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1

The Effect of HVOF Spray Distance on Solid Particle Erosion Resistance of WC-based Cermets Bonded by Co, Co-Cr and Ni Deposited on Mg-alloy Substrate

Jonda Ewa, Łatka Leszek, Lont Aleksandra, Gołombek Klaudiusz, Szala Mirosław

Advances in Science and Technology. Research Journal

|

2024

|

Vol. 18, no 2

115--128

EN

Magnesium alloys are very interesting engineering materials because of their high strength-to-density ratio. On the other hand, they are characterized by low hardness as well as low erosion resistance. Because of these reasons, their applications in the industry are very limited. The article presents the results of the high velocity oxy-fuel (HVOF) spraying of the hard cermet coatings onto AZ31 magnesium alloy substrate. Three feedstock powders were used in the process with composition (wt.%): WC-12Co, WC-10Co-4Cr and WC-20Cr3C2Ni. The spray distance (SD) was selected as a variable parameter with values equal to 320 and 400 mm. Observations carried out under a scanning electron microscope (SEM) revealed a typical HVOF-sprayed microstructure with a compact structure and low porosity (below 3 vol.%). The hardness of the manufactured coatings, ranging from 912 HV0.2 to 1328 HV0.2, what was significantly higher than the substrate. The solid particle erosion tests were carried out according to the ASTM G76-04 standard. Erosive experiments were done for 30°, 60° and 90° inclination angles of the nozzle using Al2O3 abrasive. Erosion tests confirm that cermets exhibit substantial erosion resistance better than the substrate. The highest erosion resistance was noted for WC-10Co-4Cr coatings. The erosion rate for cermet coatings was mostly below 0.9 mg/min, whereas for the AZ31 it was more than 1.5 mg/min. In the case of the average erosion value, it was between 12 and 22 times lower than for the substrate. Results analysis reveal that shorter spray distance decreases porosity, increases hardness, and finally supports erosion resistance of the cermets.

2

Effects of ageing heat treatment temperature on the properties of DMLS additive manufactured 17-4PH steel

Świetlicki Aleksander, Wlaczak Mariusz, Szala Mirosław, Turek Marcin, Chocyk Dariusz

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

|

Vol. 71, nr 4

art. no. e146237

EN

Additive manufacturing (AM) is a modern, innovative manufacturing method that enables the production of fully dense products with high mechanical properties and complex shapes that are often impossible to obtain by traditional methods. The 17-4PH grade steel is often applied where high mechanical performance is required. 17-4PH, or AISI 630, is intended for precipitation hardening, an operation that combines solution and ageing treatments and is used to significantly change the microstructure of the steel and enhance its mechanical properties. This study investigates the effect of precipitation hardening on the properties of 17-4PH steel. To examine microstructure and morphology, metallographic tests were performed together with phase composition and chemical composition analyses. Mechanical parameters were determined via Vickers hardness testing and the Oliver-Pharr method. Samples were fabricated using direct metal laser sintering (DMLS), which is one of the powder bed fusion methods. The use of a constant solution treatment temperature of 1040_C and different ageing temperatures made it possible to evaluate the effects of ageing temperature on the mechanical properties and microstructure of 17-4PH. The presence of face-centered cubic FCC g-austenite and body-centerd cubic BCC a-martensite structures were detected. The tests revealed that – similarly to the wrought material – the highest hardness of 382_10:3 HV0:2 was obtained after ageing at 450_C. The nanoindentation test showed the same H/E ratio for the sample after fabrication and after solution treatment at 0.016769, but this value increased after ageing to 127–157.5%. The sample aged at 450_C was characterized by the highest H/E ratio of 0.026367, which indicates the highest wear resistance of this material under employed treatment conditions. In general, the sample treated at 450_C showed the best performance out of all tested samples, proving to have the smallest grain size as well as high Vickers and nanoindentation hardness. On the other hand, the use of solution treatment led to reduced hardness and improved workability of the AM material.

3

Abrasive Wear Mechanisms of S235JR, S355J2, C45, AISI 304, and Hardox 500 Steels Tested Using Garnet, Corundum and Carborundum Abrasives

Szala Mirosław, Szafran Michał, Matijošius Jonas, Drozd Kazimierz

Advances in Science and Technology. Research Journal

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2023

|

Vol. 17, no 2

147--160

EN

Wear resistance is one of the main indicators of the reliability of machine parts. The selection of wear-resistant material should consider the operational environment and specific types of abrasive material. The steel abrasive wear resistance depends not only on its hardness and microstructure but also on the abrasive material's properties, such as hardness and particle morphology. This work aimed to determine abrasion wear mechanisms of a set of steels, i.e., S235, S355, C45, AISI 304 and Hardox 500, abraded by different types of grit i.e. garnet, corundum and carborundum. The abrasion tests were conducted using T-07 tribometer (rubber wheel method). Wear traces were examined with a scanning electron microscope (SEM), and a contact profilometer. SEM analysis revealed that apart from Hardox 500, ploughing and microfatigue were the dominant wear mechanisms. Microcutting was the main wear mechanism for Hardox 500 tested with carborundum (SiC). The highest mass loss was usually obtained for carborundum. The lowest wear resistance in garnet and carborundum was obtained for the S235JR and S235J2 steels and Hardox 500 tested with corundum. The effect of steel microstructure on the wear mechanism has been confirmed. AISI 304 austenitic steel abraded by carborundum grit, presented outstanding roughness parameters: Ra, Rz, RSm, Rk, Rvk and Rpk than other steels tested with carborundum. Steel hardness affects the morphology of the wear trace reducing the Ra and Rz roughness parameters. The effect of abrasive hardness and grain morphology on abraded surfaces has been stated. Contrary to fine grains of the hardest carborundum, coarse garnet grains caused high roughness parameters (Rk, Rpk and Rvk) determined in wear trace.

4

Phenomenological model of cavitation erosion of nitrogen ion implanted HIPed Stellite 6

Szala Mirosław

Advances in Materials Science

|

2023

|

Vol. 23, nr 1(75)

98--109

EN

Stellites are a group of Co-Cr-C-W/Mo-containing alloys showing outstanding behavior under cavitation erosion (CE) operational conditions. The process of ion implantation can improve the CE resistance of metal alloys. This work presents the elaborated original phenomenological model of CE of nitrogen ion implanted HIP-consolidated (Hot Isostatically Pressed) cobalt alloy grade Stellite 6. The ultrasonic vibratory test rig was used for CE testing. The nitrogen ion implantation with 120 keV and fluence of 5 × 1016 N+/cm−2 improves HIPed Stellite 6 cavitation erosion resistance two times. Ion-implanted HIPed Stellite 6 has more than ten times higher CE resistance than the reference AISI 304 stainless steel sample. Comparative analysis of AFM, SEM and XRD results done at different test intervals reveals the kinetic of CE process. The model includes the surface roughness development and clarifies the meaning of cobalt-based matrix phase transformations under the nitrogen ion implantation and cavitation loads. Ion implantation modifies the cavitation erosion mechanisms of HIPed Stellite 6. The CE of unimplanted alloy starts on material loss initiated at the carbides/matrix interfaces. Deterioration starts with cobalt matrix plastic deformation, weakening the carbides restraint in the metallic matrix. Then, the cobalt-based matrix and further hard carbides are removed. Finally, a deformed cobalt matrix undergoes cracking, accelerating material removal and formation of pits and craters' growth. The nitrogen ion implantation facilitates ɛ (hcp—hexagonal close-packed)) → γ (fcc—face-centered cubic) phase transformation, which further is reversed due to cavitation loads, i.e., CE induces the γ → ɛ martensitic phase transformation of the cobalt-based matrix. This phenomenon successfully limits carbide removal by consuming the cavitation loads for martensitic transformation at the initial stages of erosion. The CE incubation stage for ion implanted HIPed Stellite 6 lasts longer than for unimplanted due to the higher initial content of γ phase. Moreover, this phase slows the erosion rate by restraining carbides in cobalt-based matrix, facilitating strain-induced martensitic transformation and preventing the surface from severe material loss.

5

Cavitation Erosion Resistance of High-Alloyed Fe-Based Weld Hardfacings Deposited Via SMAW method

Szala Mirosław, Hejwowski Tadeusz

Tribologia

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2022

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nr 4

85--94

EN

In order to investigate the cavitation erosion (CE) resistance of high-alloyed ferrous hardfacings, the three different deposits were pad welded by the shielded metal arc welding (SMAW) method. Consumable electrodes differed in the content of carbide-forming elements, and pad welds were deposited onto the S235JR structural. The CE tests, conducted according to ASTM G32 standard, indicated that hardfacings reveal lower mass loss than the reference stainless steel AISI 304 (X5CrNi18-10). The hardfacings show increasing resistance to CE in the following order: Cr-C < Cr-C-Mo < Cr-C-Mo-V-W. The reference steel revealed more than twenty times higher material loss in the CE test than Cr-C-Mo-V-W hardfacing, which had outstanding hardness (825HV0.3). The profilometric measurements and scanning electron microscopy investigations showed large changes in valley and peak sizes of the roughness profiles for materials which displayed high erosion rates. The erosion mechanism of the coatings can be classified as brittle-ductile and relies on cracking, chunk removal of material, pits and craters formation, and deformation of fractured material tips and edges. Hardfacing materials failed primarily due to brittle fractures with different severities. Specimen surface degradation follows the changes in Ra, Rz, Rv, and Rp roughness parameters and well-corresponds to the proposed roughness rate (RR) parameter.

PL

W celu zbadania odporności na erozję kawitacyjną (EK) wysokostopowych napoin na osnowie żelaza napawano trzema materiałami metodą SMAW. Elektrody otulone różniły się zawartością pierwiastków węglikotwórczych. Napoiny wykonano na stali konstrukcyjnej S235JR. Testy EK, przeprowadzone zgodnie z normą ASTM G32, wykazały niższy ubytek masy napoin w porównaniu do referencyjnej stali odpornej na korozję AISI 304 (X5CrNi18-10). Napoiny wykazują rosnącą odporność na EK w następującej kolejności: Cr-C < Cr-C-Mo < Cr-C-Mo-V-W. Referencyjna próbka stalowa wykazała w teście EK ponad dwudziestokrotnie większy ubytek materiału niż napoina Cr-C-Mo-V-W, która miała wyjątkowo wysoką twardość (825HV0.3). Pomiary profilometryczne i badania przeprowadzone przy użyciu skaningowego mikroskopu elektronowego wykazały duże zmiany wielkości dolin i szczytów profilu chropowatości dla materiałów wykazujących wysoką szybkość erozji. Mechanizm EK powłok można sklasyfikować jako krucho-plastyczny i opiera się na pękaniu, usuwaniu kawałków materiału, tworzeniu wgłębień i kraterów oraz deformacji pękniętych fragmentów kraterów oraz deformacji wyodrębnionych szczytów i krawędzi materiału. Napawany materiał podlega niszczeniu przez jego pękanie w różnym nasileniu. Degradacja powierzchni próbek pogłębia się wraz ze zmianą parametrów chropowatości Ra, Rz, Rv i Rp i dobrze koresponduje z proponowanym parametrem RR (zmiana chropowatości pow. degradowanej).

6

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

Świetlicki Aleksander, Walczak Mariusz, Szala Mirosław

Materials Science Poland

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2022

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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.

7

Microstructure and Hardness of Cold Forged 42CrMo4 Steel Hollow Component with the Outer Flange

Szala Mirosław, Winiarski Grzegorz, Bulzak Tomasz, Wójcik Łukasz

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 4

201--210

EN

For decades, steel has been a crucial structural material. Mainly low-alloy steel grade ISO 42CrMo4 is utilized for manufacturing forgings. This paper investigates the microstructure and hardness development of the 42CrMo4 steel hollow component with an outer flange. The component has been formed via cold forging in combination with extrusion and upsetting technologies. Prior to forming, the workpiece was annealed to obtain hardness at the level of 181±9 HV0.3. The FEM analysis reveals the areas that undergo higher stress and strain. The flow lines macrostructure and microstructure of hollow parts were investigated using light optical microscopy (LOM) and scanning electron microscopy (SEM) equipped with EDS. Vickers hardness allows identifying the work hardening of the crucial element areas. The microstructure consists of ferrite matrix and semi-globular carbides. Laboratory studies confirm appropriate flow lines arrangement, which corresponds well to those shown by FEM computer simulations. The highest hardness at the level of 293±7 HV0.3 was identified in the flange area, where the material shows a higher distribution of effective strain revealed by FEM. Cold metal forming results in work-hardening of the steel. The work hardening ranges up to 1.62 of the initial 42CrMo4 steel hardness. The metal forming process did not affect the microstructural uniformity of the flanged hollow part. The final outer flange component presents high quality and is free from plastic deformation nonuniformities.

8

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

Walczak Mariusz, Szala Mirosław, Pieniak Daniel

Advances in Science and Technology. Research Journal

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2022

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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.

9

Influence of austenitic interlayer on the properties of stellite padding welds after impact-hardening

Henzler Weronika, Sawa Mateusz, Trębicki Przemysław, Szala Mirosław, Winiarski Grzegorz

Welding Technology Review

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2021

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R. 93, nr 2

13--20

EN

Stellites (Co-Cr-W-C) are the specific group of coating materials used for surface modification of the engineering materials and for remanufacturing. The aim of the paper was to research the influence of austenitic (308LSi) interlayer on hardening rate of stellite 1 and stellite 6 after impact hardening. The samples have been cladded by TIG welding method with interlayer and without. Before impact hardening the samples have been visually and penetrant non-destructive tested. The samples after impact hardening have been tested by metallographic and Vickers hardness methods. The highest impact hardening effect have been revealed for coatings deposited with interlayer. The highest impact hardening effect was achieved for the padding welds produced with the interlayer, i.e. for stellite 1 (increased by 29.8%) and stellite 6 (increased by 42.7%). The hardening of the coating samples deposited without interlayer was lower and amounted to stellite 1 (increased by 13.7%) and stellite 6 (increased by 29.8%) respectively. The highest hardness values were obtained for impact-hardened cladded welds without the use of an interlayer (stellite 1; 790 HV0.1 and stellite 6; 732 HV0.1). The use of an interlayer reduces the hardness of the stellite coating while increasing the susceptibility to hardening and plastic deformation of the produced coating.

PL

Stellity (Co-Cr-W-C) stanowią grupę materiałów stosowanych do napawania produkcyjnego i regeneracyjnego. Celem pracy było zbadanie wpływu międzywarstwy austenitycznej (308LSi) na stopień umocnienia się napoin stellitowych (stellit 1 i stellit 6), poddanych działaniu obciążeń udarowych. Próbki napawano metodą TIG z zastosowaniem międzywarstwy oraz bez udziału międzywarstwy. Po przeprowadzeniu badań wizualnych i penetracyjnych próbki zostały poddane utwardzeniu udarowemu. Wykonano badania metalograficzne oraz badania mikrotwardości sposobem Vickersa. Największe utwardzenie udarowe uzyskano dla napoin wytworzonych z międzywarstwą, tj. dla stellitu 1: 29.8% i stellitu 6: 42.7%. Utwardzenie próbek napawanych bez międzywarstwy było niższe i wynosiło kolejno dla stellitu 1: 13.7% i stellitu 6: 29.8%. Najwyższe wartości twardości uzyskano dla napoin utwardzanych udarowo bez zastosowania międzywarstwy (stellit 1; 790 HV0,1 i stellit 6; 732 HV0,1). Zastosowanie międzywarstwy obniża mikrotwardość powłoki stellitowej jednocześnie zwiększając podatność do umocnienia i odkształcenia plastycznego wytworzonej powłoki.

10

Cavitation erosion phenomenological model of MCrAlY and NiCrMoNbTa metallic coatings deposited via the HVOF method

Szala Mirosław

Tribologia

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2021

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nr 4

45--55

EN

The work describes the phenomenological model of cavitation erosion (CE) elaborated for MCrAlY (where M = Co, Ni or Co/Ni) and NiCrMoNbTa. Coatings were deposited via the HVOF method from CoNiCrAlY, NiCoCrAlY and NiCrMoNbTa feedstock powders. CE tests, conducted according to ASTM G32 standard, indicate that MCrAlYs have a 50% higher maximum erosion rate and twice lower CE resistance than the NiCrMoNbTa coating. CE kinetics of coatings were comparatively studied, combining the mass loss, erosion rate, roughness changes of the eroded surface with microstructure, and mechanical properties of the coatings. Results of SEM analysis of damaged coatings allow identifying the mechanism of CE. In the case of both types of coatings, the erosive damage is initiated at the removal of loose splats, cracking at the border splats and peeling off the coating material, and surface pitting. However, NiCrMoNbTa, due to higher ductility and microstructure homogeneity, presents lesser surface pitting contrary to the MCrAlYs, which have multiphase microstructure higher hardness and consequently was prone to cracking, resulting in the formation of craters and higher surface roughening. The CE mechanism of MCrAlYs was dominated by the brittle mode, while the NiCrMoNbTa coating has mainly a ductile damage behaviour.

PL

W pracy opisano fenomenologiczny model erozji kawitacyjnej (EK) opracowany dla powłok MCrAlY (gdzie M = Co, Ni lub Co/Ni) i NiCrMoNbTa. Powłoki wytworzono metodą HVOF z komercyjnych proszków CoNiCrAlY, NiCoCrAlY i NiCrMoNbTa. Testy erozji kawitacyjnej, przeprowadzone zgodnie z normą ASTM G32, wskazują, że MCrAlY mają o 50% wyższą prędkość erozji i dwukrotnie niższą odporność EK niż powłoka NiCrMoNbTa. Kinetyka erozji kawitacyjnej powłok została poddana analizie porównawczej syntetyzującej utratę masy, szybkość erozji, zmiany chropowatości erodowanej powierzchni z mikrostrukturą oraz właściwościami mechanicznymi badanych powłok. Wyniki analizy SEM uszkodzonych powłok umożliwiły zidentyfikowanie mechanizmu EK. Uszkodzenie erozyjne powłok inicjowane jest w wyniku usuwaniu słabo umocowany cząstek materiału, pękaniu na granicach lameli następnie usuwaniu materiału i tworzeniu wżerów. Jednak NiCrMoNbTa ze względu na wyższą ciągliwość i jednorodność mikrostruktury wykazuje mniejsze wżery powierzchniowe w przeciwieństwie do MCrAlYs, które cechują się wielofazową mikrostruktura o wyższej twardości i w konsekwencji są podatne na pękanie, co powoduje powstawanie dużych wżerów i wyższe chropowacenie powierzchni. Mechanizm erozji kawitacyjnej powłok MCrAlY jest zdominowana przez kruche pękanie, natomiast w przypadku powłoki NiCrMoNbTa dominuje plastyczne odkształcenie.

11

Cavitation erosion of electrostatic spray polyester coatings with different surface finish

Szala Mirosław, Świetlicki Aleksander, Sofińska-Chmiel Weronika

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 4

art. no. e137519

EN

Polyester coatings are among the most commonly used types of powder paints and present a wide range of applications. Apart from its decorative values, polyester coating successfully prevents the substrate from environmental deterioration. This work investigates the cavitation erosion (CE) resistance of three commercial polyester coatings electrostatic spray onto AW-6060 aluminium alloy substrate. Effect of coatings repainting (single- and double-layer deposits) and effect of surface finish (matt, silk gloss and structural) on resistance to cavitation were comparatively studied. The following research methods were used: CE testing using ASTM G32 procedure, 3D profilometry evaluation, light optical microscopy, scanning electron microscopy (SEM), optical profilometry and FTIR spectroscopy. Electrostatic spray coatings present higher CE resistance than aluminium alloy. The matt finish double-layer (M2) and single-layer silk gloss finish (S1) are the most resistant to CE. The structural paint showed the lowest resistance to cavitation wear which derives from the rougher surface finish. The CE mechanism of polyester coatings relies on the material brittle-ductile behaviour, cracks formation, lateral net-cracking growth and removal of chunk coating material and craters’ growth. Repainting does not harm the properties of the coatings. Therefore, it can be utilised to regenerate or smother the polyester coating finish along with improvement of their CE resistance.

12

Effect of shot peening on the surface properties, corrosion and wear performance of 17-4PH steel produced by DMLS additive manufacturing

Walczak Mariusz, Szala Mirosław

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 4

368--387

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 behaviour, and at the same time to ensure their high corrosion resistance. Surface modification via shot peening is considered suitable for additive manufacturing of medical devices made of 17-4PH stainless steel. The objective of this study was to determine the effect of shot peening pressures (0.3 MPa and 0.6 MPa) and three types of blasting media (CrNi steel shot, nutshell granules and ceramic beads) on the tribological characteristics and corrosion resistance of specimens of DMLS 17-4PH stainless steel. Results demonstrated that shot peening caused steel microstructure refinement and-except for the nutshell shot-peened specimens-induced both martensite (α) formation and retained austenite (γ) reduction. 17-4PH specimens peened with steel and ceramic shots showed the highest increase in surface hardening by approx. ~ 119% (from 247 to 542 HV), which significantly improved their wear resistance. The highest mechanical properties (hardness and wear resistance) and corrosion resistance were obtained for the surfaces modified using the following media: ceramic beads > CrNi steel shot > nutshell granules. Adhesive and fatigue wear were two predominant mechanisms of tribological deterioration. Results demonstrated that the application of shot peening using ceramic beads led to grain size refinement from 22.0 to 14.6 nm and surface roughness reduction, which in turn resulted in higher corrosion resistance of the material. DMLS 17-4PH specimens modified by shot peening using ceramic beads and a pressure of 0.6 MPa exhibited the optimum surface morphology, hardness and microstructure, and thus improved wear and corrosion performance.

13

Innovative device for tensile strength testing of welded joints: 3d modelling, FEM simulation and experimental validation of test rig – a case study

Sawa Mateusz, Szala Mirosław, Henzler Weronika

Applied Computer Science

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2021

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Vol. 17, no 3

92--105

EN

This work shows a case study into 3D modelling, numerical simulations, and preliminary research of self-designed test rig dedicated for uniaxial tensile testing using pillar press. Innovative device was CAD modelled, FEM optimized, build-up according to the technological documentations. Then, the device utilization for tensile testing was validated via preliminary research. 3D model of the device was designed and FEM-analyzed using Solid Edge 2020 software. The set of FEM simulations for device components made ofstructuralsteel and stainless steel and at a workload equal 20 kN were conducted. This made it possible to optimize dimensions and selection of material used for individual parts of the device structure. Elaborated technical documentation allows for a buildup of a device prototype which was fixed into the pillar press. After that, the comparative preliminary experiments regarding tensile strength tests of X5CrNi18-10 (AISI 304) specimens were carried out. Tests were done using the commercial tensile strength machine and obtained results were compared with those received from an invented device. The ultimate tensile strength of X5CrNi18-10 steel, estimated using the commercial device (634 MPa) and results obtained from the patented device (620 MPa), were in the range of the standardized values. Findings confirm the utilization of the invented device for tensile strength testing.

14

Wear-Fatigue Study of Carbon Steels

Hejwowski Tadeusz, Szala Mirosław

Advances in Science and Technology. Research Journal

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2021

|

Vol. 15, no 3

179--190

EN

The process of conjoined stress cycling and abrasive or erosive wear is encountered in industry. However, very scant attention has been paid till now to this issue. The paper presents two test rigs designed and built to cope with this experimental problem. Tests were carried out on the range of pure iron (Armco), carbon steels namely S235JR, C45, C70U, C80U, C110U and unalloyed cast steels (L40III, L45III and L50III). Tested iron-based alloys differ in chemical composition, microstructure and Brinell hardness ranging from 80HB to 350HB. Stress cycling caused strain hardening of ferrite in hypoeutectoid steels and thus reduced their abrasive wear loss. In the hypereutectoid steel stress cycling impaired integrity of the microstructure thus increasing abrasive wear loss. Alternating stresses enhanced ploughing and cutting micromechanisms of erosion. Tensile stress in the tested cast steel had a stronger effect on wear loss than the prior stress history.

15

Factors Influencing Cavitation Erosion of NiCrSiB Hardfacings Deposited by Oxy-Acetylene Powder Welding on Grey Cast Iron

Szala Mirosław, Walczak Mariusz, Hejwowski Tadeusz

Advances in Science and Technology. Research Journal

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2021

|

Vol. 15, no 4

376--386

EN

The work presents the results of a study on cavitation erosion (CE) resistance of two NiCrSiB self-fluxing powders deposited by oxy-acetylene powder welding on cast iron substrate grade EN-GJL-200. The mean hardness of deposits A-NiCrSiB, C-NiCrSiB is equal to 908 HV, 399 HV and exceeds those of EN-GJL-200 and X5CrNi18-10 reference specimens 197 HV and 209 HV, respectively. To study CE, the vibratory apparatus has been used and tests were conducted according to the ASTM G32 standard. Cavitation eroded surfaces were examined using a profilometer, optical and scanning electron microscopy. The research indicated that the CE resistance, expressed by the cumulative mass loss decreased in the following order C-NiCrSiB > A-NiCrSiB > X5CrNi18-10 > EN-GJL-200. Therefore, hardfacings were characterised by lower cumulative mass loss, in turn, higher CE resistance than the reference sample and therefore they may be applied as layers to increase resistance to cavitation of cast iron machine components. Results indicate that in the case of multiphase materials, hardness cannot be the main indicator for CE damage prediction while it strongly depends on the initial material microstructure. To qualitatively estimate the cavitation erosion damage (CEd) of NiCrSiB self-fluxing alloys at a specific test time, the following factors should be considered: material microstructure, physical and mechanical properties as well as surface morphology and material loss both estimated at specific exposure time. A general formula for the CEd prediction of NiCrSiB deposits was proposed.

16

Numerical analysis of three-stage the forming process hollow forgings with an outer flange

Wójcik Łukasz, Bulzak Tomasz, Winiarski Grzegorz, Szala Mirosław

Zeszyty Naukowe Akademii Morskiej w Szczecinie

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2020

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nr 62 (134)

142--147

EN

This article presents the results of computer simulations used to investigate the forming of a hollow coldworked forging with an outer flange. Numerical simulations were performed in Deform 2D/3D using a calculation module for axial-symmetric cases. A ϕ57×12.5 mm tube-shaped billet from 42CrMo4 grade steel was used. The forming process involved two and three stages, consisting of extrusion the shaft portion and forging the flange. The objective of this research was to determine the accuracy of the forming process used to produce the hollow part. This technology was analyzed using the effective strain distributions, the Cockcroft-Latham fracture criterion values, and the forming force progression. The results showed that it was possible to use this three-stage process to forge elements from a tube-shaped billet.

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Effect of non-zero mean stress bending-torsion fatigue on fracture surface parameters of 34CrNiMo6 steel notched bars

Macek Wojciech, Szala Mirosław, Trembacz Jarosław, Branco Ricardo, Costa José

Production Engineering Archives

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2020

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Vol. 26, Iss. 4

167--173

EN

Modern methods of testing materials require the use of the latest technologies and combining measurement and calculation methods. It is important to find a quantitative way of describing, among other things, the failures so that it can help to design with high accuracy. This paper studies loading orientations on crack shape and fracture surface changes. The advantage of the entire fracture surface method is simplicity and applicability in studies on other materials, shapes and loadings. A higher values of fracture surface parameters (Sx, Vx) was observed in failure specimens with lower σ/τ (B/T) ratios. It has been observed that largest crack lengths with a small number of cycles occur for loading combinations different then B=T. As well as analyzed surface parameters Sx, Vx, are higher for larger number of cycles to crack initiation (Ni) values.

18

Numerical Analysis of a Six Stage Forging Process for Producing Hollow Flanged Parts from Tubular Blanks

Winiarski Grzegorz, Bulzak Tomasz Adam, Wójcik Łukasz, Szala Mirosław

Advances in Science and Technology. Research Journal

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2020

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Vol. 14, no 1

201--208

EN

This paper presents the results of a numerical analysis of a cold forging process for a hollow flanged part. The analysis was performed using Deform 2D/3D. 42CrMo4 steel tubes were used as the billet material, and their material model in the annealed state was described by a constitutive equation. The forming process was performed in six stages with the use of methods such as extrusion with a movable sleeve, open-die extrusion, and upsetting. The objective of the study was to determine whether the proposed forging technique could be used to produce hollow parts with flanges. The determination was made based on the analysis of product geometry quality and process parameters, including the Cockcroft-Latham ductile fracture criterion and forming forces.

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Mechanical Properties and Sliding Wear Resistance of Suspension Plasma Sprayed YSZ Coatings

Łatka Leszek, Szala Mirosław, Macek Wojciech, Branco Ricardo

Advances in Science and Technology. Research Journal

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2020

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Vol. 14, no 4

307--314

EN

In this work, the yttria stabilised zirconia ZrO2 + 8 wt% Y2 O3 (YSZ) coatings were studied. The coatings were manufactured by using a relatively new method based on liquid feedstock, called suspension plasma spraying (SPS). The main aim of the study was to investigate the influence of one of the fundamental process parameters, stand-off distance, on the YSZ coating mechanical properties, namely adhesion, cohesion, hardness, and dry sliding wear resistance. Moreover, the coating surface morphology and microstructure were investigated. Despite the fact that in the SPS method, the heat flux into the substrate is much higher than in conventional atmospheric plasma spraying (APS), for the stand-off distances as short as 40 mm, the structure has not been damaged by thermal stresses. The results revealed that shorter spray distance leads to obtaining the coatings characterised by higher cohesion and adhesion to the substrate as well as higher hardness and resistance to sliding wear. The wear mechanism of both YSZ coatings relies on the adhesive mode, which is intensified by severe coating material delamination.

20

A New Method of Flanges Extrusion in Hollow Products – Analysis of the Limiting Phenomena

Winiarski Grzegorz, Bulzak Tomasz Adam, Wójcik Łukasz, Szala Mirosław

Advances in Science and Technology. Research Journal

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2020

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Vol. 14, no 4

78--85

EN

The paper presents an innovative method of metal forming of hollow flanged elements. In this process, flanges are formed using a movable sleeve, which moves in the opposite direction to the punch. The movement of the sleeve causes a closed impression to open, due to which the flange is also formed in a semi-free impression. The tube billets were made of the 42CrMo4 grade steel deformed under the cold metal forming conditions. The calculations were conducted using the finite elements method in Deform-2D/3D. Various technological parameters of the process were analysed, among others the diameter of the flange and the initial height of the impression of the movable sleeve. On the basis of the obtained results, the limiting phenomena of the process were determined and the influence of the analysed technological parameters on these phenomena were presented.