Effects of media parameters on enhance ability of hardness and residual stress of Ti6Al4V by fine shot peening

Ongtrakulkij, Goratouch; Khantachawana, Anak; Kondoh, Katsuyoshi

doi:10.1016/j.surfin.2019.100424

Cited by 29 publications

(43 citation statements)

References 25 publications

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“…However, the effect of surface hardening due to shot peening is not considered, as shown in Figure 20 a. In fact, the residual stress, PEEQ and surface roughness on the surface of the real Almen strip are the mechanisms for improving the fatigue life after shot peening, as shown in Figure 20 b. Ongtrakulkij and Khantachawana [ 28 ] reported that shot peening is a surface modification that can increase the bending strength by increasing the hardness and residual compressive stress. Bhuvaraghan and Srinivasan [ 4 ] proposed that the unit cell approach without superposition of the elastic theory is likely to provide accurate results when the thickness is high compared to the thickness of the plastic layer.…”

Section: Discussionmentioning

confidence: 99%

An Improved Approach to Direct Simulation of an Actual Almen Shot Peening Intensity Test with a Large Number of Shots

et al. 2020

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In existing simulations of the Almen intensity test, arc height is indirectly obtained by an equivalent method including a representative cell, a few shots and equivalent loading. Most of these equivalent methods cannot consider the transverse deformation of the strip, the complex stress state of the plastic hardening layer and process parameters, resulting in deviation from the actual test. This paper introduces an improved and experimentally validated discrete element model (DEM)-finite element model (FEM) to predict the actual Almen intensity. The improvement of this model is mainly reflected in the large and real number of shots involved in the actual Almen intensity test, shot–shot interactions, and real-size solid finite element model of the Almen strip. A new method for calculating the shot stream is proposed based on the test and considering test process parameters such as the mass flowrate, nozzle movement speed and nozzle–workpiece distance. The shot stream impacting the strip with a fully restrained underside was first simulated in improved DEM-FEM to bring the forming energy. As a second step, an implicit solver of the Almen strip FEM calculates the spring-back to simulate strip removal from the holder. The results achieved by the present approach are compared with the results obtained by the experimental results and those in the literature. The results show that the arc height and Almen intensity obtained by the present approach match much better with the literature than the traditional method. Some new results obtained by the improved coupling DEM-FEM method are presented. The influences of the transverse deformation and surface plastic layer on the deformation of the Almen strip are discussed. This improved method provides an alternative characterization method for precision peen forming simulation.

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Section: Discussionmentioning

confidence: 99%

An Improved Approach to Direct Simulation of an Actual Almen Shot Peening Intensity Test with a Large Number of Shots

et al. 2020

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“…In terms of the causes of enhanced surface microhardness in UAVM, the high-frequency vibration of the milling cutter introduced a great impact to the cutting zone similar to the effect of shot peening which was a surface modification process commonly adopted to improve the surface hardness and residual compressive stress by shooting micro media onto a workpiece surface at a high speed [29,30]. The enhanced surface hardness in shot peening was mainly attributed to the severe plastic deformation in a surface [31].…”

Section: Effect Of Feed Rate On Surface Microhardnessmentioning

confidence: 99%

Surface Integrity of Ultrasonically-Assisted Milled Ti6Al4V Alloy Manufactured by Selective Laser Melting

Guo

Jiang

et al. 2021

Chin. J. Mech. Eng.

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The Ti6Al4V parts produced by the existing selective laser melting (SLM) are mainly confronted with poor surface finish and inevitable interior defects, which substantially deteriorates the mechanical properties and performances of the parts. In this regard, ultrasonically-assisted machining (UAM) technique is commonly introduced to improve the machining quality due to its merits in increasing tool life and reducing cutting force. However, most of the previous studies focus on the performance of UAM with ultrasonic vibrations applied in the tangential and feed directions, whereas few of them on the impact of ultrasonic vibration along the vertical direction. In this study, the effects of feed rate on surface integrity in ultrasonically-assisted vertical milling (UAVM) of the Ti6Al4V alloy manufactured by SLM were systemically investigated compared with the conventional machining (CM) method. The results revealed that the milling forces in UAVM showed a lower amplitude than that in CM due to the intermittent cutting style. The surface roughness values of the parts produced by UAVM were generally greater than that by CM owing to the extra sinusoidal vibration textures induced by the milling cutter. Moreover, the extra vertical ultrasonic vibration in UAVM was beneficial to suppressing machining chatter. As feed rate increased, surface microhardness and thickness of the plastic deformation zone in CM raised due to more intensive plastic deformation, while these two material properties in UAVM were reduced owing to the mitigated impact effect by the high-frequency vibration of the milling cutter. Therefore, the improved surface microhardness and reduced thickness of the subsurface deformation layer in UAVM were ascribed to the vertical high-frequency impact of the milling cutter in UAVM. In general, the results of this study provided an in-depth understanding in UAVM of Ti6Al4V parts manufactured by SLM.

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“…Moreover, the large media would generate high roughness on surfaces, which can in turn cause lower fatigue strength [ 5 ]. On the other hand, when shooting with small media or low Almen intensity, the maximum residual stress is generated near the surface, but with a lesser effect at in-depth positions [ 6 , 7 ]. Accordingly, one significant method to improve this process is called double shot peening.…”

Section: Introductionmentioning

confidence: 99%

“…This research aims to maintain high residual compressive stress from the surface to the deeper surface and decrease the surface roughness by double shot peening. Furthermore, comparisons will be drawn with single shot peening based on some results from previous research [ 7 ]. Moreover, this research could be a guideline on how to select the media type and size of second shot to enhance the effectiveness of double shot peening to maintain the uniform residual compressive stress and hardness both on the surface and in-depth surface, while roughness is reduced.…”

Section: Introductionmentioning

confidence: 99%

Effects of the secondary shot in the double shot peening process on the residual compressive stress distribution of Ti–6Al–4V

Ongtrakulkij

Khantachawana

Kajornchaiyakul

et al. 2022

Heliyon

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Double shot peening is the development of shot peening by shooting large media as a first shot and re-shooting again with smaller media as a second shot in order to achieve high residual compressive stress and hardness at the surface, while the in-depth effect can still be maintained. This research aims to examine the effect of media type and media size when used in the second shot of double shot peening on hardness, roughness, and residual stress to identify the suitable conditions and compare them with single shot peening, such as conventional shot peening and fine shot peening, which was used as the first shot and second shot. Ti–6Al–4V was used as the substrate material, while various diameter sizes of silica and SUS304 media were selected as the media for the second shot in the process. The results showed that in the case of the larger size of silica media in the second shot of double shot peening, the hardness and residual compressive stress on the surface clearly increased more than with the smaller media due to the higher Almen intensity, which affected impact energy. On the other hand, when shooting with SUS304 media as a second shot, the increment of residual compressive stress and hardness, including roughness reduction on the surface, showed less effect than was the case for silica media, due to the lower Almen intensity, which affected the impact energy transfer. This research found that the condition of shooting with 80 μm of silica media as the second shot could generate the highest hardness and residual compressive stress on the surface, which increased by 14% and 53%, respectively, while roughness was decreased by 20% when compared with single shot peening.

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Effects of media parameters on enhance ability of hardness and residual stress of Ti6Al4V by fine shot peening

Cited by 29 publications

References 25 publications

An Improved Approach to Direct Simulation of an Actual Almen Shot Peening Intensity Test with a Large Number of Shots

An Improved Approach to Direct Simulation of an Actual Almen Shot Peening Intensity Test with a Large Number of Shots

Surface Integrity of Ultrasonically-Assisted Milled Ti6Al4V Alloy Manufactured by Selective Laser Melting

Effects of the secondary shot in the double shot peening process on the residual compressive stress distribution of Ti–6Al–4V

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