Metals

15 pages, 57188 KiB

Open AccessArticle

Effect of Carbon Content on the Phase Composition, Microstructure and Mechanical Properties of the TiC Layer Formed in Hot-Pressed Titanium-Steel Composites

by Marius Grad, Jan Zentgraf, Ulrich Schultheiss, Lukas Esper, Andreas Diemar, Ulf Noster and Lothar Spiess

Metals 2024, 14(9), 959; https://doi.org/10.3390/met14090959 (registering DOI) - 24 Aug 2024

Abstract

During the hot pressing of pure titanium and different carbon steels in a temperature range of

ϑ

= 950 – 1050

^{\circ} C

, a compound layer up to d

_{L}

≈ 10

m

thick is formed at the titanium–steel interface. With a [...] Read more.

During the hot pressing of pure titanium and different carbon steels in a temperature range of

ϑ

= 950 – 1050

^{\circ} C

, a compound layer up to d

_{L}

≈ 10

m

thick is formed at the titanium–steel interface. With a higher carbon content of the used steel, the layer thickness increases. The carbon concentration within the layer is in the range of stoichiometry for TiC. Apart from TiC, no other phases can be detected by X-ray diffraction (XRD) measurements inside the formed layer. The calculation of the activation energy for the TiC layer formation is Q = 126.5 – 136.7 kJ/mol and is independent of the carbon content of the steel. The resulting microstructure has a grain size gradient, wherein the mechanical properties, such as hardness and Young`s modulus, are almost constant. Statistical analysis using Response Surface Methodology (RSM) indicates that the carbon content of the steel has the most significant influence on layer thickness, followed by annealing temperature and annealing time. By selecting the appropriate carbon steel and the subsequent removal of the steel, it is possible to produce targeted TiC layers on titanium substrates, which holds enormous potential for this material in wear-intensive applications. Full article

(This article belongs to the Special Issue Advances in Titanium and Titanium Alloys)

21 pages, 30210 KiB

Open AccessArticle

On the Mechanical Behavior of LP-DED C103 Thin-Wall Structures

by Brandon Colón, Mehrdad Pourjam, Gabriel Demeneghi, Kavan Hazeli, Omar Mireles and Francisco Medina

Metals 2024, 14(9), 958; https://doi.org/10.3390/met14090958 (registering DOI) - 23 Aug 2024

Viewed by 140

Abstract

Laser Powder Directed Energy Deposition (LP-DED) can produce thin-wall features on the order of 1 mm. These features are essential for large structures operating in extreme environments such as regeneratively cooled nozzles and heat exchangers, which often make use of refractory metals. In this work, the mechanical behavior of LP-DED C103 was investigated via quasi-static tensile testing and low cycle fatigue (LCF) testing. The effects of vacuum stress relief (SR) and hot isostatic pressing (HIP) heat treatments were investigated for specimens in the vertical and horizontal build orientations during tensile testing. The AB and SR properties were lower than literature values for wrought and laser powder bed fusion (L-PBF) bulk components but higher than electron beam powder bed fusion (EB-PBF). The application of a HIP cycle improved strength by 7% and ductility by 27% past the initial as-built condition. Fracture images reveal that interlayer stress concentration sites are responsible for fracture in specimens in the vertical orientation. Meanwhile, fracture in the horizontal specimens mainly propagates at a slanted angle typical of plane stress conditions. The LCF results show cycles to failure ranging from 100 cycles to 8000 cycles for max strain levels of 2% and 0.5%, respectively. Fractography on the fatigue specimens reveals an increasing propagation zone as max strain levels are increased. The impact of these findings and future work are discussed in detail. Full article

(This article belongs to the Special Issue Recent Advances in Metal Processing and Manufacturing: Technique, Method, Performance, and Microstructure)

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13 pages, 22619 KiB

Open AccessArticle

Improving the Mechanical Properties of Al-Si Composites through the Synergistic Strengthening of TiB₂ Particles and BN Nanosheets

by Yiren Wang, Jian Wang, Zunyan Xu, Baoqiang Xu, Bingheng Yu, Jianwu Dong and Caiju Li

Metals 2024, 14(9), 957; https://doi.org/10.3390/met14090957 (registering DOI) - 23 Aug 2024

Viewed by 194

Abstract

The size and distribution of the silicon phase and intermetallic phase are important factors affecting the properties of Al₁₁Si₃Cu₂NiMg alloy (M142). In this study, BNNS and micro-TiB₂ were used to synergistically refine and reinforce M142 composites (M142-BNNS-TiB₂). After T6 heat treatment, the comprehensive mechanical properties of M142-BN-TiB₂ composites were excellent, with an ultimate tensile strength of 463 MPa and an elongation of 2.6%. In addition, the introduction of BNNS and micro-TiB₂ changed the fracture mode of M142 from brittle fracture to quasi-cleavage fracture, and the introduction of BNNS and micro-TiB₂ refined the Si phase and intermetallic phase, which could change the origin of the crack in the composite, thus improving the ductility of the composite. Full article

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22 pages, 8652 KiB

Open AccessArticle

Development and Characterisation of a New Die-Casting Die Cooling System Based on Internal Spray Cooling

by Alexander Haban, Stefanie Felicia Kracun, Danny Noah Rohde and Martin Fehlbier

Metals 2024, 14(9), 956; https://doi.org/10.3390/met14090956 (registering DOI) - 23 Aug 2024

Viewed by 149

Abstract

Against the backdrop of climate policy goals and the EU’s aim for a resource-efficient economy, the foundry industry must rethink product range, energy consumption, and production technologies. Light metal casting, which is performed through processes like gravity die casting and high-pressure die casting, requires effective thermal management, which is crucial for optimising mould filling, solidification, cycle times, and part quality. Against this background, this study presents the development and characterisation of a cooling system that completely dispenses with energy-intensive heating/cooling devices. The system is based on a mask shape combined with internal spray cooling. This paper shows the simulation workflow for developing the mould mask and the design of the cooling system and compares the performance with conventional temperature control using channels. In the tests, an 82% higher cooling rate was achieved with Cool-Spray than with conventional temperature control, which was approx. 2.5 mm below the cavity surface. In addition to the more dynamic temperature control, the potential for process control was utilised, and the component quality of the test part was significantly improved compared to conventional temperature control. Full article

(This article belongs to the Special Issue Casting Process, Processing Deformation and Microstructure Optimization of Advanced Metallic Materials)

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Metals, Volume 14, Issue 9 (September 2024) – 4 articles

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