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Analysis and Verification of Physical Properties of an AISI 4140 Steel by Vickers Indentation Analysis According to the Presence of Residual Stresses

Jung Changho, Lee Moon G., Jeon Yongho

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 3

823--827

EN

Residual stress has a great influence on the metal, but it is difficult to measure at small area using a general method. Residual stress calculations using the Vickers indentation can solve this problem. In this paper, a numerical simulation has been made for the residual stress measurement method of metal material deformed by high-speed impact. Then, the stress-strain curve at the high-speed deformation was confirmed through actual experiments, and the residual stresses generated thereafter were calculated by the Vickers indenter method. A Vickers indentation analysis under the same conditions was performed at the position where a residual stress of about 169.39 MPa was generated. Experiments were carried out and high speed impact was applied to the specimen to generate residual stress. The obtained results indicate that it is possible to identify residual stresses in various metals with various shapes through Vickers indentation measurements, and to use them for process and quality control.

2

Modelling fatigue crack growth in HAZ of welded area

Gliha V., Hutsaylyuk V., Sniezek L., Vuherer T.

Archive of Mechanical Engineering

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2008

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Vol. LV, nr 4

389-403

EN

The small artificial surface defects in the coarse-grain steel are studied. The size of the used defects is smaller than the most relevant microstructural unit of steel, i.e. the average grain size. The samples of coarse-grain steel are prepared using a welding thermal-cycle simulator and a laboratory furnace. The defects are made by indenting with a Vickers pyramid. One of the final results of the defect making is the existence of local residual stresses. The influence of residual stresses on the crack initiation from those artificial defects is discussed in the article.

PL

W pracy dokonano analizy inicjacji pęknięć zmęczeniowych w obrębie defektu powierzchniowego w zamodelowanej strefie wpływu ciepła złącza spawanego elementów ze stali konstrukcyjnej. Próbki z pasmami ziaren o strukturze martenzytycznej wykonano z wykorzystaniem termocyklicznego symulatora spawania oraz pieca laboratoryjnego. Inicjator pękania wykonano w obszarze struktury gruboziarnistej za pomocą wgłębnika twardościomierza Vickersa, uzyskując lokalne spiętrzenie naprężeń. Wielkość uzyskanego odcisku nie przekraczała wielkości pojedynczego ziarna. Badane próbki poddano stałoamplitudowemu zginaniu z częstotliwością f podobne do 115 Hz, przy współczynniku asymetrii R podobne do 0. Otrzymane wyniki badań poddano analizie a pracę zakończono wnioskami.

3

Evaluation of cracks profile under the Vickers indentation

Blažková K., Jonšta Z., Mazanec K.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2007

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Vol. 321, z. 89

85-86

EN

This work is devoted to the investigation of indentation crack profiles under Vickers indentation on two types cutting tool ceramics. First type of ceramics was aluminium oxide with zirconium oxide and the second one was silicon nitride ceramics. Vickers indents are created into the ceramic surface by hardness testing machine with a load of 294 N, loading time of indentations is 10 s. The value of investigated ceramics A12O3 + ZrO2 is equal to 1765 HV and Si3N4 ceramics reaches the average hardness value of 1574 HV. After Vickers indentation a system of initiated cracks and deformed area are initiated. The attention of this work is given up to the experimental technique by using serial sectioning to obtain depth profile of indentation cracks. By using this method it is possible to obtain a complete system of crack profiles under the Vickers indent and shape of deformed area. Serial sectioning methods are consisted of removing thin layers of material by ceramographic polishing. For each layer three polishing steps with diamond suspension 6,3 and 1 nm were performed. Two different processes of removing material method layer-by-layer are used. The first method consists in obtaining depth profile of the crack determined by ablating in steps from the surface into which the indentations was made. Diagonals of Vickers indents are measured before consecutive polishing and between every polishing step. In the case where the indents are already ablated there is no way how to determine the depth of polishing. To prevent to lose the depth reference new indents have to be created into the specimen surface before ablating previous ones, The second technique is based on layer removal from plane perpendicular to the indented surface. According the results the second method is more precise because of easier control of removed material, obtaining real profile of cracks system and deformed area under the Vickers indent.

4

Surface microstructure of high performance concrete submit to abrasive wear

Horszczaruk E., Kasperkiewicz J.

Tribologia

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2006

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nr 5

43-55

EN

The paper presents the results of the examinations of the abrasive resistance of the seven types of high performance concrete (HPC) with compressive strength of 75-115 MPa. The abrasion resistance of concrete was evaluated according to "underwater method" (ASTM C 1138). In the analysis of the microstructure of concrete applied were Vickers microhardness measurements and SEM photography on abraded of HPC samples.

PL

Betony wysokowartościowe (BWW) są coraz częściej stosowane w konstrukcjach narażonych na erozję abrazyjną, np. w konstrukcjach hydrotechnicznych czy filarach mostów. W pracy przedstawiono wyniki badań odporności na zużycie ścierne siedmiu betonów wysokowartościowych, których skład modyfikowany był dodatkami włókien: stalowych i polipropylenowych. Na podstawie badań mikrostrukturalnych powierzchni próbek betonowych, które wcześniej poddane były zużyciu ściernemu, dokonano analizy wpływu zastosowanych włókien na odporność na zużycie ścierne badanych betonów. Badania mikrotwardości wykonano z zastosowaniem metody DSI oznaczając twardość Vickersa matrycy cementowej. Wykonano również badania mikrostruktury warstwy powierzchniowej próbek betonowych za pomocą mikroskopu skaningowego.