Superplastic-like forming of Ti-6Al-4V alloy

Liu, Jun; Tan, Ming Jen; Aue‐u‐lan, Yingyot; Guo, Meiling; Castagne, Sylvie; Chua, Bih Lii

doi:10.1007/s00170-013-5101-z

Cited by 25 publications

(14 citation statements)

References 22 publications

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“…In Table 7, this test case has the greatest longitudinal strain ( ), and has the smallest transverse stress which indicates that plastic deformation has occured. In super plastic forming of Ti-6Al-4V, parts can be manufactured without suffering from residual stress or spring back, at low shear rates [41] and likewise shows that the formation of residuals stresses can be controlled by temperature. Depending on the substrate (powder or solid), varying the scan area size will enable control over the sustained temperature achieved in a scanned region.…”

Section: Discussionmentioning

confidence: 97%

“…The temperature oscillations are damped and tend towards a steady state of 400°C, as a result of the energy balance of the heat input and losses in the system, as defined in equation (2). 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 In Figure 10, the total area held above 825°C, the point at which Ti-6Al-4V begins to acquire superplastic behaviour [41], increases with time. This indicates the accumulation of heat into the part since the power is kept constant throughout scanning the hatched region.…”

Section: Thermal Analysis Of Single Layer Sectionsmentioning

confidence: 99%

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Understanding the effect of laser scan strategy on residual stress in selective laser melting through thermo-mechanical simulation

Parry

Ashcroft

Wildman

2016

Additive Manufacturing

410

287

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A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. Abstract: Selective laser melting (SLM) is an attractive technology, enabling the manufacture of customised, complex metallic designs, with minimal wastage. However, uptake by industry is currently impeded by several technical barriers, such as the control of residual stress, which have a detrimental effect on the manufacturability and integrity of a component. Indirectly, these impose severe design restrictions and reduce the reliability of components, driving up costs. This paper uses a thermo-mechanical model to better understand the effect of laser scan strategy on the generation of residual stress in SLM. A complex interaction between transient thermal history and the build-up of residual stress has been observed in the two laser scan strategies investigated. The temperature gradient mechanism was discovered for the creation of residual stress. The greatest stress component was found to develop parallel to the scan vectors, creating an anisotropic stress distribution in the part. The stress distribution varied between laser scan strategies and the cause has been determined by observing the thermal history during scanning. Using this, proposals are suggested for designing laser scan strategies used in SLM. Abstract:Selective laser melting (SLM) is an attractive technology, enabling the manufacture of customised, complex metallic designs, with minimal wastage. However, uptake by industry is currently impeded by several technical barriers, such as the control of residual stress, which have a detrimental effect on the manufacturability and integrity of a component. Indirectly, these impose severe design restrictions and reduce the reliability of components, driving up costs. This paper uses a thermomechanical model to better understand the effect of laser scan strategy on the generation of residual stress in SLM. A complex interaction between transient thermal history and the build-up of residual stress has been observed in the two laser scan strategies investigated. The temperature gradient mechanism was discovered for the creation of residual stress. The greatest stress component was found to develop parallel to the scan vectors, creating an anisotropic stress distribution in the part. The stress distribution varied between laser scan strategies and the cause has been determined by observing the thermal history during scanning. Using this, proposals are suggested for designing laser scan strategies used in SLM. Nomenclature:Specific

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Section: Discussionmentioning

confidence: 97%

Section: Thermal Analysis Of Single Layer Sectionsmentioning

confidence: 99%

Understanding the effect of laser scan strategy on residual stress in selective laser melting through thermo-mechanical simulation

Parry

Ashcroft

Wildman

2016

Additive Manufacturing

410

287

View full text Add to dashboard Cite

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“…Liu et al combined deep drawing and blow forming into one operation. Together with a non-isothermal heating system, they successfully formed Ti-6Al-4V alloy sheets at 800°C in 16 min [10]. Tang used hot-bend assisted gas forming (HBAGF) to fabricate aluminium airplane strakelets with improved thickness profiles [11].…”

Section: Introductionmentioning

confidence: 99%

Effects of flow stress behaviour, pressure loading path and temperature variation on high-pressure pneumatic forming of Ti-3Al-2.5V tubes

Liu

Wang

Dang

et al. 2015

Int J Adv Manuf Technol

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High-pressure pneumatic forming (HPPF) is an internal high-pressure forming process at elevated temperatures, which is based on quick plastic forming (QPF), hot metal gas forming (HMGF) and hydroforming. In this study, the HPPF experiments were performed on Ti-3Al-2.5V tubes using a square cross-sectional die at higher pressure levels and lower temperatures. The uniaxial tensile tests were carried out at various temperatures and strain rates before the HPPF experiments. The flow stress of Ti-3Al-2.5V tubes is evidently affected by both temperature and strain rate. Because of this, the corner radii all change linearly over time at the pressurization stage but exponentially over time at the constant pressure stage. The cooling effect of the inflow process on the tubes results in temperature differences between the centre of the straight wall areas and the corner areas of the tubes during the inflow process. Adopting the lower pressurization rate and filling regenerative materials into the tube are effective methods for decreasing or eliminating the temperature difference.

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“…Nevertheless, their poor formability has prevented widespread application as cold-formed wrought components [3]. Superplastic forming is an interesting process of shaping titanium alloys.…”

Section: Introductionmentioning

confidence: 99%

Resistance heating superplastic forming and influence of current on deformation mechanism of TA15 titanium alloy

Liu

Zhang

2014

Int J Adv Manuf Technol

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The resistance heating is adopted in bulging process of TA15 titanium alloy to improve the heating efficiency and reduce the energy consumption. The experiments of TA15 titanium alloy resistance heating tension and bulging are performed to investigate the influence of current on titanium alloy hot deformation. Compared with conventional hot deformation, the current will lead to strain concentration due to resistance changing when the necking appears. The TA15 titanium alloy resistance heating superplastic bulging can be carried out with a current density of 7 A/mm 2 and the current can improve the forming property of material. The results show that the dynamic recrystallization takes place during hot bulging process. In deformation process, a part of α phase transforms into β phase that makes the grains grow up and the β phase changes into the basket weave structure in the subsequent cooling process. Under the action of current, the grain orientation of deformation titanium alloy shows directivity and the dislocation line is approximately in parallel with others with little tangle and screw that can strengthen the ability of the dislocation glide and enhance the deformation ability of TA15 titanium alloy. The resistance heating forming parts are obtained.

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Superplastic-like forming of Ti-6Al-4V alloy

Cited by 25 publications

References 22 publications

Understanding the effect of laser scan strategy on residual stress in selective laser melting through thermo-mechanical simulation

Understanding the effect of laser scan strategy on residual stress in selective laser melting through thermo-mechanical simulation

Effects of flow stress behaviour, pressure loading path and temperature variation on high-pressure pneumatic forming of Ti-3Al-2.5V tubes

Resistance heating superplastic forming and influence of current on deformation mechanism of TA15 titanium alloy

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