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6 pages, 212 KiB

Open AccessEditorial

Quality, Microstructure, and Properties of Metal Alloys

by Tomasz Lipiński

Materials 2023, 16(8), 3019; https://doi.org/10.3390/ma16083019 - 11 Apr 2023

Cited by 2 | Viewed by 1199

Abstract

In the course of evolution, humankind has used many construction materials [...] Full article

(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys)

Research

Jump to: Editorial, Review

12 pages, 1397 KiB

Open AccessArticle

Influence of the Scatter Index of Non-Metallic Inclusions in Structural Steel on the Fatigue Resistance Coefficient

by Tomasz Lipiński

Materials 2023, 16(7), 2758; https://doi.org/10.3390/ma16072758 - 30 Mar 2023

Cited by 3 | Viewed by 1286

Abstract

One of the main parameters characterizing steel is tensile strength. Conducting actual research is time consuming and expensive. For this reason, the technique uses simplified methods that allow one to quickly estimate the resistance of the material to fatigue. They are conducted mainly [...] Read more.

One of the main parameters characterizing steel is tensile strength. Conducting actual research is time consuming and expensive. For this reason, the technique uses simplified methods that allow one to quickly estimate the resistance of the material to fatigue. They are conducted mainly by computer methods. For the proper development of programs to determine the fatigue parameters of steel, solid data preparation is necessary. Unfortunately, some studies are performed on materials produced in laboratory conditions, which is only an approximation of the actual production conditions. Real alloys contain natural impurities which can affect their properties. Therefore, it is important to use real results obtained on an industrial scale for analysis including computer simulations. One of the important parameters that can be used to describe the properties of steel is the scatter index. It is the quotient of the average distance between the pollution and the average size of the pollution. This parameter makes it possible to take into account the fatigue strength of steel, taking into account the size of impurities and the distance between these impurities. The paper attempted to determine the scatter index and its impact on the fatigue resistance coefficient for steel melted in an industrial 140 ton electric furnace. The tests were carried out on structural steel with an average carbon content of 0.26%. The steel was hardened and tempered in all temperature tempering ranges (low, medium, and high). The fatigue resistance coefficient in the scatter index function was determined and discussed for each of the applied heat treatment parameters. Full article

(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys)

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21 pages, 2036 KiB

Open AccessArticle

A Rank Model of Casting Non-Conformity Detection Methods in the Context of Industry 4.0

by Robert Ulewicz, Karolina Czerwińska and Andrzej Pacana

Materials 2023, 16(2), 723; https://doi.org/10.3390/ma16020723 - 11 Jan 2023

Cited by 13 | Viewed by 1943

Abstract

In the face of ongoing market changes, multifaceted quality analyses contribute to ensuring production continuity, increasing the quality of the products offered and maintaining a stable market position. The aim of the research was to create a unified rank model for detection methods [...] Read more.

In the face of ongoing market changes, multifaceted quality analyses contribute to ensuring production continuity, increasing the quality of the products offered and maintaining a stable market position. The aim of the research was to create a unified rank model for detection methods in the identification of aluminium casting non-conformities, in line with the paradigms of the fourth industrial revolution. The originality of the model enables the creation of a rank for the effectiveness of total inspection points allowing for the optimisation of detection methods. Verification of the model was carried out against the production process of aluminium casting. The model included the integration of non-destructive testing (NDT) methods and the analysis of critical product non-conformities, along with the determination of the level of effectiveness and efficiency of inspection points. The resulting ranking of detection methods indicated the NDT method as the most effective, which was influenced by the significant detection of critical non-conformities and the automation of the process. The study observed little difference in the visual inspection and measurement efficiency parameters, which was due to the identifiability of non-conformities with a lower degree of significance and the low level of inspection cost. Further research will look at the implications of the model in other production processes. Full article

(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys)

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10 pages, 1218 KiB

Open AccessArticle

On Structural and Magnetic Properties of Substituted SmCo₅ Materials

by Margariti Gjoka, Georgios Sempros, Stefanos Giaremis, Joseph Kioseoglou and Charalampos Sarafidis

Materials 2023, 16(2), 547; https://doi.org/10.3390/ma16020547 - 5 Jan 2023

Cited by 10 | Viewed by 1815

Abstract

SmCo₅ is a well-established material in the permanent magnet industry, a sector which constantly gains market share due to increasing demand but also suffers from criticality of some raw materials. In this work we study the possibility of replacement of Sm with [...] Read more.

SmCo₅ is a well-established material in the permanent magnet industry, a sector which constantly gains market share due to increasing demand but also suffers from criticality of some raw materials. In this work we study the possibility of replacement of Sm with other, more abundant rare earth atoms like Ce-La. These raw materials are usually called “free” rare-earth minerals, appearing as a by-product during mining and processing of other raw materials. Samples with nominal stoichiometry Sm_1−xMM_xCo₅ (x = 0.1–1.0) were prepared in bulk form with conventional metallurgy techniques and their basic structural and magnetic properties were examined. The materials retain the hexagonal CaCu₅-type structure while minor fluctuations in unit cell parameters as observed with X-ray diffraction. Incorporation of Ce-La degrade intrinsic magnetic properties, Curie temperature drops from 920 K to 800 K across the series and mass magnetization from 98 Am²/kg to 60 Am²/kg; effects which trade off for the significantly reduced price. Atomistic simulations, implemented based on Density Functional Theory calculations are used in the case of the stoichiometry with x = 0.5 to calculate atomic magnetic moments and provide additional insight in the complex interactions that dominate the magnetic properties of the material. Full article

(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys)

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19 pages, 4720 KiB

Open AccessArticle

Computer Alloy Design of Ti Modified Al-Si-Mg-Sr Casting Alloys for Achieving Simultaneous Enhancement in Strength and Ductility

by Shaoji Zhang, Wang Yi, Jing Zhong, Jianbao Gao, Zhao Lu and Lijun Zhang

Materials 2023, 16(1), 306; https://doi.org/10.3390/ma16010306 - 28 Dec 2022

Cited by 16 | Viewed by 2242

Abstract

In this paper, an efficient design of a Ti-modified Al-Si-Mg-Sr casting alloy with simultaneously enhanced strength and ductility was achieved by integrating computational thermodynamics, machine learning, and key experiments within the Bayesian optimization framework. Firstly, a self-consistent Al-Si-Mg-Sr-Ti quinary thermodynamic database was established [...] Read more.

In this paper, an efficient design of a Ti-modified Al-Si-Mg-Sr casting alloy with simultaneously enhanced strength and ductility was achieved by integrating computational thermodynamics, machine learning, and key experiments within the Bayesian optimization framework. Firstly, a self-consistent Al-Si-Mg-Sr-Ti quinary thermodynamic database was established by the calculation of phase diagram method and verified by key experiments. Based on the established thermodynamic database, a high-throughput Scheil-Gulliver solidification simulation of the A356-0.005Sr alloy with different Ti contents was carried out to establish the “composition-microstructure” quantitative relationship of the alloy. Then, by combining the computational thermodynamic, machine learning, and experimental data within the Bayesian optimization framework, the relationship “composition/processing-microstructure-properties” of A356-0.005Sr with different Ti contents was constructed and validated by the key experiments. Furthermore, the optimum alloy composition of the Ti-modified A356-0.005Sr casting alloy was designed based on this integration method with the Bayesian optimization framework and verified by the experiments. It is anticipated that the present integration method may serve as a general one for the efficient design of casting alloys, especially in the high-dimensional composition space. Full article

(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys)

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15 pages, 35677 KiB

Open AccessArticle

Effect of Cu on the Microstructure and Mechanical Properties of a Low-Carbon Martensitic Stainless Steel

by Jun Ma, Yuanyuan Song, Haichang Jiang and Lijian Rong

Materials 2022, 15(24), 8849; https://doi.org/10.3390/ma15248849 - 11 Dec 2022

Cited by 8 | Viewed by 2543

Abstract

Reversed austenite is of vital importance in low-carbon martensitic stainless steel because it improves impact toughness. However, a proper amount of reversed austenite is obtained by tempering at a critical temperature, which reduces the strength of the steel. Therefore, how to improve strength–toughness [...] Read more.

Reversed austenite is of vital importance in low-carbon martensitic stainless steel because it improves impact toughness. However, a proper amount of reversed austenite is obtained by tempering at a critical temperature, which reduces the strength of the steel. Therefore, how to improve strength–toughness matching is an important problem. Copper (Cu) is an effective strengthening element in steels. However, there is little in-depth discussion on the role of Cu on the microstructure and mechanical properties of low-carbon martensite steel. In this work, the effect of different Cu content on the reversed austenite formation, tensile strength, and impact toughness of a low-carbon martensitic stainless steel (0Cr13Ni4Mo) was systematically investigated through use of a transmission electron microscope (TEM), transmission Kikuchi diffraction (TKD), atom probe tomography (APT), and other characterization methods and mechanical property tests. The results showed that the addition of Cu decreased the phase transition temperatures of martensite and austenite and increased the volume fraction of the reversed austenite. APT results indicated that Cu-rich clusters first formed with alloying elements such as ferrum (Fe) and nickel (Ni) and then grew to be precipitates through rejection of the alloying elements. The Ni atoms diffused towards the interface between the precipitates and the martensite matrix, which provided heterogeneous nucleation sites for the reversed austenite. Cu precipitations strengthened tensile strength during tempering. However, it generated temper brittleness in the steel at a tempering temperature of 450 °C, resulting in the impact energy of the 3Cu-steel being only 7 J. A good combination with higher tensile strength (863 MPa) and ductility (192 J) was obtained when tempering at 600 °C in the presence of Cu-rich precipitates and a sufficient volume fraction of the reversed austenite. The results provide guidance for the design of steels with reversed austenite and Cu and promote the development of high-strength and high-toughness steels. Full article

(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys)

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11 pages, 4354 KiB

Open AccessArticle

Corrosion Behavior of Sensitized AISI 304 Stainless Steel in Acid Chloride Solution

by Viera Zatkalíková, Milan Uhríčik, Lenka Markovičová and Lenka Kuchariková

Materials 2022, 15(23), 8543; https://doi.org/10.3390/ma15238543 - 30 Nov 2022

Cited by 10 | Viewed by 2220

Abstract

Corrosion resistance of sensitized austenitic stainless steel (SS) in chloride environments is currently the subject of numerous studies. Most of them are focused on neutral chloride solutions at room temperature and the experiments are carried out on ground stainless steels surfaces. This paper [...] Read more.

Corrosion resistance of sensitized austenitic stainless steel (SS) in chloride environments is currently the subject of numerous studies. Most of them are focused on neutral chloride solutions at room temperature and the experiments are carried out on ground stainless steels surfaces. This paper deals with the corrosion behavior of sensitized AISI 304 stainless steel in acid 1 M chloride solution (pH = 1.1) at the temperatures of 20 ± 3 °C and 50 °C. The specimens after sensitization are tested as covered by high-temperature surface oxides (“heat tinted”), and also after their chemical removal to assess the impact of the surface state on corrosion resistance. Potentiodynamic polarization (PP) and exposure immersion test are used as the independent corrosion tests. Microstructure before/after exposure immersion test is evaluated by optical microscopy (OM) and SEM. The results obtained showed that sensitization significantly conditions corrosion regardless of the removal of high-temperature oxides, and the elevated temperature mainly acts as its accelerating factor. Full article

(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys)

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22 pages, 7716 KiB

Open AccessArticle

Analysis of Filler Metals Influence on Quality of Hard-Faced Surfaces of Gears Based on Tests in Experimental and Operating Conditions

by Svetislav Marković, Vukić Lazić, Dušan Arsić, Ružica R. Nikolić, Djordje Ivković, Robert Ulewicz and Otakar Bokuvka

Materials 2022, 15(21), 7795; https://doi.org/10.3390/ma15217795 - 4 Nov 2022

Cited by 2 | Viewed by 1229

Abstract

Hard-facing as a type of the coating depositing is increasingly used today. Physical-chemical-metallurgical characteristics of contact layers in tribo-mechanical systems depend on the operating conditions and the conditions under which the work surfaces were created. That is the reason the influence of the [...] Read more.

Hard-facing as a type of the coating depositing is increasingly used today. Physical-chemical-metallurgical characteristics of contact layers in tribo-mechanical systems depend on the operating conditions and the conditions under which the work surfaces were created. That is the reason the influence of the processing procedures and regime, used in the contact surfaces formation, on development of the wear process of contact elements, is being considered ever more. To determine the influence of the hard-facing technology on characteristics of the gears’ working surfaces, the experimental investigations were performed on samples hard-faced on the steel for cementation, by varying the filler metals (FM) and the hard-facing regimes. The samples tested were hard-faced by five “hard” and three “soft” filler metals. Experimental investigations included measuring the hard-faced layers’ hardness and determination of their microstructure, as well as the wear resistance in the laboratory conditions, on tribometer and on a specially designed device for tests in the real operating conditions of gears. The wear intensity was monitored by the wear trace’s width in the laboratory conditions and by the share of the teeth surfaces affected by the destructive pitting in the operating conditions. The results obtained were compared to results of the base metal (BM) tests, which provided the certain conclusions on which filler metal and which welding procedure are the optimal ones for regeneration of the worn teeth surfaces. Full article

(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys)

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12 pages, 5308 KiB

Open AccessArticle

Effect of Mo on the Microstructures and Mechanical Properties of the Polycrystalline Superalloy with High W Content

by Qiongrui Quan, Shijie Sun, Naicheng Sheng, Juan Deng, Guichen Hou, Jinguo Li, Jidong Chen, Yizhou Zhou and Xiaofeng Sun

Materials 2022, 15(21), 7509; https://doi.org/10.3390/ma15217509 - 26 Oct 2022

Cited by 2 | Viewed by 1407

Abstract

The effect of the Mo contents of 1.0 wt.%, 1.5 wt.%, 2.0 wt.%, and 3.0 wt.% on the microstructures and mechanical properties of the polycrystalline superalloy with a high W content was studied. The typical dendrite morphology was observed in the high-W superalloy [...] Read more.

The effect of the Mo contents of 1.0 wt.%, 1.5 wt.%, 2.0 wt.%, and 3.0 wt.% on the microstructures and mechanical properties of the polycrystalline superalloy with a high W content was studied. The typical dendrite morphology was observed in the high-W superalloy with different Mo contents, containing γ matrix, γ′ phase, eutectic, and MC carbide. After the heat treatment, the primary MC carbides were decomposed into M₆C carbides, while a needle-like topologically close-packed (TCP) phase was formed in the alloy with high Mo content, in contrast to the other three alloys with low Mo content. The Mo addition increased the lattice parameter of the γ and γ′ phases and also changed the lattice misfits of the γ and γ′ phase lattice misfits towards a larger negative. The addition of Mo improved the yield strength at room temperature due to the solid solution strengthening and coherency strengthening. The improvement of the stress rupture lives at 975 °C/225 MPa was due to the combination of the suppressed propagation of the microcracks by the carbides and a more negative misfit. When the Mo content reached 3.0 wt.%, the TCP phases formed and decreased the ultimate tensile strength and the stress rupture lives as a result. Full article

(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys)

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12 pages, 2495 KiB

Open AccessArticle

Influence of Non-Metallic Inclusions on Bending Fatigue Strength of High-Quality Carbon Constructional Steel Heated in an Industrial Electric Arc Furnace

by Tomasz Lipiński

Materials 2022, 15(17), 6140; https://doi.org/10.3390/ma15176140 - 4 Sep 2022

Cited by 7 | Viewed by 1413

Abstract

Non-metallic inclusions are one of the many factors influencing the strength of materials operating under variable loads. Their influence on the strength of the material depends not only on the morphology of the impurities themselves, but it is also closely related to the [...] Read more.

Non-metallic inclusions are one of the many factors influencing the strength of materials operating under variable loads. Their influence on the strength of the material depends not only on the morphology of the impurities themselves, but it is also closely related to the microstructure of the material. This microstructure is the matrix for non-metallic inclusions. This article discusses the results of a study investigating the effect of non-metallic inclusions on the fatigue strength of structural steel during rotary bending. The study was performed at 12 heats produced in an industrial plant’s 140-ton electric furnaces. Six heats were desulphurised, and six were refined with argon. This paper presents the bending fatigue strength of steel hardened and tempered at different temperatures, subject to the relative volume of inclusions. This paper also presents the dimensional structure of non-metallic inclusions divided by different two technologies. The research shows that the main fraction of non-metallic inclusions is Al₂O₃; the most numerous were impurities with a diameter of less than 2 µm; argon refining does not affect the proportion of non-metallic inclusions of large dimensions (with a diameter of over 15 µm); the influence of non-metallic inclusions on the strength of the steel is also related to the microstructure of the steel constituting the matrix of inclusions. Full article

(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys)

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14 pages, 6526 KiB

Open AccessArticle

Controlled Atmosphere Brazing of 3003 Aluminum Alloy Using Low-Melting-Point Filler Metal Fabricated by Melt-Spinning Technology

by Zeng Gao, Zhen Qin and Qingsong Lu

Materials 2022, 15(17), 6080; https://doi.org/10.3390/ma15176080 - 1 Sep 2022

Cited by 6 | Viewed by 2607

Abstract

3003 aluminum alloy was widely used for the manufacturing of heat exchangers in the automotive industry by employing controlled atmosphere brazing (CAB) with NOCOLOK flux brazing technology. However, commercially available filler metals for NOCOLOK flux brazing technology are usually required to be carried [...] Read more.

3003 aluminum alloy was widely used for the manufacturing of heat exchangers in the automotive industry by employing controlled atmosphere brazing (CAB) with NOCOLOK flux brazing technology. However, commercially available filler metals for NOCOLOK flux brazing technology are usually required to be carried out at a relatively high temperature, causing the assembled heat exchanger to be partially molten or easily deformed. A new low-melting-point brazing filler metal Al-5.0Si-20.5Cu-2.0Ni was prepared by using melt-spinning technology and then applied to CAB of 3003 aluminum alloy in this research. The solidus and liquidus of brazing filler metal was 513.21 °C and 532.48 °C. All elements were evenly distributed and free from elemental segregation. The microstructure of brazing filler metal was uniform, and the grain size was less than 500 nm. As the brazing temperature reached 575 °C, the void in the joint disappeared completely. The morphology of CuAl₂ was sensitive to the brazing temperature and dwell time. The appearance of net-like CuAl₂ brazed at 575 °C for 20 min was more beneficial to improve joint mechanical properties. The leakage rate of the joint was qualified to be 10⁻¹⁰ Pa·m³/s when the brazing temperature was 570 °C or higher. The maximum shear strength of 76.1 MPa can be obtained when the joint was brazed at 575 °C for 20 min. More dwell time induced growth of the interfacial layer and reduced joint shear strength. The open circuit potential and corrosion current density test indicated that the brazing filler metal Al-5.0Si-20.5Cu-2.0Ni had better corrosion resistance than that of 3003 aluminum alloy. Full article

(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys)

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12 pages, 2743 KiB

Open AccessArticle

Effects of Isothermal Temperature on Dislocation Density in Bainite Transformation of 4140 Steel

by Jian Zhu, Gary Barber and Xichen Sun

Materials 2022, 15(17), 6066; https://doi.org/10.3390/ma15176066 - 1 Sep 2022

Cited by 6 | Viewed by 1570

Abstract

To relate the bainitic microstructures to the mechanical properties of steel, the average dislocation density needs to be determined. Using X-ray diffraction and diffraction line broadening analysis, this research quantifies the average dislocation density in the four bainite phase matrices, (upper bainite, upper [...] Read more.

To relate the bainitic microstructures to the mechanical properties of steel, the average dislocation density needs to be determined. Using X-ray diffraction and diffraction line broadening analysis, this research quantifies the average dislocation density in the four bainite phase matrices, (upper bainite, upper and lower bainite mixture, lower bainite, lower bainite and martensite mixture), which are transformed in a wide range of isothermal temperatures. The effects of isothermal temperatures on the average dislocation density are assessed for different thermal dynamic driving forces in terms of activation energy and cooling rate. It is found that as isothermal holding temperature is increased, the dislocation density in the bainite matrix decreases from 1.55 × 10¹⁷ to 8.33 × 10¹⁵ (m⁻²) due to the reduction in the plastic deformation in the austenite in the transformation. At the same time, the activation energy required decreases only after passing the martensite and lower bainite mixed phase. A new method for better estimating the average dislocation density in bainitic steel is also proposed. Full article

(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys)

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13 pages, 3344 KiB

Open AccessArticle

Plasma Electrolytic Polishing—An Ecological Way for Increased Corrosion Resistance in Austenitic Stainless Steels

by Viera Zatkalíková, Štefan Podhorský, Milan Štrbák, Tatiana Liptáková, Lenka Markovičová and Lenka Kuchariková

Materials 2022, 15(12), 4223; https://doi.org/10.3390/ma15124223 - 14 Jun 2022

Cited by 8 | Viewed by 2781

Abstract

Plasma electrolytic polishing (PEP) is an environment-friendly alternative to the conventional electrochemical polishing (EP), giving optimal surface properties and improved corrosion resistance with minimum energy and time consumption, which leads to both economic and environmental benefits. This paper is focused on the corrosion [...] Read more.

Plasma electrolytic polishing (PEP) is an environment-friendly alternative to the conventional electrochemical polishing (EP), giving optimal surface properties and improved corrosion resistance with minimum energy and time consumption, which leads to both economic and environmental benefits. This paper is focused on the corrosion behavior of PEP treated AISI 316L stainless steel widely used as a biomaterial. Corrosion resistance of plasma electrolytic polished surfaces without/with chemical pretreatment (acid cleaning) is evaluated and compared with original non-treated (as received) surfaces by three independent test methods: electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PP), and exposure immersion test. All corrosion tests are carried out in the 0.9 wt.% NaCl solution at a temperature of 37 ± 0.5 °C to simulate the internal environment of a human body. The quality of tested surfaces is also characterized by optical microscopy and by the surface roughness parameters. The results obtained indicated high corrosion resistance of PEP treated surfaces also without chemical pretreatment, which increases the ecological benefits of PEP technology. Full article

(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys)

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12 pages, 5377 KiB

Open AccessArticle

Microstructure and Texture Evolution during Superplastic Deformation of SP700 Titanium Alloy

by Ning Tian, Wenjun Ye, Xiaoyun Song and Songxiao Hui

Materials 2022, 15(5), 1808; https://doi.org/10.3390/ma15051808 - 28 Feb 2022

Cited by 4 | Viewed by 2369

Abstract

The superplastic tensile test was carried out on SP700 (Ti-4.5Al-3V-2Mo-2Fe) titanium alloy sheet at 760 °C by the method of maximum m value, and the microstructure characteristics were investigated to understand the deformation mechanism. The results indicated that the examined alloy showed an [...] Read more.

The superplastic tensile test was carried out on SP700 (Ti-4.5Al-3V-2Mo-2Fe) titanium alloy sheet at 760 °C by the method of maximum m value, and the microstructure characteristics were investigated to understand the deformation mechanism. The results indicated that the examined alloy showed an extremely fine grain size of ~1.3 μm and an excellent superplasticity with fracture elongation of up to 3000%. The grain size and the volume fraction of the β phase increased as the strain increased, accompanied by the elements’ diffusion. The β-stabilizing elements (Mo, Fe, and V) were mainly dissolved within the β phase and diffused from α to β phase furthermore during deformation. The increase in strain leads to the accumulation of dislocations, which results in the increase in the proportion of low angle grain boundaries by 15%. As the deformation process, the crystal of α grains rotated, and the texture changed, accompanied by the accumulation of dislocations. The phase boundary (α/β) sliding accommodated by dislocation slip was the predominant mechanism for SP700 alloy during superplastic deformation. Full article

(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys)

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13 pages, 7685 KiB

Open AccessArticle

Influence of Heat Treatment of Steel AISI316L Produced by the Selective Laser Melting Method on the Properties of Welded Joint

by Petr Mohyla, Jiri Hajnys, Lucie Gembalová, Andrea Zapletalová and Pavel Krpec

Materials 2022, 15(5), 1690; https://doi.org/10.3390/ma15051690 - 24 Feb 2022

Cited by 3 | Viewed by 1914

Abstract

This work is focused on the influence of heat treatment of a part produced by the SLM (selective laser melting) method of stainless steel, 316L. Two heat treatment regimens were tested and compared with the state without heat treatment. Subsequently, TIG (tungsten inert [...] Read more.

This work is focused on the influence of heat treatment of a part produced by the SLM (selective laser melting) method of stainless steel, 316L. Two heat treatment regimens were tested and compared with the state without heat treatment. Subsequently, TIG (tungsten inert gas) welds were created on the base materials processed in this way. All welds were subjected to mechanical tests and microstructural analysis. The tensile test was performed both for the welded joint and for the base material in the transverse and longitudinal directions. The tensile strength values of the samples with the welded joint were compared with the values required for the base material, 316L forged steel (1.4404). Microstructural analysis revealed significant differences between samples with and without heat treatment. The results of these tests are supported by SEM analysis. EDAX (energy dispersive analysis of X-rays) semiquantitative analysis confirmed the presence of ultra-fine pores in the structure. The results of mechanical tests show that the solution annealing at 1040 °C for 0.5 h gives better results than the same heat treatment with a duration of 2 h. Full article

(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys)

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16 pages, 4503 KiB

Open AccessArticle

Optimization of Heat Treatment Parameters of AlSi7Mg Alloy

by Jacek Pezda

Materials 2022, 15(3), 1163; https://doi.org/10.3390/ma15031163 - 2 Feb 2022

Cited by 11 | Viewed by 2466

Abstract

Constantly growing requirements concerning the quality of poured machinery components give rise to the need to find new solutions to improve their mechanical and technological properties, considering economic and ecological aspects resulting from energy consumption of the casting and heat treatment processes. This [...] Read more.

Constantly growing requirements concerning the quality of poured machinery components give rise to the need to find new solutions to improve their mechanical and technological properties, considering economic and ecological aspects resulting from energy consumption of the casting and heat treatment processes. This study presents the investigation of the effect of heat treatment on mechanical properties (tensile strength R_m, elongation A₅, hardness HBW) of the AlSi7Mg alloy without modification and modified with strontium. Obtained results allowed us to determine T6 heat treatment parameters associated with the improvement of mechanical properties of the alloy with simultaneous limitation of duration of solutioning and aging treatments. The maximum increase in R_m was 67%, and 55% in the case of HBW, with a slight decrease in elongation (approx. 10%) in relation to an alloy not subjected to heat treatment in the adopted scope of tests for the total time of heat treatment of 4–6 h. The increase in elongation of up to 250% requires aging at a temperature exceeding 300 °C, which also causes a decrease in durability and hardness by 20%. Modification of the alloy using strontium before heat treatment facilitates the process of fragmentation and balling of silicone precipitates. Full article

(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys)

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10 pages, 4829 KiB

Open AccessArticle

Corrosion Resistance of AISI 316L Stainless Steel Biomaterial after Plasma Immersion Ion Implantation of Nitrogen

by Viera Zatkalíková, Juraj Halanda, Dušan Vaňa, Milan Uhríčik, Lenka Markovičová, Milan Štrbák and Lenka Kuchariková

Materials 2021, 14(22), 6790; https://doi.org/10.3390/ma14226790 - 10 Nov 2021

Cited by 10 | Viewed by 2375

Abstract

Plasma immersion ion implantation (PIII) of nitrogen is low-temperature surface technology which enables the improvement of tribological properties without a deterioration of the corrosion behavior of austenitic stainless steels. In this paper the corrosion properties of PIII-treated AISI 316L stainless steel surfaces are [...] Read more.

Plasma immersion ion implantation (PIII) of nitrogen is low-temperature surface technology which enables the improvement of tribological properties without a deterioration of the corrosion behavior of austenitic stainless steels. In this paper the corrosion properties of PIII-treated AISI 316L stainless steel surfaces are evaluated by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PP) and exposure immersion tests (all carried out in the 0.9 wt. % NaCl solution at 37 ± 0.5 °C) and compared with a non-treated surface. Results of the three performed independent corrosion tests consistently confirmed a significant increase in the corrosion resistance after two doses of PIII nitriding. Full article

(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys)

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21 pages, 7389 KiB

Open AccessArticle

Optimization of Mechanical Properties of Cr₃C₂-Ni20Cr/Graphite Cold Sprayed Coatings

by Wojciech Żórawski, Anna Góral, Medard Makrenek, Dominika Soboń, Anna Trelka and Marek Bara

Materials 2021, 14(13), 3458; https://doi.org/10.3390/ma14133458 - 22 Jun 2021

Cited by 5 | Viewed by 1768

Abstract

This study analyzed the mechanical properties of cold-sprayed Cr₃C₂-25(Ni20Cr) blended with Ni-graphite as a solid lubricant deposited on 7075 aluminum alloy substrate. To optimize the coating properties, different sets of parameters (graphite content in feedstock, process gas composition, spraying [...] Read more.

This study analyzed the mechanical properties of cold-sprayed Cr₃C₂-25(Ni20Cr) blended with Ni-graphite as a solid lubricant deposited on 7075 aluminum alloy substrate. To optimize the coating properties, different sets of parameters (graphite content in feedstock, process gas composition, spraying distance, and traverse gun speed) were tested in the frame of the Taguchi experiment. The cold-sprayed coatings were evaluated for their chromium carbide and graphite content, hardness, and coefficient of friction. Analysis of the microstructure of the deposited coatings revealed that graphite as a soft and brittle component fills all voids in the coating and its quantity depends on its content in the feedstock. The experimental results show that the composition of the process gas has the greatest impact on the Cr₃C₂ content in the coating and the proportion of graphite in the sprayed blend directly affects its hardness. In the case of the coefficient of friction, the most significant parameters were the graphite content in the sprayed blend, the spraying distance, and process gas composition. The conducted verification experiment with the optimum parameter values allowed a coating with the highest hardness and the lowest coefficient of friction to be obtained. Full article

(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys)

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11 pages, 3897 KiB

Open AccessArticle

Bifilm Inclusions in High Alloyed Cast Iron

by Marcin Stawarz and Malwina Dojka

Materials 2021, 14(11), 3067; https://doi.org/10.3390/ma14113067 - 4 Jun 2021

Cited by 5 | Viewed by 2846

Abstract

Continuous improvement in the quality of castings is especially important since a cast without defects is a more competitive product due to its longer lifecycle and cheaper operation. Producing quality castings requires comprehensive knowledge of their production, crystallization process, and chemical composition. The [...] Read more.

Continuous improvement in the quality of castings is especially important since a cast without defects is a more competitive product due to its longer lifecycle and cheaper operation. Producing quality castings requires comprehensive knowledge of their production, crystallization process, and chemical composition. The crystallization of alloyed ductile iron (without the addition of magnesium) with oxide bifilm inclusions is discussed. These inclusions reduce the quality of the castings, but they are a catalyst for the growth of spheroidal graphite that crystallizes in their vicinity. The research was carried out for cast iron with a highly hyper-eutectic composition. Scanning electron microscopy and EDS analysis were used in the research. A detailed analysis of the chemical composition was also carried out based on the spectrometric method, weight method, etc. Based on the obtained results, a model of spheroidal graphite crystallization near bifilm inclusions was proposed. The surface of the analyzed graphite particles was smooth, which suggests a primary crystallization process. The phenomenon of simple graphite and bifilm segregation towards the heat center of the castings was also documented. Full article

(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys)

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Review

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17 pages, 7549 KiB

Open AccessReview

Oxide Metallurgy Technology in High Strength Steel: A Review

by Wei Liang, Ruming Geng, Jianguo Zhi, Jing Li and Fei Huang

Materials 2022, 15(4), 1350; https://doi.org/10.3390/ma15041350 - 11 Feb 2022

Cited by 26 | Viewed by 3308

Abstract

Oxide metallurgy technology plays an important role in inclusion control and is also applied to improve the weldability of high strength steel. Based on the requirements of the weldability in high strength steel, the influencing factors of weld heat affected zone (HAZ) as [...] Read more.

Oxide metallurgy technology plays an important role in inclusion control and is also applied to improve the weldability of high strength steel. Based on the requirements of the weldability in high strength steel, the influencing factors of weld heat affected zone (HAZ) as well as the development and application status of oxide metallurgy technology are summarized in this review. Moreover, the advantages and difficulties in the application of rare earth (RE) oxide metallurgy technology are analyzed, combined with the performance mechanism of RE and its formation characteristics of fine and high melting point RE inclusions with distribution dispersed in liquid steel. With the weldability diversities of different high strength steels, the research status of weldability of high strength steel with high carbon equivalent and the effects of RE on the microstructure and properties of HAZ are discussed, and some suggestions about further research in the future are proposed. Full article

(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys)

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