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1

Corrosion Resistance of the Nanostructured X37CrMoV5-1 Steel

100%

Skołek E. , Kamiński J. , Marciniak S. , Świątnicki W. A.

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2020

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tom Vol. 65, iss. 1

133--140

EN

The aim of this study is to compare the corrosion resistance of X37CrMoV5-l tool steel after nanostructurization and after a conventional heat treatment. The nanostructuring treatment consisted of austempering at 300°C, which produced a microstructure composed of nanometric carbide-free bainite separated by nanometric layers of retained austenite. The retained austenite occurred also in form of blocks which partially undergo martensitic transformation during final cooling. For comparison, a series of steel samples were subjected to a standard quenching and high tempering treatment, which produced a microstructure of tempered martensite. The obtained results showed that the corrosion resistance of steel after both variants of heat treatment is similar. The results indicate that the nanocrystalline structure with high density of intercrystalline boundaries do not deteriorate the corrosion resistance of steel, which depends to a greater extent on its phase composition.

2

Corrosion Resistance of the Nanostructured X37CrMoV5-1 Steel

100%

Skołek E. , Kamiński J. , Marciniak S. , Świątnicki W. A. , Skołek E. , Kamiński J. , Marciniak S. , Świątnicki W. A.

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3

Skuteczność ochronna blach pancernych ze stali nanobainitycznej

84%

Marcisz J. , Garbarz B. , Stępień J. , Tomczak T. , Starczewski L. , Nyc R. , Gmitrzuk M. , Gołuński M.

Journal of Metallic Materials

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2020

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tom Vol. 72, no. 1

21--38

PL

W artykule przedstawiono wyniki badań odporności na przebicie blach ze stali nanobainitycznej o grubości w zakresie 6÷9 mm za pomocą pocisków o zróżnicowanym mechanizmie penetracji. Testy ostrzałem prowadzono stosując amunicję kal. 7,62×39 mm BZ zgodnie z wymaganiami dokumentu standaryzacyjnego NATO Stanag 4569A (poziom 2) oraz amunicję kal. 7,62×54R mm B32 w celu wyznaczenia parametru V50 dla wytypowanych wariantów i grubości blach. Blachy arkuszowe stanowiące materiał badań wytworzono w skali przemysłowej z dwóch wytopów o różnym składzie chemicznym. Arkusze blach ze stali nanobainitycznej poddano obróbce cieplnej obejmującej austenityzowanie, regulowane chłodzenie i bezpośrednie wygrzewanie izotermiczne, której parametry zoptymalizowano w celu uzyskania jak najwyższej zdolności ochronnej. W miejscach oddziaływania pocisku z blachą przeprowadzono badania mikrostruktury w celu szczegółowej analizy skutków ostrzału. Uzyskane wyniki badań wskazały graniczne wartości prędkości pocisków oraz grubości blach dla których ochrona balistyczna jest skuteczna. Określono zakres właściwości mechanicznych wyznaczanych w statycznej próbie rozciągania oraz rodzaj mikrostruktury, w tym zawartość i postać austenitu resztkowego, gwarantujące spełnienie wymaganego poziomu odporności na przebicie. Na podstawie wyników testów ostrzałem wytypowano warianty obróbki cieplnej dla blach o określonej grubości, przeznaczonych na opancerzenie kontenera obserwacyjno-obronnego. Badania i testy wykonano w ramach projektu POIR 04.01.04-00-0047/16, którego głównym celem jest obniżenie masy opancerzenia kontenera LOOK.

EN

The article presents the results of tests on resistance to perforation of nanobainitic steel plates with a thickness in the range of 6-9 mm with the use of projectiles with different perforation mechanisms. Firing tests were carried out using 7.62×39 mm BZ ammunition in accordance with the requirements of the NATO Stanag 4569A standard document (level 2) and 7.62×54R mm B32 ammunition to determine the V50 parameter for selected variants and plate thickness. The plates constituting the testing material were manufactured on an industrial scale from two heats with different chemical composition. The nanobainitic steel plates were subjected to heat treatment including austenitisation, controlled cooling and direct isothermal annealing, the parameters of which were optimised in order to achieve the highest protective capacity. Microstructure studies were carried out in places where the projectile and the plate interacted, in order to analyse the effects of firing in detail. The obtained test results indicated limit values of projectile velocities and plate thicknesses for which ballistic protection is effective. The range of mechanical properties determined in a static tensile test as well as the type of microstructure were determined, including the content and form of retained austenite, guaranteeing compliance with the required level of resistance to perforation. Based on the results of the firing tests, heat treatment variants were selected for plates of a certain thickness intended for the armour of an observation and protective container. The studies and tests were carried out as part of the POIR 04.01.04-00-0047/16 project, the main goal of which is to reduce the weight of a LOOK container armour.

4

Evaluation of cracking risk of 80MnSi8-6 nanobainitic steel during hot forging in the range of lower temperature limits

84%

Lisiecka-Graca P. , Lisiecki Ł. , Zyguła K. , Wojtaszek M.

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2024

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tom Vol. 42, No. 1

171--185

EN

Nanobainitic steels exhibit an exceptional combination of high strength, good plasticity, impact toughness, and wear resistance. They are suitable for the production of large mass components through the open-die forging process. Subsequently, the forgings are air-cooled. An obstacle of this method is the extended time required for the large forgings to undergo a bainitic transformation, making the industrial implementation of this process economically unjustifiable. Nevertheless, nanobainitic steels also allow for the open-die forging of small batches of structural elements with high property requirements. A technological limitation lies in the necessity of performing a series of operations, leading to a prolonged processing time dependent on the shape of the product and the degree of deformation. Therefore, inter-operational reheating is often necessary, incurring costs and time consumption. This is particularly relevant to forgings with a mass ranging from a few to several dozen kilograms, which, due to their low thermal capacity, rapidly dissipate heat to the surroundings and tools. Designing an economical process with a limited number of reheating cycles requires advanced knowledge of material behavior under thermo-mechanical deformation parameters, including boundary conditions where a significant decrease in plasticity occurs and the risk of crack initiation. To obtain this information, a comprehensive analysis of the influence of thermo-mechanical parameters applied during the deformation of nanobainitic steel at relatively low temperatures on the flow characteristics and crack formation was conducted. To achieve this goal, the Digital Image Correlation method, the finite element method modeling considering damage criteria, and the macrostructural evaluation of deformed specimens were employed.