Research

13 pages, 4196 KiB

Open AccessArticle

Cavity Swelling of 15-15Ti Steel at High Doses by Ion Irradiation

by Cong Liu, Hailiang Ma, Ping Fan, Ke Li, Qiaoli Zhang, Aibing Du, Wei Feng, Xiping Su, Shengyun Zhu and Daqing Yuan

Materials 2024, 17(4), 925; https://doi.org/10.3390/ma17040925 - 17 Feb 2024

Viewed by 432

Abstract

The titanium-stabilized austenitic stainless steel Fe-15Cr-15Ni, which shows enhanced resistance to irradiation swelling compared with more traditional 316Ti, has been selected as a core material for fast reactors. Data on the evolution of irradiation swelling in 15-15Ti steels at very high doses, which [...] Read more.

The titanium-stabilized austenitic stainless steel Fe-15Cr-15Ni, which shows enhanced resistance to irradiation swelling compared with more traditional 316Ti, has been selected as a core material for fast reactors. Data on the evolution of irradiation swelling in 15-15Ti steels at very high doses, which cannot be easily achieved by neutron irradiation, are still lacking. In this paper, the swelling behavior of the titanium-modified austenitic stainless steel 15-15Ti was investigated by pre-implantation of He at room temperature followed by Ni-ion irradiation at 580 °C to peak doses of 120, 240 and 400 dpa. Relatively small cavities were observed in the zone of helium implantation, while large cavities appeared in the region near the damage peak. A correction formula for the dpa curve was proposed and applied to samples with large swelling. It was found that the steady-state swelling rate of 15-15Ti remains at ~1%/dpa even at high doses. By comparing the swelling data of the helium-implanted and helium-free regions at same doses, 70 dpa and 122 dpa, the suppression of swelling by excessive helium can be deduced at such doses. Full article

(This article belongs to the Special Issue Research on the Microstructure and Properties of Metal Alloys)

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25 pages, 24019 KiB

Open AccessArticle

Investigation of Microstructures and Tensile Properties of 316L Stainless Steel Fabricated via Laser Powder Bed Fusion

by Melody Chepkoech, Gbadebo Owolabi and Grant Warner

Materials 2024, 17(4), 913; https://doi.org/10.3390/ma17040913 - 16 Feb 2024

Viewed by 655

Abstract

In this study, a thorough investigation of the microstructures and tensile properties of 316L stainless steel fabricated via laser powder bed fusion (L-PBF) was done. 316L stainless steel specimens with two different thicknesses of 1.5 mm and 4.0 mm fabricated under similar conditions [...] Read more.

In this study, a thorough investigation of the microstructures and tensile properties of 316L stainless steel fabricated via laser powder bed fusion (L-PBF) was done. 316L stainless steel specimens with two different thicknesses of 1.5 mm and 4.0 mm fabricated under similar conditions were utilized. Microstructural characterization was performed using optical microscopy (OM) and scanning electron microscopy (SEM) equipped with electron backscatter diffraction (EBSD). Melt pools and cellular structures were observed using OM, whereas EBSD was utilized to obtain the grain size, grain boundary characteristics, and crystallographic texture. The 1.5 mm thick sample demonstrated a yield strength (YS) of 538.42 MPa, ultimate tensile strength (UTS) of 606.47 MPa, and elongation to failure of 69.88%, whereas the 4.0 mm thick sample had a YS of 551.21 MPa, UTS of 619.58 MPa, and elongation to failure of 73.66%. These results demonstrated a slight decrease in mechanical properties with decreasing thickness, with a 2.4% reduction in YS, 2.1% reduction in UTS, and 5.8% reduction in elongation to failure. In addition to other microstructural features, the cellular structures were observed to be the major contributors to the high mechanical properties. Using the inverse pole figure (IPF) maps, both thicknesses depicted a crystallographic texture of {001} <101> in their as-built state. However, when subjected to tensile loads, texture transitions to {111} <001> and {111} <011> were observed for the 1.5 mm and 4.0 mm samples, respectively. Additionally, EBSD analysis revealed the pre-existence of high-density dislocation networks and a high fraction of low-angle grain boundaries. Interestingly, twinning was observed, suggesting that the plastic deformation occurred through dislocation gliding and deformation twinning. Full article

(This article belongs to the Special Issue Research on the Microstructure and Properties of Metal Alloys)

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22 pages, 17935 KiB

Open AccessArticle

Experimental Study on Liquid Metal Embrittlement of Al-Zn-Mg Aluminum Alloy (7075): From Macromechanical Property Experiment to Microscopic Characterization

by Daixin Zhang, Kaikai Cai, Jian Zheng, Haiyun Feng, Pu Song, Hongwei Hu and Zhiyuan Mao

Materials 2024, 17(3), 628; https://doi.org/10.3390/ma17030628 - 27 Jan 2024

Viewed by 710

Abstract

This study is a multiscale experimental investigation into the embrittlement of Al-Zn-Mg aluminum alloy (7075-T6) caused by liquid metal gallium. The results of the experiment demonstrate that the tensile strength of the 7075-T6 aluminum alloy significantly weakens with an increase in the embrittlement [...] Read more.

This study is a multiscale experimental investigation into the embrittlement of Al-Zn-Mg aluminum alloy (7075-T6) caused by liquid metal gallium. The results of the experiment demonstrate that the tensile strength of the 7075-T6 aluminum alloy significantly weakens with an increase in the embrittlement temperature and a prolonged embrittlement time, whereas it improves with an increase in the strain rate. On the basis of the analysis of the experimental data, the sensitivity of the embrittlement of 7075-T6 aluminum alloy by liquid gallium to the loading strain rate is significantly higher compared to other environmental factors. In addition, this study also includes several experiments for microscopic observation, such as Scanning Electron Microscope (SEM) observation, Energy-Dispersive Spectrometer (EDS) spectroscopy, and Electron Back Scatter Diffraction (EBSD) analysis. The experimental observations confirmed the following: (1) gallium is enriched in the intergranular space of aluminum; (2) the fracture mode of 7075-T6 aluminum alloy changes from ductile to brittle fracture; and (3) the infiltration of liquid gallium into aluminum alloys and its enrichment in the intergranular space result in the formation of new dislocation nucleation sites, in addition to the original dislocations cutting and entanglement. This reduces the material’s ability to undergo plastic deformation, intensifies stress concentration at the dislocation nucleation point, and, ultimately, leads to the evolution of dislocations into cracks. Full article

(This article belongs to the Special Issue Research on the Microstructure and Properties of Metal Alloys)

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33 pages, 40292 KiB

Open AccessArticle

Bronze Age Raw Material Hoard from Greater Poland: Archaeometallurgical Study Based on Material Research, Thermodynamic Analysis, and Experiments

by Aldona Garbacz-Klempka, Marcin Piękoś, Janusz Kozana, Małgorzata Perek-Nowak, Marta Wardas-Lasoń, Patrycja Silska and Mateusz Stróżyk

Materials 2024, 17(1), 230; https://doi.org/10.3390/ma17010230 - 31 Dec 2023

Cited by 2 | Viewed by 778

Abstract

Hoard finds from the Bronze Age have appeared all over Europe, prompting questions about their functions (either as raw materials for recycling or votive objects). The hoard trove of raw materials from Przybysław in Greater Poland is an interesting example of a discovery [...] Read more.

Hoard finds from the Bronze Age have appeared all over Europe, prompting questions about their functions (either as raw materials for recycling or votive objects). The hoard trove of raw materials from Przybysław in Greater Poland is an interesting example of a discovery that is related to the foundry activities of Late Bronze Age and Early Iron Age communities (c. 600 BC). The deposit consists of fragments of raw materials that were damaged end products intended for smelting. The research included the characterisation of the material in terms of the variety of the raw materials that were used. The individual elements of the hoard were characterised in terms of their chemical compositions, microstructures, and properties. A range of modern instrumental research methods were used: metallographic macroscopic and microscopic observations by optical microscopy (OM), scanning electron microscopy (SEM), chemical-composition analysis by X-ray fluorescence spectroscopy (ED-XRF), X-ray microanalysis (EDS), and detailed crystallisation analysis by electron microscopy with an emphasis on electron backscatter diffraction (EBSD). As part of this study, model alloys were also prepared for two of the selected chemical compositions, (i.e., CuPbSn and CuPb). These alloys were analysed for their mechanical and technological properties. This research of the hoard from Przybysław (Jarocin district, Greater Poland) has contributed to the recognition and interpretation of the function and nature of the hoard by using modern research and modelling methods as a cultic raw material deposit. Full article

(This article belongs to the Special Issue Research on the Microstructure and Properties of Metal Alloys)

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23 pages, 33654 KiB

Open AccessArticle

Numerical and Experimental Analysis of Strength Loss of 1.2709 Maraging Steel Produced by Selective Laser Melting (SLM) under Thermo-Mechanical Fatigue Conditions

by Jarosław Piekło, Aldona Garbacz-Klempka, Dawid Myszka and Krzysztof Figurski

Materials 2023, 16(24), 7682; https://doi.org/10.3390/ma16247682 - 17 Dec 2023

Viewed by 702

Abstract

The result of the development of additive manufacturing (AM) methods is the increasing use of the selective laser melting (SLM) method as a technique for producing tooling for injection moulds and die casting pressure moulds from maraging steel powders. The mould components are [...] Read more.

The result of the development of additive manufacturing (AM) methods is the increasing use of the selective laser melting (SLM) method as a technique for producing tooling for injection moulds and die casting pressure moulds from maraging steel powders. The mould components are subjected to varying thermo-mechanical loads during these operations. This paper presents a numerical model that is used to predict the fatigue life of a material that is loaded with a time-varying temperature field according to the classic and modified Coffin test. Using a computational model, the temperature changes in the resistance-heated specimen and the stress and strain fields that are caused by this phenomenon were determined. Using three different multiaxial fatigue criteria, the fatigue life of SLM steel was determined. Numerical calculations were verified using experimental thermal fatigue tests on 1.2709 SLM steel that was aged at 490 °C as well as via metallographic tests. The numerical model was used to predict the durability of the same steel aged at 540 °C. The effect of specimen clamping conditions on the fatigue life of SLM steel was determined numerically. The value of the decrease in strength of SLM steel as a result of the increasing number of cycles of temperature changes was determined experimentally; a great influence of ageing temperature on fatigue life was found. Changes in the structure of steel occurring during cyclic changes in temperature are presented. Full article

(This article belongs to the Special Issue Research on the Microstructure and Properties of Metal Alloys)

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24 pages, 15805 KiB

Open AccessArticle

Selection of Effective Temperature for Thermal Regeneration of Spent Alkali-Phenolic Binder Moulding Sand

by Mariusz Łucarz

Materials 2023, 16(24), 7629; https://doi.org/10.3390/ma16247629 - 13 Dec 2023

Viewed by 585

Abstract

This article presents the results of research on alkali-phenolic binders used in moulding sands. The results of the presented experiments are part of a search for the optimum conditions to implement the thermal regeneration of spent alkali-phenolic binder moulding sands. The cured binders [...] Read more.

This article presents the results of research on alkali-phenolic binders used in moulding sands. The results of the presented experiments are part of a search for the optimum conditions to implement the thermal regeneration of spent alkali-phenolic binder moulding sands. The cured binders were subjected to thermogravimetric analysis in aerobic and anaerobic atmospheres. On the basis of the resin decomposition curves, the integral polymer decomposition temperature was determined, and the required thermal regeneration temperature for the alkali-phenolic binder moulding sands that were used was determined according to a specific procedure. The spent moulding sand was subjected to roasting procedures at different temperatures in order to confirm the necessary regeneration temperatures. The effects of the procedures that were carried out were evaluated by means of weight losses and ignition losses, microscopic pictures were taken, and using scanning microscopy, an analysis of the chemical composition in the micro areas on the surfaces of the matrix grains was carried out using scanning microscopy. The indicators for the comparisons between the individual binders were also calculated from the mass losses. The research and analysis that were carried out made it possible to indicate the required temperature for the thermal regeneration of the spent alkali-phenolic binder moulding sand to reduce the involved energy expenditure. The factors that can determine the successful implementation of the process and the obtaining of the best possible grain matrix for reuse were also indicated. Full article

(This article belongs to the Special Issue Research on the Microstructure and Properties of Metal Alloys)

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18 pages, 13222 KiB

Open AccessArticle

Effect of Alloying Additives and Moulding Technology on Microstructure, Tightness, and Mechanical Properties of CuSn10 Bronze

by Dawid Witasiak, Aldona Garbacz-Klempka, Marcin Papaj, Piotr Papaj, Maria Maj, Marcin Piękoś and Janusz Kozana

Materials 2023, 16(24), 7593; https://doi.org/10.3390/ma16247593 - 11 Dec 2023

Cited by 1 | Viewed by 735

Abstract

Thise research was conducted to determine the impact of the applied casting technology, mould and alloying additives on the tightness of the CuSn10 cast alloy. Under industrial conditions, a series of experimental melts were made that were characterised by varying the concentrations of [...] Read more.

Thise research was conducted to determine the impact of the applied casting technology, mould and alloying additives on the tightness of the CuSn10 cast alloy. Under industrial conditions, a series of experimental melts were made that were characterised by varying the concentrations of the main alloying element (Sn) and the introduced alloying additives (Si, Zn, Zr). The mould was made from green sand and used the CO₂ moulding process. To assess the influence of the alloying additives, a metallographic analysis of the studied alloy was carried out, and the alloy’s microstructure was examined using optical and scanning electron microscopy. The introduced alloying additives affected the properties and microstructure of the studied alloy. As alloying additives, zirconium resulted in a visible refinement of the microstructure, while silicon improved the fluidity and quality of the casting’s external surface. The use of alloying additives and moulds made using different technologies is intended to improve the structure of the tin bronze castings produced and to find the best solution to significantly eliminate the lack of leakage of the castings. The castings were subjected to mechanical processing, and a leak test was performed using the pressure drop method. The conducted research allowed us to determine which technology, applied to production, will bring about a reduction in the problem and will inform further investigations. Full article

(This article belongs to the Special Issue Research on the Microstructure and Properties of Metal Alloys)

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15 pages, 8589 KiB

Open AccessArticle

The Effect of Changes in the Aging Temperature Combined with Deep Cryogenic Treatment on the Structure, Phase Composition, and Micromechanical Properties of the WE43 Magnesium Alloy

by Adrian Barylski, Krzysztof Aniołek, Grzegorz Dercz, Izabela Matuła, Jan Rak and Izabela Mazur

Materials 2023, 16(23), 7447; https://doi.org/10.3390/ma16237447 - 30 Nov 2023

Viewed by 638

Abstract

This paper examines the optimal aging temperature of WE43 alloy that has undergone precipitation hardening in conjunction with deep cryogenic treatment. The microstructure and phase composition were investigated, a microanalysis of the chemical composition was performed, and instrumental indentation tests were performed to [...] Read more.

This paper examines the optimal aging temperature of WE43 alloy that has undergone precipitation hardening in conjunction with deep cryogenic treatment. The microstructure and phase composition were investigated, a microanalysis of the chemical composition was performed, and instrumental indentation tests were performed to determine the parameters of the micro-mechanical properties of the alloy after different heat treatment variants. It has been proven that a decrease in the aging temperature from 250 °C to 225 °C and the introduction of a deep cryogenic treatment lead to favorable changes in the microstructure of the alloy (reduction in grain size, increase in the number, and change in the type of β-phase precipitates). The changes in the alloy structure achieved by lowering the aging temperature contribute to the improvement of the micromechanical properties of the test material. The most advantageous results were recorded for an alloy subjected to solution treatment and aged at 225 °C for 24 h with deep cryogenic treatment: a 30% increase in hardness, a 10% increase in Young’s modulus, an improvement in elastic properties, and increased resistance to deformation of the alloy were shown compared to the initial (as-received) state. Raising the aging temperature to 250 °C leads to a phenomenon known as alloy overaging for both alloys after classical precipitation hardening and after deep cryogenic treatment. The results indicate the significant effectiveness of the proposed heat treatment in improving the service life of the Mg-Y-Nd-Zr (WE43) alloy. Full article

(This article belongs to the Special Issue Research on the Microstructure and Properties of Metal Alloys)

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17 pages, 4020 KiB

Open AccessArticle

Deformation Behavior and Processing Maps of 7075 Aluminum Alloy under Large-Strain Thermal Compression

by Erli Xia, Tuo Ye, Sawei Qiu, Limei Liu, Fang Luo, Huanyu Yue and Yuanzhi Wu

Materials 2023, 16(23), 7432; https://doi.org/10.3390/ma16237432 - 29 Nov 2023

Viewed by 622

Abstract

The investigation of thermal deformation behavior plays a significant role in guaranteeing the overall performance of alloy materials. In this manuscript, a series of isothermal compression tests at different temperatures (300, 350, 400, and 450 °C) and strain rates (0.001, 0.01, 0.1, and [...] Read more.

The investigation of thermal deformation behavior plays a significant role in guaranteeing the overall performance of alloy materials. In this manuscript, a series of isothermal compression tests at different temperatures (300, 350, 400, and 450 °C) and strain rates (0.001, 0.01, 0.1, and 1 s⁻¹) were conducted to study the thermal deformation behavior of 7075 aluminum alloy. Subsequently, processing maps at a strain from 0.4 to 1.39 were established according to the stress–strain data obtained from various deformation parameters. The microstructural evolution of the target alloy was observed with an optical microscope and transmission electron microscope. The results reveal the unstable regions are located at (360–450 °C, 0.04–1 s⁻¹) and (300–315 °C, 0.01–0.22 s⁻¹). Precipitation particles, pinned dislocations, and highly dislocated areas can be observed in the microstructure of the alloy in the unstable regions. This is a potential crack and defect formation point. The identified optimum processing parameters are located at (375–450 °C, 0.001–0.03 s⁻¹), with a maximum dissipation efficiency of 0.6. Full article

(This article belongs to the Special Issue Research on the Microstructure and Properties of Metal Alloys)

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20 pages, 9454 KiB

Open AccessArticle

The Effect of Vacuum Forming on the Quality of Refractory Materials

by Marcin Brzeziński, Mariusz Łucarz, Alicja Trela, Alena Pribulova and Peter Futáš

Materials 2023, 16(23), 7260; https://doi.org/10.3390/ma16237260 - 21 Nov 2023

Viewed by 808

Abstract

Various designs of furnaces for melting alloys are used in the foundry industry. Regardless of their design, they have one common detail, which is the lining of their interiors with refractory materials. This component in the design of a metal-melting furnace has a [...] Read more.

Various designs of furnaces for melting alloys are used in the foundry industry. Regardless of their design, they have one common detail, which is the lining of their interiors with refractory materials. This component in the design of a metal-melting furnace has a very important task—to protect the rest of the furnace assemblies from thermal and mechanical damage. Continuous technical progress and the quality requirements of casting production produce increasingly higher demands for refractory materials in connection with their development as well. The article presents the results of an innovative method of vibratory compaction of refractory material (high-alumina aluminosilicate) using reduced pressure. The analysis presents a comparative study of two methods used for forming refractory materials, i.e., the application of the mentioned innovative method and the classical (standard) method of compaction by vibration only. The effects of the introduced modification in the manufacture of ceramic shapes were evaluated by means of the material’s resistance to thermal shock, linear expansion, and dimensional change due to firing, apparent density, open porosity, and apparent specific gravity, determination of total pore volume and pore size distribution by mercury porosimetry, and slag resistance. The tests performed indicate that the procedure of lowering the pressure during the vibratory compaction of the refractory material creates a more homogeneous structure with a smaller number and size of pores. This makes it possible to improve most of the parameters that determine the quality of the refractories used for the linings of the foundry furnace. Full article

(This article belongs to the Special Issue Research on the Microstructure and Properties of Metal Alloys)

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31 pages, 12274 KiB

Open AccessArticle

Thermal Regeneration of Spent Sand with Furfuryl Binder from an Ecological and Economic Point of View

by Mariusz Łucarz and Michał Dereń

Materials 2023, 16(22), 7102; https://doi.org/10.3390/ma16227102 - 09 Nov 2023

Viewed by 596

Abstract

The recovery of the grain matrix from spent moulding sand is a constant challenge in making the best possible use of the deposits of quartz sand material, as well as in protecting them. In the case of spent sand with organic binders, the [...] Read more.

The recovery of the grain matrix from spent moulding sand is a constant challenge in making the best possible use of the deposits of quartz sand material, as well as in protecting them. In the case of spent sand with organic binders, the best method to recover the grain matrix is thermal regeneration. However, this method is expensive and requires adequate attention to the emission of harmful compounds into the atmosphere. This paper presents a new concept for implementing the thermal regeneration process. A suitable regeneration temperature was adopted for the furfuryl binder moulding sand, and a change in the design of the device was introduced in the area of the utilisation of gases generated during the combustion of the spent binder. To confirm the assumptions made, and to assess the appropriate suitability of the material recovered, the technological parameters of the material obtained were verified, namely, ignition losses, sieve analysis, bending strength, and pH value. The consumption of media for the process was also analysed from an economic point of view, as well as the emission of BTEX (a mixture of volatile aromatic hydrocarbons-benzene, toluene and three isomers of xylene) gases under different conditions of the process. On the basis of the research conducted, it was concluded that lowering the regeneration temperature of regeneration does not adversely affect the technological parameters of the moulding sand on the regenerate matrix. Changing the design of the regenerator does not result in increased emissions of harmful substances to the environment. Studies indicate that the appropriate setting of thermal regeneration parameters and the optimal design of the employed equipment are favourable factors in reducing the cost of the process while not compromising the quality of the moulding sand and the environmental impact. Full article

(This article belongs to the Special Issue Research on the Microstructure and Properties of Metal Alloys)

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14 pages, 10454 KiB

Open AccessArticle

Effect of Heat Treatment on Microstructure and Properties Evolution of Stainless Steel Cladding Plate

by Luyan Li, Boshen Zhao, Yongtong Chen and Yi Ding

Materials 2023, 16(13), 4809; https://doi.org/10.3390/ma16134809 - 04 Jul 2023

Viewed by 1327

Abstract

Heat treatments are necessary sometimes in order to improve comprehensive properties of stainless steel cladding plate (SSCP). However, carbon atoms in carbon steel diffuse into stainless cladding during the heat treatment process, thus decreasing its corrosion resistance. In this paper, optical microscopy, scanning [...] Read more.

Heat treatments are necessary sometimes in order to improve comprehensive properties of stainless steel cladding plate (SSCP). However, carbon atoms in carbon steel diffuse into stainless cladding during the heat treatment process, thus decreasing its corrosion resistance. In this paper, optical microscopy, scanning electron microscopy, and microhardness and shear testing were employed to characterize the microstructure and mechanical properties of the bonding interface in SSCP. Then, the corrosion resistance of the stainless steel cladding surface was evaluated by electrochemical tests. The results showed that the diffusion of carbon atoms played an important role in enhancing the bonding strength of SSCP, but might lead to intergranular sensitization of the cladding surface because of chromium carbide precipitation. Notably, this precipitation could be induced by quenching and tempering treatment, and hindered by solution treatment. Hence, the cladding surface on SSCP after single solution treatment possessed the superior corrosion resistance, and SSCP with continuous solution and tempering treatment exhibited the highest bonding strength. Full article

(This article belongs to the Special Issue Research on the Microstructure and Properties of Metal Alloys)

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14 pages, 4585 KiB

Open AccessArticle

A Study on the Fatigue Performance and Corrosion Resistance of 304/45 Bimetallic Composite Bolts

by Ziming Zhou and Yi Ding

Materials 2023, 16(12), 4454; https://doi.org/10.3390/ma16124454 - 18 Jun 2023

Viewed by 855

Abstract

This paper utilized a hot-rolling process to produce composite rods and subsequently manufactured 304/45 composite bolts through the process of drawing and thread rolling. The study focused on examining the microstructure, fatigue performance, and corrosion resistance of these composite bolts. Additionally, the impacts [...] Read more.

This paper utilized a hot-rolling process to produce composite rods and subsequently manufactured 304/45 composite bolts through the process of drawing and thread rolling. The study focused on examining the microstructure, fatigue performance, and corrosion resistance of these composite bolts. Additionally, the impacts of quenching and tempering on the fatigue performance of the composite bolts were explored and compared to the performance of 304 stainless steel (SS) bolts and Grade 6.8 35K carbon steel (CS) bolts. The results indicate that the SS cladding of the cold-worked 304/45 composite (304/45-CW) bolts was primarily strengthened by the cold deformation mechanism, which resulted in high microhardness, averaging 474 HV. At a maximum surface bending stress of 300 MPa, the fatigue cycles of the 304/45-CW reached 342,600 cycles at a 63.2% failure probability, which was significantly higher than that of commercial 35K CS bolts. The S-N fatigue curves showed that the fatigue strength of the 304/45-CW bolts was approximately 240 MPa, but the fatigue strength of the quenched and tempered 304/45 composite (304/45-QT) bolts decreased significantly to 85 MPa, due to the loss of the cold deformation strengthening effect. The corrosion resistance of the SS cladding of the 304/45-CW bolts was impressive and remained largely unaffected by carbon element diffusion. Full article

(This article belongs to the Special Issue Research on the Microstructure and Properties of Metal Alloys)

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22 pages, 8807 KiB

Open AccessArticle

Analysis of Phenomenon of Plasticity Loss of Steel Core Made by Selective Laser Melting Method in Zone of Pressure Mould Conformal Cooling Channel

by Jarosław Piekło and Aldona Garbacz-Klempka

Materials 2023, 16(12), 4205; https://doi.org/10.3390/ma16124205 - 06 Jun 2023

Cited by 2 | Viewed by 940

Abstract

This paper presents the results of testing the mechanical properties of maraging steel 1.2709 that were obtained by the SLM method under uniaxial and triaxial states of stress. The triaxial state of stress was realised by making circumferential notches in the samples with [...] Read more.

This paper presents the results of testing the mechanical properties of maraging steel 1.2709 that were obtained by the SLM method under uniaxial and triaxial states of stress. The triaxial state of stress was realised by making circumferential notches in the samples with different radii of rounding. The specimens were subjected to two types of heat treatment, which consisted of ageing at 490 °C and 540 °C for 8 h. The results of the tests that were conducted on the samples were considered as references and compared with the results of the strength tests that were conducted directly on the SLM-made core model. Differences were found between the results of these tests. Based on the experimental results, the relationship between the equivalent strain of the specimen in the bottom of notch ε_eq and triaxiality factor η was determined. Function ε_eq = f(η) was proposed as a criterion for the decrease in the plasticity of the material in the area of the pressure mould cooling channel. Using the FEM method, equivalent strain field ε_eq and triaxiality factor η were determined in the conformal channel cooled core model. Based on the proposed criterion of plasticity loss and the results of numerical calculations, it was shown that the values of equivalent strain ε_eq and triaxiality factor η in the core that was aged at 490 °C did not meet this criterion. On the other hand, the values of strain ε_eq and triaxiality factor η did not exceed the safety limit when ageing was carried out at 540 °C. The plasticity loss method presented in this paper assumes that the value of the triaxiality factor in the vicinity of the channel is influenced by the shape, cross-sectional dimensions and trajectory of the channel axis. Using the methodology proposed in this paper, it is possible to determine the value of allowable deformations in the cooling channel zone and to determine whether the heat treatment applied to the SLM steel does not cause an excessive reduction in the plastic properties. Full article

(This article belongs to the Special Issue Research on the Microstructure and Properties of Metal Alloys)

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