Investigation of Homogenization Process of the 5019 Alloy Extrusion Billets

2016 ◽  
Vol 682 ◽  
pp. 10-17 ◽  
Author(s):  
Antoni Woźnicki ◽  
Dariusz Leśniak ◽  
Grzegorz Włoch ◽  
Alicja Wojtyna ◽  
Monika Zabrzańska
Keyword(s):  
Cross Section ◽  
Cast Alloy ◽  
Solidus Temperature ◽  
Magnesium Concentration ◽  
Cast State ◽  
Dendritic Microstructure ◽  
Cast Material ◽  
Soaking Time ◽  
Prolonged Annealing ◽  
Microstructural Effects

In the paper, the influence of homogenization parameters on the microstructure and properties of the 5019 alloy DC-cast billets was analysed. At the first stage, the microstructure of the alloy in as-cast state was investigated using SEM/EDS technique. Additionally, a DSC test and hardness measurements were performed. In the as-cast material, the presence of the dendritic microstructure with a pronounced microsegregation of magnesium in the dendrites cross-section was found. Subsequently, the specimens were subjected to laboratory homogenization experiments, with different soaking conditions and water quenching. The microstructural effects of the investigated variants of homogenization were evaluated using the same techniques as in the case of the as-cast alloy. It was found that after homogenization, with soaking at the temperature of 530 °C for 6 hours, the microsegregation is eliminated and the concentration of magnesium in the grains centres is over two times greater than in the dendrites cores before annealing. The solidus temperature rises by about 12 °C in comparison to the as-cast state. Neither extending the soaking time nor rising the temperature contributes to a further increase of the solidus temperature, or the magnesium concentration in the grains interiors. However, the tendency of dispersoids to grow and the change of Fe-bearing constituents chemical composition were observed after the high temperature, or prolonged annealing variants.

Phase Transformation for Primary Particles in the Surface Regions of an AA1200 Alloy

2007 ◽  
Vol 539-543 ◽  
pp. 311-316 ◽  
Author(s):  
Tanja Pettersen
Keyword(s):  
Heat Treatment ◽  
Phase Transformation ◽  
Cross Section ◽  
Long Strings ◽  
Particle Type ◽  
Particle Structure ◽  
Cast Material ◽  
Cast Ingot ◽  
Primary Particles ◽  
Before And After

In the present investigation the particle structure in an AA1200 sheet ingot used for litho applications has been studied. Caustic etching of the as-cast material was seen to result in a zone close to the surface with a different etching response. This zone was identified as what is known as a fir-tree zone or an Altenpohl zone [1,2,3,4]. A variation in particle type over the cross section of the as-cast ingot was seen to follow the differences in etching response. After heat treatment of the material, the fir-tree zones were no longer visible, and the accompanying change in particle structure was studied. Samples from the subsurface regions and from a distance of ~20 cm from the surface has been investigated before and after heat treatment. In the as-cast material, the sample from the surface was dominated by featherlike particles with long strings of particles, identified as AlmFe. While closer to the centre Al3Fe and Al6Fe were seen to be the main phases, however, some AlmFe and probably some α-AlFeSi was also found in this sample. After heat treatment, the particle structure was seen to change, and the surface sample contained mainly Al3Fe in addition to a small amount of AlmFe. The change in particle structure during heat treatment is discussed with reference to the change in etching response.

scholarly journals The Applicability of Die Cast A356 Alloy to Additive Friction Stir Deposition at Various Feeding Speeds

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6018
Author(s):  
Bandar Alzahrani ◽  
Mohamed M. El-Sayed Seleman ◽  
Mohamed M. Z. Ahmed ◽  
Ebtessam Elfishawy ◽  
Adham M. Z. Ahmed ◽  
...  
Keyword(s):  
Grain Size ◽  
Cast Alloy ◽  
A356 Alloy ◽  
Deposition Process ◽  
Al Alloy ◽  
Cast Material ◽  
Mean Values ◽  
Friction Stir ◽  
Eutectic Si ◽  
Hardness Values

In the current investigation, additive friction stir-deposition (AFS-D) of as-cast hypoeutectic A356 Al alloy was conducted. The effect of feeding speeds of 3, 4, and 5 mm/min at a constant rotational speed of 1200 rpm on the macrostructure, microstructure, and hardness of the additive manufacturing parts (AMPs) was investigated. Various techniques (OM, SEM, and XRD) were used to evaluate grain microstructure, presence phases, and intermetallics for the as-cast material and the AMPs. The results showed that the friction stir deposition technique successfully produced sound additive manufactured parts at all the applied feeding speeds. The friction stir deposition process significantly improved the microstructure of the as-cast alloy by eliminating porosity and refining the dendritic α-Al grains, eutectic Si phase, and the primary Si plates in addition to intermetallic fragmentation. The mean values of the grain size of the produced AMPs at the feeding speeds of 3, 4, and 5 mm/min were 0.62 ± 0.1, 1.54 ± 0.2, and 2.40 ± 0.15 µm, respectively, compared to the grain size value of 30.85 ± 2 for the as-cast alloy. The AMPs exhibited higher hardness values than the as-cast A356 alloy. The as-cast A356 alloy showed highly scattered hardness values between 55 and 75.8 VHN. The AMP fabricated at a 3 mm/min feeding speed exhibited the maximum hardness values between 88 and 98.1 VHN.

scholarly journals Low neutron cross-section FeCrVTiNi based high-entropy alloys: design, additive manufacturing and characterization

2022 ◽  
Author(s):  
Bosheng Dong ◽  
Zhiyang Wang ◽  
Hanliang Zhu ◽  
Ondrej Muránsky ◽  
Zhijun Qiu ◽  
...  
Keyword(s):  
Mechanical Property ◽  
Additive Manufacturing ◽  
Cross Section ◽  
Neutron Cross Section ◽  
Nominal Composition ◽  
High Entropy Alloys ◽  
Contributing Factors ◽  
Dendritic Microstructure ◽  
High Entropy ◽  
Chemical Segregation

The development of high-entropy alloys (HEAs) based on the novel alloying concept of multi-principal components presents opportunities for achieving new materials with desired properties for increasingly demanding applications. In this study, a low neutron cross-section FeCrVTiNi-based HEA was developed for potential nuclear applications. A face-centred cubic (FCC) HEA with the nominal composition of FeCr0.4V0.3Ti0.2Ni1.3 is proposed based on the empirical thermodynamic models and the CALculation of PHAse diagrams (CALPHAD) calculation. Verifications of the predictions were performed, including the additive manufacturing of the proposal material and a range of microstructural characterizations and mechanical property tests. Consistent with the prediction, the as-fabricated HEA consists of a dominant FCC phase and minor Ni3Ti precipitates. Moreover, significant chemical segregation in the alloy, as predicted by the CALPHAD modelling, was observed experimentally in the produced dendritic microstructure showing the enrichment of Ni and Ti elements in the interdendritic regions and the segregation of Cr and V elements in the dendritic cores. Heterogenous mechanical properties, including microhardness and tensile strengths, were observed along the building direction of the additively manufactured HEA. The various solid solution strengthening effects, due to the chemical segregation (in particular Cr and V elements) during solidification, are identified as significant contributing factors to the observed mechanical heterogeneity. Our study provides useful knowledge for the design and additive manufacturing of compositionally complex HEAs and their composition-microstructure-mechanical property correlation.

scholarly journals On the evolution of microstructure and mechanical properties of type 316 austenitic stainless steel during ingot to billet conversion process

2021 ◽  
Author(s):  
Arthur Paquette ◽  
Salah Rahimi ◽  
Ioannis Violatos ◽  
Laurent Langlois ◽  
Christian Dumont ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Conversion Process ◽  
Fe Model ◽  
Dendritic Microstructure ◽  
Cast Material ◽  
Plastic Properties ◽  
Microstructure And Mechanical Properties ◽  
Evolution Of Microstructure

Manufacturing high value components involves complex and non-linear thermo-mechanical processes to obtain optimum combination of microstructure and mechanical properties required for the final part. Among these, the ingot-to-billet conversion process, involving forging operations of upsetting and cogging, are critical to refine the as-cast coarse, elongated, and dendritic microstructure. In this study, the first stage of the ingot-to-billet conversion process has been investigated in type 316 austenitic stainless steel, aiming to propose a novel methodology for the characterisation of the as-cast material behaviour. Hot upsetting tests were carried out on cylindrical samples taken out from an industrial-scale ingot. The resulted microstructures were analysed, using advanced image analysis method, for the fraction and distribution of the recrystallised grains, highlighting the strong dependency of recrystallisation behaviour on the initial microstructure of the as-cast material. Using a finite element (FE) model considering the anisotropic behaviour of the material, originated from the preferential grain growth during casting, the deformation of the samples were predicted with a good accuracy. The results demonstrate the importance of considering the anisotropic plastic properties in the FE models to effectively predict the as-cast material deformation, shape and thus the thermo-mechanical characteristics applied during forging.

scholarly journals Fabrication and Characterization of the Newly Developed Superalloys Based on Inconel 740

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2362 ◽  
Author(s):  
Małgorzata Grudzień-Rakoczy ◽  
Łukasz Rakoczy ◽  
Rafał Cygan ◽  
František Kromka ◽  
Zenon Pirowski ◽  
...  
Keyword(s):  
Solidus Temperature ◽  
Chemical Compositions ◽  
Scanning Calorimetry ◽  
Dendritic Microstructure ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Fabrication And Characterization ◽  
The Difference

The chemical composition of standard Inconel 740 superalloy was modified by changes in the Al/Ti ratio (0.7, 1.5, 3.4) and addition of Ta (2.0, 3.0, 4.0%). Remelted Inconel 740 (A0) and nine variants with various chemical compositions were fabricated by lost-wax casting. The microstructure, microsegregation, phase transformation temperatures, thermal expansion coefficients and hardness of the superalloys were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, differential scanning calorimetry, dilatometry and Vickers measurements. Typical dendritic microstructure was revealed with microsegregation of the alloying elements. Segregation coefficient ki for Ti, Nb and Ta did not exceed unity, and so precipitates enriched mainly in these elements were found in interdendritic spaces. The Nb-rich blocky precipitates, MC carbides, MN nitrides, oxides, and fine γ’ was in all modified castings. Presence of other microstructural features, such as Ti-rich needles, eutectic γ-γ’ islands, small Al-rich and Cr-rich precipitates depended on the casting composition. The lowest solidus and liquidus temperatures were observed in superalloys with a high Al/Ti ratio. Consequently, in A7–A9 variants, the solidification range did not exceed 100 °C. In the A0 variant the difference between liquidus and solidus temperature was 138 °C. Hardness of all modified superalloys was at least 50% higher than for the remelted Inconel 740 (209 HV10).

Preparation of Non-Dendritic Microstructure of AZ31 Alloy Using Isothermal Heat Treatment of the Refined Billet

2014 ◽  
Vol 1030-1032 ◽  
pp. 147-150
Author(s):  
Bo Xing
Keyword(s):  
Cast Alloy ◽  
Az31 Alloy ◽  
Production Method ◽  
Mg Alloy ◽  
Semisolid Slurry ◽  
Isothermal Heat Treatment ◽  
Dendritic Microstructure ◽  
Alloy Base ◽  
Result Show ◽  
Holding Temperature

Semisolid metal forming (SSF) has been regarded as a potential process to shape the wrough Mg alloy base on the thixotropy and low deformation resistance of non-dendritic semisolid slurry. Therefore, it is necessary to develop the slurry production method of wrought Mg alloy as most current researches are focused on the cast alloy. In this paper, the AZ31 billet was refined by the self-inoculation method, and the partialy remelt method was employed to produce the non-dendritic microstructure. Results indicate that both the morphology and size of the primary Mg phase in AZ31 were refined by the grain refining treatment. When the billet were reheated under 595°C and 610°C with different holding times, the morphology of primary Mg phase undergo an evolution pattern from rosette or tiny dendritic to spherical, and with the prolonged holding time, the size of primary Mg phase increased and the shape turn to irregular. Moreover, the result show that the high holding temperature shorten the evolution time from irregular to spherical and the deteriorative grains obtained earlier compared to the low holding temperature.

Grain growth and the microstructural effects on the properties of YBa2Cu3O7−y superconductor

1990 ◽  
Vol 5 (9) ◽  
pp. 1819-1826 ◽  
Author(s):  
C. T. Chu ◽  
B. Dunn
Keyword(s):  
Liquid Phase ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Tetragonal Phase ◽  
Sintering Temperature ◽  
Oxygen Stoichiometry ◽  
Microstructural Development ◽  
Prolonged Annealing ◽  
Microstructural Effects ◽  
Oxygenation Rate

The microstructural development and grain growth of YBa2Cu3O7−y ceramics at 925, 950, and 975 °C were studied. Densification occurred quite rapidly at temperatures below 925 °C. The grain growth of YBa2Cu3O7−y followed a D5 − D50 = Kt relation when sintered at 925 and 950 °C. At 975 °C, the kinetics changed to cubic (D3) behavior, which can be attributed to the formation of a liquid phase at grain boundaries. A trend of decreasing Jc with increasing sintering temperature was observed. Other properties including Tc and the width of the transition were virtually unaffected by the change in microstructure. Without prolonged annealing, a relatively homogeneous oxygen stoichiometry of 6.8 was obtained for fairly dense samples (>93% of theoretical). These results suggest that the oxygenation rate of YBa2Cu3O7−y was quite rapid between the tetragonal phase and the orthorhombic composition of YBa2Cu3O6.8.

Mechanical Milling of Quasicrystalline Al-Cu-Fe Alloys

2014 ◽  
Vol 794-796 ◽  
pp. 761-765
Author(s):  
Pavel Bryantsev ◽  
Marina Samoshina
Keyword(s):  
Mechanical Milling ◽  
Cast Alloy ◽  
Coherent Scattering ◽  
Argon Atmosphere ◽  
Quasicrystalline Phase ◽  
Cast State ◽  
Graphite Mold ◽  
Alloy Particles ◽  
Fe Alloys ◽  
Average Size

Ingots of alloys Al-Cu-Fe were obtained by casting in a graphite mold. Mechanical milling of alloy particles in the as-cast state and after homogenization annealing was carried out in planetary ball mill Retsch PM400 in an argon atmosphere. As a result of mechanical milling granules with an average size of 35-40 μm and fine internal microstructure are formed. The size of coherent scattering regions in quasicrystalline phase after mechanical milling was about 10-15 nm. Mechanical milling after homogenization heat treatment allows much refines the quasicrystalline phase than in the case of mechanical milling of cast alloy.

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