Gigacycle Fatigue Behaviour of Sintered WC-Co Hardmetals Investigated by Ultrasonic Resonance Testing

2015 ◽  
Vol 825-826 ◽  
pp. 1016-1023
Author(s):  
Agnieszka Betzwar Kotas ◽  
Brigitte Weiss ◽  
Herbert Danninger
Keyword(s):  
Powder Metallurgy ◽  
Fatigue Limit ◽  
Fatigue Testing ◽  
Fatigue Behaviour ◽  
Horizontal Branch ◽  
Loading Cycle ◽  
Tool Materials ◽  
Ultrasonic Resonance ◽  
Ultrasonic Fatigue ◽  
Percussion Drilling

Hardmetals, manufactured from powders by pressing and sintering, are the most important tool materials in service today. In many applications, such as milling or percussion drilling, they are subjected to fatigue with considerable loading cycle numbers. In the present study, the fatigue behaviour of hardmetals in push-pull loading was investigated up to Nmax= 1010using ultrasonic resonance fatigue testing. It showed that with all hardmetal grades investigated there is no fatigue “limit”, i.e. a horizontal branch of the S-N curve, but a consistent drop of the curve up to maximum N. Crack initiation was found to occur predominantly microstructure-controlled, as compared to defect controlled as typical for powder metallurgy tool steels.Keywords: gigacycle fatigue, WC-Co hardmetals, ultrasonic fatigue testing, fatigue limit

Influence of Frequency and Testing Technique on the Fatigue Behaviour of Quenched and Tempered Steel in the VHCF-Regime

2014 ◽  
Vol 891-892 ◽  
pp. 1430-1435 ◽  
Author(s):  
Norbert Schneider ◽  
Brita Pyttel ◽  
Christina Berger ◽  
Matthias Oechsner
Keyword(s):  
High Frequency ◽  
Fatigue Testing ◽  
Testing Machine ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Frequency Effect ◽  
Low Frequencies ◽  
Ultrasonic Fatigue ◽  
Quenched And Tempered Steel ◽  
Tempered Steel

Today in many cases ultrasonic testing machines with a frequency of f ≈ 20 kHz are used for investigations of the fatigue behaviour up to the very high cycle regime (VHCF-regime). A question that arises is if the results of these high frequency fatigue tests are comparable to conventional fatigue tests. This paper compares the fatigue behaviour of a quenched and tempered steel 50CrMo4 in two different tempered conditions investigated at low frequencies (f ≤ 400 Hz) on a servohydraulic testing machine and at a high frequency (f ≈ 20 kHz) on an ultrasonic fatigue testing machine. Effects which can occur because of the different testing techniques and testing frequencies are investigated. A concept is derived to describe the frequency effect caused by the strain rate. The estimations are compared with results of the fatigue tests.

scholarly journals Study of the fatigue behaviour of synthetic nodular cast irons at low and high frequency cyclic loading

2018 ◽  
Vol 157 ◽  
pp. 07014 ◽  
Author(s):  
Alan Vaško ◽  
Juraj Belan ◽  
Eva Tillová
Keyword(s):  
Cyclic Loading ◽  
High Frequency ◽  
Fatigue Testing ◽  
Low Frequency ◽  
Nodular Cast Iron ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Cast Irons ◽  
Ultrasonic Fatigue ◽  
The Relationship

The paper presents the results of low and high frequency fatigue tests carried out on nodular cast iron. The specimens of synthetic nodular cast irons from three different melts were studied in the high cycle fatigue region (from 105 to 108 cycles) using fatigue experimental equipments for low and high frequency cyclic loading. Low frequency fatigue tests were carried out at frequency f ≈ 120 Hz using the fatigue experimental machine Zwick/Roell Amsler 150HFP 5100. High frequency fatigue tests were carried out at frequency f ≈ 20 kHz using the ultrasonic fatigue testing device KAUP-ZU. Both of them were carried out at sinusoidal cyclic push-pull loading (stress ratio R = -1) at ambient temperature (T ≈ 20 °C). The relationship σa = f (N) and fatigue strengths were determined experimentally; mechanical properties, microstructures and fracture surfaces were investigated.

ULTRASONIC FATIGUE BEHAVIOR OF A Fe-BASED WARM-COMPACTED POWDER METALLURGY MATERIAL

2013 ◽  
Vol 27 (19) ◽  
pp. 1341027
Author(s):  
YU-HENG LU ◽  
XUAN YE ◽  
LEI HU ◽  
FEI LUO ◽  
ZHI-YU XIAO
Keyword(s):  
Heat Treatment ◽  
Powder Metallurgy ◽  
Fatigue Strength ◽  
Fatigue Test ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Powder Metallurgy Material ◽  
Ultrasonic Fatigue ◽  
Ultrasonic Fatigue Test ◽  
Axial Fatigue

Fe -2 Cu -2 Ni -1 Mo -1 C powder metallurgy material was fabricated by die-wall lubricated warm compaction and ultrasonic fatigue test was carried out for as-sintered and heat treatment samples. Material fatigue strength reaches 249 MPa under axial fatigue testing. The sintered material consists of acicular martensite, pearlite, bainite and retained austenite. Tempered martensite is the major phases after heat-treatment. Cleavage plane and dimples is mixed fracture for sample after axial fatigue test. Mechanical properties of after heat treatment materials are improved and fatigue strength reaches 382 MPa under 107 cycles in bending ultrasonic fatigue test. The fatigue strength increases significantly in high cycles range.

Ultrasonic fatigue testing in the scanning electron microscope

2016 ◽  
Vol 58 (2) ◽  
pp. 97-101 ◽  
Author(s):  
Marcus Söker ◽  
Michael Galster ◽  
Ulrich Krupp ◽  
Benjamin Dönges
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Fatigue Testing ◽  
Ultrasonic Fatigue ◽  
Scanning Electron

scholarly journals Ultrasonic fatigue testing in as-built and polished Ti6Al4V alloy manufactured by SLM

2021 ◽  
pp. 100024
Author(s):  
Pedro R. da Costa ◽  
Manuel Sardinha ◽  
Luís Reis ◽  
Manuel Freitas ◽  
Manuel Fonte
Keyword(s):  
Fatigue Testing ◽  
Ti6al4v Alloy ◽  
Ultrasonic Fatigue

A new method for ultrasonic fatigue testing of equibiaxial and pure shear cruciform specimens

2021 ◽  
pp. 106423
Author(s):  
Pedro R. da Costa ◽  
Luís Reis ◽  
Diogo Montalvão ◽  
Manuel Freitas
Keyword(s):  
Fatigue Testing ◽  
Pure Shear ◽  
New Method ◽  
Ultrasonic Fatigue

Gigacycle Fatigue of Welded Joints of Structural Materials (A Review)

2016 ◽  
Vol 17 ◽  
pp. 14-30 ◽  
Author(s):  
Okechukwu P. Nwachukwu ◽  
Alexander V. Gridasov ◽  
Ekaterina A. Gridasova
Keyword(s):  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Testing Machine ◽  
Structural Materials ◽  
Fatigue Tests ◽  
Material Defects ◽  
Graphite Cast Iron ◽  
Ultrasonic Fatigue ◽  
Materials Used ◽  
Fatigue Failures

This review looks into the state of gigacycle fatigue behavior of some structural materials used in engineering works. Particular attention is given to the use of ultrasonic fatigue testing machine (USF-2000) due to its important role in conducting gigacycle fatigue tests. Gigacycle fatigue behavior of most materials used for very long life engineering applications is reviewed.Gigacycle fatigue behavior of magnesium alloys, aluminum alloys, titanium alloys, spheroid graphite cast iron, steels and nickel alloys are reviewed together with the examination of the most common material defects that initiate gigacycle fatigue failures in these materials. In addition, the stage-by-stage fatigue crack developments in the gigacycle regime are reviewed. This review is concluded by suggesting the directions for future works in gigacycle fatigue.

A Comparative Study on Infrared Thermography during Ultrasonic Fatigue Testing of Cast Steel 42CrMo4 and Cast Aluminium Alloy AlSi7Mg

2013 ◽  
Vol 592-593 ◽  
pp. 501-504 ◽  
Author(s):  
Dominik Krewerth ◽  
Anja Weidner ◽  
Horst Biermann
Keyword(s):  
Aluminium Alloy ◽  
Infrared Thermography ◽  
Fatigue Testing ◽  
Cast Steel ◽  
Material Testing ◽  
Initiation Point ◽  
Testing Method ◽  
Cast Aluminium ◽  
Ultrasonic Fatigue ◽  
Non Destructive

The present paper illustrates a comparison of infrared thermography during ultrasonic fatigue testing of cast steel 42CrMo4 and cast aluminium alloy AlSi7Mg. Against the background of different material properties (e.g. mechanical properties as well as thermal properties) the benefit of this non-destructive material testing method in terms of determining the crack initiation point and time during fatigue testing as well as crack propagation is evaluated and discussed. Moreover, correlations between fractography and infrared thermography are performed for both materials.

scholarly journals Experimental Evidence of Specimen-Size Effects on EN-AW6082 Aluminum Alloy in VHCF Regime

2021 ◽  
Vol 11 (9) ◽  
pp. 4272
Author(s):  
Stefano Invernizzi ◽  
Francesco Montagnoli ◽  
Alberto Carpinteri
Keyword(s):  
Aluminium Alloy ◽  
Cross Section ◽  
Fatigue Testing ◽  
Testing Machine ◽  
Experimental Tests ◽  
Theoretical Explanation ◽  
Specimen Size ◽  
Section Surface ◽  
Middle Cross Section ◽  
Ultrasonic Fatigue

The present paper investigates the influence of the specimen size of EN-AW6082 wrought aluminium alloy subjected to very high cycle fatigue (VHCF) tests. The hourglass specimens were tested under fully reversed loading condition, up to 109 cycles, by means of the ultrasonic fatigue testing machine developed by Italsigma® (Italy). Three specimens groups were considered, with a diameter in the middle cross-section ranging from 3 mm up to 12 mm. The stress field in the specimens was determined numerically and by strain gauge measurements in correspondence of the cross-section surface. The dispersion of experimental results has been accounted for, and data are reported in P-S-N diagrams. The decrease in fatigue resistance with increasing specimen size is evident. Theoretical explanation for the observed specimen-size effect is provided, based on Fractal Geometry concepts, allowing to obtain scale independent P-S*-N curves. The fatigue life expectation in the VHCF regime of the EN-AW6082 aluminium alloy full-scale components is rather overestimated if it is assessed only from standard small specimens of 3 mm in diameter. Experimental tests carried out on larger specimens, and a proper extrapolation, are required to assure safe structural design.

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