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1

Abrasion Resistance of Nickel- and Iron-base Hardfacings

Hejwowski Tadeusz, Łukasik Daniel

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 1

48--60

EN

The present study is directed to the problem of hardfacing and restoration of worn industrial equipment. Wear tests were carried out using especially built rig which reproduces working conditions of machinery applied in cement plants. The results of tribological tests on 20 Fe- and Ni-base hardfacings are presented. The effect of hardfacing hardness and chemical com-position was evaluated. It was found in SEM examinations that matrix was removed from the zone adjacent to carbides which made them liable to cracking and digging out. The mechanism of matrix removal depended on its hardness and include microcutting and low cycle fatigue. Ni-based hardfacings outperformed Fe-based coatings. The abrasion resistance of the best Ni-base coating, the Stelcar 6 was 38.7 times higher than that of S235JR steel. Eutectics in Ni-base coatings disturb motion of abrasive grains and force them to rotate in-stead of sliding over hardfacing surface. Ni-based coatings can be considered in hardfacing or reclamation of numerous industrial components applied in cement plants.

2

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).

3

Wear-Fatigue Study of Carbon Steels

Hejwowski Tadeusz, Szala Mirosław

Advances in Science and Technology. Research Journal

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2021

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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.

4

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

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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.

5

Abrasion Resistance of S235, S355, C45, AISI 304 and Hardox 500 Steels with Usage of Garnet, Corundum and Carborundum Abrasives

Szala Mirosław, Szafran Michał, Macek Wojciech, Marchenko Stanislav, Hejwowski Tadeusz

Advances in Science and Technology. Research Journal

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2019

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Vol. 13, no 4

151--161

EN

The steel presents a wide field of application. The abrasive wear resistance of steel relies mainly on the microstructure, hardness as well as on the abrasive material properties. Moreover, the selection of a abrasion-resistant grade of steel still seems to be a crucial and unsolved problem, especially due to the fact that the actual operating conditions can be affected by the presence of different abrasive materials. The aim of this work was to determine the effect of different abrasive grit materials i.e. garnet, corundum and carborundum on the abrasive wear result of a commonly used in industry practice steels i.e. S235, S355, C45, AISI 304 and Hardox 500. The microstructure of the steel was investigated using light optical microscopy. Moreover, hardness was measured with Vickers hardness tester. Additionally, the size and morphology of the abrasive materials were characterized. The abrasion tests were conducted with the usage of T-07 tribotester (dry sand rubber wheel). The results demonstrate that the hardness and structure of steels and hardness of abrasive grids influenced the wear results. The abrasive wear behavior of steels was dominated by microscratching and microcutting wear mechanisms. The highest mass loss was obtained for garnet, corundum, and carborundum, respectively. The usage of various abrasives results in different abrasion resistance for each tested steel grade. The AISI 304 austenitic stainless steel presents an outstanding abrasive wear resistance while usage of corundum and Hardox 500 while using a garnet as abrasive material. The C45 carbon steel was less resistant than AISI 304 for all three examined abrasives. The lowest resistance to wear in garnet and carborundum was obtained for the S235JR and S355J2 ferritic-perlitic carbon steels and in corundum for Hardox 500 which has tempered martensitic structure.

6

The influence of microstructure of arc sprayed coatings on wear resistance

Majewski Daniel, Hejwowski Tadeusz, Łukasik Daniel

Advances in Science and Technology. Research Journal

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2018

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Vol. 12, no 1

285--292

EN

The paper presents the test results of microstructure and resistance to abrasion and erosive wear of single and double-layer coatings with arc-coated powder wires on the iron matrix. It was shown that adhesion of coatings is in the range of 14.39 – 24.72 MPa. The closed porosity of the coatings determined from SEM images is in the range of 0.69 – 2.45% and was significantly lower than the porosity determined from the images obtained from the optical microscope, which was 5.49 – 8.11%. The 95 MXC coating’s hardness of the matrix was about 100HV0.05 higher compared to the AMI 100 coating matrix. The intensity of the erosion of AMI 100 coatings was lower than the intensity of the erosion of 95 MXC coatings.