Effect Of Ultrasonic Peening Treatment Research Articles

Effect of ultrasonic peening treatment on the fatigue behaviors of a magnesium alloy up to very high cycle regime

• Complete change of crack initiation site. • Quantitative evaluation of grain-boundary retarding effect. • Crack type affects the formation of FGA. Ultrasonic fatigue tests are performed on a magnesium alloy with and without ultrasonic peening treatment (UPT). Surface enhancement layer leads to the complete change of crack initiation sites. However, crack initiation mechanism keeps the same and results in a single-faceted morphology at crack initiation site. Microcracks initiate as Mode II crack within the original grain, but deflect to Mode I crack outside of the original cracked grain. A threshold SIF value is proposed to evaluate the retarding effect of grain boundary on microcrack propagation. Outside of the original cracked grain, Mode I crack propagation below the threshold ΔK σ-th is responsible for the formation of fine granular area (FGA, a nano-grain layer). Based on the Numerous Cyclic Pressing (NCP) model, it is proposed that crack type should be another necessary condition for the formation of FGA.

Effect of ultrasonic peening treatment on microstructure and properties of CMT additive-manufactured Ti6Al4V/Al6.21Cu dissimilar alloys with Nb interlayer

The layer-by-layer ultrasonic peening treatment (UPT) was utilized to refine the coarse microstructure and decrease the pore number and size in the Al alloy of the Ti6Al4V/Al6.21Cu bimetallic structure with Nb interlayer manufactured by cold metal transfer additive manufacturing. After UPT, the pore in the deposited Al layer was compressed. Grains were compressed and refined significantly in the transition layer under the effect of UPT. The Nb interlayer still acted as the diffusion barrier and impeded the formation of harmful Ti-Al intermetallic compounds after UPT. The mean ultimate tensile strength of the bimetallic structure with Nb interlayer after UPT was 164.5 MPa, and increased by 36.1% compared to that of the bimetallic structure without UPT. The fracture occurred at brittle Al3Nb reaction layer for all samples.

Effects of ultrasonic peening treatment layer by layer on microstructure of components fabricated by wire and arc additive manufacturing

To improve the coarse grains of Al alloy, the ultrasonic peening treatment layer by layer was used during wire and arc additive manufacturing process of Al alloy. The severe deformation layer of last deposited layer was remelted when a new layer was deposited. In an Al alloy component, the matrix and transition layer were formed alternately. The pore was compressed under the effect of ultrasonic peening treatment, which led to a decrease of pore diameter. The equiaxed grain area was formed due to the anisotropy in grain growth and the increase of nucleation particles. In equiaxed grain area, the grains with a diameter of 200–400 nm, dislocation wall and dislocation tangle were formed.

Effects of ultrasonic peening treatment in three directions on grain refinement and anisotropy of cold metal transfer additive manufactured Ti-6Al-4V thin wall structure

In the cold metal transfer additive manufacturing process of Ti-6Al-4V thin wall structure, ultrasonic peening treatment (UPT) in three directions is proposed to refine the large columnar prior-β grains and secondary α grains, and to improve anisotropy in tensile properties. The experimental results showed that UPT in three directions applied to each weld right after arc extinguishing has a minor influence on the surface appearance, which shows no apparent plastic deformation, but has a great improvement in grain refinement. The changes in microstructure and dislocations of thin wall structure treated by UPT in three directions were observed. By comparing with those without UPT, the main causes for refinement of columnar prior-β and secondary α grains was explored, namely mechanical effects of ultrasonic at the temperature range of α’ dissolution temperature Tdiss – liquidus temperature Tl. Specimens with UPT have better properties, higher loads with the same indentation displacement in nano-indentation tests, an increase in ultimate tensile strength and a reduction in anisotropic percentage in tensile tests.

Effect of Ultrasonic Peening Treatment on VHCF Behavior of Friction Stir Welded Joints in Aluminum Alloys

Studying the mechanical properties of aluminum alloy 6061 friction stir welded (FSW) joints after ultrasonic peening treatment (UPT) under very high cycle fatigue (VHCF) loading. The effect of joints ultrasonic peening treatment was explored. It can be seen from the results that the ultrasonic peening treatment can form a reinforced layer on the surface of joints, and the fatigue crack source is transferred from the surface of the specimen to the inside. However, the change of fatigue crack initiation site does not improve the fatigue strength of specimen through ultrasonic peening treatment. The fatigue strength of the aluminum alloy 6061 joint after ultrasonic peening treatment is even lower than as a received condition. The characteristics of fatigue crack initiation and the mechanism of surface strengthened layer on fatigue strength were analyzed and discussed.

Ultrasonic Peening Treatment Used to Improve Stress Corrosion Resistance of AlSi10Mg Components Fabricated Using Selective Laser Melting

As a rapidly evolving advanced digital manufacturing technology, additive manufacturing (AM) has its advantages including short manufacturing cycle, material saving, and complexity for free. It has great potential for application in marine and offshore engineering. However, stress corrosion damage will be a big threat for the additively manufactured metal parts in the ocean environment due to large residual stresses generated in the building process. This paper focuses on the effect of ultrasonic peening treatment (UPT) on stress corrosion resistance of AlSi10Mg components fabricated using Selective Laser Melting (SLM). Firstly, AlSi10Mg specimens were prepared using an SLM machine, and UPT was conducted on the specimen’s top surface. Then, a series of measurements and analyses were carried out for the specimens before and after the UPT process. The residual stresses and hardness of the specimens were measured, and the surface morphology was observed using a scanning electron microscope (SEM). The resistance of stress corrosion was evaluated by the electrochemical corrosion test. The experimental results show that UPT can significantly improve stress corrosion resistance of SLM-fabricated specimens.

Effects of ultrasonic peening treatment on surface quality of CMT-welds of Al alloys

The porosity number and porosity area percentage of weld beads close to the weld surface reduce after ultrasonic peening treatment. The grains are refined significantly in severe deformation layer and transition layer. The refined grain size is approximately 200nm on the surface of weld bead after ultrasonic peening treatment. The loads on severe deformation layer and transition layer are larger than those on weld beads without ultrasonic peening treatment with the same indentation displacement in nano-indentation tests. After ultrasonic peening treatment, the elastic modulus of the weld bead surface increases slightly due to the decrease of porosity fraction. The hardness values of severe deformation layer and transition layer increase, which leads to the enhancement of wear resistance of welded joints.

Application of ultrasonic peening during DMLS production of 316L stainless steel and its effect on material behavior

PurposeAdditive manufacturing (AM) processes involve a layer-by-layer sintering of metallic powders to produce fully functional three-dimensional parts. This layer-by-layer building process provides a unique opportunity to enhance mechanical properties by applying treatments that previously were possible only on the surface in traditional manufacturing techniques. The purpose of the study is to examine the effect of ultrasonic peening (UP) applied during a layer-by-layer direct metal laser sintering (DMLS) fabrication of 316L stainless steel on its mechanical properties and microstructure.Design/methodology/approachUniaxial tensile tests were performed at 1.27 mm/s to determine the effect of UP treatment on the average global behavior of a 316L part, whereas hardness measurements using nanoindentation were performed to determine the modification of local mechanical properties. Compressive buckling tests at a loading rate of 3 mm/min were performed on sample coupons with a large aspect ratio to evaluate the effect of UP on any potential delamination of DMLS layers. Techniques such as optical and scanning electron microscopy (SEM) imaging were utilized to determine the effect of UP on the microstructure.FindingsOverall, significant modification in mechanical properties such as hardness and yield strength, along with microstructure, was observed. Large increases in both the average global and local mechanical properties, as well as a disruption in the columnar grain microstructure, was observed in DMLS parts treated with UP treatment.Originality/valueResults indicate an opportunity for UP to be used as an in-situ process during AM processes for dynamically altering the mechanical behavior, microstructure, and distortion due to residual stress formation, in a tunable fashion.

Effects of ultrasonic peening treatment on hydrogen sulphide corrosion behaviour

ABSTRACTAfter being subjected to ultrasonic peening treatment (UPT), the resistance of X65 pipeline steel to hydrogen sulphide corrosion was investigated through electrochemical, immersion and slow-strain-rate testing. In addition, the UPT-induced compressive residual stresses layer and related changes in the steel near-surface microstructure and hardness were examined by scanning electron microscopy, optical microscopy and X-ray diffraction. The obtained results revealed that UPT was able to significantly improve the corrosion potential of X65 pipeline steel and reduce its hydrogen sulphide corrosion rate, while the formation of the compressive stress layer increased the steel’s tensile strength and inhibited hydrogen blistering.

Improvement of very high cycle fatigue properties in an AA7075 friction stir welded joint by ultrasonic peening treatment

AbstractThe present paper aims to investigate the effect of ultrasonic peening treatment on the very high cycle fatigue resistance of an AA7075 friction stir welded joint. Microscopy observation, microhardness and X‐ray diffraction measurements were carried out to characterize the treated surface of peened specimens. Fatigue crack initiation sites were investigated through scanning electron microscope, and the role of enhanced surface on fatigue resistance was analyzed. The results indicate that a sensible fatigue strength improvement can be obtained through application of ultrasonic peening treatment and that fatigue cracks can initiate from the interior of the specimen. To clarify the fatigue failure mechanism, we analyzed the microstructure characteristics, compressive residual stress profile and intermetallic inclusion distribution in the surface layers, and we discussed the capability of ultrasonic peening treatment to hinder the surface crack initiation.

The Effect of Ultrasonic Peening Treatment on Fatigue Performance of Welded Joints.

Ultrasonic peening treatment (UPT) as a method of severe plastic deformation was used to treat cruciform welded joints of Q345 steel. The application of UPT achieves material surface nanocrystallization of the peening zone, reduces stress concentration, and produces residual compressive stresses at the welded toe. Micro-structure, hardness, stress relief, S-N curve, and the fatigue fracture mechanism of cruciform welded joint of Q345 steel, both before and after UPT, were analyzed in detail. The main results show that: stress concentration and residual tensile stress are the main reasons to reduce fatigue strength of cruciform welded joints. The fatigue life of cruciform welded joints is improved for surface hardening, compressive stress, and grain refinement by UPT. Residual compressive stress caused by UPT is released with the increase of fatigue life. A very significant fatigue strength improvement happens when UPT is replenished repeatedly after a certain number of cycles.

A review of ultrasonic peening treatment

Abstract Ultrasonic peening treatment (UPT) has recently had significantly more attention in several manufacturing processes. UPT modifies the surface of a material and enhances the mechanical and/or chemical properties. This is especially true for welded components when working under fatigue dynamic loading conditions. The current review paper has been devoted to introduce this technology for its underlying mechanisms and effects. The UPT tools and devices are reviewed in terms of device configurations and process conditions. The effects of UPT are thoroughly discussed in terms of fatigue performance, resistance to wear and corrosion, and micro-structural evolutions.

The effects of ultrasonic peening treatment on the ultra-long life fatigue behavior of welded joints

The conventional fatigue design codes was formulated based on the data from test stress cycles less than 1 × 10 7. Most of them could not be applied for welded structures serviced in the ultra-long life region so the new recommendations were discussed. The method of ultrasonic peening treatment (UPT) was introduced in this thesis as a post-weld treatment to improve the fatigue strength of the welded structures. The fatigue behavior of welded structures in the ultra-long life region was investigated using an ultrasonic fatigue test machine under two post-weld treatment states: the as-welded and the UPT. Discussion had also been made about the fracture mechanism on the UPT joints in ultra-long life fatigue test.