Improving the scratch test properties of plasma-nitrided stainless austenitic steel by preliminary nanostructuring frictional treatment

The paper studies the effect of nanostructuring deformation surface processing - frictional treatment performed prior to the operation of nitriding in electron beam plasma - on the quality of the surface and tribological properties of the nitrided layer of the AISI 321 chromium-nickel austenitic steel. For the surface layers nitrided in the undeformed coarse-crystalline and nanostructured states, considerable differences in the critical loads and the fracture patterns under scratch testing are observed, despite practically the same microhardness of the nitrided surfaces under study. It is demonstrated that preliminary frictional treatment increases the rupture strength of the nitrided layer under scratch testing and stabilizes the tribological properties of the surface on the macroscopic scale. © 2018 Author(s)

The effect of ultrasonic impact-frictional treatment on the surface roughness and hardening of 09Mn2Si constructional steel

The paper compares the strengthening of constructional steel 09Mn2Si achieved by traditional ultrasonic impact treatment (UIT), and, the new method of ultrasonic impact-frictional treatment (UIFT), proposed by the authors. UIT is usually performed normally on the surface of the part with lubrication in the contact zone. The idea of UIFT is based on plastic shear deformation, activated by the friction effect of impulse impacts at a certain angle to the surface to be processed. In order to raise the friction coefficient, UIFT is performed without lubrication. It is shown that a decrease in the load application angle to the sample surface (α) increases the depth and hardness of the deformed surface layer of 09G2S structural steel. At the same time, the strengthening effect of treatment in the range of angles of 90 – 70° mainly manifests itself in a thin (a few microns) near-surface layer, and the surface roughness remains almost unchanged. A further decrease in the angle increases the contribution of the friction component. Thus, UIFT at α = 50° gives the depth of the deformed layer 1.5 times, and the surface hardness is 2.5 times higher than after the traditional UIT. It was found that the profile of the pile-ups behind a moving instrument changed from symmetrical after UIT to shifted in the impact direction after UIFT, which led to a twofold increase in surface roughness for α = 50°. It was established that reduction of the UIFT scanning step from 0.2 mm to 0.1 mm (load of 149 N and processing speed of 600 mm/min), improved the surface roughness Ra by a factor of 5 from 3.9 μm to 0.7 μm. A further decrease in the scanning step resulted in a surface coarsening due to fatigue degradation. © 2019, Institute for Metals Superplasticity Problems of Russian Academy of Sciences. All rights reserved.Russian Foundation for Basic Research, RFBR: 18-38-00868Благодарность/Acknowledgment. Авторы выражают благодарность Гибзуну М. С., Соболевой Н. Н. и Скоры-ниной П. А. за помощь в проведении профилометриче-ских исследований. Работа выполнена в рамках государ-ственного задания МИНОБРНАУКИ России по темам № АААА-А18-118020190116-6 (проект № 18-10-2-39) и № АААА-А18-118020790148-1 при поддержке РФФИ (проект № 18-38-00868_мол_а). Измерения микротвердо-сти и 3D-профилометрия выполнены в ЦКП «Пластоме-трия» ИМАШ УрО РАН./The research was carried out within the state assignment of Minobrnauki of Russia on themes No. АААА-А18-118020190116-6 (project No. 18-10-2-39) and № АААА-А18-118020790148-1, supported by RFBR (project No. 18-38-00868). Microhardness and 3D-profilometry tests were performed in the “Plastometriya” collective use center of the Institute of Engineering Science UB RAS

Cavitation Resistance of WC-10Co4Cr and WC-20CrC-7Ni HVAF Coatings

Machines operating in aqueous environments may be subjected to cavitation damage during operation. This study aims to evaluate the cavitation resistance of WC-10Co4Cr and WC-20CrC-7Ni coatings under cavitation erosion conditions with additional electrochemical effects. The coatings were deposited on AISI 1040 steel substrates using a high velocity air fuel thermal spray process. The microstructure of the coatings was observed by a scanning electron microscope, while their phase composition was analyzed using an energy-dispersive microanalysis system. In addition, the microhardness of the coatings and substrate was measured, and the surface topography of the eroded surface layers was observed using a 3D optical profilometer. The results revealed that the cavitation resistance of the WC-20CrC-7Ni coatings was better than that of the WC-10Co4Cr coatings. The observation of the structure and surface topography made it possible to identity the reasons for the differences between the cavitation resistance of both coatings: The WC-20CrC-7Ni coatings had a finer grain structure, lower pore density, and lower as-sprayed surface roughness. These differences, along with the presence of a high Cr and Ni content in the feedstock powder, that increased the coating corrosion resistance, contributed to improving the cavitation resistance and reducing the material loss of the WC-20CrC-7Ni coatings. © 2021, ASM International.The work was completed within state assignments from FASO Russia for IMP UB RAS on the subjects No. AAAA-A18-118020190116-6, № AAAA-A19-119070490049-8 and for IES UB RAS on the subject No. AAAA-A18-118020790147-4. The present study was supported by project № IRA-SME-66316 cladHEA+ (M-ERA.NET Call 2019-II) and M-ERA.Net ETAG18012 DuraCer. The experimental research was carried out using the equipment of the Plastometriya Collective Use Center of IES UB RAS

Adhesion Strength of Ti1-xCx – DLC Multilayer Nanocomposite Thin Films Coated by Ion-Plasma Deposition on Martensitic Stainless Steel Produced by Selective Laser Melting Followed by Plasma-Nitriding and Burnishing

[Ti0.2C0.8/a-C]40 multilayer thin films composed of forty pairs of TiC and pure carbon layers were formed on a selective laser melted (SLM) martensitic stainless steel by means of ion-plasma deposition process. SLM steel was pre-treated by one of the two following schemes: (1) oil quenching from 1040°C followed by heating to 480°C for 4 hours and air cooling (HT), finish milling (FM); (2) HT, FM, ion-plasma nitriding followed by burnishing. Mechanical failure mode and critical load LС for damaging the coatings were determined using linear scratch tests performed at linearly-increased normal force. Indentation by conical diamond tip were carried out in order to asses an elastic recovery and energy dissipation coefficient defined as the ratio of plastic to total deformation energy. The scratch test results showed that the post-processing of the substrate strongly influenced the failure mode of the coating and increased the critical load from 320 mN to 920 mN. Indentation revealed that nitriding and burnishing before coating deposition increase the elastic recovery of the [Ti0.2C0.8/a-C]40 coating-substrate system from 24% to 68%. The energy dissipation coefficient drops from 79% to 45%. © 2021 Institute of Physics Publishing. All rights reserved.The research was funded by RFBR for Basic Research and Sverdlovsk Oblast (project No. 20-48-660065) and partially carried out within the state assignment for IMP UB RAS, theme “Structure” No. AAAA-A18-118020190116-6. The authors are grateful to A G Merkushev for his participation in the preparation of the part

Behavior of a welded-deposited stainless steel tested at different cavitation test conditions

Two different ultrasonic vibratory-cavitation test conditions have been applied to a welded-deposited austenitic stainless steel AISI 321 to evaluate the resistance of deposited layer to cavitation erosion-corrosion. The cavitation test was conducted utilizing two test fluids; water and 3.5% NaCl solution. In addition, a certain voltage difference has been applied between the test specimen and water to form a combination effect. The welding wire of the AISI 321 stainless steel was deposited onto AISI 1040 steel substrate by using tungsten inert gas welding process. To evaluate and compare the behavior of the deposited material, the cumulative mass loss curves were attained and discussed. Moreover, the surface topography and scanning electron microscope (SEM) micrographs were utilized to characterize the worn surface after the cavitation tests. The results showed that the surface subjected to cavitation was more affected when applying water-voltage condition comparing with the 3.5% NaCl solution condition. The results of material loss, surface roughness and scanning electron microscope are fairly consistent with each other. This study highlights the effect of electrochemical-mechanical combinations on resistance to cavitation erosion-corrosion. © 2019 IOP Publishing Ltd.Foundation for Assistance to Small Innovative Enterprises in Science and Technology, FASIE: 0035960This work was done within the state order of IMP UB RAS on the subject no. AAAA-A18-118020190116-6, within the state order of IMP UB RAS on the subject “Laser”, and IES UB RAS on the subject no. AAAA-A18-118020790147-4. The present study was supported by FASIE, program Development-NTI 2017, project No. 0035960. Microhardness, surface roughness and SEM were done on the equipment installed at the Plastometriya collective use center of IES UB RAS

Plasma Nitriding in Complex Post-Processing of Stainless Steel Parts Obtained by Additive Laser Technology

Considered are the prospects of applying complex post-processing for an additive manufactured product with the deposition of a multilayer composite coating [Ti0.2C0.8/a-C]40 at the final stage. It is shown that heat treatment, finish milling, ion-plasma nitriding and burnishing with a sliding diamond indenter of a PH1 steel part obtained by selective laser melting (SLM) before deposition of a thin-film coating provides the coating with a minimum surface roughness Ra = 82-86 nm and a maximum hardness of 25.2 ± 1.4 GPa with an increase in the microhardness of the entire “coating-substrate” system. © 2021 Institute of Physics Publishing. All rights reserved.The research was funded by RFBR for Basic Research and Sverdlovsk Oblast (project No. 20-48-660065) and partially carried out within the state assignment for IMP UB RAS, theme “Structure” No. AAAA-A18-118020190116-6. The authors express particular gratitude to A.G. Merkushev and I.Y. Malygina for their participation in the work

Comparison of the resistance to cavitation and abrasive wear of deposited layers prepared from steels 06X19H9T and Fe-Cr-Ti-Al

The resistance of deposited layers to cavitation erosion and abrasive wear was evaluated for the steels AISI 321 (known as 06X19H9T manufactured according to the Russian standard GOST 18143-72) and Fe-Cr-Ti-Al (two materials namely Ural AS-3 and PPM-6). The Gas Tungsten Arc Welding (GTAW or TIG) process was utilized to deposit these welding material wires onto a medium carbon steel substrate AISI 1040. Cavitation test was conducted by using ultrasonic vibratory method to induce the erosion. In addition, a three-body abrasion test was used to evaluate the resistance of the studied materials to abrasive wear. The material loss criterion and wear rate of each material as a function to testing time were evaluated and discussed. The cavitation and abrasive wear tests have shown similar results regarding the PPM-6 steel. Among the tested material, PPM-6 exhibited the better resistance to cavitation and abrasion. The 06X19H9T stainless steel exhibited a higher resistance to cavitation comparing with the Ural AS-3. With respect to the abrasive wear, Ural AS-3 was to some degree better than the 06X19H9T in resistance to abrasion. © 2019 IOP Publishing Ltd.Foundation for Assistance to Small Innovative Enterprises in Science and Technology, FASIE: 0035960This work was done within the state order of IMP UB RAS on the subject no. AAAA-A18-118020190116-6, within the state order of IMP UB RAS on the subject ―Laser, and IES UB RAS on the subject no. AAAA-A18-118020790147-4. The present study was supported by FASIE, program Development-NTI 2017, project No. 0035960

Development strategy of service sector in conditions of federal states entities autonomy increasing

© 2016, Econjournals. All rights reserved.The relevance of the study is caused by the necessity to develop the sphere of services as a component of balanced socio-economic development of Federal State’s territories. The purpose of the paper is to define strategies for the development of services in conditions of increasing independence of the Federal State’s entities. A leading approach is the institutional one that considers the strategy of development of service sector in the Federal State as long-term programs of transition to innovative socially oriented type of economic development, reducing interregional differentiation in the level and quality of life of the population, creating equal opportunities for citizens and promoting human development. In the conditions of Federal State entities’ autonomy increasing the strategy of development in the sphere of services consists of citizens’ life conditions and social environment’ quality improving; accelerated development of human potential; competitiveness improving of human and ensuring it economic social sectors’ capital; development of competitive service markets; improving of the efficiency of politico-legal institutions providing social services to the population. Strategies’ defining for the development of services in the conditions of Federal State entities’ autonomy increasing is based on the principles of subsidiarity, sustainability, selectivity, fractals and transvers. Certain strategies of development of services are aimed at reducing territorial socio-economic differentiation to the level, caused by objective differences of the Federation’s entities, as well as ensuring the balance of the revenue base and expenditure commitments

Восстановление стенок кристаллизаторов машин непрерывного литья заготовок из хромоциркониевой бронзы методом многопроходной сварки трением с перемешиванием

An innovative technology has been developed and implemented for the restoration and manufacturing of new mold copper plates for continuous casting machines (CCMs) using wear-resistant composite coatings. These copper plates significantly surpass the service life of imported copper plates featuring galvanic coatings, sometimes by up to 20 times. However, the pressing challenge of restoring the copper plates of molds once they have reached the minimum permissible thickness remains unresolved. This study aimed to explore the feasibility of restoring a plate composed of precipitation-hardening Cr–Zr bronze with the same material by employing friction stir lap welding (FSLW). The objectives were to examine the structure, quality, and hardness of the welded joint, alongside investigating the impact of heat treatment (quenching and aging). By utilizing multi-pass FSLW method with a rotating tool crafted from a heat-resistant alloy and overlapping (partially overlapping) successive passes, a welded joint with a thickness of ~5 mm was achieved, devoid of critical continuity flaws (cracks or voids). Within the bronze layer restored through FSW, a softening effect ranging from 85–105 HV1 was observed compared to the initial hardness of the bronze in its hardened and aged state while in service (116–126 HV1). This is attributed to recrystallization and overaging, specifically the coarsening of chromium particles within the Cr–Zr bronze due to the heating of the weld nugget (stir zone) to 600–700 °C. The observed softening effect during FSW can be effectively rectified through heat treatment involving dissolution of the hardening phases followed by aging, resulting in a hardness increase to approximately 120–150 HV1. The process of restoring copper plates to their original thickness via the progressive and environmentally friendly FSW method, followed be the subsequent application of wear-resistant composite coatings, presents the opportunity for an almost infinite operational cycle of molds. This advancement could potentially eradicate the necessity for Russia to rely on importing such molds copper plates.Разработана и практически реализована инновационная технология восстановительного ремонта и производства новых стенок кристаллизаторов машин непрерывного литья заготовок (МНЛЗ) с износостойкими композиционными покрытиями, значительно (до 20 раз) превосходящих ресурс импортных стенок с гальваническими покрытиями. Однако нерешенной остается актуальная задача восстановления медных стенок (плит) кристаллизаторов после достижения ими минимально допустимой толщины. Целью работы являлось исследование возможности восстановления плиты из дисперсионно-твердеющей хромоциркониевой бронзы марки БрХЦр этим же материалом с использованием сварки трением с перемешиванием (СТП), изучение структуры, качества и твердости сварного соединения, а также влияния на его структуру и твердость термической обработки (закалки и старения). С применением многопроходной плоскостной СТП вращающимся инструментом из жаропрочного сплава при наложении (частичном перекрытии) последовательных дорожек получено сварное соединение толщиной ~5 мм без критичных дефектов сплошности (трещин, пор). В восстановленном способом СТП слое бронзы обнаружено разупрочнение до 85–105 HV1 по сравнению с исходной твердостью бронзы в закаленном и состаренном состоянии плиты, бывшей в эксплуатации (116–126 HV1). Это связано с рекристаллизацией и перестариванием (укрупнением частиц хрома) в Cr–Zr-бронзе в результате нагрева ядра сварки (зоны перемешивания) до температур 600–700 °С. Отмеченное разупрочнение при СТП может быть эффективно устранено термической обработкой (закалкой с последующим старением), приводящей к повышению твердости до 120–150 HV1. Восстановление медных плит до первоначальной толщины прогрессивным экологичным методом СТП с последующим нанесением износостойких композиционных покрытий открывает перспективы практически бесконечного цикла эксплуатации кристаллизаторов и исключения потребности России в их импорте