Influence of Technology of Hot Forming of Plates from Aluminum Alloys Al-Cu-Li-Zn and Al-Zn-Mg-Cu on Resistance to Fatigue Fracture

2020 ◽  
Vol 22 (4) ◽  
pp. 94-109
Author(s):  
Kirill Zakharchenko ◽  
◽  
Vladimir Kapustin ◽  
Alexey Larichkin ◽  
Yaroslav Lukyanov ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Aluminum Alloys ◽  
Fatigue Fracture ◽  
Fatigue Failure ◽  
Strength Properties ◽  
Fatigue Tests ◽  
Measuring System ◽  
Fatigue Properties ◽  
Thick Plates ◽  
Pressure Shaping

Introduction. One of the primary objectives in the development of promising aircraft products is to reduce the weight of the aircraft structure. This problem can be solved by applying new low density materials such as aluminum alloys alloyed with lithium (for example, Al-Cu-Li-Zn) in the design of parts. The use of these materials in aircraft construction is limited by the processing technology, which must be such as not to damage the material and not reduce its strength properties. Such technologies include processing by pressure with heating, when creep processes are activated and the material passes into a state close to superplasticity. The purpose of the work: assessment of the effect of pressure shaping of aluminum alloys Al-Cu-Li-Zn and Al-Zn-Mg-Cu in creep mode on strength. The paper investigates the influence of the technology of pressure shaping of aluminum alloys Al-Cu-Li-Zn and Al-Zn-Mg-Cu on the resistance to fatigue failure. The work uses a method that allows to determine the ultimate stresses using diagrams of the accumulation of irreversible deformations; method of forming thick plates (40 mm) in the creep mode. The previously selected optimum temperatures for forming the plates are used. A non-contact coordinate measuring system is used to perform surface inspection after shaping. Fractography of the fracture of samples of alloy Al-Cu-Li-Zn and Al-Zn-Mg-Cu after fatigue failure is performed. Mathematical modeling of the deformation process of plates in creep mode is carried out in the MSC.Marc package. As a result, a conservative evaluation of the endurance limit for aluminum alloys Al-Cu-Li-Zn and Al-Zn-Mg-Cu is obtained. The shaping of thick plates in the creep mode is carried out. More than 80% of the board surface is formed with a deviation of less than 1 mm from the target size. Fatigue tests of samples made of molded panels of alloys Al-Cu-Li-Zn and Al-Zn-Mg-Cu are carried out, fatigue curves are plotted. The fractography of the surface of the fatigue fracture showed the presence of oxides in the samples of alloy Al-Cu-Li-Zn, in contrast to alloy Al-Zn-Mg-Cu. The results of fatigue tests are discussed, showing that the characteristics of the technological process of shaping and heat treatment do not deteriorate the fatigue properties of the investigated alloys. Comparative tests show that alloy Al-Cu-Li-Zn has higher fatigue characteristics. Mathematical modeling show that the use of the Boyle-Norton steady-state creep law is not enough to describe the process of plate forming. The necessity of setting the inverse problem of creep age forming is noted, where the coordinates of the punches of the loading device should act as boundary conditions.

Fatigue Properties and Fracture Characteristics of the Aluminum Alloys for High-Speed Train Carbody

2015 ◽  
Vol 1095 ◽  
pp. 437-441
Author(s):  
Fan Qiu ◽  
Qiang Li
Keyword(s):  
Tensile Strength ◽  
Aluminum Alloys ◽  
Fatigue Fracture ◽  
High Speed ◽  
Fatigue Cracks ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Fracture Characteristics ◽  
Initiation Zone ◽  
Propagation Zone

The fatigue tests on two types of domestic aluminum alloys were conducted and the P-S-N curves of both aluminum alloys were obtained. The microscopic characteristics at the fatigue fracture surface were observed with scanning electron microscopy. The results show that the tensile strength of A7 is 376MPa, while the tensile strength of A6 is 311MPa. The fatigue strength of A7 is 75MPa at 107 circles, and it is just a little higher than that of A6, which is 71.57MPa. The fatigue cracks initiated from or near the surface of the specimen. The fatigue fracture can be divided into three parts, namely, the initiation zone, the propagation zone and the sudden fracture zone. Typical characteristics could be observed on fracture surface.A6 has better plasticity than A7.

scholarly journals Evaluation of Fatigue Characteristics of Aluminum Alloys and Mechanical Components Using Extreme Value Statistics and C-specimens

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1915
Author(s):  
Jungsub Lee ◽  
Sang-Youn Park ◽  
Byoung-Ho Choi
Keyword(s):  
Aluminum Alloys ◽  
Fem Analysis ◽  
Extreme Value ◽  
Fatigue Tests ◽  
Extreme Value Statistics ◽  
Fatigue Properties ◽  
Chemical Compositions ◽  
Cross Sectional ◽  
Fatigue Characteristics ◽  
Mechanical Components

In this study, the fatigue characteristics of aluminum alloys and mechanical components were investigated. To evaluate the effect of forging, fatigue specimens with the same chemical compositions were prepared from billets and forged mechanical components. To evaluate the cleanliness of the aluminum alloys, the cross-sectional area of specimens was observed, and the maximum inclusion sizes were obtained using extreme value statistics. Rotary bending fatigue tests were performed, and the fracture surfaces of the specimens were analyzed. The results show that the forging process not only elevated the fatigue strength but also reduced the scatter of the fatigue life of aluminum alloys. The fatigue characteristics of C-specimens were obtained to develop finite-element method (FEM) models. With the intrinsic fatigue properties and strain–life approach, the FEM analysis results agreed well with the test results.

Experimental analysis of constant-amplitude fatigue properties in 6156 (Al-Mg-Si) sheet aluminum alloy

2018 ◽  
Vol 53 (8) ◽  
pp. 676-686
Author(s):  
Nikolaos D Alexopoulos ◽  
Evangelos Migklis ◽  
Dimitrios Myriounis
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Aluminum Alloys ◽  
Work Hardening ◽  
Endurance Limit ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Constant Amplitude ◽  
The Matrix ◽  
Fatigue Endurance

Fatigue mechanical behavior of wrought aluminum alloy (Al-Mg-Si) 6156 at T4 temper is experimentally investigated. Constant-amplitude fatigue tests, at fixed stress ratio R = 0.1, were carried out, and the respective stress–life diagram was constructed and compared against the competitive 6xxx aluminum alloys, for example, 6082 and 6061. Fatigue endurance limit of AA6156 was found to be approximately 155 ± 5 MPa, that is, almost 30% below yield stress Rp of the material. AA6156 presents almost 50% higher fatigue life in the high-cycle fatigue area and approximately 20% higher fatigue endurance limit, when compared with other 6xxx series aluminum alloys. Significant work hardening was induced due to fatigue and was experimentally validated by the measurements of residual stiffness of fatigue loops as well as of absorbed energy per fatigue loop. Work-hardening exponent was essentially decreased by almost 25% from the first fatigue cycles and up to 10% of fatigue life. Fracture surfaces of specimens loaded at applied stresses close to fatigue endurance limit exhibited signs of coarse voids due to the formed precipitates at the matrix. The fracture mechanism was a mixture of transgranunal and intergranular fracture for the fatigue specimens tested at higher applied fatigue loadings.

FATIGUE STRENGTH IMPROVEMENT BY PEENING TREATMENT IN DEGASSING PROCESSED CAST ALUMINUM ALLOYS

2006 ◽  
Vol 20 (25n27) ◽  
pp. 3593-3598 ◽  
Author(s):  
YASUO OCHI ◽  
KIYOTAKA MASAKI ◽  
TAKASHI MATSUMURA ◽  
YOHEI KUMAGAI ◽  
TATSUHIKO HAMAGUCHI ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Aluminum Alloys ◽  
Shot Peening ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Laser Peening ◽  
Cast Aluminum ◽  
Cast Aluminum Alloys ◽  
Rotating Bending Fatigue ◽  
Cast Alloys

Rotating bending fatigue tests were carried out in order to investigate effects of shot peening and laser peening treatment on fatigue properties of degassing processed cast aluminum alloys. Degassing was useful for decreasing cast defects and increasing the range of fatigue life and fatigue strength at 107 cycles compared with those of non-degassed cast alloys. The shot peening and the laser peening treatments also showed remarkable effects for increasing the resistance of crack propagation behaviors and improving the fatigue strength of the degassing processed cast aluminum alloys.

scholarly journals Corrosion Fatigue Fracture Characteristics of FSW 7075 Aluminum Alloy Joints

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4196
Author(s):  
Qingna Ma ◽  
Fei Shao ◽  
Linyue Bai ◽  
Qian Xu ◽  
Xingkun Xie ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Aluminum Alloys ◽  
Fatigue Fracture ◽  
Corrosion Fatigue ◽  
Weld Nugget ◽  
Fatigue Properties ◽  
Nugget Zone ◽  
Fracture Characteristics ◽  
Friction Stir ◽  
Secondary Cracks

The corrosion fatigue properties and fracture characteristics of friction stir welding joints of 7075 aluminum alloys were studied via corrosion fatigue tests, electrochemical measurements, and corrosion fatigue morphology and microstructure observations. The results show that the corrosion fatigue crack of the friction stir welding (FSW) joint of 7075 aluminum alloys originated in the junction zone between the thermomechanically affected zone and the weld nugget zone. The corrosion fatigue life of the joint decreased with increasing stress amplitude, with an S–N curve equation of lgN = 5.845 − 0.014S. Multiple crack sources were observed in the corrosion fatigue fracture. The main crack source originated from the corrosion pits at the interface between the thermomechanically affected zone and the weld nugget zone due to the influence of the coarse microstructure and the large potential difference between both zones. Corrosion morphologies of a rock candy block and an ant nest appeared in the crack propagation zone and the grain boundary of the weld nugget zone. In addition, fatigue speckles and intergranular fractures were observed, as well as brittle fracture characterized by cleavage steps and secondary cracks in the final fracture zone.

scholarly journals Microstructure and Fatigue Behavior of a Ni-Cu-Sn Alloy

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 888 ◽  
Author(s):  
Leonardo Bertini ◽  
Francesco Bucchi ◽  
Francesco Frendo ◽  
Renzo Valentini
Keyword(s):  
Fatigue Behavior ◽  
Load Ratio ◽  
Tensile Tests ◽  
Strength Properties ◽  
Fatigue Tests ◽  
Raw Material ◽  
Fatigue Properties ◽  
Test Results ◽  
Hardness Tests ◽  
Sem Analyses

In this paper, the static and fatigue properties of a Cu-Ni-Sn alloy are investigated. Tensile tests, hardness tests and microstructural analyses using optical and scanning electron microscopy (SEM) were performed and two sets of fatigue tests, with load ratio (R) R = − 1 and R = 0 , respectively, were carried out. The results showed the capability of the alloy to bear high static stress, thanks to its good strength properties. However, the fatigue tests showed a strong sensitivity of the alloy fatigue properties depending on the raw material batch. The comparison between microstructural analyses and fatigue test results showed a strong correlation; in particular, the specimens having a more inhomogeneous microstructure showed lower durability. In addition, the different microstructure also affected the fracture surface morphology as highlighted by SEM analyses.

Fatigue Properties of Surface-Micromachined Al-3%Ti Thin Films

2007 ◽  
Vol 353-358 ◽  
pp. 299-302
Author(s):  
Jun Hyub Park ◽  
Man Sik Myung ◽  
Yun Jae Kim
Keyword(s):  
Thin Film ◽  
Fatigue Strength ◽  
Fatigue Test ◽  
Rf Mems ◽  
Type Specimen ◽  
Fatigue Tests ◽  
Measuring System ◽  
Fatigue Properties ◽  
Test Machine ◽  
Ti Alloy

This paper describes new structure of specimen easy to manipulate, align and grip a thin-film and test machine for a fatigue test. High cycle fatigue test has been performed on tensile type specimen of Al-3%Ti alloy using the newly developed fatigue test machine. The material used in this study was Al-3%Ti thin film, which was used in RF MEMS switch. The structure of the suggested specimen has two holes and several bridges. The holes at centre of grip end are able to make alignment and gripping easy. The bridges are to remove the side support strip easily and extract specimen from wafer without sawing. The test machine was developed using the voice coil of speaker. The new tensile loading system has a load cell with maximum capacity of 0.5N and a non-contact position measuring system based on the principle of capacitance micrometry with 0.1nm resolution for displacement measurement. Fatigue tests was performed on 7 specimens. The thickness and width of the thin film of specimen are 1.0μm and 150μm, respectively. The fatigue strength coefficient and the fatigue strength exponent of Al-3%Ti alloy micro-sized specimen are determined to be 164MPa and -0.01322, respectively

scholarly journals Fatigue Properties of AZ31B Magnesium Alloy Processed by Equal-Channel Angular Pressing

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1191
Author(s):  
Ryuichi Yamada ◽  
Shoichiro Yoshihara ◽  
Yasumi Ito
Keyword(s):  
Magnesium Alloy ◽  
Equal Channel Angular Pressing ◽  
Low Cycle Fatigue ◽  
Annealed Sample ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Angular Pressing ◽  
Fundamental Research ◽  
Number Of Cycles ◽  
Biodegradable Magnesium

A stent is employed to expand a narrowed tubular organ, such as a blood vessel. However, the persistent presence of a stainless steel stent yields several problems of late thrombosis, restenosis and chronic inflammation reactions. Biodegradable magnesium stents have been introduced to solve these problems. However, magnesium-based alloys suffer from poor ductility and lower than desired fatigue performance. There is still a huge demand for further research on new alloys and stent designs. Then, as fundamental research for this, AZ31 B magnesium alloy has been investigated for the effect of equal-channel angular pressing on the fatigue properties. ECAP was conducted for one pass and eight passes at 300 °C using a die with a channel angle of 90°. An annealed sample and ECAP sample of AZ31 B magnesium alloy were subjected to tensile and fatigue tests. As a result of the tensile test, strength in the ECAP (one pass) sample was higher than in the annealed sample. As a result of the fatigue test, at stress amplitude σa = 100 MPa, the number of cycles to failure was largest in the annealed sample, medium in the ECAP (one pass) sample and lowest in the ECAP (eight passes) sample. It was suggested that the small low cycle fatigue life of the ECAP (eight passes) sample is attributable to severe plastic deformation.

Bending fatigue of single-wall and double-wall corrugated paperboards under sinusoidal and random loads

2021 ◽  
pp. 109963622110204
Author(s):  
Zhi-Wei Wang ◽  
Yang-Zhou Lai ◽  
Li-Jun Wang
Keyword(s):  
Energy Dissipation ◽  
Fatigue Failure ◽  
Fatigue Tests ◽  
Stiffness Degradation ◽  
Random Load ◽  
Bending Fatigue ◽  
Random Loads ◽  
Vibration Fatigue ◽  
Sinusoidal Load ◽  
Double Wall

The bending fatigue tests of single-wall and double-wall corrugated paperboards were conducted to obtain the εrms– N curves under sinusoidal and random loads in this paper. The εrms– N equation of corrugated paperboard can be described by modified Coffin–Manson model considering the effect of mean stress. Four independent fatigue parameters are obtained for single-wall and double-wall corrugated paperboards. The εrms– N curve under random load moves left and rotates clockwise compared with that under sinusoidal load. The fatigue life under random load is much less than that under sinusoidal load, and the fatigue design of corrugated box should be based on the fatigue result under random load. The stiffness degradation and energy dissipation of double-wall corrugated paperboard before approaching fatigue failure are very different from that of single-wall one. For double-wall corrugated paperboard, two turning points occur in the stiffness degradation, and fluctuation occurs in the energy dissipation. Different from metal materials, the bending fatigue failure of corrugated paperboard is a process of wrinkle forming, spreading, and folding. The results obtained have practical values for the design of vibration fatigue of corrugated box.

Fatigue Behaviour of Friction Stir Welded Steel Joints

2014 ◽  
Vol 891-892 ◽  
pp. 1488-1493 ◽  
Author(s):  
José Azevedo ◽  
Virgínia Infante ◽  
Luisa Quintino ◽  
Jorge dos Santos
Keyword(s):  
Base Material ◽  
Welding Process ◽  
Steel Structures ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Welded Steel ◽  
Shipbuilding Industry ◽  
Friction Stir ◽  
Steel Joints

The development and application of friction stir welding (FSW) technology in steel structures in the shipbuilding industry provide an effective tool of achieving superior joint integrity especially where reliability and damage tolerance are of major concerns. Since the shipbuilding components are inevitably subjected to dynamic or cyclic stresses in services, the fatigue properties of the friction stir welded joints must be properly evaluated to ensure the safety and longevity. This research intends to fulfill a clear knowledge gap that exists nowadays and, as such, it is dedicated to the study of welded steel shipbuilding joints in GL-A36 steel, with 4 mm thick. The fatigue resistance of base material and four plates in as-welded condition (using several different parameters, tools and pre-welding conditions) were investigated. The joints culminate globally with defect-free welds, from which tensile, microhardness, and fatigue analyses were performed. The fatigue tests were carried out with a constant amplitude loading, a stress ratio of R=0.1 and frequency between 100 and 120 Hz. The experimental results show the quality of the welding process applied to steel GL-A36 which is reflected in the mechanical properties of joints tested.

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