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1

Influence of heat treatment conditions of Hardox 500 steel on its resistance to abrasive wear

Zemlik Martyna, Bialobrzeska Beata, Stachowicz Mateusz, Konat Łukasz

Materials Science Poland

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2025

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Vol. 43, No. 1

173--195

EN

The type, magnitude, and distribution of thermal stress arising during the hardening process of steel primarily depend – apart from the geometry of the treated component and the type of metallic material used – on the type of cooling medium employed. The difference in cooling rates between the core and the surface of the object affects the extent of deformation, particularly in large-scale components with complex shapes. Due to their high hardness, boron-alloyed steels are frequently used for components exposed to abrasive wear, and their heat treatment is typically performed on profiled structural elements such as plowshares or cultivator coulters. The critical cooling rate is primarily dependent on the chemical composition of the material and increases as its hardenability index decreases. Consequently, it is essential to investigate the feasibility of applying various heat treatment processes to medium-carbon steels, including the widely used martensitic steel Hardox 500. This study presents the results of abrasive wear tests conducted on the aforementioned steel, subjected to different heat treatment variants, which involved varying cooling rates following austenitization. For this purpose, the cooling media used included deoxygenated quenching water, mineral transformer oil, synthetic quenching oil, and air-blast cooling. For comparative purposes, equilibrium-cooled samples were also analyzed. The research findings demonstrated that the highest resistance to abrasive wear was achieved by samples quenched in water, whereas a gradual decrease in wear resistance was observed in samples cooled in media with lower cooling intensity coefficients. Furthermore, it was found that the traditionally employed roughness parameters are not suitable for evaluating the condition of surfaces subjected to abrasion. Therefore, for a comprehensive assessment of the tribological resistance of Hardox 500 steel, more advanced surface topography analysis methods must be employed.

2

Evaluating the stress intensity factor for R350HT rail steel in relation to microstructure parameters

Żak Sylwester, Junak Grzegorz, Woźniak Dariusz, Żak Artur, Chmiela Bartosz, Jabłońska Magdalena Barbara

Advances in Science and Technology. Research Journal

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2025

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Vol. 19, no. 4

349–364

EN

The study highlights the advancement of rail transport, focusing on the distinct requirements of high-speed passenger transit and robust freight operations. Passenger rails emphasize geometric precision, such as straightness and minimal dimensional deviation, to reduce vibrations and improve safety and comfort. Freight rails, in contrast, require exceptional durability to withstand high axial loads, plastic deformation, and abrasive wear due to heavy tonnage. A key parameter for all rail types is the stress intensity factor (KIc), which ensures rail integrity by preventing crack propagation. The study confirmed that tested rail types (60E2, 54E4, and 49E1) meet the EN 13674-1 standard for mechanical properties, indicating effective heat treatment. Residual stress levels were found to be low, particularly in lighter rails, enhancing resistance to brittle fracture. All rails exhibited a fine, fully pearlitic microstructure with cementite lamellae spacing between 92 and 106 nm, contributing to mechanical strength and durability. The low residual stress and high KIc support extended rail life and safety, as larger critical crack sizes minimize fracture risk. These findings underline the reliability and safety of rail materials under operational conditions, with consistent pearlitic structures and optimized stress properties ensuring robust performance.

3

Enhancing microstructural and thermal properties of TiNiPd shape memory alloys through copper addition

Hussain Abid, Khan Afzal, Khan Muhammad Imran, Ur Rehman Saif

Advances in Materials Science

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2025

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Vol. 25, nr 1(83)

66--81

EN

This study explores how the addition of copper (Cu) addition impacts the microstructural and thermal properties of shape memory alloys (SMAs), specifically TiNiPd alloys. Two compositions, 0Cu and 10Cu, were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), Optical Microscopy (OM) and differential scanning calorimetry (DSC). SEM revealed second-phase precipitates distributed along grain boundaries in both alloys, with sizes ranging from 0.9 to 2.9 μm; however, Cu addition reduced precipitate density without affecting size. The grain size increased significantly from 12.5 μm in 0Cu to 17.5 μm in 10Cu, attributed to decreased nickel content and reduced pinning effects of precipitates. Aging at 600°C and 700°C further influenced precipitate behavior and transformation temperatures, with Cu-containing alloys demonstrating enhanced thermal characteristics. DSC analysis indicated significant increases in transformation temperatures and decreased thermal hysteresis with Cu addition. These results highlight the promise of Cu as a viable substitute for Ni in enhancing the properties of TiNiPd SMAs.

4

Structure and Properties of the Nitrided Layer with Sulfides

Kazimierski Grzegorz, Stodolny Jerzy, Lewandowski Albert, Wróbel Rafał J.

Tribologia

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2024

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nr 1

57--66

EN

This study contains a brief overview of sulfur nitriding methods, i.e. a modified version of nitriding. This information is accompanied by the results of our own tests of nitrided and sulfur-nitrided coatings with the addition of MoS2 in the scope of structure assessment by means of a scanning microscope – SEM/EDS and the results of tribological tests performed under dry friction conditions on the T-05 apparatus for four variants of thermo-chemical treatment. In tribological tests, the degree of wear was observed by measuring the weight loss of both samples and counter-samples, and the beneficial effect of sulfides on reducing wear was indicated, with the sulfur nitriding variant with MoS2 added being the most advantageous. In this case, the lowest degree of wear was found for the friction pair with a sulfur-nitrogen coating reinforced with MoS2, which may lead to extending the operating time.

PL

Opracowanie zawiera krótki przegląd metod azotonasiarczania tj. zmodyfikowanej wersji azotowania. Do tych informacji dołączono wyniki własnych badań powłok azotowanych i azotonasiarczanych z dodatkiem MoS2 w zakresie obejmującym ocenę struktury za pomocą mikroskopu skaningowego – SEM/EDS i wyniki testów tribologicznych wykonanych w warunkach tarcia suchego na aparacie T-05 dla czterech wariantów obróbki cieplno-chemicznej. W testach tribologicznych obserwowano stopień zużycia przez pomiar ubytku wagi zarówno próbek, jak i przeciwpróbek, a także wskazano na korzystny wpływ siarczków na zmniejszenie zużycia, przy czym najkorzystniejszy okazał się wariant azotonasiarczania z dodatkiem MoS2. W tym przypadku stwierdzono najmniejszy stopień zużycia, co dla pary ciernej z powłoką azotonasiarczaną wzmocnioną dodatkiem MoS2 oznacza możliwość wydłużenia czasu eksploatacji.

5

Effect of Heat Treatment on Abrasion Wear Resistance of Steel with Micro-Additives of Boron and Vanadium

Białobrzeska Beata, Konat Łukasz

Tribologia

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2024

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nr 1

7--19

EN

This paper presents the results of own research regarding the role of microstructure and mechanical properties in the abrasive wear of metallic materials, demonstrated on the example of low-alloyed steel with microadditives of boron and vanadium. The first section discusses the current knowledge relating to the influence of microstructure and hardness on tribological conditions of materials. Further sections present the results of microstructure observations performed with light microscopy as well as with scanning electron microscopy and transmission electron microscopy. This research has focused on the material both in the as-delivered condition (directly after casting) and after heat treatment, which involved quenching and tempering at three temperatures: 200, 400, and 600°C. The tribological tests were performed with the use of the T-07 tribometer, in the presence of loose #90 electro corundum abrasive particles. The test results have been discussed and an attempt has been made to correlate them with the microstructure and selected mechanical properties. In order to identify wear mechanisms, the surfaces were visually inspected after the abrasion process. The inspection results indicate that the main wear mechanisms were microcutting and microploughing.

PL

W pracy zreferowano wyniki badań własnych w zakresie roli mikrostruktury i właściwości mechanicznych w zużywaniu ściernym materiałów metalicznych na przykładzie niskostopowego staliwa z mikrododatkami boru i wanadu. W początkowej części omówiono stan wiedzy dotyczący wpływu mikrostruktury i twardości na właściwości tribologiczne materiałów. Następnie przedstawiono wyniki obserwacji mikrostrukturalnych przeprowadzonych za pomocą mikroskopii świetlnej oraz elektronowej mikroskopii skaningowej. W referowanych badaniach skupiono się na materiale w stanie dostarczenia (bezpośrednio po odlewaniu) oraz na stanie obrobionym cieplnie, obejmującym hartowanie i odpuszczanie w trzech temperaturach, tj. 200, 400 i 600°C. Badania tribologiczne zostały przeprowadzone za pomocą testera T-07 w obecności luźnego ścierniwa, które stanowił elektrokorund #90. Wyniki badań zostały dodatkowe poszerzone o dyskusję oraz próbę ich korelacji z mikrostrukturą i wybranymi własnościami mechanicznymi. W celu ustalenia mechanizmów zużywania, dokonano obserwacji powierzchni po ścieraniu. Na tej podstawie stwierdzono, że głównymi mechanizmami zużycia były mikroskrawanie i mikrobruzdowanie.

6

Abrasion Wear Resistance of Welded Joints Between Hardox Steel 400 and Grade A Ship Steel

Konat Łukasz, Białobrzeska Beata

Tribologia

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2024

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nr 4

23--42

EN

This paper presents the technological and microstructural aspects of the formation and heat treatment of a welded joint between two types of steel having significantly different chemical and mechanical properties, i.e. between low-alloy high-strength, abrasion wear resistant Hardox 400 steel and grade A marine construction steel. The test results indicate that connecting the two types of steel by welding leads to the formation of a heat-affected zone in the entire welded joint area with hardness levels reduced to approximately 170–180 HV. This zone shows various microstructural changes which prevent a reliable evaluation of the abrasion wear resistance of the welded joint. Therefore, the article proposes an optimal technology of welding the two steel types, and welding technological parameters of the thermal post-treatment that allow the formation of microstructures having an increased–in comparison to the pre-welding condition–resistance to abrasion wear processes, as measured with the electro corundum #90 abrasive particles. Heat treatment optimized the microstructure, improving the abrasion wear resistance by 16% compared to the as-welded condition.

PL

W pracy przedstawiono technologiczne i mikrostrukturalne aspekty wykonywania i obróbki cieplnej połączenia spawanego dwóch stali o bardzo odmiennych właściwościach chemicznych i mechanicznych, tj. niskostopowej, wysokowytrzymałej stali odpornej na zużywanie ścierne Hardox 400 ze stalą konstrukcyjną, predefiniowaną do zastosowań w przemyśle okrętowym kategorii A. W wyniku przeprowadzonych badań stwierdzono, że zastosowanie do łączenia tych stali procesów spawalniczych prowadzi do powstawania w obrębie całego połączenia spawanego szerokiej strefy wpływu ciepła o twardości 170-180 HV, charakteryzującej się zróżnicowanymi zmianami mikrostrukturalnymi, uniemożliwiającymi miarodajną ocenę odporności na zużywanie ścierne wykonanego połączenia. W związku z tym zaproponowano optymalną technologię spawania obu stali oraz warunki i parametry postobróbki cieplnej, prowadzących do uzyskania w strefie połączenia spawanego mikrostruktur odznaczających się podwyższoną – w stosunku do stanu bezpośrednio po spawaniu – odpornością na procesy zużycia ściernego, wyznaczoną odziaływaniem luźnego ścierniwa, tj. elektrokorundu 90. Przeprowadzona obróbka cieplna spowodowała zmiany właściwości mikrostrukturalnych, co przełożyło się na wzrost odporności na zużywanie ścierne o 16% w porównaniu ze stanem po spawaniu.

7

The study of porosity in a356 secondary aluminium alloys with higher iron content

Šurdová Zuzana, Tillová Eva, Kuchariková Lenka, Mikolajčík Martin

System Safety : Human - Technical Facility - Environment

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2024

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Vol. 6, iss. 1

430--438

EN

The production of secondary (recycled) aluminium has gained significant importance in recent years, driven by the need to reduce electricity consumption and waste associated with primary aluminium production. Secondary aluminium alloys thus play a vital role in sustainable industrial practices, particularly within sectors such as automotive, aerospace and marine. Recently, these alloys have gained traction in electric vehicle components manufacturing, where lightweight and sustainable materials are critical to enhancing energy efficiency and extending vehicle range. However, secondary aluminium alloys are prone to impurities and casting defects, notably porosity, which presents challenges in achieving optimal mechanical properties and surface quality. Porosity reduces corrosion resistance, fatigue, and tensile strength, thus impacting overall material performance. This porosity can be categorised by size (microporosity and macroporosity) and origin, with gas and shrinkage porosity being the primary types. This study examined experimental A356 secondary aluminium alloys with varying iron contents in as-cast and T6 heat-treated conditions. The analysis focused on the quantitative assessment of casting defects within the microstructure, specifically, the types of pores present, the area percentage of pores, and average pore size. These insights contribute to a deeper understanding of how casting defects impact the performance of recycled aluminium alloys in sustainable applications, particularly in the context of nextgeneration electric vehicles.

8

Mechanical properties of chromium steel drills in the context of durability and safety of use

Bałaga Zbigniew, Opydo Michał, Dudek Agata, Lisiecka Barbara

System Safety : Human - Technical Facility - Environment

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2024

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Vol. 6, iss. 1

311--319

EN

This article presents the research results on the influence of heat treatment of chromium steel, used in the production of drill bits, on their mechanical properties and operational safety. The analyses revealed that the steel used in manufacturing the studied drill bit underwent hardening and tempering processes, which affected its structure and hardness. The presence of tempered martensite and manganese sulfides was observed, which, although not having a destructive impact on the steel's properties, may limit the formation of undesirable iron sulfides. Additionally, a layer with reduced hardness was identified on the working surface of the drill bit, suggesting the possibility of tool overheating during operation. During the tool's use, complex mechanical stresses, such as torsional, compressive, and bending stresses, may accumulate in areas prone to damage, especially at the interface between the tooth and the drill bit shank. The article emphasizes the importance of proper tool usage, including adjusting pressure and drilling angle and maintaining optimal operational conditions to ensure safety and durability. The research findings aim to enhance workplace safety and improve the performance of cutting tools in materials engineering.

9

Testing and evaluation of mechanical properties of C45 steel with bainitic structure

Sąsiadek M., Woźniak W., Melichar M.

Journal of Achievements in Materials and Manufacturing Engineering

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2024

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Vol. 125, nr 2

49--55

EN

Purpose: The article aims to investigate the mechanical properties of C45 steel with a previously constituted bainitic structure, due to its widespread use in the machine industry. Design/methodology/approach: The input ferritic-pearlitic structure of steel was subjected to heat treatment in the form of quenching and tempering in order to obtain a bainitic structure. Tempering was carried out at different temperature and time values. It allowed various properties of the steel samples to be obtained, which were subsequently subjected to tensile strength and hardness testing. In addition, metallographic images of the resulting structures were taken. Findings: The results obtained from the tests were compiled in tabular form. Based on the results, correlations were observed in the tensile strength and hardness of the tested steel relative to various parameters of the hardening and tempering processes. Research limitations/implications: The strength properties testing of C45 steel with a bainitic structure was limited to determining the yield strength Re, tensile strength Rm, elongation A, and microhardness HV0.5. Practical implications: The tests confirmed the possibility of controlling heat treatment process parameters to achieve the desired mechanical properties of the steel. This may contribute to the practical control of the steel’s properties due to economic aspects and functional requirements. Originality/value: The article is primarily addressed to industrial practice, i.e., manufacturers of machine parts made of medium-carbon steel, due to the reduction in heat treatment time and energy consumption costs while maintaining the steel’s machinability and strength properties.

10

Rework and repair of steam turbine components subject to flexible operation

Biesinger Frank, Huáscar Lorini, Banaszkiewicz Mariusz

Energetyka

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2024

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nr 12

520--524

EN

The increase in renewable energy penetration on the grid has accelerated the need to transition conventional fossil-based energy sources from their traditional base load operation to more flexible operational regimes. The mode of operation changed dramatically in terms of number of starts, operating hours per annum, and variation in load level. This results in greater thermal transients on operational equipment leading to an increase in low cycle fatigue damage. To ensure the continued integrity of the steam turbine components, it is essential to assess the lifetime status by applying residual lifetime analysis methods. Depending on the amount of lifetime consumption and the extent of potential crack findings, different component repair options are possible. The rework or repair options can be divided into two main groups, namely cold and hot rework. These two options can also be carried out consecutively. All rework or repair options provide the opportunity to improve the application of a component by applying profiling with improved stress fields and even superior materials, in the case of hot rework. The aim of the rework/reconditioning is to ensure that the steam turbine component is suitable for future operation. This ensures that plants are well placed to deliver more flexible operation in the energy industry through careful tailored refurbishments and reworks.

PL

Wzrost znaczenia energii odnawialnych w sieciach energetycznych przyspieszył potrzebę przejścia konwencjonalnych źródeł energii bazujących na paliw kopalnych z tradycyjnej pracy w podstawie na bardziej elastyczne reżimy pracy. Warunki eksploatacji uległy drastycznej zmianie w zakresie liczby uruchomi rocznych godzin pracy oraz zakresu zmian mocy. Skutkuje to występowaniem zwiększonych obciążeń termicznych elementów prowadzących do wzro zużycia z tytułu zmęczenia niskocyklowego. W celu zapewnienia dalszej wytrzymałości elementów turbin parowych podstawową kwestią staje się ocena sti żywotności z zastosowaniem metod analizy trwałości resztkowej. W zależności od poziomu wyczerpania żywotności i zakresu potencjalnego występowe pęknięć możliwe są różne opcje naprawy elementów. Obróbki i naprawy można generalnie podzielić na dwie grupy: naprawy na zimno i naprawy na gors, Te operacje mogą być również wykonywane kolejno jedna po drugiej. Obie opcje dają możliwość poprawy własności użytkowych elementów pope zastosowanie zoptymalizowanych kształtów poprawiających rozkład naprężeń, a nawet użycie lepszych materiałów w przypadku napraw na gorąco. Cel proponowanych obróbek i napraw jest zapewnienie przydatności elementów turbin parowych do dalszej eksploatacji. Umożliwia to elektrowniom oferowa rynkom energii bardziej elastycznej eksploatacji właśnie dzięki wykonaniu starannie dobranych obróbek i napraw.

11

Investigation on Mechanical Properties of MAR-M247 Superalloy for Turbine Blades by Experiment and Simulation

Lin Hao, Geng Haipeng, Zhou Xifeng, Song Leiming, Hu Xiaojun

Archives of Metallurgy and Materials

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2024

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Vol. 69, iss. 1

189--196

EN

This study aimed to investigate the metallographic structure and the impact of the heat treatment process on the MAR-M247 superalloy, a high-temperature nickel-based superalloy commonly used in turbine blades. The heat treatment process can potentially influence the mechanical properties of the MAR-M247 superalloy at different temperatures. A strength simulation analysis of gas turbine blades should include the variations in the mechanical properties of the material. The effect of heat treatment on grain size was investigated by metallographic experiments, and numerical calculations of material mechanical properties were conducted. The mechanical property parameters necessary for finite element analysis of turbine blades were determined. Finally, a finite element simulation model of the blade was established based on these mechanical property parameters, and strength analysis was performed. The simulation results provided the stress distribution and the strength of the turbine blade.

12

Influences of Hardened Aluminium HMMC on Tribological, Flexural and Impact Strength of Wheel Rim Element with Prognostications

Kamatchisankaran S., Bovas Herbert Bejaxhin Alphonse, Ramkumar Kathalingam, Ramanan Nandagopan

Archives of Metallurgy and Materials

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2024

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Vol. 69, iss. 3

1015--1025

EN

The primary goal of this research is to develop hybrid non-ferrous material composites with high flexural and impact strengths by testing the mechanical, thermal, and corrosion properties of AA 6061 wheel rims with various silicon carbide (SiC) and zirconium sulphide (ZrSO4) compositions. This produces an alloy with high strength and perceptible hardenability that is used in a variety of marine space industries. Because of its exceptional strength-to-density ratio, it is a highly sought-after metal matrix composite in the automobile industry. This innovative composite material offers lower weight and higher impact strength when compared to the current wheel rim alloy. Designs of experiments based recommendations and results of simulations in order to prolong the life of the wheel rim.

13

High Temperature Isothermal Oxidation at 950°C of Ni-based Fe-40Ni-24Cr Alloy

Anuar Aqmar Ikhmal, Parimin Noraziana, Ahad Nor Azwin, Derman Mohd Nazree, Garus Sebastian, Vizureanu Petrica

Archives of Metallurgy and Materials

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2024

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Vol. 69, iss. 3

1191--1198

EN

The effect of different heat treatment temperatures on the isothermal oxidation of Ni-based Fe-40Ni-24Cr alloy was studied. The alloy underwent a heat treatment process at 1000°C and 1200°C for 3 hours of soaking time, followed by water quenching. These samples are labeled as N10 and N12. The heat-treated samples were characterized in terms of grain size using an optical microscope and hardness testing using a Rockwell hardness. As a result, increasing the heat treatment temperature increases the average grain size of the alloy and lowers the hardness value. Heat-treated N10 and N12 samples were subjected to an isothermal oxidation test at 950°C for an exposure time of 150 h. Oxidized heat-treated samples were characterized in terms of oxidation kinetics calculated based on weight change per surface area as a function of time. In addition, phase analysis and oxide surface morphology were measured using x-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. As a result, the oxidation kinetics of both samples showed a pattern of weight gain with N10 recording the lowest weight gain. Both samples obey a parabolic rate law, indicating a controlled oxide growth rate. N10 recorded the lowest parabolic rate constant of 2.5×10-8 mg2cm-4s-1, indicating a low oxidation rate, thus having good oxidation resistance. Phase analysis using XRD shows that several oxide phases have been formed consisting of Cr-containing oxides Cr2O3 and MnCr2O4. In addition, SEM analysis displayed a uniform oxide layer formed on the N10 sample, indicating good oxide adhesion. This finding shows an important contribution to the oxidation protection mechanism that records the fine grain obtained from the heat treatment process can increase good oxidation resistance.

14

Effect of Post-Heat Treatment on the Mechanical Properties and Corrosion Behavior of Duplex Stainless Steel Fabricated by Wire Arc Additive Manufacturing

Zhang Long, Liu Liang, Liu Feihong, Sun Jian, Wang Dongsheng

Archives of Metallurgy and Materials

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2024

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Vol. 69, iss. 2

667--674

EN

In this study, the effect of heat treatment on the microstructure and mechanical properties of 2209 duplex stainless steel fabricated by wire arc additive was analyzed. It was found that solution treatment at 1100°C for 2 hours and tempering at 300°C for 2 hours can effectively improve the grain inhomogeneity of 2209 duplex stainless steel, eliminate γ2 and harmful brittle phases, and take into account the mechanical properties and corrosion resistance. Compared with the original deposition state, the hardness and yield strength increased by 10% and 31.8% to 245.6 HV and 499.7 MPa, which meet the requirements of engineering propellers. Electron back-scattered diffraction studies showed that the grains became refined and austenite maintained <101>//Z orientation after solution heat treatment. Many small-angle grain boundaries were present in both the original sample and the solid solution, but further tempering transformed the small-angle grain boundaries into large-angle grain boundaries.

15

Effect of Cooling Rate on Microstructure and Mechanical Properties According to Heat Treatment Temperature of Inconel 625

Park Minha, Lee Gang Ho, Kim Hyo-Seong, Kim Byoungkoo, Noh Sanghoon, Kim Byung Jun

Archives of Metallurgy and Materials

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2024

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Vol. 69, iss. 1

95--98

EN

Inconel 625 is typically used in extreme environments due to excellent mechanical properties such as high strength, corrosion resistance, abrasion resistance and low-temperature toughness. When manufacturing a hot forged flange with a thick and complex shape, the cooling rate varies depending on the location due to the difference in thermal gradient during the cooling process after hot forging. In this study, to evaluate the microstructure and mechanical properties of Inconel 625 according to the cooling rate, we performed heat treatment at 950°C, 1050°C, and 1150°C for 4 hours followed by water cooling. Additionally, temperature data for each location on the flange were obtained using finite element method (FEM) simulation for each heat treatment temperature, revealing a discrepancy in the cooling rate between the surface and the center. Therefore, the correlation between microstructure and mechanical properties according to cooling rate was investigated.

16

Effect of Aging Parameters of EN AW-7021 Aluminium Alloys on Stress Corrosion Cracking

Boczkal Sonia, Węgrzyn Mateusz, Szymański Wojciech, Bem Jakub, Wala Katarzyna, Płonka Bartłomiej, Leśniak Dariusz, Nowak M.

Archives of Metallurgy and Materials

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2024

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Vol. 69, iss. 3

1061--1069

EN

The main assumption of the conducted research was the selection of appropriate heat treatment parameters to obtain the best possible resistance to stress corrosion cracking (SCC) and the highest strength properties of the extruded profiles. The work selected the temperature and time of one- and two-stage treatment of the EN AW-7021 alloy based on aging curves. Tests carried out for samples after aging at 135°C for 24 h and two-stage aging at 90°C/8 h + 135°C/8 h revealed the highest resistance to SCC. The 7021 alloy, after heat treatment at 90°C/8 h + 135°C/16 h, reached the highest tensile strength of 534 MPa. Transmission electron microscopy (TEM) observations showed slight differences in the finely dispersed nucleoids between the selected parameters of the artificial aging process.

17

Comparison of the Properties of Cold Work Tool Steels with the Same Hardness but Different Manufacturing Processes

Tóth László, Fábián Enikő Réka, Pinke Peter, Kovács Tunde Anna, Nabiałek Marcin, Sandu Andrei Victor, Vizureanu Petrica

Archives of Metallurgy and Materials

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2024

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Vol. 69, iss. 3

809--817

EN

The required important properties of cold work tool steels are hardness, wear resistance, suitable toughness and in many cases corrosion resistance. For cold work tool steels, hardness can be well controlled by heat treatment, but steels of the same hardness do not necessarily have similar wear, corrosion resistance or even toughness. These properties are influenced by the chemical composition of the steels and their manufacturing processes. The study is performed on Böhler K390 PM produced by powder metallurgy (PM) process, Böhler K360 ESR made by electro-slag remelting (ESR) methods and Böhler K110 produced conventionally (C). The specimens were heat treated to obtain the same hardness of 61 HRC. It was made a comparative test of the abrasive wear resistance, corrosion resistance and toughness of the heat-treated cold work tool steel test specimens. The comparative test results show that the Böhler K110 steel has the best corrosion resistance against the 20% acetic acid, and the Böhler K390 PM steel has the best wear resistance and toughness. The goal of the research was to find the optimal cold work tool steel quality for special applications (as a function of wear resistance, corrosion resistance and toughness). The K390 reached the best wear resistance which is two times better than the K360 and about ten times better than the K110. About the corrosion test results, it can be concluded that K110 showed the lowest weight loss after the corrosion test, and the K390 and K360 showed higher weight loss and lower corrosion resistance. Impact energy values from the Charpy impact test were the highest in the case of K390 followed by the K360 and the K110. The results were confirmed by the microscopic analysis.

18

Friction wear resistance of 42CrMo4 surface layer after low-pressure ferritic nitrocarburising (FNC)

Pawęta S., Pietrasik R., Wołowiec-Korecka E.

Archives of Materials Science and Engineering

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2024

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Vol. 129, nr 1

24--30

EN

Purpose: The work aimed to assess the performance properties of layers produced using the low-pressure ferritic nitrocarburising technology, in particular wear resistance under friction conditions. The assessment has been made in relation to analogous elements subjected only to heat treatment (hardening with tempering). Design/methodology/approach: The material for the tests consisted of two groups of friction pairs (5 friction pairs in each group) made of 42CrMo4 steel. The 42CrMo4 steel has been heat-treated (hardening at 880°C in oil, tempering at 570°C for 2 hours). Half of the samples have been subjected to low-pressure ferritic nitrocarburising at 560°C for 6 hours. The friction test has been conducted according to the PN-75/M-04308 standard for 2 minutes at a load of 445 N. Findings: The test results showed that the elements after ferritic nitrocarburising had almost twice the surface hardness (662 HV1) than the control group (339 HV1). The average weight wear of the heat-treated and ferritic nitrocarburised elements has been 0.011 g, with an average wear in the control group of 1.022 g. The average friction coefficient in the heat-treated and ferritic nitrocarburised friction pairs was 0.188, while in the heat-treated only pairs, it was 0.358. The Man-Whitney U test has shown that the differences between the average weight wear and the average friction coefficient values are significant (p<0.05). Research limitations/implications: The paper investigates the effect of low-pressure ferritic nitrocarburising technology on the surface layer of steel materials. Practical implications: Low-pressure ferritic nitrocarburising technology shows the potential for practical applications in industrial reality at a level at least equivalent to those currently used worldwide. Originality/value: It is the first known publication on the effect of low-pressure ferritic nitrocarburising technology on the performance properties of the surface layer of elements improved by this method.

19

Study on Preparation Technology and Heat Conduction Mechanism of High-Purity & Ultra-Fine Alumina Powder from Scrap Aluminum Cans

Wang Chengmin, Politov Anatoly, Wang Xiuhui, Yang Jinlong

Archives of Foundry Engineering

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2024

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Vol. 24, iss. 1

158--164

EN

In view of the increasing scarcity of bauxite resources in China, the high energy consumption and high pollution of electrolytic aluminum, and the requirements for energy conservation and environmental protection, aluminum recycling and high-value utilization of its derivatives have evolved into a crucial development requirement for the aluminum industry in the future. As an important part of the development of recycled aluminum resources, the high-value application of scrap aluminum cans has always been a hot research topic in various recycled aluminum processing enterprises and scientific research units. The traditional regeneration system of waste cans includes a series of complex technological processes such as pretreatment, paint removal, smelting system and casting system, which is difficult to control in the middle of the process. Most of the recycled scrap aluminum cans are cast and downgraded for later use, except for a part of them used as alloy materials for new cans. In this paper, combined with the research on the preparation of metal aluminum alkoxide, combined with recrystallization heat conduction to further study the effective dissolution or adsorption how to remove impurity elements to obtain high-purity aluminum alcohol salt mechanism research, and thermal effect of alcohols with different carbon chains on the synthesis of high-purity aluminum alkoxide was further investigated. Moreover, the changes in morphology and pore size distribution of hydrolyzed alumina precursor materials under different hydrothermal temperature conditions were discussed by means of the alkoxide hydrolysis-sol-gel process. Eventually, the aluminum alkoxide was obtained by the reaction of waste cans with isopropanol and heavy crystal thermal conductivity, and the high-purity aluminum alkoxide was purified by vacuum distillation. Under the hydrothermal condition of 160°C, the high-purity alumina material with a purity of 99.99% and an original crystal size of 200nm was prepared.

20

Structure of ADI Cast Iron as a Cast “in situ” Composite Reinforced with TiC Ceramic Particles

Marosz J., Kawalec M., Górny M.

Archives of Foundry Engineering

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2024

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Vol. 24, iss. 4

95--102

EN

This paper presents a novel technology for the production of a casting material, which is an “in situ” composite on an ADI iron matrix reinforced with titanium carbide particles. As a result of the initiated Self-propagating High-temperature Synethesis reaction in Bath (liquid metal) of the type “solid Ti” – “solid C” type, led to the formation of ceramic phases in the form of titanium carbides. This method, allowed the synthesis of a cast composite based on ductile cast iron and, after subsequent heat treatment, the transformation of this material into ADI cast iron. The greatest advantage of “in situ” composites is that they are produced in a one-step metallurgical process, which is characterised, among other things, by: high thermodynamic stability, synthesis of a reinforcing phase in a metal bath, small size of ceramic particles with the possibility of controlling their dimensions by reaction kinetics parameters during the synthesis process. In this study, metallographic analysis of the composite obtained, both in the initial state and after heat treatment, was carried out using optical and scanning electron microscopy. An analysis of the chemical composition in the micro-area was carried out using the EDS method, the chemical composition was studied using the XRF spark X-ray fluorescence method, and the proportion of graphite and the carbide phase, i.e. titanium carbide TiC, was determined. The results obtained confirmed the possibility of obtaining the composite material via the SHSB reaction route. The heat treatment results showed that the carbides are thermodynamically stable and do not dissolve at temperatures designed for the production of ADI cast iron. The SHSB reaction guarantees a uniform distribution of titanium carbides on the ADI cast iron matrix.