High strain rate deformation microstructures of stainless steel 316L by cold spraying and explosive powder compaction

Borchers, C.; Schmidt, Tobias; Gärtner, F.; Kreye, H.

doi:10.1007/s00339-007-4314-0

Cited by 60 publications

(28 citation statements)

References 28 publications

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“…That is, the impact can result in deformation-induced transformation of an initially metastable phase into a more stable state, e.g. bcc to fcc in steel 316L [134] and in MCrAlY [135].…”

Section: Microstructurementioning

confidence: 99%

“…Ni-based superalloys [195,196] High-temperature applications NiTi [197,198] Shape memory Nanocrystals Steel 316L, 304L [134,[199][200][201] Heat treatment Phase transformation Stellite [202][203][204] Wear resistance Ta [197,198] Oxygen evolution reaction Corrosion protection Ti [205,206] Review Zn, Zn alloys [176,207] Printing rolls Corrosion protection CS is a particularly attractive method for the deposition of metastable materials such as metallic glasses, without dimensional restriction. In this respect, CS may be considered as the only practical method through which bulk metallic glasses of any size may be produced.…”

Section: Metallic Materialsmentioning

confidence: 99%

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Cold spraying – A materials perspective

et al. 2016

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Cold spraying is a solid-state powder deposition process with several unique characteristics, allowing production of coatings or bulk components from a wide range of materials. The process has attracted much attention from academia and industry over the past two decades.The technical interest in cold spraying is twofold: first as a coating process for applications in surface technology, and second as a solid-state additive manufacturing process, offering an alternative to selective laser melting or electron beam melting methods. Moreover, cold spraying can be used to study materials behaviour under extremely high strain rates, high pressures and high cooling rates. The cold spraying process is thus considered to be relevant for various industrial applications, as well as for fundamental studies in materials science.This article aims to provide an overview of the cold spray process, the current understanding of the deposition mechanisms, and the related models and experiments, from a materials science perspective. IntroductionCold spraying (CS) is a solid-state material deposition technique, where micron-sized particles of a powder bond to a substrate as a result of high-velocity impact and the associated severe plastic deformation. Acceleration of particles to high velocities is obtained via expansion of a pressurised and (ironically) 'hot' gas through a diverging-converging nozzle.Despite heating the process gas -which is to provide higher acceleration of the gas and also to facilitate particle deformation through thermal softening -the feedstock remains in the solid state throughout the entire process; hence the name 'cold' spraying. This is to underline the contrast to conventional thermal spraying where particles are completely or partially molten upon impact onto the substrate. Alternative terminology includes cold gas spray, micro cold spray, cold gas dynamic spray, kinetic spray, supersonic particle deposition and metal powder application (MPA), all of which refer to the same principle of solid-state powder deposition as described above. CS is used for coating and repair. It is also used for additive manufacturing (AM) at relatively high deposition rates as compared to the methods based on selective laser or electron beam melting. The main advantage of CS is that it alleviates the problems associated with high temperature processing of materials, such as oxidation and unfavourable structural changes. It is possibly the only continuous method to produce bulk components of metastable materials that are available only in the powder form, e.g. as obtained from mechanical attrition or gas atomisation. The aim of the present paper is to provide an overview of CS from a materials perspective, particularly for a broader audience in materials research, e.g. with interest in dynamic phenomena, plasticity and phase transformations. In terms of application and properties, CS is perhaps best to be compared to thermal spraying processes, as in [24,25]. In view of relevant physical phenomena, however, CS is mos...

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“…That is, the impact can result in deformation-induced transformation of an initially metastable phase into a more stable state, e.g. bcc to fcc in steel 316L [134] and in MCrAlY [135].…”

Section: Microstructurementioning

confidence: 99%

Section: Metallic Materialsmentioning

confidence: 99%

Cold spraying – A materials perspective

et al. 2016

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“…A most determining factor for bonding is the velocity of the impacting particle. Bonding occurs if the particle velocity upon impact, v pi , becomes greater than a critical value, v cr (Ref [10][11][12][13][14][15][16][17][18]. The conditions that lead to particle bonding can be identified with respect to what is referred to as window of deposition.…”

Section: Introductionmentioning

confidence: 99%

“…As shown in the table, some properties influence both v pi and v cr , while others influence either v pi or v cr . Moreover, some of these influences, such as the effect of particle size on v pi , do not follow a monotonic trend (Ref 13,18,20,21). Because of these complexities, identification of optimum spraying parameters for different materials continues to be a challenging aspect of cold spraying.…”

Section: Introductionmentioning

confidence: 99%

On Parameter Selection in Cold Spraying

et al. 2011

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For cold spraying, a method for the construction of the window of deposition and the selection of optimum process parameters is presented. Initially, particle impact velocity and the critical particle velocity for bonding are worked out and expressed explicitly in terms of key process and material parameters. Subsequently, the influence of particle velocity on coating characteristics is examined in view of the results of experiments and simulations. It has been found that main coating characteristics can be described as a unique function of the ratio of particle velocity to critical velocity, here referred to as g. Finally, coating properties are linked directly to primary process parameters via parameter selection maps, where contours of constant g are plotted on a plane of gas temperature versus gas pressure. Inferences of the presented method and the resulting parameter selection maps are discussed for the example of copper as feedstock material.

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“…The high hardness of the coatings relative to the feedstock powder is attributed to high strain rate plastic deformation that the deposited particles undergo during deposition, which is typical to cold spray. Such high strain rate plastic deformation is characterized by the presence of dislocation loops which have been observed directly via TEM in the case of pure copper and stainless steel (Ref 32,33). The predominant strengthening mechanism is likely to be work hardening due to an increased dislocation density calculated in the as-sprayed coatings (0.8 9 10 15 m -2 ).…”

Section: Heat-treated Coating Morphology and Microstructurementioning

confidence: 90%

Heat Treatment of Cold-Sprayed C355 Al for Repair: Microstructure and Mechanical Properties

2017

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Cold gas dynamic spraying of commercially pure aluminum is widely used for dimensional repair in the aerospace sector as it is capable of producing oxide-free deposits of hundreds of micrometer thickness with strong bonding to the substrate, based on adhesive pull-off tests, and often with enhanced hardness compared to the powder prior to spraying. There is significant interest in extending this application to structural, load-bearing repairs. Particularly, in the case of high-strength aluminum alloys, cold spray deposits can exhibit high levels of porosity and microcracks, leading to mechanical properties that are inadequate for most load-bearing applications. Here, heat treatment was investigated as a potential means of improving the properties of cold-sprayed coatings from Al alloy C355. Coatings produced with process conditions of 500°C and 60 bar were heat-treated at 175, 200, 225, 250°C for 4 h in air, and the evolution of the microstructure and microhardness was analyzed. Heat treatment at 225 and 250°C revealed a decreased porosity (* 0.14% and 0.02%, respectively) with the former yielding slightly reduced hardness (105 versus 130 HV 0.05 as-sprayed). Compressive residual stress levels were approximately halved at all depths into the coating after heat treatment, and tensile testing showed an improvement in ductility.

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High strain rate deformation microstructures of stainless steel 316L by cold spraying and explosive powder compaction

Cited by 60 publications

References 28 publications

Cold spraying – A materials perspective

Cold spraying – A materials perspective

On Parameter Selection in Cold Spraying

Heat Treatment of Cold-Sprayed C355 Al for Repair: Microstructure and Mechanical Properties

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