Thermochemical surface hardening of Ti-6Al-4V: On the role of temperature and treatment media

Yang, Meng; Villa, Matteo; Dahl, Kristian Vinter; Wang, Bo; Drouet, M.; Dubois, Jean-Baptiste; Christiansen, Thomas

doi:10.1016/j.surfcoat.2021.127505

Cited by 6 publications

(3 citation statements)

References 72 publications

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“…Os moldes de injeção, em geral, são submetidos a tratamentos superficiais para aumentar a durabilidade, funcionalidade e elevar a resistência à corrosão (Nikolov et al, 2014;Marteau et al, 2016;Meng et al, 2021). Esses tratamentos podem ser mecânicos ou termoquímicos, havendo diferentes tipos como nitretação à alta temperatura seguida de sobrecementação; cementação à baixa temperatura; implantação de íons de nitrogênio e; jateamento ultrassônico, todos objetivando cobrir ampla faixa de profundidades, que podem ser compreendidas entre alguns micrômetros a várias centenas de micrômetros (Marteau et al, 2016).…”

Section: Tratamentos Superficiais Termoquímicos (Primeformⓡ)unclassified

Análise e redução da variação do brilho em peças plásticas por injeção

Pereira,

Corrêa

2024

Revista PO: R. Eletr. de Eng. de Produção e Correlatas

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A injeção de peças poliméricas é amplamente empregada pelo setor produtivo, em particular, o automotivo. No entanto, para atender às crescentes demandas de consumo sem perda de qualidade, avaliações criteriosas devem ser adotadas. Uma delas é a análise do brilho que, somado a outros defeitos, como dilatação, encolhimento e empenamento da peça, torna-se importante para controle de qualidade. Devido à natureza particular do processo produtivo adotado pelas montadoras, muitas peças são injetadas em unidades diferentes, sendo juntadas em outras linhas de produção. Nesses casos, quando o padrão de brilho não está compatível entre elas, há não conformidade, perda de produção e atrasos nas entregas. Assim, é fundamental que estudos sejam conduzidos para avaliar a influência que parâmetros de injeção, como também, o tipo de molde, possam exercer sobre o brilho de peças injetadas. Esse trabalho objetivou estudar, por meio da caracterização do brilho, 380 peças do cover de cinto de segurança de um veículo de passeio. Para tanto, foram empregadas misturas de acrilonitrila-butadieno-estireno/policarbonato, ABS/PC (PC > 60%), as quais foram injetadas em moldes não-tratados e tratados termoquimicamente, bem como analisados parâmetros de temperatura do molde e pressão de recalque. Os resultados apontaram que o tratamento superficial fornecido ao molde não foi suficiente para garantia e adequação do brilho, o que só foi conseguido através de ajustes na temperatura do molde e pressão de recalque da injetora.

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Section: Tratamentos Superficiais Termoquímicos (Primeformⓡ)unclassified

Análise e redução da variação do brilho em peças plásticas por injeção

Pereira,

Corrêa

2024

Revista PO: R. Eletr. de Eng. de Produção e Correlatas

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“…The aim of this investigation is the realization of a microstructure which exhibits a microstructure gradient depending on the surface distance, which improves the properties relevant for the application of cyclically stressed components, particularly the strength of aircraft components subjected to cyclic loading in the HCF (High Cycle Fatigue) and LCF (Low Cycle Fatigue) regimes. Microstructure gradients can be generated by thermomechanical treatment in general [20][21][22] and in Ti alloys [23][24][25][26][27] and thermochemical treatments [28][29][30][31][32], such as THT [33,34]. By employing THT (a process similar to ref.…”

Section: Introductionmentioning

confidence: 99%

Feasibility of THT-Induced Microstructure Gradients and Their Effects on Fatigue Properties in Additively Manufactured Cylindrical and in Conventionally Manufactured Tube-Like Ti-6Al-4V Specimens

Schmidt,

El-Chaikh,

Danzig

et al. 2024

Preprint

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Technical components should be produced sustainably and are subject to growing demands in terms of durability and reliability. To meet these expectations, the development of thermochemical processes is auspicious. Titanium alloys, which have a comparatively high gas solubility, allow temporary hydrogen (H) loading, often called thermo hydrogen treatment (THT). THT causes lattice deformation and reduces the β transformation temperature. These effects enable an adjustment of the microstructure, which improves the mechanical properties as compared to those produced conventionally. Furthermore, the process is applicable to complex geometries that cannot be surface hardened by mechanical surface treatment techniques. The investigation presented intends to realize a local microstructure gradient in additively via laser-powder bed fusion (L-PBF) manufactured cylindrical Ti–6Al–4V specimens by changing the distribution and morphology of strengthening precipitates as well as the β grain size depending on the distance to the surface, which should improve the material fatigue properties. To evaluate the mechanical properties of such THT-induced microstructure gradients, the resulting change in fatigue life in the LCF and HCF range was determined by stress-controlled cyclic deformation tests. Besides, the resulting microstructure was characterized by means of XRD and TEM. In addition to the additively manufactured and thermo hydrogen treated cylindrical specimens, conventionally produced tube-like specimens were thermo hydrogen treated and examined. For the THT-induced microstructure gradients, numerically simulated H concentration profiles as well as experimentally determined hardness profiles were used for the evaluation of the THT process. The study shows that H-loading at 500°C and H-degassing at 750°C, followed by aging at 550°C, allows the establishment of a microstructure gradient that shows an 8% improvement in fatigue properties compared to a reference condition without THT. The reason for this improvement is an increased volume fraction secondary alpha phase in the near-surface area of the specimens. Moreover, the results show that the process is applicable a tube-like specimen with varying wall thicknesses.

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“…Almeida et al reported that a Ti-N compound layer about 1 μm thick was formed on Ti6Al4V after nitrided for 4 h at 690 °C [20]. Meng et al conducted plasma nitriding of Ti6Al4V in a N 2 /H 2 gas mixture at 750 °C and 850 °C for 24 h. After treatments, a compound layer about 1 ∼ 2 μm for 750 and 4 ∼ 5 μm thick for 850 °C was obtained [21]. Therefore, plasma nitriding of titanium and titanium alloys was generally carried out at high temperatures (900 °C-1100 °C) [22,23] which exceed the phase transformation temperature of α-Ti to β-Ti and maybe cause an evident deformation of treated workpieces.…”

Section: Introductionmentioning

confidence: 99%

Characterization and electrochemical performance of plasma-nitrided titanium alloy for bipolar plates

Shen,

Wang

2024

Eng. Res. Express

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Ti-N layer with a thickness about 1~2.2 μm was formed on titanium alloys through plasma nitriding at 750 °C in NH3 and a mixture of NH3 and N2 (1:2) for 4 h. SEM and XRD were employed to characterize the microstructure and phase composition of nitrided layer. Electrochemical tests evaluated the anti-corrosion properties of the samples before and after nitrided in a simulated proton exchange membrane fuel cells (PEMFC) environment. Interface contact resistance (ICR) was also measured. Results indicated that the corrosion potential in cathodic conditions was increased from -415 mV for untreated titanium to 148 mV for that nitrided in mixture gas. While, the corrosion current density was reduced from 6.64 A to 0.86A. Under a pressure of 140 N/cm², the interfacial contact resistance of the untreated sample increased from 22.1 mΩ cm2 before corrosion testing to 40.5 mΩ cm2 after corrosion at cathodic conditions. The nitrided sample, on the other hand, saw its contact resistance rise from 4.5 mΩ cm2 before corrosion to 7.3 mΩ cm2 after corrosion. The Ti-N compound layer effectively diminished the corrosion current density and sustained an exceptionally low ICR under the simulated operating conditions of a bipolar plate.

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Thermochemical surface hardening of Ti-6Al-4V: On the role of temperature and treatment media

Cited by 6 publications

References 72 publications

Análise e redução da variação do brilho em peças plásticas por injeção

Análise e redução da variação do brilho em peças plásticas por injeção

Feasibility of THT-Induced Microstructure Gradients and Their Effects on Fatigue Properties in Additively Manufactured Cylindrical and in Conventionally Manufactured Tube-Like Ti-6Al-4V Specimens

Characterization and electrochemical performance of plasma-nitrided titanium alloy for bipolar plates

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