Direct laser fabrication of three dimensional components using SC420 stainless steel

Ravi, G.A.; Hao, Xinjiang; Wain, N.; Wu, Xinhua; Attallah, Moataz M.

doi:10.1016/j.matdes.2012.12.062

Cited by 66 publications

(29 citation statements)

References 15 publications

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“…In fact, the assumption of a lower ductility in the rejected deposit 3 is supported either by the nature of the matrix that is almost fully martensitic, and by the fact very low (or little) heat accumulation is achieved under this configuration. In addition Ravi et al in their study [1] show that more ductility can be expected from stainless steel cladded materials that undergo ageing during laser processing due to the building strategy which allows heat accumulation.…”

Section: Tensile Behaviormentioning

confidence: 98%

“…Laser cladding is an economic layer-by-layer near-net-shape process for the production of three-dimensional complex parts [1]. It also appears as a very interesting solution for the low-cost repair of damaged high-value components [2] and for coatings with improved surface properties [3,4].…”

Section: Introductionmentioning

confidence: 99%

“…Graf et al [2] investigated the feasibility of LMD for re-filling milled grooves of different shapes to repair parts made from stainless steel or titanium alloys, but the influence of the building strategy on the microstructure was not addressed. In fact, Ravi et al [1] showed that the deposition strategy in relation with the thermal history strongly influence both the microstructure and the ductility of stainless steels alloys. Therefore it is worth enhancing the building strategy effect during laser cladding repair of Ti-6Al-4V alloys.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Laser cladding as repair technology for Ti–6Al–4V alloy: Influence of building strategy on microstructure and hardness

et al. 2015

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Section: Tensile Behaviormentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Laser cladding as repair technology for Ti–6Al–4V alloy: Influence of building strategy on microstructure and hardness

et al. 2015

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“…During the process, powder is fed at a controlled rate into the laser focal point where it is melted into the melt pool. The path of the laser in the X-Y plane and along the Z axis is defined by a numerical control (NC) program which is derived from a CAD file of a component [1]. The technology has many potential applications, including production of functional prototypes, fabrication and repair of components, and fabrication of functionally graded materials and composites.…”

Section: Introductionmentioning

confidence: 99%

Microstructural control during direct laser deposition of a β-titanium alloy

2015

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a b s t r a c tA concern associated with Direct Laser Deposition (DLD) is the difficulty in controlling microstructure due to rapid cooling rates after deposition, particularly in beta-Ti alloys. In these alloys, the beta-phase is likely to exist following DLD, instead of the desirable duplex alpha + beta microstructure that gives a good balance of properties. Thus, in this work, a parametric study was performed to assess the role of DLD parameters on porosity, build geometry, and microstructure in a beta-Ti alloy, Ti-5Al-5Mo-5V-3 Cr (Ti5553). The builds were examined using optical microscopy, scanning electron microscopy, and X-ray diffraction. Microhardness measurements were performed to assess the degree of re-precipitation of alpha-phase following an in situ dwelling and laser annealing procedure. The study identified several processing conditions that enable deposition of samples with the desired geometry and low porosity level. The microstructure was dominated by beta-phase, except for the region near the substrate where a limited amount of alpha-precipitates was present due to reheating effect. Although the microstructure was a mixture of equiaxed and columnar beta-grains alongside infrequent fine alpha-precipitates, the builds showed fairly uniform microhardness in different regions. In situ dwelling and annealing did not cause an obvious change in porosity, but did promote the formation of alpha-precipitates.

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“…(a) Schematic illustration of the setting up of the Trumpf DLD system, d s is the spacing between laser nozzle tip and build surface[17]; (b) a photo showing the 3-beam laser nozzle. CAD model of a T-section, a and b represent the specified lengths of the two webs of a T-section and c and h represent the specified width and height of the walls, respectively.…”

mentioning

confidence: 99%

Fabrication of large Ti–6Al–4V structures by direct laser deposition

Qiu

Ravi

Dance

et al. 2015

Journal of Alloys and Compounds

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268

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a b s t r a c tTi-6Al-4V samples have been prepared by direct laser deposition (DLD) using varied processing conditions. Some of the as-fabricated samples were stress-relieved or hot isostatically pressed (HIPed). The microstructures of all the samples were characterised using optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) and the tensile properties assessed. It was found that a high laser power together with a reasonably low powder feed rate was essential for achieving minimum porosity. The build height and geometrical integrity of samples were sensitive to the specified laser nozzle moving step along the build height direction (or Z step) with a too big Z step usually leading to a build height smaller than specified height (or under build) and a too small Z step to excessive building (or excess build). Particularly, scaling-up of samples requires a smaller Z step to obtain specified build height and geometry. The as-fabricated microstructure was characterised by columnar grains together with martensitic needle structure and a small fraction of b phase. This led generally to high tensile strengths but low elongations. The vertically machined samples showed even lower elongation than horizontally machined ones due to the presence of large lack-of-fusion pores at interlayer interfaces. HIPing effectively closed pores and fully transformed the martensites into lamellar a + b phases, which considerably improved ductility but caused slight reduction in strength. With optimisation of processing conditions together with post-DLD HIPing, a couple of large spars with structural integrity comparable to conventionally manufactured parts have been fabricated. Pronounced distortion was observed after unclamping of the as-fabricated structures. HIPing on the unclamped structures was found to significantly reduce the distortion. It is suggested that DLD plus HIPing is a feasible route for manufacturing high quality and high performance aerospace structures.

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Direct laser fabrication of three dimensional components using SC420 stainless steel

Cited by 66 publications

References 15 publications

Laser cladding as repair technology for Ti–6Al–4V alloy: Influence of building strategy on microstructure and hardness

Laser cladding as repair technology for Ti–6Al–4V alloy: Influence of building strategy on microstructure and hardness

Microstructural control during direct laser deposition of a β-titanium alloy

Fabrication of large Ti–6Al–4V structures by direct laser deposition

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