Effect Of Ultrasonic Shot Peening Research Articles

Effect of ultrasonic shot peening on microstructure and mechanical properties of GH3230 superalloy during selective laser melt solution heat treatment

Additive manufacturing (AM) is widely used because of its well-known advantages, but there are some disadvantages including microstructure inconsistencies and harmful residual stresses, which can lead to premature part failure. In this study, the microstructure, and mechanical properties of GH3230 alloy processed by AM are changed by a new post-treatment method, which combines thermal solution treatment (ST) and ultrasonic shot peening (USP). The microstructure evolution of GH3230 after ST and USP after ST is investigated experimentally. The experimental results show that equiaxed crystals and M23C6 carbides appear after solution treatment. After ST, USP is performed, and the gradient microstructure is formed perpendicular to the shot peening surface. Dislocation entanglement and grain refinement occur in the plastically deformed layer. In addition, the carbide interacts with the dislocation. After ST, USP can produce a high level of residual compressive stress in the plastic deformation layer. This combination of ST and USP helps to improve the mechanical properties of additive manufactured parts by changing their microstructure and residual stress distribution.

Effect of ultrasonic shot peening and intermediate cerium salt conversion bath treatment controlling corrosion of Mg-Y-Zn-based alloy in salt water

Ultrasonic shot peening (USP) is often regarded as beneficial in mitigating corrosion of Mg alloys. However, increasing surface roughness induced by USP promotes localized corrosion pitting. Herein, we show that an intermediate phosphate bath treatment (CePT) before USP can minimize the surface roughness and ameliorate corrosion resistance of Mg-4.0Y-4.0Zn-0.5Zr-0.2Ca alloy (wt.%) in 0.1 M NaClsolution. In this regard, WZ44 alloy was subjected to Ce(NO3)3 + NaH2PO4bath treatment followed by USP for 30 s using AISI52100 steel balls and vice versa. The sub-surface features ofspecimens analyzed using XRD, FESEM, surface topography, and Vickers hardness reveal that CePT coating before USP increases microhardness (∼142–149 HV0.05 vs ∼ 125–135 HV0.05) and decreases surface roughness (Ra = 1.91–2.38 μm vs Ra = 2.58–2.76 μm). Potentiodynamic polarizationand electrochemical impedance spectroscopy demonstrate that corrosion current decreased (Icorr ∼ 9.81–13.69 µA/cm2 vs. ∼ 23.82–26.22 µA/cm2), coating (R1), and polarization resistance (R2) increased to ∼ 1704–1907 Ω.cm2,and ∼ 1834–1902 Ω.cm2, respectively,for specimens subjected to USP + CePT treatment together indicating superior corrosion resistance.Overall, an intermediate CePT before USP can effectively minimize corrosion pitting phenomena of WZ44 alloy in chlorinated solution by developing a ceramic coating interlocked with surface acting as a barrier between the metal/solution interface.

The effect of ultrasonic shot peening on micro-arc oxidation results of Ti-6Al-4V alloy

Micro-arc oxidation (MAO) is widely used in Ti‐6Al‐4V (TC4) alloy for surface modification and good biocompatibility in dental and orthopedic applications. However, it is a big challenge to produce thick MAO layers and nanoscale pores, both of which are crucial for biocompatibility. In this study, a new method called USMAO has been proposed, which involves performing USP as a pretreatment on the surface of TC4 before MAO. The results showed that USP could cause significant grain fragmentation and plastic deformation. After USMAO, composite architectures at the micron and nanoscale formed on the surfaces, and a thick MAO layer with a thickness of up to 30 µm could be also obtained, which was very useful for TC4 to enhance biocompatibility.

Effect of Ultrasonic Shot Peening and Laser Shock Peening on the Microstructure and Microhardness of IN738LC Alloys.

IN738LC is a conventional-cast Ni-based superalloy intended for power generation and aerospace applications. Typically, ultrasonic shot peening (USP) and laser shock peening (LSP) are utilized to enhance cracking, creep, and fatigue resistance. In this study, the optimal process parameters for USP and LSP were established by observing the microstructure and measuring the microhardness of the near-surface region of IN738LC alloys. The LSP impact region (modification depth) was approximately 2500 μm, which was much higher than the USP impact depth of 600 μm. The observation of the microstructural modification and resulting strengthening mechanism revealed that the build-up of dislocations upon peening with plastic deformation was crucial for alloy strengthening in both methods. In contrast, significant strengthening via γ' shearing was observed only in the USP-treated alloys.

Effect of ultrasonic shot peening on electrodeposited Ni and Cu coatings on Cu substrate

In this study, the effect of ultrasonic shot peening (USSP) on bilayered Ni and Cu coatings on Cu substrate was studied. On the Cu substrate, Ni and Cu coatings were sequentially electrodeposited followed by ultrasonic shot peening with a varying shot diameter and peening time. Apart from phase analysis and microscopy study of the coatings (before and after peening), hardness, compressive residual stress, wear, and corrosion resistances are also examined. Improvement of surface-mechanical properties and electrochemical properties were observed in specific peening conditions. There was also a noticeable improvement in residual compressive stress as an effect of peening.

Effect of Ultrasonic Shot Peening on Fatigue Crack Growth Behavior of Commercial-Purity Zr

Effect of Ultrasonic Shot Peening on Fatigue Crack Growth Behavior of Commercial-Purity Zr

Effect of Ultrasonic Shot Peening on the Microstructure, Surface Residual Stress, and Wear Properties of Ti-6al-4v Alloy

Effect of Ultrasonic Shot Peening on the Microstructure, Surface Residual Stress, and Wear Properties of Ti-6al-4v Alloy

Effect of Peening Process on Corrosion Fatigue Life for TiNi Shape Memory Alloy

The effect of ultrasonic shot peening on corrosion fatigue properties of a TiNi shape memory alloy was investigated. In this study, the surface condition of the peened specimens was optically observed and the arithmetic mean roughness of the specimen surface was measured. The main points of the results obtained in this study are as follows: (1) The surface roughness of as-peened specimen decreases with increasing the peening coverage because of smoothing effect by shot media. (2) Surface roughing derived from adhesion of Fe in the shot media was observed on the as-peened specimen, especially under high coverage conditions. (3) Mechanical polishing after the peening reduces the surface roughness to the level before peening. (4) No change was observed on the specimen surface even if the peened and then polished materials were heated to induce the reverse transformation.

Role of Ultrasonic Shot Peening in Environmental Hydrogen Embrittlement Behavior of 7075-T6 Alloy

The effect of ultrasonic shot peening on the environmental hydrogen embrittlement behavior of the 7075-T6 aluminum alloy is investigated. The 7075-T6 tensile specimens were treated by ultrasonic shot peening for 50 s. Surface residual stress and the depth of residual stress under the surface were evaluated using an X-ray diffractometer. Then, the specimens were tensile tested in humid air and dry nitrogen gas by the slow strain rate technique. The results showed that the ultrasonic shot-peened specimen has a superior hydrogen embrittlement resistance. Further, the ultrasonic shot peening changes the fracture mode from an intergranular fracture mode to the transgranular one. It was suggested that ultrasonic shot-peening has two effects on hydrogen embrittlement behavior; the distribution of hydrogen inside the surface layer by introducing dislocations/vacancies as hydrogen traps and reducing the normalized amount of hydrogen trapped per unit length of the grain boundary.

Effect of ultrasonic shot peening on surface integrity and fatigue performance of single-crystal superalloy

• Ultrasonic shot peening applied to improve fatigue performance of single crystal alloys. • Notch fatigue limit after peening increased to higher than the oringinal smooth fatigue limit. • Three anti-fatigue mechanisms: (1) machining marks elimination; (2) surface nanoscale sub-crystalline structure; (3) deformation promotion of casting micro-pores. We investigated the effect of ultrasonic shot peening on the surface integrity and fatigue properties of single-crystal superalloys. The results show that ultrasonic shot peening significantly reduces the surface roughness of single-crystal specimens and improves surface finishing. The surface hardness increases by 49 %, reaching more than HV660. At the same time, the microstructural analysis illustrates that the single-crystal surface layer after ultrasonic shot peening forms a nanoscale refined sub-crystalline structure that rotates along the [110] axis. It significantly improves the mechanical properties of the surface metal. The originally existing round casting micro-pores are elongated along the [001] axis, forming a willow shape - elliptical shapes from the surface inward, reducing the stress concentration of the casting micro-pores perpendicular to the [001] axis. Combining the above three modification effects, the fatigue limit of the single-crystal notched Kt = 3 sample at 650 ℃ strengthened by ultrasonic shot peening is 94.2 % higher than that of the as-received notched sample, and 17.4 % higher than that of the smooth sample.

Effect of ultrasonic shot peening on microstructure evolution and corrosion resistance of selective laser melted Ti–6Al–4V alloy

The ultrasonic shot peening (USP) treatment was adopted to improve the compressive residual stress, microhardness and corrosion resistance of Ti–6Al–4V (TC4) titanium alloy fabricated by selective laser melting (SLM). The optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD) and hardness test were used to investigate the microstructure evolution. The effect of the USP on electrochemical behaviour of the SLM TC4 alloy in a 3.5 wt. % NaCl solution was studied using potentiodynamic polarization. After USP treatment, compressive residual stress was induced and microhardness significantly increased. Proper USP treatment can effectively improve corrosion resistance of the SLM TC4 alloy, which is manifested by the increase in corrosion potential and decrease in corrosion current density.

The effect of ultrasonic shot peening on the fatigue life of alloy materials: a review

The effect of ultrasonic shot peening on the fatigue life of alloy materials: a review

The effect of ultrasonic shot peening on the fatigue life of alloy materials: a review

It is more and more widespread to introduce nano-structured grains on the surface of alloys to improve their strength. One of the technologies to achieve this is the ultrasonic shot peening (USP) technique, which has attracted special attention. With this technology, uniform nano-structured grains can be formed on the surface and compressive residual stress can be developed that can improve the fatigue life. However, pits will be formed during the USP process, which will cause stress concentration and lower the fatigue life. This paper reviews the effects of USP processing parameters on the evolution of the surface morphology, microstructure and residual stress. A finite element simulation based on the velocity model was established to simulate the impact of the USP processing on the fatigue performance.

Effect of Ultrasonic Shot Peening on the Microstructure of Austenitic Stainless Steel 316 and Super Duplex Stainless Steel UNS S32750.

Shot peening for nanocrystallization of the surface region is a good way of improving corrosion-, fatigue-, and wear-resistance, etc. of metallic parts (Lu, K., 2014. Making strong nanomaterials ductile with gradients. Science, 345(6203), pp.1455-1456). The technique has been widely used for various materials as a method of surface modification. SUS316 has excellent corrosion and oxidation resistance with good formability However, its application is limited by the low mechanical strength and hardness. S32750 (duplex stainless steel) is one of most used tubing materials for oil/gas delivery systems in a corrosive environment under high pressure (Nilsson, J.O., 1992. Super duplex stainless steels. Materials Science and Technology, 8(8), pp.685-700). Thus, improving corrosion resistance is a key for the wider application and better maintenance of S32750. In our study, the alloy S32750 was heat-treated at 1070°C to obtain a precipitation-free microstructure (γ and δ dual-phase structure). It was then ultrasonic shot peened and microstructures were analyzed for: (1) surface nanocrystallization, (2) effect of the treatment processing parameters, and (3) the determination of microstructural evolution and the effect of the shot peening process.

Effect of Ultrasonic Shot Peening on Oxidation Behavior of T91 and SS347 Steels in Air and Steam at 650 °C

Ultrasonic shot peening (USP) is a relatively new process of surface modification to improve mechanical properties as well as corrosion and high-temperature oxidation resistance of metallic materials. The effect of USP on surface properties and the process of high-temperature oxidation in air and steam environment, following USP of the T91 and SS347 steels, was studied in this investigation. Surface modification by USP was done on the T91 and SS347 steels for different time periods of 0.5, 1.0, 1.5, 2.0 and 3.0 min. Microstructural modification, increase in surface roughness and enhancement in microhardness up to a depth of 300-350 µm were observed due to USP. There was also increment in surface roughness as well as microhardness with USP time duration. Thermogravimetric analysis of the oxidation tests showed parabolic oxidation kinetics at 650 °C for both the steels. Comparatively more protective oxide scales, containing high amount of Cr, were formed on the USP-treated samples. The thickness of the oxide scale was reduced with increase in the USP time duration. Oxidation resistance of the T91 steel at 650 °C, both in air and steam, was improved by the USP treatment. Oxidation resistance of the SS347 steel at 650 °C was also improved for the USP2.0 and the USP3.0 conditions.

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 ultrasonic shot peening on the surface defects of thin struts built by electron beam melting: Consequences on fatigue resistance

Ti-6Al-4V thin struts, built by selective electron beam melting have been submitted to hot isostatic pressing and further processed with ultrasonic shot peening to investigate the effect of this surface treatment on surface defects. The consequence of those surface defects on the fatigue resistance of thin struts has been evaluated before and after treatment. X-ray microtomography has been used to track the defect population with repeated scans before and after ultrasonic shot peening as well as after fatigue tests conducted to failure. Our results show that the fatigue resistance of surface-treated struts (measured at 105 cycles) is doubled compared to the fatigue resistance of struts with an as-built surface. This enhancement in fatigue resistance is attributed to a refinement of the sub-surface microstructure, to the introduction of local compressive residual stresses and to a significant surface smoothing effect induced by ultrasonic shot peening. Ultrasonic shot peening fails to “heal” the most tortuous surface defects observed in the as-built condition, leaving residual defects in the sub-surface region. The presence of those residual surface defects limits the fatigue resistance when compared to struts with a machined surface.

Assessment of Residual Stresses in ITER CS Helium Inlet Welds Fatigue Tested at Cryogenic Temperature

The ITER Central Solenoid (CS) consists of six independent wound modules. The cooling of the cable-in-conduit conductor is assured by a forced flow of supercritical He at 4.5 K supplied by He inlets located at the innermost radius of the coil. The inlets consist of a racetrack-shaped boss welded to the outer conduit wall through a full penetration Tungsten Inert Gas (TIG) weld. They are critical structural elements submitted to severe cyclic stresses due to the electro-magnetic forces acting on the coils. The weld contour is shape-optimised and locally processed by Ultrasonic Shot Peening (USP), conferring large compressive residual stresses on a subsurface layer of several millimetres thickness to improve fatigue strength. The distribution of the residual stresses and the effect of USP on microstructure and mechanical properties is assessed, with reference to the results of a cryogenic fatigue test campaign, performed on peened and as-welded inlets for comparison.

Surface Nanocrystallization Induced by Ultrasonic Shot Peening and Its Effect on Corrosion Resistance of Ti–6Al–4V Alloy

Alloy Ti–6Al–4V was subjected to ultrasonic shot peening (USP) for 1 min (min) and 5 min to examine the effect of surface nanostructure on corrosion resistance of this alloy in simulated body fluid (SBF). USPed samples were also subjected to stress relieving (SR) treatment at 400 °C for 1 h in the argon atmosphere (AR). The surface nanostructure and constituted phases were characterized by TEM, and the effect of USP was examined on electrochemical corrosion resistance in SBF solution. It has been observed that corrosion resistance is enhanced due to USP. The development of the resistance to corrosion is attributed to the quick formation of protective oxide scale due to extensive increase in number of grain boundaries and the associated compressive residual stress induced by USP. The relatively lower corrosion resistance and higher tendency of pitting following SR treatment of the USPed specimens are due to decreasing the associated residual stress.

Optimization of USSP duration for enhanced corrosion resistance of AA7075

This investigation was carried out following our earlier work on the effect of ultrasonic shot peening (USSP) on corrosion resistance of the 7075 aluminium alloy in 3.5 wt% NaCl solution to optimize the duration of USSP. The samples not treated with USSP and different samples treated with USSP were subjected to potentiodynamic polarization and electrochemical impedance spectroscopy. Among the specimens USSP treated from 5 to 30 s, the one USSP treated for 15 s (USSP 15) was found to exhibit highest corrosion potential (Ecorr) and lowest corrosion current density (icorr). Corrosion products were characterized by Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). Scanning Kelvin Probe Force Microscopy (SKPFM) was used to measure the surface free potential. The enhanced corrosion resistance of the USSP 15 sample was found to be due to combined effect of surface nanostructure of the matrix, homogeneity and refinement of second phase precipitates. There was enhancement in formation of adherent passive layer in the USSP15 specimen.