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1

Surface Characteristics and Wear Resistance of 316L Stainless Steel after Different Shot Peening Parameters

100%

Walczak M.

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tom Vol. 17, no 3

124--132

EN

The study was conducted to evaluate the effect of ZrO2-based ceramic beads shot peening on the performance properties of AISI 316L austenitic steel. The results obtained in the roughness and microhardness measurements, the state of the surface layer, and the tribological properties (ball-on-disc) of the specimens after the peening process were compared to the results obtained for the reference specimen. The tests were carried out with varying parameters of pressure (0.3 MPa, 0.4MPa) and time (30s, 60s). The lowest values of COF (µ=0.576) and wear factor (K=3.95*10-4 mm3N-1m-1) were observed for the surface peened using parameters: 0.4 MPa and 60s. By increasing the time twice, a much lower wear factor can be achieved unlike when increasing the shot peening by 0.1 MPa. Observations of wear traces indicate that abrasive wear is predominant and the transfer of specimen material by countersample is also observed.

2

Effect of the shot peening on surface properties of Ti-6Al-4V alloy produced by means of DMLS technology

51%

Żebrowski R. , Walczak M. , Klepka T. , Pasierbiewicz K.

Eksploatacja i Niezawodność

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2019

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tom Vol. 21, no. 1

46--53

EN

The state of the surface layer and biocompatibility are the key parameters contributing to successful implantation of prostheses such as bone implants which are now increasingly often produced by means of DMLS technologies. The analysis of these factors and proper selection of material are required in order to determine the most favourable technological parameters contributing to long term functioning in course of their presence in human body. Therefore, the purpose of the present paper is to investigate the effect of shot peening on the state of the surface layer and corrosion resistance of specimens made of Ti-6Al-4V titanium alloy produced in Direct Metal Laser Sintering (DMLS) process. The specimens have been produced by means of EOSINT M280 system dedicated for laser sintering of metal powders and their surfaces have been subjected to the shot peening process under three different working pressures (0.2, 0.3 and 0.4 MPa) and by means of three different media i.e. CrNi steel shot, crushed nut shells and ceramic balls based on ZrO2. It has been found that the process conditions i.e. working pressure in course of shot peening and proper selection of applied shot will make it possible to achieve the properties in modified material sufficient to ensure that assumed functions associated with the improvement of surface layer condition are invariable during required period in specified implant operation conditions. In such case, these factors have been determined in course of microhardness tests, evaluation of surface development degree as well as potentiodynamic tests. The increase of working pressure caused deteriorated corrosion resistance. Simultaneously, it has been found the corrosion resistance was most satisfactory for the surfaces modified by means of: ceramic balls based on ZrO2 > crushed nut shells > CrNi steel shot correspondingly.

PL

Stan warstwy wierzchniej i biozgodność to podstawowe czynniki mające wpływ na efektywną implantację. W przypadku wyrobów medycznych takich jak: implanty kostne, które obecnie są coraz częściej wytwarzane z wykorzystaniem technologii przyrostowych, analiza tych czynników oraz właściwy dobór materiału jest niezbędny do określenia najbardziej korzystnych parametrów technologicznych przyczyniających się do długotrwałego działania podczas ich eksploatacji w organizmie. Dlatego też celem niniejszego artykułu jest zbadanie wpływu obróbki nagniataniem strumieniowym (ang. shot peening), na stan warstwy wierzchniej i odporność korozyjną próbek ze stopu tytanu Ti-6Al-4V wytworzonych technologią przyrostową DMLS (Direct Metal Laser Sintering). Przy zastosowaniu systemu laserowego spiekania proszków metali EOSINT M280 wykonano próbki, których powierzchnie następnie poddano obróbce nagniatania strumieniowego przy trzech rożnych ciśnieniach roboczych (0.2, 0.3 i 0.4 MPa) z wykorzystaniem trzech różnych mediów tj.: śrutem ze stali CrNi, rozdrobnionymi łupinami orzechów oraz kulkami ceramicznymi na bazie ZrO2. Stwierdzono dla wszystkich badanych powierzchni, że warunki procesu tj. ciśnienia roboczego obróbki nagniataniem strumieniowym oraz odpowiedni dobór śrutu pozwolą na uzyskanie takich właściwości w modyfikowanym materiale, że założone funkcje poprawy stanu warstwy wierzchniej będą niezmienne przez wymagany czas w określonych warunkach eksploatacji implantu. W tym przypadku wskaźniki te określono podczas badań mikrotwardości, oceny stopnia rozwinięcia powierzchni oraz testów potencjodynamicznych. Wzrost ciśnienia roboczego powodował pogorszenie odporności na korozję. Przy czym najbardziej korzystnie pod względem odporności korozyjnej zachowywały się powierzchnie modyfikowane kolejno: ceramiką na bazie ZrO2> łupinami orzechów> śrutem stalowym CrNi.

3

Effect of Water Absorption on Tribological Properties of Thermoplastics Matrix Composites Reinforced with Glass Fibres

51%

Walczak M. , Szala M. , Pieniak D.

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2022

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tom Vol. 16, no 2

232--239

EN

The present work investigated the water absorption of thermoplastic matrix composites and their effect on tribological behaviour. Four thermoplastic composites were researched based on Polyamide 6 and Polyamide 66 matrix reinforced with glass fibres. The composites fabricated using the injection moulding technique were immersed in distilled water at room temperature for a water absorption test for 14 days. Dry sliding wear was conducted using a pin-on-disc trbiotester. The coefficient of friction (COF) and the wear rate (K) was determined. The sliding trace was analyzed using a scanning electron microscope (SEM) to reveal the sliding wear mechanism of composites. Studies have shown that polyamide PA6 based composites are less prone to absorb water than PA66 matrix. In addition, the composites richer in fibreglass exhibit lower water absorption. Tribological results indicated that polymer composites showed higher COF and K after water absorption testing. Mean COF and K were in the range of 0.071÷0.321 and 2.51∙10-6÷1.81∙10-4 mm3N-1m-1, respectively. Wear traces SEM analysis revealed that untreated samples are characterized by less intense abrasive and adhesive wear mode than the hydrated polymers. Besides, the degradation process took place primarily at the polymer matrix-fibreglass interfaces.

4

Effect of shot peening on corrosion resistance of additive manufactured 17-4PH steel

51%

Świetlicki A. , Walczak M. , Szala M.

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tom Vol. 40, No. 3

135--151

EN

Components produced by additive manufacturing (AM) via direct metal laser sintering (DMLS) have typical as-fabricated surface defects. As a result, surface properties of AM products should be modified to increase their strength, anti-wear behavior, and at the same time ensure their high corrosion resistance. Surface modification via shot peening (SP) is considered suitable for AM of engineering devices made of 17-4PH (X5CrNiCuNb16-4) stainless steel. The objective of this study was to determine the effect of three types of peening media (CrNi steel shot, glass, and ceramic beads) on the corrosion resistance of specimens of DMLS 17-4PH stainless steel. Results demonstrated that SP caused steel microstructure refinement and induced both martensite (α) formation and retained austenite (γ) reduction. 17-4PH specimens peened showed the increase in surface hardness of 255, 281, and 260 HV0.2 for ceramic, glass, and steel, respectively. DMLS 17-4PH specimens modified by SP exhibited different surface morphology, hardness, and microstructure and thus, these properties affect corrosion performance. The results implied that steel shot peened with steel shot showed the highest resistance to corrosion processes (Icorr= 0.019μA/cm2), slightly worse with glass (Icorr= 0.227μA/cm2) and ceramics (Icorr= 0.660μA/cm2) peened. In the case of ceramic and glass beads, it was possible to confirm the presence of the above-mentioned particles in the surface layer after SP.

5

Zużycie tłoków silnikowych – charakterystyka mikrostrukturalna materiałów wykorzystywanych do ich produkcji

45%

Walczak M. , Bieniaś J. , Stradomska B. , Jankowski A. , Bielecki D.

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tom T 1, nr 1

59--72

PL

Dynamiczny rozwój motoryzacji wyznacza nowe kierunki w zakresie inżynierii materiałowej, stawiając konstruktorom i technologom początku XXI wieku potrzebę intensywnego poszukiwania nowych materiałów konstrukcyjnych, zapewniających podwyższenie trwałości eksploatacyjnej elementów składowych silnika. Obserwowana tendencja w motoryzacji do podwyższanie osiągów silników wskazuje, że efektywność działania tłoków silników spalinowych zależy w głównej mierze od trwałości materiałów stosowanych do produkcji tych elementów jak i warunków pracy samego silnika. Jednymi z najbardziej perspektywicznych, a zarazem nowoczesnych materiałów są metalowe materiały kompozytowe. W artykule przedstawiono uszkodzenia tłoków silnikowych powstałe w wyniku przeciążeń cieplnych oraz mechanicznych. Ponadto scharakteryzowano mikrostrukturalne właściwości wybranych metalowych materiałów kompozytowych o osnowie stopu aluminium zbrojonych: popiołami lotnymi (fly ash) cząsteczkami grafitu i cząsteczkami SiC (F3S.20S), a także monolitycznego stopu AK12.

EN

Dynamic development of automotive sector determines new tendencies in the area of material engineering, creating for the engineers and technologists of early twenty-first century the need for intensive search for new structural materials, providing increased service life of engine components. The observed trend in the automotive industry for increasing engine performance indicates that the effectiveness of the internal combustion engine piston depends largely on the durability of materials used to manufacture this items, as well as on working conditions of the engine itself. One of the most promising, and modern materials are metal composite materials. The paper presents examples of damages to engine pistons caused by thermal and mechanical overload. Microstructural properties of selected metal composite materials with aluminum alloy matrix reinforced with fly ash, graphite particles, SiC particles (F3S.20S) and the monolithic alloy AK12.

6

Properties of new-generation hybrid layers combining hardfacing and nitriding dedicated to improvement in forging tools’ durability

38%

Kaszuba M. , Widomski P. , Białucki P. , Lange A. , Boryczko B. , Walczak M.

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2020

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tom Vol. 20, no. 3

212--223

EN

This article deals with the subject of layers produced in a hybrid process combining hardfacing and nitriding. These layers are characterized by improved resistance to wear, which arises from the synergy between favorable materials during hardfacing and nitriding treatment. Tests were conducted on hot-work tool steel (H11) samples. Hardfaced layers consisting of three layers were applied to these samples, where layers were made from two materials-Robotool 46 and Hardface VMolc powder wires. Next, samples of both materials were nitrided using ZeroFlow gas nitriding technology, with control of potential aimed at obtaining a diffusion layer without a white zone of nitrides on the surface. The next step was to investigate the properties of hardfaced layers and of layers hardfaced after nitriding treatment. Conducted tests covered observations of the microstructure, microhardness measurements as a function of distance from the surface, measurement of stresses in the surface layer by means of X-ray diffraction, and tribological tests. Obtained test results show that hybrid layers combining hardfacing and nitriding may be suitable for improving the lifetime of tools applied in hot forging processes.