hardness and wear for testing, respectively. The results showed that the shot peening operation resulted in grain refining on the surface, in addition, the wear resistance increased with increasing shot peening time. This is because of grain refining on the surface and the micro strains created by shot peening. Assessment of surface wearing indicated the application of an adhesive wear mechanism on the untreated specimen and the abrasive wear mechanism in the shot peened specimens. Moreover, by increasing the duration of shot peening, the abrasive wear decreased due to increased hardness.

Effect of shot peening on surface properties of Al7075 hybrid aluminum metal matrix composites

Various fields of engineering such as automobile, aerospace and construction industries are employs Aluminum alloys and its composites due to its high strength to weight ratio. But they possess poor wear resistance due to low hardness. In this research, shot peening treatment is used to enhance the wear resistance ability of the composites. Micro hardness and surface roughness of AL7075 Hybrid metal matrix composites are examined after shot peening treatment. For this, the aluminum alloy specimens are subjected to shot peening for 30, 60, 90, 120 and 150 s time. The results reveal that the shot peening treatment increases micro -hardness and surface roughness up to 90 s. The specimen after 120 s peening demonstrates the marginal improvement in micro hardness and slight reduction in surface roughness.

Evaluation of Mechanical Behavior and Surface Morphology of Shot-Peened Ti-6Al-4V Alloy

The effects of shot peening (SP) on mechanical behavior and surface morphology of Ti-6Al-4V were investigated in detail. After SP, the uniformity of compressive residual stress (CRS) was analyzed. The CRS decreased as SP intensity increased because of the severe impact of shots. The CRS was enhanced from − 762.7 to − 795.5 MPa with an increase in SP intensity. The fatigue life was increased from 0.46 × 106 cycles to 8.10 × 106 cycles after SP when the loading amplitude was 610 MPa. This increase was mainly attributed to the enhancement of the crack initiation hindering and propagation by the high CRS and refined domain sizes. The results of surface morphology showed that the convexity and concave regions were generated after SP and the improvement in SP intensity aggravated the increase in roughness. Although the roughness increased after SP, it did not hinder the enhancement of fatigue lives, indicating that CRS played a leading role in the improvement in fatigue lives. Thus, the analysis and discussion revealed that SP was beneficial for the improvement of the surface mechanical behavior of titanium alloys.

Excessive coverage effect (over peening) in the blasting operation of aluminum alloy “AA 7475-T7351” with steel shot

ABSTRACT Aluminum and its alloys are widely used in the aeronautics industry due to its high lightness and ductility, and it can add other elements, thus changing its characteristics. Fatigue is the major cause of failure of metal materials due to the dynamic and oscillating stresses of the finished materials. The objective of this work is to evaluate the effect of Shot Peening with coverage percentages 1blasting, 3 blasting and 10 blasting in fatigue life of aluminum alloy AA 7475-T351. Shot Peening is a cold surface treatment used to increase fatigue life of the alloy by inducing residual stresses of compression on the surface of the part. In the Shot Peening process, spherical steel grids of type S230 were used, in which the specimens were subjected to 1blasting, 3 blasting and 10 blasting coverage in two stress levels (42 Ksi and 50 Ksi). The results presented in the fatigue tests and electron scanning (SEM) showed the increase in the mechanical properties of all the samples, and those exposed to 1 blasting and 3 blasting presented better results.

Optimization of shot peening for titanium alloys Ti 10-2-3 in CONDOR project

CONDOR is an R&D project lead by IRT-M2P with different industrial partnership to increase knowledge and simulation models of shot peening. This surface hardening process aims to perform different shots with high velocity on metallic surfaces to introduce compressive stresses on it. Fatigue behavior of shot peened parts is significantly improved. During this research project a DOE has been carried out to optimize shot peening parameters on titanium alloys (surface roughness before shot peening, size and shot’s hardness, covering and intensity). The DoE is composed by more than 300 fatigue specimens. All this data allows us to define specifically each shot peening parameter influence on shot penned parts efficiency. CONDOR project allows simulation development of models to simulate shot peening effect by taking into account the parameters introduced above. Those models are used to evaluate residual stress level and fatigue lifetime after shot peening and to confirm models readiness level. This study has defined optimized machining and shot peening conditions in order to increase parts fatigue lifetime.

Analysis of the Influence of High Peening Coverage on Almen Intensity and Residual Compressive Stress

The effectiveness of shot peening is mainly determined by the peening coverage. The peening coverage is required to be 100% for current technical standards of shot peening. With the increase of material strength, higher peening coverage is required in shot peening process. However, the influence of high peening coverage on Almen intensity and residual compressive stress is unclear, the difficulty mainly lies in the lack of quantitative description of peening coverage in finite element analysis. To analyze the influence of high peening coverage on Almen intensity and residual compressive stress, firstly an approximate quantitative description of peening coverage based on dent size, the distance of shots and shot numbers is proposed in this study. Based on this quantitative description of peening coverage, the arc height and residual stress of the Almen test are simulated with the finite element method. The simulation results of arc height and saturation curve agree well with that of the Almen test, by which the effectiveness of the quantitative description and FE simulation are proved. The further study indicates that in shot peening processes, the excessive peening coverage doesn’t improve Almen intensity and residual compressive stress.

The Effect of Shot Peening on Steam Oxidation of 304H Stainless Steel

Shot peening is currently utilized in coal-fired power plant components to mitigate scale exfoliation issues from steamside oxidation of austenitic stainless steel superheater and reheater tubing. To focus on commercially available material, this study exposed quarter-ring specimens cut from two different commercially shot peened type 304H tubes and exposed to 1 bar steam for up to 15,000 h at 550°, 600°, 625°, and 650 °C. Specimens were removed at increments to characterize the oxide thickness and microstructure. The shot peened inner surface generally retained a thin, protective Cr-rich scale with occasional Fe-rich oxide nodules at 550–625 °C. The increased oxidation resistance from shot peening began to degrade at 650 °C after as little as 5,000 h. Cut and polished faces of these specimens formed thick, Fe-rich oxides similar to polished 304H coupons. Surprisingly, the mechanically machined outer surface of the tube specimens performed similarly to the shot peened inner diameter, suggesting it had sufficient cold work to achieve a similar benefit. Electron backscatter diffraction and Vickers-hardness measurements were used to characterize post-exposure changes in underlying microstructure and mechanical properties, respectively, imparted by shot peening.

Effect of Shot Peening on the Mechanical Properties and Cytotoxicity Behaviour of Titanium Implants Produced by 3D Printing Technology.

Structural discontinuities characterize the implants produced directly from metal powders in 3D printing technology. Mainly, the surface defects should be subjected to procedures associated with surface layer modification (likewise shot peening) resulting in the increase of the implant service life maintaining optimal biocompatibility. Therefore, the purpose of the present study was to investigate the effect of type of shot used for the peening process on the Ti-6Al-4V implants functional properties as well as the biological properties. The components were produced by DMLS (direct metal laser sintering) additive technology. The surfaces of titanium specimens have been subjected to the shot peening process by means of three different shots, i.e., CrNi steel shot, crushed nut shells, and ceramic balls shot. Then, the specimens have been subjected to profilometric analysis, microhardness tests, and static strength testing as well as to the assessment of biocompatibility in respect of cytotoxicity using human BJ fibroblasts. The shot peening process causes the strengthening of surface layer and the increase of strength parameters. Furthermore, the test results indicate good biocompatibility of surfaces being tested, and the effect of shot peening process on the titanium alloy cytotoxicity is acceptable. At the same time, most favourable behaviour in respect of cytotoxicity has been found in the case of surfaces modified by means of ceramic balls > nut shells > CrNi steel shot correspondingly.

Effectiveness of Ultrasonic Shot Peening on Stainless Cast Steel SCS6 Containing a Fatigue Crack

Effectiveness of Ultrasonic Shot Peening on Stainless Cast Steel SCS6 Containing a Fatigue Crack

Design and Fatigue Analysis of Shot Peened Leaf Spring

The paper handles the fatigue and failing analysis of serial shot-peened leaf springs of cumbersome vehicles emphasizing on the impact of shot peening on fatigue life, coping with automotive leaf springs, the shot peening method turns into an important step in production.In the situation of leaf spring suspensions, however, asystematic research of the effect of shot peening about fatigue life isstill required. Experimental stress-life curves are determined with the aid of the usage of investigating clean specimen subjected to shot peening. those test consequences are as compared to corresponding ones identified from cyclic three-point test on shot peened serial leaf springs in order to show the influence of applied heat treatment and shot peening approach on fatigue existence of high-strength used to get leaf spring manufacturing, reliant on the load level. Analyses are performed to explain the effects resulting from shot peening practice on the surface features of the high-strength spring steel under examination. The evaluation of fatigue results shows that almost no life improvement due to production highlighting the importance for mutual variation in parameters of shot peening and thermal treatment so that there is sufficient progress in life

Corrosion Resistance of 316L Biomaterial in Simulated Body Fluid by Modification of Shot Distance and Shot Angle of Shot Peening

Corrosion resistance of 316L biomaterial can be improved by mechanical surface treatment such as shot peening. Shot peening can create plastic deformation as a nanocrystal surface layer on the metal surface to protect the material from corrosion attack. This study aims to investigate the effect of shot peening on the corrosion resistance of 316L to reach the best rate of corrosion. The shot peening parameters in this research are shot distance (6, 8, 10, and 12 cm), shot angle (30, 60, and 90°), compressor pressure (7 kg/cm2), shot duration (20 minutes), and steel balls S-170 (diameter of 0.6 mm). Simulated Body Fluid (SBF) was used as a corrosion media with ion concentrations nearly equal to human blood plasma. Corrosion tests were used versaSTAT, and the data were analyzed by VersaStudio. The result shows that the shot peening can decrease the corrosion rate of the 316L biomaterial. The larger the shot angle, the lower the corrosion rate and the nearer the shot distance, the lower the corrosion rate. The nearest shot distance (6 cm) and the largest shot angle (90°) give the best result to decrease the corrosion rate from 0.8617 mpy to 0.1096 mpy.

Softening Effects Induced by Shot Peening for an Aluminum-Lithium Alloy

The effects of shot peening on the mechanical properties of a 2060 Al-Li alloy were investigated through tensile tests and microhardness tests on longitudinal sections of the specimens. Moreover, the microstructural evolution of the rolled (non-shot-peened) and shot-peened specimens was analyzed. Experimental results indicated that the phenomenon of work softening occurred due to shot peening. Therefore, the tensile strength, yield strength, and microhardness decreased, while the total elongation increased. Furthermore, microstructural analysis showed that softening effects were primarily ascribable to the partial dynamic recrystallization and textural transition from β to α fiber textures. These resulted from simultaneous influences of heat effect and plastic deformation during the shot peening process. Consequently, the dislocation density decreased while the weighted average of the Schmid factor increased, making the deformation easier and the material softened. As a result, the 2060 Al-Li alloy was softened by the relatively high-intensity shot peening, and an empirical equation was proposed to embody the comprehensive effects of the grain size and orientation on the mechanical properties of Al-Li alloys.

Influence of severe double shot peening on microstructure properties of Ti 6Al-4V and Titanium Grade 2 dissimilar joints using laser beam welding

The present investigation deals with the effect of Severe Double Shot Peening (SDSP) of Peening pre-weldment and Post peening weldment on microstructure properties of Ti 6Al-4V and Titanium Grade 2 dissimilar joint made by laser beam welding. Laser beam welding was performed for butt joint configuration. Full depth of penetration was obtained for the laser beam of 1200 W, welding speeds of 250 mm/min and focus distance of 8 mm configuration. Microstructure studies at weld zone and heat affected zone revealed the presence of more amounts of α martensite and B phases. Tensile study displayed that all the failures occurred at the weld zone in both Peening pre-weldment and Post peening weldment of SDSP. X-rays Diffraction analysis showed the slight presence of residual stress in the Post peening weldment of SDSP. Average hardness value of both dissimilar material reached 285 HV. While comparing the hardness at heat affected zone and welded zone, the hardness of welded zone gradually decreased owing to the failure of conversion of α phase into β1/β2 phase. SEM image exhibited the depth of Peening pre-weldment and Post peening weldment weldments of 8 µm and 10 µm respectively which led to the enhancement of hardness value. Further, the coarse grain boundaries, O-phases and α/α′ phases were observed in the heat affected zone. Fracture morphology of tensile samples revealed the inner minor cracks and voids at fusion zone. Moreover, the formation of Cr2N and CrN was not observed in both welded and heat affected zone that improved the better tensile and bending strength.

Effect of shot peening on short crack propagation in 300M steel

The short crack growth behaviour of high strength martensitic 300M steel was studied for as-machined, polished and 2 peening conditions subjected to axial fatigue at 2 stress amplitudes. It was observed that prior austenite grain boundaries acted as barriers to short crack propagation in peened specimens within the peening induced compressive residual stress layer, causing crack decelerations upto 6 grains. Using the da/dN-ΔK trend of the short cracks, fatigue lives of the peened specimens were predicted at both the stress amplitudes. These analytical predictions (which reflect the effect of microstructure and compressive residual stresses) were within 15% of the experimental fatigue lives.

Effects of laser shock processing and shot peening on 253 MA austenitic stainless steel and their consequences on fatigue properties

A comparative study of the influence of laser shock peening without coating (LSPwC) and shot peening (SP) treatments on the low cycle fatigue life of 253 MA austenitic stainless steel was investigated. LSPwC treatments were performed with 2500 pulse/cm2 and 5000 pulse/cm2. To evaluate the effects of each treatment, residual stress, roughness, hardness, and microstructure were analyzed. It is of particular interest the correlation of the fatigue performance with the dislocation microstructure evolution. The results reveal that all the surface treatments increase the surface hardness, induce compressive residual stresses (CRS) and a high density of mechanical twins and dislocations. The stability of the workhardened near surface microstructure results in the improvement of the fatigue life of peened 253 MA. Moreover, the best improvement of fatigue life reached for SP is mainly due to the highest number of twins and the more superficial CRS.

Surface layer microstructures and wear properties modifications of Mg-8Gd-3Y alloy treated by shot peening

Shot peening effects on the microstructure, residual stress and wear properties of Mg-8Gd-3Y alloy were systematically studied. The results showed that the grain sizes were greatly refined and high-level dislocations were induced in the deformation layer. The grain size decreased with increasing the peening intensity, and nanograins were obtained when the peening intensity reached 0.46 mmN. The formation of nanograins was mainly attributed to the activity of dislocations and occurrence of dynamic rotation recrystallization. In parallel, compressive residual stress was developed in the deformation layer, the maximum magnitude of which reached −174 MPa under the peening intensity of 0.46 mmN. Additionally, owing to the modification of microstructures and the introduction of compressive residual stress after shot peening, the microhardness and wear resistance of Mg-8Gd-3Y alloy were promoted prominently. In comparison with the untreated counterpart, the average wear volumes of the peened ones were decreased by 9.47%, 36.26% and 40.70% corresponding to 0.13, 0.23, 0.46 mmN, respectively. Therefore, it is concluded that SP can be considered as a promising technology to improve the surface microstructures and wear properties of Mg-8Gd-3Y alloy.

Shot peening effects on corrosion behavior of commercial pure titanium in body simulating solution

In this study, the effect of shot peening on the corrosion behavior and the microstructure of commercial pure titanium was studied. The experiments including measuring the compressive residual stresses created by shot peening using steel balls (0.3 mm in diameter) and the durations of 20 and 60 s as well as the intensities of 0.8 and 0.1 mm Almen, and the electrochemical corrosion tests after 1, 4, and 7 days of immersion were carried out. The studies performed showed that, with an increase in the shot peening duration and the shot peening intensity or both, the compressive residual stress increased at the sample surface. The highest amount of residual stresses was in the T3 sample, which exhibited the lowest depth, as well. The results of the electrochemical impedance spectroscopy of the original (non-shot-peened sample) sample and the shot-peened samples after 1, 4 and 7 days of immersion in the Ringer’s body simulator solution showed that the samples with the highest intensity or the longest shot peening duration showed better corrosion behavior compared with that of other parameters and the original sample. As the immersion time increased, the impedance values increased and as a result, the electrochemical behavior of the samples improved. The polarization tests after seven days of immersion in Ringer’s solution showed that the potential of the shot-peened samples was more positive. Also, the lowest corrosion current density was obtained in the T3 sample with the highest compressive residual stress.