Effect of Microstructure on Crack of Al-Mg-Si Alloy Extrusions during Axial Compression

2006 ◽  
Vol 519-521 ◽  
pp. 895-900
Author(s):  
Keiji Morita ◽  
Shinji Yoshihara ◽  
Takashi Oka
Keyword(s):  
Grain Size ◽  
Crack Initiation ◽  
Rectangular Cross Section ◽  
Tensile Tests ◽  
Initiation Site ◽  
Mechanical Tests ◽  
Cracking Behavior ◽  
Microstructure Observation ◽  
Compressive Loads ◽  
Effect Of Microstructure

Effect of microstructure on micro-cracking behavior of Al-Mg-Si alloy extrusions during axial compressive deformation was studied. Extrusions of Al-Mg-Si alloys with two different compositions were used for the mechanical tests and microstructure observation. Compressive loads were applied parallel to the axes of the tubular specimens with rectangular cross section. As deformation proceeded, the specimens changed their shape into bellows-like ones. Specimens with finer grains showed higher critical strength and strain for crack initiation. Microscopic observation showed that cracks initiated at the bulge surface of the bellows and propagated into the depth. The observed behavior of crack initiation and propagation was interpreted in connection with those in simple tensile tests. The stress and strain at the crack initiation site of the bulge were assumed to correspond to the tensile strength of the alloy. The effect of grain size on the crack behavior was well explained by the grain size dependence of stress concentration at grain boundaries due to dislocation pile-ups. The effects of over-aging on the microstructure and crack initiation behavior were also discussed.

Effect of Frequency on the Fatigue Behavior of IN718 Superalloy

2017 ◽  
Vol 1142 ◽  
pp. 23-30 ◽  
Author(s):  
Jin Hui Du ◽  
Xu Dong Lu ◽  
Qun Deng
Keyword(s):  
Grain Size ◽  
Fatigue Life ◽  
Crack Initiation ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Low Frequency ◽  
Initiation Site ◽  
Fatigue Properties ◽  
Crack Initiation Site

IN718 alloy possesses excellent mechanical properties at high temperatures, good process ability, therefore, it has been widely used in aero engine turbine disks, compressor disks, and power turbine shafts (i.e., rotating components). The fatigue properties of the alloy are a key factor that determines the safety and reliability of the engine. In this paper, the fatigue properties of IN718 alloy are investigated under low-and middle-frequency conditions at 600 °C and 455 °C, the initiation of fatigue cracks, and the relation between fatigue life and grain size are discussed. The results show that the carbides response as a crack initiation site at low-frequency fatigue condition (1 Hz), and string-type or heap-type carbides distribution promotes crack propagation and shortens fatigue life, the twin boundaries in large grains are act as a crack initiation site at middle-frequency fatigue condition (10 Hz). The grain size is smaller, and the low cycle fatigue properties of the alloy are better.

scholarly journals Forecast of the fatigue crack initiation site of commercially pure Titanium miniature specimens with local surface topography data

2020 ◽  
Vol 321 ◽  
pp. 11008
Author(s):  
L. Böhme ◽  
F. Ströer ◽  
A. Keksel ◽  
J. Seewig ◽  
E. Kerscher
Keyword(s):  
Grain Size ◽  
Crack Initiation ◽  
Surface Topography ◽  
Fatigue Crack Initiation ◽  
Pure Titanium ◽  
Initiation Site ◽  
Commercially Pure Titanium ◽  
Crack Initiation Site ◽  
Average Grain Size ◽  
Cp Ti

Surfaces of technical components rarely appear in perfectly smooth condition. During fatigue loading, stress concentrations at surface asperities cause localized plastic deformation that can lead to crack initiation. Therefore, we have established a computer-aided method based on material ratio curves to investigate the possibility to predict the crack initiation site in fatigue tests by using detailed information on the local surface topography. The present study shows the results of investigations on the mutual influence of the average grain size and the surface condition on the fatigue behavior of commercially pure Titanium (cp-Ti) miniature specimens. Three cp-Ti states were investigated: two types of coarse-grained cp-Ti Grade 2 with 35 µm and with 100 µm average grain size and one ultrafine-grained cp-Ti Grade 4 state with less than 2.5 µm average grain size. Confocal microscopy provided the surface topography data of all specimens and data post-processing was applied to the topography in order to locate critical areas where crack initiation may preferentially occur. These areas were compared with the actual crack initiation areas in fatigue test. Finally, scanning electron microscopy (SEM) images of the fracture surfaces were studied to analyze fatigue crack initiation site and crack path of the three microstructural states.

scholarly journals The Investigation of Mechanical and Functional Properties and Microstructural Features of Coarse-Grained SME Ti49.0Ni51.0 Alloy during Multiple Martensitic Transformations and Annealing

2021 ◽  
Vol 346 ◽  
pp. 02011
Author(s):  
Anna Churakova ◽  
Elina Kayumova ◽  
Dmitry Gunderov
Keyword(s):  
Grain Size ◽  
Thermal Cycling ◽  
Yield Stress ◽  
Martensitic Transformations ◽  
Tensile Tests ◽  
Mechanical Tests ◽  
Coarse Grained ◽  
Initial State ◽  
Subsequent Aging ◽  
Mechanical Tensile

The paper was investigated the effect of preliminary multiple martensitic transformations on the microstructure and mechanical and functional stability during subsequent annealing in the range of aging temperatures of the Ti49.051.0 alloy in the coarse-grained state. The structure in the initial state has an austenitic structure with a grain size of 30 ± 5 μm; after TC, the structure is martensite with a grain size of 30 ± 5 μm. According to the results of mechanical tensile tests, thermal cycling leads to an increase in the yield stress, which is associated with the generation and accumulation of dislocations. An increase in the number of cycles to n = 100 led to a slight decrease in the yield stress, which may be due to the saturation effect during thermal cycling. Subsequent aging at T=400 °C after thermal cycling showed that the yield stress increases. At the same time, the results of mechanical tests showed that, in general, the preliminary TC (n = 100) with subsequent aging contributes to an increase in the yield strength and strength. The structure revealed after thermal cycling and subsequent low-temperature annealing confirms the precipitation of aging strengthening particles Ti3Ni4.

scholarly journals The Improvement of Impact on Manganese Steel for Bucket Tooth Product

2019 ◽  
Author(s):  
Eko Wismo Winarto ◽  
Suryo Darmo ◽  
Nugroho Santoso ◽  
Lilik Dwi Setyana
Keyword(s):  
Grain Size ◽  
Impact Strength ◽  
Induction Furnace ◽  
Mechanical Tests ◽  
Manganese Steel ◽  
Austenite Stability ◽  
Microstructure Observation ◽  
Average Grain Size ◽  
The Right ◽  
The Impact

The bucket tooth is one of an excavator components made of manganese steel used to dig and load land into a truck or elsewhere. The impact of the bucket tooth product needs to be increased so that it has longer lifetime. The objective of this research is to know the right composition of manganese in order to obtain the optimal impact strength. Varying the composition of manganese from 11,2% to 15,1% wt Mn are carried out in an induction furnace. Mechanical tests carried out include microstructure observation, impact and hardness testing. The structure of austenite dominates manganese steel with an average grain size of 60 μm (11,2% Mn) and increases up to 45% for the contents of 15,1% Mn. The lowest impact strength (0,08 J/mm2) in specimens with 11,2% Mn, increases up to 42% (0,142 J/mm2) in specimens with 15,1% Mn. The increase of impact strength is affected by grain size and austenite stability. The hardness of manganese steel with 11,2% Mn (330 VHN) increases up to 376 VHN with 15,1% Mn.

Effect of Previous Grain Size on Recystallization Texture and the Formability of the Nb Ferritic Stainless Steel

2016 ◽  
Vol 879 ◽  
pp. 1594-1599
Author(s):  
Daniella Gomes Rodrigues ◽  
Cláudio Moreira Alcântara ◽  
Dagoberto Brandão Santos ◽  
Tarcísio Reis de Oliveira ◽  
Berenice Mendonça Gonzalez
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Stainless Steel ◽  
Ferritic Stainless Steel ◽  
Longitudinal Section ◽  
Tensile Tests ◽  
Mechanical Tests ◽  
Planar Anisotropy ◽  
Electron Backscattered Diffraction ◽  
R Value

The ferritic stainless steels are materials used in several segments due to the excellent combination of mechanical properties and corrosion resistance. The mechanical properties of these alloys are strongly dependent on the microstructural characteristics and crystallography texture. The aim of this experimental study is to investigate the roles of the grain size of the hot rolled sample on the development of the microstructure, texture and formability of ferritic stainless steel. The main elements of chemical composition of the steel under investigation were 16.0 %Cr, 0.021 %C, 0.024 %N and 0.35 %Nb. Coarse and fine grains samples were cold rolled up to 90% thickness reduction and annealed at 880°C with soaking time of the 24 s. The texture measurements were performed by Electron Backscattered Diffraction (EBSD) in the longitudinal section. The formability was evaluated by the R-value and planar anisotropy (Δr) in tensile tests. The final microstructure after annealed was more homogenous for smaller initial grain size sample. This condition was favorable to develop γ-fiber, with sharpness intensity in 111121 components. The highest R-value and smallest planar anisotropy was obtained for a {111}/{001} ratio around 5.37. On the other hand, coarser initial grain size sample had showed a heterogeneous microstructure and texture, performing badly in mechanical tests (anisotropy).

High Cycle Fatigue Behavior of Eco7075-T73 Aluminum Alloy

2013 ◽  
Vol 690-693 ◽  
pp. 1775-1778 ◽  
Author(s):  
Gwan Yeung Kim ◽  
Kyu Sik Kim ◽  
Shae K. Kim ◽  
Young Ok Yoon ◽  
Kyu Sang Cho ◽  
...  
Keyword(s):  
Grain Size ◽  
Fatigue Behavior ◽  
Tensile Tests ◽  
Fatigue Properties ◽  
Homogeneous Distribution ◽  
Size Refinement ◽  
Microstructure Observation ◽  
Average Grain Size ◽  
7075 Alloy ◽  
Strengthening Phases

This study examined the microstructures, mechanical and fatigue properties of the recently developed Eco7075 alloy. Eco7075 is made using Eco-Mg (Mg-Al2Ca) in place of the element Mg during the manufacture of alloy 7075, having economically advantageous and superior properties. In the microstructure observation, average grain size was measured to be 5.2 μm. It consisted of Al matrix containing minute amounts of Al2CuMg, MgZn2, and Ca phases and showed microstructures with reduced amounts of Fe-based phases or oxides. Tensile tests exhibited that this alloy had yield strength of 492 MPa, tensile strength of 548 MPa, and elongation of 12.8%, which showed higher strengths than the conventional 7075 alloy but the similar elongation. Fatigue properties improved significantly compared to those of conventional 7075 alloys (Eco7075: fatigue limit of 330MPa). The superior tensile and fatigue properties of Eco7075-T73 alloy were mainly attributed to grain size refinement, homogeneous distribution of main strengthening phases, and reduced harmful phases of Fe-based intermetallic and oxide.

The Effect of Grain Size on Superplastic Deformation of Ti-6Al-4V Alloy

2007 ◽  
Vol 551-552 ◽  
pp. 387-392 ◽  
Author(s):  
Wen Juan Zhao ◽  
Hua Ding ◽  
D. Song ◽  
F.R. Cao ◽  
Hong Liang Hou
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Superplastic Deformation ◽  
Initial Strain Rate ◽  
Deformation Mode ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Coarse Grained ◽  
Transmission Electron ◽  
Grain Growth Model

In this study, superplastic tensile tests were carried out for Ti-6Al-4V alloy using different initial grain sizes (2.6 μm, 6.5μm and 16.2 μm) at a temperature of 920°C with an initial strain rate of 1×10-3 s-1. To get an insight into the effect of grain size on the superplastic deformation mechanisms, the microstructures of deformed alloy were investigated by using an optical microscope and transmission electron microscope (TEM). The results indicate that there is dramatic difference in the superplastic deformation mode of fine and coarse grained Ti-6Al-4V alloy. Meanwhile, grain growth induced by superplastic deformation has also been clearly observed during deformation process, and the grain growth model including the static and strain induced part during superplastic deformation was utilized to analyze the data of Ti-6Al-4V alloy.

Fabrication of Nanostructured Fe-Co Alloy Powders by Hydrogen Reduction and Its Magnetic Properties

2007 ◽  
Vol 534-536 ◽  
pp. 1389-1392
Author(s):  
Young Jung Lee ◽  
Baek Hee Lee ◽  
Gil Su Kim ◽  
Kyu Hwan Lee ◽  
Young Do Kim
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
Grain Size ◽  
Magnetic Properties ◽  
Nanostructured Materials ◽  
Hydrogen Reduction ◽  
Internal Strain ◽  
Oxide Powder ◽  
Powder Mixtures ◽  
Effect Of Microstructure

Magnetic properties of nanostructured materials are affected by the microstructures such as grain size (or particle size), internal strain and crystal structure. Thus, it is necessary to study the synthesis of nanostructured materials to make significant improvements in their magnetic properties. In this study, nanostructured Fe-20at.%Co and Fe-50at.%Co alloy powders were prepared by hydrogen reduction from the two oxide powder mixtures, Fe2O3 and Co3O4. Furthermore, the effect of microstructure on the magnetic properties of hydrogen reduced Fe-Co alloy powders was examined using XRD, SEM, TEM, and VSM.

Investigation of the Staging of Damage Accumulation in Polymer Composite Materials during Bending and Tensile Tests

2021 ◽  
Vol 887 ◽  
pp. 116-122
Author(s):  
A.A. Bryansky ◽  
O.V. Bashkov ◽  
Daria P. Malysheva ◽  
Denis B. Solovev
Keyword(s):  
Acoustic Emission ◽  
Composite Materials ◽  
Polymer Composite ◽  
Loading Rate ◽  
Tensile Tests ◽  
Mechanical Tests ◽  
Rate Effect ◽  
Polymer Composite Materials ◽  
Static Tension ◽  
Point Bend

The paper presents the results of the study of registered acoustic emission (AE) parameters during static deformation and damaging of polymer composite materials (PCM). Mechanical tests were done by a static tension and a static three-point bend, accompanied by an acoustic emission method. The assessment of the loading rate effect on defects formation processes was done by additional static tension test at rate equal half of recommended by the standard and static three-point bend test at rate ten times lower than that calculated by the standard. Clustering by frequency components of the recorded AE signals with a self-organizing Kohonen map was performed. The characteristics of the types of PCM structure damage by the centroids of the obtained clusters are given. Based on the clusters accumulation during mechanical tests, the stages of damage formation for static tension and static three-point bend, the loading rate effect on the process of damage formation are described.

Influence of Severe Plastic Deformation on the PLC Effect and Mechanical Properties in Al 5XXX Alloy

2006 ◽  
Vol 114 ◽  
pp. 171-176 ◽  
Author(s):  
Joanna Zdunek ◽  
Pawel Widlicki ◽  
Halina Garbacz ◽  
Jaroslaw Mizera ◽  
Krzysztof Jan Kurzydlowski
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Grain Size ◽  
Severe Plastic Deformation ◽  
True Strain ◽  
Tensile Tests ◽  
Size Reduction ◽  
Hydrostatic Extrusion ◽  
Stress Strain ◽  
Chatelier Effect

In this work, Al-Mg-Mn-Si alloy (5483) in the as-received and severe plastically deformed states was used. Plastic deformation was carried out by hydrostatic extrusion, and three different true strain values were applied 1.4, 2.8 and 3.8. All specimens were subjected to tensile tests and microhardness measurements. The investigated material revealed an instability during plastic deformation in the form of serration on the stress-strain curves, the so called Portevin-Le Chatelier effect It was shown that grain size reduction effected the character of the instability.

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