scholarly journals The Effect of Hydrogen on the Nanoindentation Behavior of Heat Treated 718 Alloy

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1451
Author(s):  
Gaute Stenerud ◽  
Tarlan Hajilou ◽  
Jim Stian Olsen ◽  
Iman Taji ◽  
Afrooz Barnoush ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Nickel Superalloy ◽  
Heat Treatments ◽  
New Method ◽  
Solution Annealing ◽  
Anodic Potential ◽  
Heat Treated ◽  
Hardness Increase ◽  
Cathodic Charging

In this study, the effect of precipitates on the surface mechanical properties in the presence of hydrogen (H) is investigated by in situ electrochemical nanoindentation. The nickel superalloy 718 is subjected to three different heat treatments, leading to different sizes of the precipitates: (i) solution annealing (SA) to eliminate all precipitates, (ii) the as-received (AR) sample with fine, dispersed precipitates, and (iii) the over-aged (OA) specimen with coarser precipitates. The nanoindentation is performed using a conical tip, and a new method of reverse imaging is employed to calculate the nano-hardness. The results show that the hardness of the SA sample is significantly affected by H diffusion. However, it could be recovered by removing the H from its matrix by applying an anodic potential. Since the precipitates in the OA and AR samples are different, they are influenced by H differently. The hardness increase for the OA sample is more significant in −1200mV, while for the AR specimen, the H is more effective in −1500mV. In addition, the pop-in load is reduced when the samples are exposed to cathodic charging, and it cannot be fully recovered by switching to an anodic potential.

scholarly journals Electron Beam Melting of Ti-6Al-4V Lattice Structures; Correlation between Post Heat Treatment and Mechanical Properties

2021 ◽  
Author(s):  
Giuseppe Del Guercio ◽  
Manuela Galati ◽  
Abdollah Saboori
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Computer Aided Design ◽  
Mechanical Performance ◽  
Industrial Applications ◽  
Heat Treatments ◽  
Layer By Layer ◽  
Lattice Structures ◽  
Heat Treated ◽  
Aided Design

Abstract Additive Manufacturing processes are considered advanced manufacturing methods. It would be possible to produce complex shape components from a Computer-Aided Design model in a layer-by-layer manner. Lattice structures as one of the complex geometries could attract lots of attention for both medical and industrial applications. In these structures, besides cell size and cell type, the microstructure of lattice structures can play a key role in these structures' mechanical performance. On the other hand, heat treatment has a significant influence on the mechanical properties of the material. Therefore, in this work, the effect of the heat treatments on the microstructure and mechanical behaviour of Ti-6Al-4V lattice structures manufactured by EBM was analyzed. The main mechanical properties were compared with the Ashby and Gibson model. It is very interesting to notice that a more homogeneous failure mode was found for the heat-treated samples. The structures' relative density was the main factor influencing their mechanical performance of the heat-treated samples. It is also found that the heat treatments were able to preserve the stiffness and the compressive strength of the lattice structures. Besides, an increment of both the elongation at failure and the absorbed energy was obtained after the heat treatments. Microstructure analysis of the heat-treated samples confirms the increment of ductility of the heat-treated samples with respect to the as-built one.

On the role of different annealing heat treatments on mechanical properties and microstructure of selective laser melted and conventional wrought Ti-6Al-4V

2017 ◽  
Vol 23 (2) ◽  
pp. 295-304 ◽  
Author(s):  
AmirMahyar Khorasani ◽  
Ian Gibson ◽  
Moshe Goldberg ◽  
Guy Littlefair
Keyword(s):  
Mechanical Properties ◽  
Design Methodology ◽  
Stress Relief ◽  
Heat Treatments ◽  
Recrystallization Annealing ◽  
Content Type ◽  
Hardness Increase ◽  
As Stress ◽  
Different Characteristics

Purpose The purpose of this study was to conduct various heat treatments (HT) such as stress relief annealing, mill annealing, recrystallization (α + β) annealing and β annealing followed by furnace cooling (FC) that were implemented to determine the effect of these on mechanical properties and the microstructure of selective laser melted and wrought samples. The mentioned annealings have been carried out to achieve the related standards in the fabrication of surgery implants. Design/methodology/approach In this paper, based on F2924-14 ASTM standard SLM and conventionally wrought parts were prepared. Then HT was performed and different characteristics such as microstructure, mechanical properties, macro-hardness and fracture surface for selective laser melted and wrought parts were analysed. Findings The results show that the high cooling rate in selective laser melting (SLM) generates finer grains. Therefore, tensile strength and hardness increase along with a reduction in ductility was noticed. Recrystallization annealing appears to give the best combination of ductility, strength and hardness for selective laser melted parts, whilst for equivalent wrought samples, increasing HT temperature results in reduction of mechanical properties. Originality/value The contributions of this paper are discussing the effect of different annealing on mechanical properties and microstructural evolution based on new ASTM standards for selective laser melted samples and comparing them with wrought parts.

The Effects of Thermal History on Toughness of Ni-Based Corrosion Resistant Alloys During In-Situ Hydrogen Charging

2021 ◽  
Author(s):  
Michelle Kent ◽  
Kip Findley
Keyword(s):  
Thermal History ◽  
Potential Drop ◽  
Heat Treatments ◽  
Alloy 718 ◽  
Unstable Crack ◽  
Heat Treated ◽  
Δ Phase ◽  
Incremental Step ◽  
M23c6 Carbides

Abstract Hydrogen embrittlement (HE) susceptibility was investigated for Alloy 718 and Alloy 945X specimens heat treated to a set of conditions within the specifications of API Standard 6ACRA. Heat treatments were selected to simulate the potential variation in thermal history in thick sections of bar or forged products and produce various amounts of discontinuous grain boundary δ phase in Alloy 718 and M23C6 carbides in Alloy 945X, while maintaining a constant hardness in the range of 35-45 HRC for Alloy 718 and 34-42 HRC for Alloy 945X. Time-temperature-transformation (TTT) diagrams and experimentation were used to select a set of heat treatments containing no δ phase, a small quantity of δ, and a larger quantity of δ in Alloy 718. The presence of δ phase has not been verified for the moderate condition. A similar approach was taken regarding M23C6 carbides in Alloy 945X. Incremental step loading (ISL) tests were conducted under in-situ cathodic charging on circular notch tensile (CNT) specimens in a 0.5 M H2SO4 solution. During the test, the direct current potential drop (DCPD) was measured across the notch to determine the stress intensity associated with unstable crack growth. Results indicate that even very small quantities of δ phase in Alloy 718 are detrimental to HE resistance. Both Alloy 718 and Alloy 945X show decreases in HE resistance with aging, with a greater degradation in Alloy 718.

New method to determine the mechanical properties of heat treated steels

2001 ◽  
Vol 43 (11) ◽  
pp. 2679-2697 ◽  
Author(s):  
A. Nayebi ◽  
O. Bartier ◽  
G. Mauvoisin ◽  
R. El Abdi
Keyword(s):  
Mechanical Properties ◽  
New Method ◽  
Heat Treated

Three Point Bend Performance of Solutionized, Die Quenched and Heat Treated AA7075 Beam Members

2014 ◽  
Vol 794-796 ◽  
pp. 431-436 ◽  
Author(s):  
Alexander Bardelcik ◽  
Alexandre Bouhier ◽  
Michael J. Worswick
Keyword(s):  
Mechanical Properties ◽  
Peak Load ◽  
Natural Aging ◽  
High Strength ◽  
Total Elongation ◽  
Strength Properties ◽  
Heat Treatments ◽  
Forming Process ◽  
Heat Treated ◽  
Point Bend

To overcome the low room temperature formability of AA7075-T6 aluminum sheet, without sacrificing the high strength properties of this alloy, a hat section beam member was formed and quenched within a cold die immediately after a 20 minute solutionizing treatment. Natural aging for 24 hours followed the forming process which was then followed by various heat treatments that included a typical precipitation hardening (PH) and industrial paint bake (PB) temperature-time treatment. Tensile specimens were extracted from the beams to evaluate their mechanical properties. When compared to the as-received AA7075-T6 mechanical properties, the beams heat treated with the PH, PHPB and PB treatment resulted in a 5%, 13% and 20% reduction in ultimate tensile strength respectively. A similar trend was shown for the yield strength measurements. There was little effect of the heat treatments on the total elongation, with the PH condition showing a slight improvement. A backing plate was riveted to the beams and a quasi-static 3 point bend test was conducted to evaluate the crush performance. The peak load for the PH, PHPB and PB beams was 9.2, 8.5 and 7.3 kN respectively, but the calculated energy-displacement (or energy absorption) curves were similar for the PH and PHPB parts due to a more ductile fracture behavior for the PHPB material condition.

scholarly journals Experimental Analysis of Nitrogen as an Alloying Element in WC9 Grade Steel

2017 ◽  
Vol 62 (3) ◽  
pp. 1889-1894 ◽  
Author(s):  
V. Vishnuh ◽  
S. Sudhakar ◽  
K. Tamilarasu ◽  
P. Prabhakaran ◽  
R. Rajasekar
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Yield Strength ◽  
Cost Analysis ◽  
Annealing Process ◽  
Solution Annealing ◽  
Alloying Element ◽  
Heat Treated ◽  
Solid Form ◽  
Grade Steel

AbstractIn the present work the effect of nitrogen on WC9 alloy at various weight percentages was analyzed and tested for their microstructural and mechanical properties. The nitrogen was added at 0.05, 0.10, 0.15, 0.20 and 0.25 wt. % in the solid form as nitrided ferrochrome to WC9 alloy. The samples were heat treated by solution annealing process at a temperature of 1100°C for 5 hours to improve the austenitic formation. Microstructures and mechanical properties such as tensile strength, yield strength, hardness, % elongation and % reduction of WC9-N alloy were examined. It was observed that increasing nitrogen wt. % increases the mechanical properties. The obtained mechanical properties were compared with base WC9 and C12A grade steel, where it was found to be replacement for C12A grade steel at its composition at lower end. The material cost analysis for WC9-N and C12A grade steel was done and both were compared.

Precipitation Behaviour and Mechanical Properties during Short-Term Heat Treatment for Tailor Heat Treated Profiles (THTP) of Aluminium Alloy 6060 T4

2016 ◽  
Vol 877 ◽  
pp. 400-406 ◽  
Author(s):  
Hannes Fröck ◽  
Matthias Graser ◽  
Benjamin Milkereit ◽  
Michael Reich ◽  
Michael Lechner ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Aluminium Alloy ◽  
Heat Treatments ◽  
Maximum Temperature ◽  
Short Term ◽  
Scanning Calorimetry ◽  
Heat Treated ◽  
Precipitation Behaviour ◽  
Dissolution And Precipitation

Precipitation hardening aluminium alloys are widely used for automotive applications. To enhance the application of aluminium profiles, improved formability is needed. Tailor Heat Treated Profiles (THTP) with locally different material properties attempt to increase formability e.g. in bending processes. Tailoring of local properties is obtained by a local short-term heat treatment, dissolving the initial precipitate state (retrogression) and still allowing subsequent ageing. In the present study, the dissolution and precipitation behaviour of the aluminium alloy EN AW-6060 T4 was investigated during heating with differential scanning calorimetry (DSC). Heating curves from 20 to 600 °C with heating rates of 0.01 up to 5 K/s were recorded. Interrupted heat treatments with different maximum temperatures were performed in a deformation dilatometer. Immediately afterwards, tensile tests were carried out at room temperature. The course of the recorded mechanical properties as a function of the maximum temperature is discussed with regard to the dissolution and precipitation behaviour during heating. Finally, the aging behaviour of the investigated alloy was recorded after different typical short-term heat treatments and is discussed with reference to the DSC‐curves. The correlation of the microstructure and the mechanical properties enables the derivation of optimal parameters for the development of THTP through a local softening.

Advanced β-Solidifying Titanium Aluminides – Development Status and Perspectives

2013 ◽  
Vol 1516 ◽  
pp. 3-16 ◽  
Author(s):  
Helmut Clemens ◽  
Martin Schloffer ◽  
Emanuel Schwaighofer ◽  
Robert Werner ◽  
Andrea Gaitzenauer ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Titanium Aluminides ◽  
Aircraft Engine ◽  
High Energy ◽  
Heat Treatments ◽  
Mechanical Processing ◽  
Tial Alloys ◽  
Precision Casting

ABSTRACTAfter almost three decades of intensive fundamental research and development activities intermetallic titanium aluminides based on the -TiAl phase have found applications in automotive and aircraft engine industries. The advantages of this class of innovative high-temperature materials are their low density as well as their good strength and creep properties up to 750°C. A drawback, however, is their limited ductility at room temperature, which is reflected by a low plastic strain at fracture. This behavior can be attributed to a limited dislocation movement along with microstructural inhomogeneity. Advanced TiAl alloys, such as β-solidifying TNM™ alloys, are complex multi-phase materials which can be processed by ingot or powder metallurgy as well as precision casting methods. Each production process leads to specific microstructures which can be altered and optimized by thermo-mechanical processing and/or subsequent heat-treatments. The background of these heat-treatments is at least twofold, i.e. concurrent increase of ductility at room temperature and creep strength at elevated temperature. In order to achieve this goal the knowledge of the occurring solidification processes and phase transformation sequences is essential. Therefore, thermodynamic calculations were conducted to predict phase fraction diagrams of engineering TiAl alloys. After experimental verification, these phase diagrams provided the base for the development of heat treatments to adjust balanced mechanical properties. To determine the influence of deformation and kinetic aspects, sophisticated ex- and in-situ methods have been employed to investigate the evolution of the microstructure during thermo-mechanical processing and subsequent multi-step heat-treatments. For example, in-situ high-energy X-ray diffraction was conducted to study dynamic recovery and recrystallization processes during hot-deformation tests. Summarizing all results a consistent picture regarding microstructure formation and its impact on mechanical properties in TNM alloys can be given.

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