Effects of T5 and T6 Heat Treatments Applied to Rheocast A356 Parts for Automotive Applications

2008 ◽  
Vol 141-143 ◽  
pp. 237-242 ◽  
Author(s):  
Mario Rosso ◽  
Ildiko Peter ◽  
R. Villa
Keyword(s):  
Fatigue Behaviour ◽  
Cyclic Stress ◽  
Industrial Applications ◽  
Fatigue Tests ◽  
Controlled Cooling ◽  
Test Analysis ◽  
Heat Treated ◽  
Mechanical Performances ◽  
Semi Solid ◽  
Number Of Cycles

The correlation between the evaluation of the mechanical and of the fatigue behaviour of the rheocast, T5 and T6 heat treated SSM A356 aluminium alloy with respect to the microstructures of the component has been investigated. The study has been carried out on a suspension arm injected in a rheocasting 800 tons plant in Stampal S.p.A. The new rheocasting is a process that allows obtaining the alloys in a semisolid state directly from the liquid state, by controlled cooling of the molten alloys. The resulting microstructures are very fine, free from defects and homogeneous: these characteristics improve the mechanical properties of the alloys and specially the response to cyclic stress, an important issue for a suspension component. After a preliminary tensile test analysis, axial high frequency fatigue tests have been carried out at room temperature on specimen cut out from the suspension arm to determine the Wöhler curve and the number of cycles to failure. The results of this work allow a comparison of the effects of heat treatment process, T5 or T6, on Semi-Solid components for industrial applications in the automotive field. On the basis of these analysis the correlation between microstructure and mechanical performances can be established.

Low Cycle Fatigue Tests and Simulations on Steel Elbows

2013 ◽  
Author(s):  
Patricia Pappa ◽  
George E. Varelis ◽  
Spyros A. Karamanos ◽  
Arnold M. Gresnigt
Keyword(s):  
Finite Element ◽  
Low Cycle Fatigue ◽  
Local Strain ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Element Analysis ◽  
Out Of Plane ◽  
Strain Gauge Measurements ◽  
Number Of Cycles

In this paper the low cycle fatigue behaviour of steel elbows under strong cyclic loading conditions (in-plane and out-of-plane) is examined. The investigation is conducted through advanced finite element analysis tools, supported by real-scale test data for in-plane bending. The numerical results are successfully compared with the experimental measurements. In addition, a parametric study is conducted, which is aimed at investigating the effects of the diameter-to-thickness ratio on the low-cycle fatigue of elbows, focusing on the stress and strain variations. Strain gauge measurements are compared with finite element models. Upon calculation of local strain variation at the critical location, the number of cycles to fracture can be estimated.

Crack Initiation Under Low-Cycle Multiaxial Fatigue in Type 316L Stainless Steel

1983 ◽  
Vol 105 (2) ◽  
pp. 138-143 ◽  
Author(s):  
B. Jacquelin ◽  
F. Hourlier ◽  
A. Pineau
Keyword(s):  
Stainless Steel ◽  
Crack Initiation ◽  
Low Cycle Fatigue ◽  
Cyclic Stress ◽  
Fatigue Tests ◽  
Multiaxial Fatigue ◽  
Stage I ◽  
Type B ◽  
Strain Behavior ◽  
Number Of Cycles

Low-cycle fatigue tests corresponding to fatigue life range between 103 and 105 cycles were carried out at room temperature on one heat of 316 L austenitic stainless steel. These tests included: (i) reversed tension-compression, (ii) reversed tension-compression with a superimposed steady torque, (iii) pulsated tension-compression with a stress ratio (Rσ) such that −0.5<Rσ<0, (iv) reversed and pulsated tension-compression with a superimposed steady internal pressure. In tests (ii), the torsional ratcheting effect was measured. SEM observations were used to determine the number of cycles corresponding to Stage I crack initiation and the orientation of Stage I microcracks. It was observed that the in-depth growing Type B shear microcracks were most damaging. A simple criterion is proposed Ni=No(Δγp B)α•(σnB)β where Ni is the number of cycles to crack initiation, Δγp B is the range of plastic shear strain on Type B planes, σnB is the maximum normal stress acting on these planes, No,α and β are parameters adjusted from the Manson-Coffin law and reversed cyclic stress-strain behavior.

Impact of High-Pressure Gaseous Hydrogen on the Fatigue Behaviour of Austenitic Steel A-286 under Asymmetric Loading Conditions

2015 ◽  
Vol 664 ◽  
pp. 156-167
Author(s):  
Matthias Bruchhausen ◽  
Burkhard Fischer ◽  
Ana Ruiz ◽  
Peter Hähner ◽  
Sebstian Soller
Keyword(s):  
High Pressure ◽  
Pressure Vessel ◽  
Fatigue Behaviour ◽  
Sem Analysis ◽  
Fatigue Tests ◽  
Gaseous Hydrogen ◽  
R Ratio ◽  
Number Of Cycles ◽  
Standing Ultrasonic Wave ◽  
Short Time

Ultrasonic techniques are an established means for carrying out fatigue tests at very highnumbers of cycles. These techniques are based on the formation of a standing ultrasonic wave inthe specimen and usually use frequencies around 20 kHz. Although such systems allow testing to avery high number of cycles in a relatively short time, the use of a standing wave for creating thestrains restricts them to symmetric push-pull mode. This limitation can be overcome by coupling an ultrasonic test device to a universal test rig. In this work a different approach is presented that is particularly well suited for studying environmental effects. The load train with the specimen is enclosed in a pressure vessel. An acoustic horn divides this pressure vessel into two separate chambers. Applying a pressure difference between the two chambers then leads to a static stress in the specimenon which the oscillating stress from ultrasonic excitation is superposed. The addition of both stresses allows testing at varying R ratio. The deteriorating effect of high-pressure gaseous hydrogen on the steel A-286 is investigated as function of oscillating and static stresses at room temperature. SEM analysis of the fracture surface is presented.

Fatigue Tests on Aluminum Specimens Subjected to Constant and Random Amplitude Loadings

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Morteza Rahimi Abkenar ◽  
David P. Kihl ◽  
Majid T. Manzari
Keyword(s):  
Fatigue Life ◽  
Aluminum Alloys ◽  
Cyclic Stress ◽  
Fatigue Tests ◽  
Test Results ◽  
Number Of Cycles ◽  
Mechanical Devices ◽  
Cycles To Failure ◽  
Amplitude Versus ◽  
Weight Structures

Increasing interest in using aluminum as the structural component of light-weight structures, mechanical devices, and ships necessitates further investigations on fatigue life of aluminum alloys. The investigation reported here focuses on characterizing the performance of cruciform-shaped weldments made of 5083 aluminum alloys in thickness of 9.53 mm (3/8 in.) under constant, random, and bilevel amplitude loadings. The results are presented as S/N curves that show cyclic stress amplitude versus the number of cycles to failure. Statistical procedures show good agreements between test results and predicted fatigue life of aluminum weldments. Moreover, the results are compared to the results obtained from previous experiments on aluminum specimens with thicknesses of 12.7 mm (1/2 in.) and 6.35 mm (1/4 in.).

Low Cycle Fatigue Behaviour of GX12CrMoVNbN9 -1 Cast Steel at Room Temperature

2011 ◽  
Vol 291-294 ◽  
pp. 1106-1109 ◽  
Author(s):  
Grzegorz Golański ◽  
Krzysztof Werner ◽  
Stanisław Mroziński
Keyword(s):  
Heat Treatment ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Cast Steel ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Total Strain Amplitude ◽  
Cycle Fatigue ◽  
Number Of Cycles ◽  
Stabilization Period

The report treats of the low cycle fatigue (LCF) behaviour of GX12CrMoVNbN9-1 (GP91) cast steel after heat treatment (1040°C/12h/oil + 760°C/12h/air + 750°C/8h/furnace). Fatigue tests were carried out at room temperature for five levels of the controlled total strain amplitude εac = 0.25, 0.30, 0.35, 0.50 and 0.60 %. The research performed within the scope of LCF has shown in general that the investigated cast steel was subject to strong cyclic weakening, revealing no stabilization period at the same time. At the final stage of fatigue there was quick weakening of the material which proceeded till its destruction. The growth of amplitude εac resulted in reducing the number of cycles till the destruction stage.

Influence of Process-Related Defects on the Fatigue Behaviour of Welded Aluminium Joints at Very High Cycles

2014 ◽  
Vol 891-892 ◽  
pp. 1476-1481 ◽  
Author(s):  
Martin Cremer ◽  
Anton Kolyshkin ◽  
Martina Zimmermann ◽  
Hans Jürgen Christ
Keyword(s):  
Fatigue Life ◽  
Cross Sections ◽  
Base Material ◽  
Threshold Value ◽  
Fatigue Behaviour ◽  
Cyclic Stress ◽  
Fatigue Tests ◽  
Filler Material ◽  
Weld Defects ◽  
Very High

The influence of geometrical notch and weld defects (pores and incomplete fusions) on the fatigue behaviour at very high numbers of loading cycles is shown for welded samples made of the base material EN AW-5083 and EN AW-6082 and the filler material S Al 5183. High frequency fatigue tests with specimens highest stressed cross-sections representing different welding zones show no endurance limit up to 2·109 load cycles. The weakest link of the weld seams are the geometrical notch and (if present) pores and incomplete fusions in the seam interior and at the surface. Considering weld defects in the filler material as fatigue crack initiating notches, a threshold value for the cyclic stress intensity factor (ΔKmin) of 0.9 MPam was found. Using ΔKmin the fatigue life of the samples is discussed on the basis of stress amplitude, the projected area of the defect and its position. X-ray examinations revealed a good correlation between the failure-relevant defect areas and the overall fatigue life of welded samples.

scholarly journals Analytical Model for the Fatigue Analysis of Steel Joints by Clamps According to the Lever Length

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7726
Author(s):  
Manuel Cabaleiro ◽  
Rafael Comesaña ◽  
Cristina González-Gaya ◽  
Carlos Caamaño
Keyword(s):  
Fatigue Limit ◽  
Analytical Model ◽  
Steel Structure ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Original Structure ◽  
Iron And Steel ◽  
Number Of Cycles ◽  
Reconfigurable Structures ◽  
Steel Joints

Among the most commonly used materials in the construction of structures in the last two centuries are iron and steel. Clamp joints are a suitable type of joint when it is necessary to rehabilitate or modify a historical steel structure for new uses, reinforcing or modifying it with new beams, without the need to drill or weld on the original structure. The clamps allow beams to be joined with a flange (such as I-beams) without the need for any prior operation on the beams and allow the manufacture of completely removable and reconfigurable structures. Developing and analysing this type of fully removable and reconfigurable structure is necessary. To date, no studies have been carried out on the fatigue behaviour of steel joints by clamps, especially taking into account their main geometric characteristics, such as the size of the clamp levers. In this work, an analytical model is proposed that allows for the analysis of the number of cycles and the fatigue limit of clamp joints as a function of the size of the clamp levers. In addition, various fatigue tests are performed with different clamp sizes. The experimental results are compared with those obtained with the proposed methodology. Finally, the relationships between the lever length and the fatigue behaviour of the clamp joints have been determined. It is concluded that an increase in the size of the front lever is associated to a decrease in the fatigue limit. On the contrary, if the size of the rear lever is increased, the fatigue limit of the joint increases. In general, according to the obtained results, the resistance of the joint can be reduced to approximately one third when it is subjected to fatigue loads.

Fatigue Behaviour and Mechanical Properties of ECAP'ed and Thixoformed AA7075

2014 ◽  
Vol 33 (3) ◽  
pp. 277-285 ◽  
Author(s):  
Hasan Kaya ◽  
Mehmet Uçar
Keyword(s):  
Electron Microscope ◽  
High Hardness ◽  
Fatigue Behaviour ◽  
Optical Microscope ◽  
Fatigue Tests ◽  
Grain Structure ◽  
Angular Pressing ◽  
Ecap Process ◽  
Transmission Electron ◽  
Semi Solid

AbstractIn this study, the effects of thixoforming, both equal channel angular pressing (ECAP) and thixoforming on high cycle fatigue and fatigue surface morphology of AA7075 have been examined. Experiments are carried out with the same sample materials (AA7075) at a constant temperature (483 K) and the ``C'' route for 4 passes at ECAP process. In the process of thixoforming is 20 min at 888 K for waiting and 1 min at 673 K for pressing implemented. 140 MPa, 120 MPa and 100 MPa strength values were used at fatigue tests. The microstructural characterizations of the samples were carried out by using optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). This study is an attempt in detail to transformation fine and spherical grain structure with thixoforming process of minimized grain structure by ECAP. As a result of this study, it was seen that ECAP (1 pass) + semi-solid processing (SSP) applied samples have the highest hardness value (171 HV). When the values that are obtained after fatigue strength analyzed, SSP applied materials' property gave the best results and ECAP (1 pass) + SSP applied samples' results were second. When the both process applied materials' optimum values are investigated, it was observed that ECAP 1 pass + SSP applied material is more appropriate in terms of high hardness and fatigue life.

Evaluation of Fatigue Strength of Heat Treated and Laser Hardened 42CrMo4 Steel Considering Localized Initiation Mechanisms

2014 ◽  
Vol 606 ◽  
pp. 31-34
Author(s):  
Ivo Černý ◽  
Jiří Sís ◽  
Dagmar Mikulová
Keyword(s):  
Fatigue Strength ◽  
Residual Stresses ◽  
Fatigue Resistance ◽  
Fatigue Crack Initiation ◽  
Industrial Applications ◽  
Fatigue Tests ◽  
Laser Hardening ◽  
Basic Material ◽  
Heat Treated ◽  
42Crmo4 Steel

Laser surface hardening is an advanced method of surface treatment of structural steels with a great potential for wide industrial applications. According to the recent literature results and knowledge about laser hardening, fatigue resistance can be either reduced or increased, even considerably, depending on numerous parameters of basic material, the technology parameters etc. This contribution contains results of a partial study of effect of laser hardening of relatively small specimens on fatigue resistance of 42CrMo4 steel. Two different parameters of laser hardening were used, one of them resulted in considerable longitudinal residual stresses surface speed of laser beam 4 mm/s. Results of fatigue tests of basic reference material had a surprisingly high, atypical scatter, particularly in the region near fatigue limit. Fractographical analyses indicated that this scatter was connected with presence of single inclusions, even quite large, which in some cases caused fatigue crack initiation. Compressive residual stresses after the laser treatment improved fatigue strength and reduced the scatter, likely due to short crack retardation in the compressive residuals tress field. Further analyses and discussion are provided using Murakami method of fatigue life evaluation of materials containing defects.

Fatigue Behaviour of the Laminates Jute/Epoxy

2013 ◽  
Vol 682 ◽  
pp. 65-71
Author(s):  
A. Mir ◽  
C. Aribi ◽  
B. Bezzazi
Keyword(s):  
Mechanical Properties ◽  
Tensile Tests ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Natural Fibres ◽  
Mechanical Resistance ◽  
Static Tests ◽  
Vegetable Fibre ◽  
Static Mechanical ◽  
Number Of Cycles

Work presented is interested in the characterization of the quasistatic mechanical properties and in fatigue of a composite laminated in jute/epoxy. The natural fibres offer promising prospects thanks to their interesting specific properties, because of their low density, but also with their bio deterioration. Several scientific studies highlighted the good mechanical resistance of the vegetable fibre composites reinforced, even after several recycling. Because of the environmental standards which become increasingly severe, one attends the emergence of eco-materials at the base of natural fibres such as flax, bamboo, hemp, sisal, jute. The fatigue tests on elementary vegetable fibres show an increase of about 60% of the rigidity of elementary fibres of hemp subjected to cyclic loadings. In this study, the test-tubes manufactured by the method infusion have sequences of stacking of 0/90° and ± 45° for the shearing and tensile tests. The quasistatic tests reveal a variability of the mechanical properties of about 8%. The tensile fatigue tests were carried out for levels of constraints equivalent to half of the ultimate values of the composite. Once the fatigue tests carried out for well defined values of cycles, a series of static tests of traction type highlights the influence of the number of cycles on the quasi static mechanical behavior of the laminate jute/epoxy.

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