Fluoride and nitrate contamination in groundwater is a global concern due to their toxicity and associated negative health effects. This study incorporated a comprehensive methodology, including hydrogeochemical analysis, drinking and irrigation water quality assessment, source apportionment, and health risk estimation of groundwater fluoride and nitrate in a lithium ore deposit basin in western Serbia. Groundwater major ion hydrogeochemistry was governed by water–rock interactions, with Ca-Mg-HCO3 identified as the predominant groundwater type. The entropy-weighted water quality index (EWQI), sodium adsorption ratio (SAR), and sodium percentage (%Na) revealed that 95% of the samples were of excellent to good quality for both drinking and irrigation. Moreover, the results showed that fluorides were of geogenic origin, whereas nitrates originated from agricultural activities. Although the fluoride and nitrate levels in groundwater were relatively low, averaging 1.0 mg/L and 11.1 mg/L, respectively, the results of the health risk assessment revealed that the ingestion of such groundwater can still lead to non-cancerous diseases. The threshold of one for the hazard index was exceeded in 15% and 35% of the samples for adults and children, respectively. Children were more vulnerable to non-carcinogenic risk, with fluorides being the primary contributing factor. The study outcomes can serve as a reference for other lithium-bearing ore areas and guide the management of regional groundwater resources.
{"title":"Hydrogeochemical Facies and Health Hazards of Fluoride and Nitrate in Groundwater of a Lithium Ore Deposit Basin","authors":"Jelena Vesković, Milica Sentić, Antonije Onjia","doi":"10.3390/met14091062","DOIUrl":"https://doi.org/10.3390/met14091062","url":null,"abstract":"Fluoride and nitrate contamination in groundwater is a global concern due to their toxicity and associated negative health effects. This study incorporated a comprehensive methodology, including hydrogeochemical analysis, drinking and irrigation water quality assessment, source apportionment, and health risk estimation of groundwater fluoride and nitrate in a lithium ore deposit basin in western Serbia. Groundwater major ion hydrogeochemistry was governed by water–rock interactions, with Ca-Mg-HCO3 identified as the predominant groundwater type. The entropy-weighted water quality index (EWQI), sodium adsorption ratio (SAR), and sodium percentage (%Na) revealed that 95% of the samples were of excellent to good quality for both drinking and irrigation. Moreover, the results showed that fluorides were of geogenic origin, whereas nitrates originated from agricultural activities. Although the fluoride and nitrate levels in groundwater were relatively low, averaging 1.0 mg/L and 11.1 mg/L, respectively, the results of the health risk assessment revealed that the ingestion of such groundwater can still lead to non-cancerous diseases. The threshold of one for the hazard index was exceeded in 15% and 35% of the samples for adults and children, respectively. Children were more vulnerable to non-carcinogenic risk, with fluorides being the primary contributing factor. The study outcomes can serve as a reference for other lithium-bearing ore areas and guide the management of regional groundwater resources.","PeriodicalId":18461,"journal":{"name":"Metals","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Minglei Qu, Dunji Yu, Lianyi Chen, Ke An, Yan Chen
Aluminum matrix composites (AMCs) are designed to enhance the performance of conventional aluminum alloys for engineering applications at both room and elevated temperatures. However, the dynamic phase-specific deformation behavior and load-sharing mechanisms of AMCs at elevated temperatures have not been extensively studied and remain unclear. Here, in situ neutron diffraction experiments are employed to reveal the phase-specific structure evolution of additively manufactured Al6061+TiC composites under compressive loading at 250 °C. It is found that the addition of a small amount of nano-size TiC significantly alters the deformation behavior and increases the strength at 250 °C in comparison to the as-printed Al6061. Unlike the two-stage behavior observed in Al6061, the Al6061+TiC composites exhibit three stages during compression triggered by changes in the interphase stress states. Further analysis of Bragg peak intensity and broadening reveals that the presence of TiC alters the dislocation activity during deformation at 250 °C by influencing dislocation slip planes and promoting dislocation accumulation. These findings provide direct experimental observations of the phase-specific dynamic process in AMCs under deformation at an elevated temperature. The revealed mechanisms provide insights for the future design and optimization of high-performance AMCs.
{"title":"Understanding the High-Temperature Deformation Behaviors in Additively Manufactured Al6061+TiC Composites via In Situ Neutron Diffraction","authors":"Minglei Qu, Dunji Yu, Lianyi Chen, Ke An, Yan Chen","doi":"10.3390/met14091064","DOIUrl":"https://doi.org/10.3390/met14091064","url":null,"abstract":"Aluminum matrix composites (AMCs) are designed to enhance the performance of conventional aluminum alloys for engineering applications at both room and elevated temperatures. However, the dynamic phase-specific deformation behavior and load-sharing mechanisms of AMCs at elevated temperatures have not been extensively studied and remain unclear. Here, in situ neutron diffraction experiments are employed to reveal the phase-specific structure evolution of additively manufactured Al6061+TiC composites under compressive loading at 250 °C. It is found that the addition of a small amount of nano-size TiC significantly alters the deformation behavior and increases the strength at 250 °C in comparison to the as-printed Al6061. Unlike the two-stage behavior observed in Al6061, the Al6061+TiC composites exhibit three stages during compression triggered by changes in the interphase stress states. Further analysis of Bragg peak intensity and broadening reveals that the presence of TiC alters the dislocation activity during deformation at 250 °C by influencing dislocation slip planes and promoting dislocation accumulation. These findings provide direct experimental observations of the phase-specific dynamic process in AMCs under deformation at an elevated temperature. The revealed mechanisms provide insights for the future design and optimization of high-performance AMCs.","PeriodicalId":18461,"journal":{"name":"Metals","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rui Gomes, Gonçalo Soares, Rui Madureira, Rui Pedro Silva, José Silva, Rui Neto, Ana Reis, Cristina Fernandes
In this work, we intended to study the effect of heat treatments (T5 and flash T6) on blistering, mechanical properties and microstructure for different parts produced by vacuum-assisted HPDC. These parts were produced with primary and secondary aluminium alloys (AlSi10MnMg alloy and AlSi10Mg(Fe) alloy, respectively). The parts presented blisters for all combinations of temperature (between 360 °C and 520 °C) and stage times (15 and 30 min) of solution heat treatments. However, when subjected to the T5 heat treatment, blisters were no longer visible. With this heat treatment, there was an increase in yield strength of 64% for both aluminium alloys and an increase in UTS of 31% in AlSi10Mg(Fe) alloy and of 24% in AlSi10MnMg alloy, when compared to the mechanical properties in the as-cast state. However, there was a decrease in ductility. The AlSi10Mg(Fe) alloy presented a lot of contaminations (especially iron), which impaired the mechanical properties compared to the primary aluminium alloy, AlSi10MnMg.
{"title":"Development of Heat Treatments for Structural Parts in Aluminium Alloys Produced by High-Pressure Die Casting (HPDC)","authors":"Rui Gomes, Gonçalo Soares, Rui Madureira, Rui Pedro Silva, José Silva, Rui Neto, Ana Reis, Cristina Fernandes","doi":"10.3390/met14091059","DOIUrl":"https://doi.org/10.3390/met14091059","url":null,"abstract":"In this work, we intended to study the effect of heat treatments (T5 and flash T6) on blistering, mechanical properties and microstructure for different parts produced by vacuum-assisted HPDC. These parts were produced with primary and secondary aluminium alloys (AlSi10MnMg alloy and AlSi10Mg(Fe) alloy, respectively). The parts presented blisters for all combinations of temperature (between 360 °C and 520 °C) and stage times (15 and 30 min) of solution heat treatments. However, when subjected to the T5 heat treatment, blisters were no longer visible. With this heat treatment, there was an increase in yield strength of 64% for both aluminium alloys and an increase in UTS of 31% in AlSi10Mg(Fe) alloy and of 24% in AlSi10MnMg alloy, when compared to the mechanical properties in the as-cast state. However, there was a decrease in ductility. The AlSi10Mg(Fe) alloy presented a lot of contaminations (especially iron), which impaired the mechanical properties compared to the primary aluminium alloy, AlSi10MnMg.","PeriodicalId":18461,"journal":{"name":"Metals","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Siegfried Baehr, Fabian Fritz, Stefan Adami, Thomas Ammann, Nikolaus A. Adams, Michael F. Zaeh
During the powder bed fusion of metals using a laser beam (PBF-LB/M), an inert atmosphere is maintained in the build chamber to avoid reactions of the liquid metal with ambient air leading to the creation of oxides or nitrides, which alter the mechanical properties of the processed part. A continuous gas flow is guided over the process zone to remove spatters and fumes. This flow induces a convective heat transfer from the molten metal to the gas, which, depending on the level of the heat flow, may alter the melt pool dimensions by influencing the cooling rate. The present work investigated these phenomena with single-line trials, both experimentally and numerically. For this reason, a smoothed-particle hydrodynamics model was utilized to investigate the temperatures of the melt pool, cooling rates, and the integral heat balance with various gas atmospheres. In parallel, an on-axis pyrometer was set up on an experimental PBF-LB/M machine to capture the surface emissions of the melt pool. The atmosphere in the simulations and experiments was varied between argon, helium, and two mixtures thereof. The results showed a slight increase in the cooling rates with an increasing fraction of helium in the process gas. Consistently, a slight decrease in the melt pool temperatures and dimensions was found.
{"title":"Investigations on the Heat Balance of the Melt Pool During PBF-LB/M Under Various Process Gases","authors":"Siegfried Baehr, Fabian Fritz, Stefan Adami, Thomas Ammann, Nikolaus A. Adams, Michael F. Zaeh","doi":"10.3390/met14091058","DOIUrl":"https://doi.org/10.3390/met14091058","url":null,"abstract":"During the powder bed fusion of metals using a laser beam (PBF-LB/M), an inert atmosphere is maintained in the build chamber to avoid reactions of the liquid metal with ambient air leading to the creation of oxides or nitrides, which alter the mechanical properties of the processed part. A continuous gas flow is guided over the process zone to remove spatters and fumes. This flow induces a convective heat transfer from the molten metal to the gas, which, depending on the level of the heat flow, may alter the melt pool dimensions by influencing the cooling rate. The present work investigated these phenomena with single-line trials, both experimentally and numerically. For this reason, a smoothed-particle hydrodynamics model was utilized to investigate the temperatures of the melt pool, cooling rates, and the integral heat balance with various gas atmospheres. In parallel, an on-axis pyrometer was set up on an experimental PBF-LB/M machine to capture the surface emissions of the melt pool. The atmosphere in the simulations and experiments was varied between argon, helium, and two mixtures thereof. The results showed a slight increase in the cooling rates with an increasing fraction of helium in the process gas. Consistently, a slight decrease in the melt pool temperatures and dimensions was found.","PeriodicalId":18461,"journal":{"name":"Metals","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Metal matrix composites (MMCs) are dynamic and fascinating materials as they can be designed to suit the end property requirements for any present and futuristic application [...]
{"title":"Feature Papers in Metal Matrix Composites","authors":"Manoj Gupta","doi":"10.3390/met14091056","DOIUrl":"https://doi.org/10.3390/met14091056","url":null,"abstract":"Metal matrix composites (MMCs) are dynamic and fascinating materials as they can be designed to suit the end property requirements for any present and futuristic application [...]","PeriodicalId":18461,"journal":{"name":"Metals","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Muhammad Faizan Khan, Abdul Samad Mohammed, Ihsan-ul-Haq Toor
The electrochemical performance of in-house developed, spark plasma-sintered, Aluminum metal–matrix composites (MMCs) was evaluated using different electrochemical techniques. X-ray diffraction (XRD) and Raman spectra were used to characterize the nanocomposites along with FE-SEM and EDS for morphological, structural, and elemental analysis, respectively. The highest charge transfer resistance (Rct), lowest corrosion current density, lowest electrochemical potential noise (EPN), and electrochemical current noise (ECN) were observed for GO-reinforced Al-MMC. The addition of honeycomb-like structure in the Al matrix assisted in blocking the diffusion of Cl− or SO4−2. However, poor wettability in between Al matrix and Al2O3 reinforcement resulted in the formation of porous interface regions, leading to a degradation in the corrosion resistance of the composite. Post-corrosion surface analysis by optical profilometer indicated that, unlike its counterparts, the lowest surface roughness (Ra) was provided by GO-reinforced MMC.
{"title":"A Comprehensive Evaluation of Electrochemical Performance of Aluminum Hybrid Nanocomposites Reinforced with Alumina (Al2O3) and Graphene Oxide (GO)","authors":"Muhammad Faizan Khan, Abdul Samad Mohammed, Ihsan-ul-Haq Toor","doi":"10.3390/met14091057","DOIUrl":"https://doi.org/10.3390/met14091057","url":null,"abstract":"The electrochemical performance of in-house developed, spark plasma-sintered, Aluminum metal–matrix composites (MMCs) was evaluated using different electrochemical techniques. X-ray diffraction (XRD) and Raman spectra were used to characterize the nanocomposites along with FE-SEM and EDS for morphological, structural, and elemental analysis, respectively. The highest charge transfer resistance (Rct), lowest corrosion current density, lowest electrochemical potential noise (EPN), and electrochemical current noise (ECN) were observed for GO-reinforced Al-MMC. The addition of honeycomb-like structure in the Al matrix assisted in blocking the diffusion of Cl− or SO4−2. However, poor wettability in between Al matrix and Al2O3 reinforcement resulted in the formation of porous interface regions, leading to a degradation in the corrosion resistance of the composite. Post-corrosion surface analysis by optical profilometer indicated that, unlike its counterparts, the lowest surface roughness (Ra) was provided by GO-reinforced MMC.","PeriodicalId":18461,"journal":{"name":"Metals","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In depositing multiple layers on the surface of failed metal parts, the overlap rate is a critical factor in determining the surface smoothness and uniformity of the coating thickness. Therefore, special attention must be given to the spacing between adjacent melt tracks when planning laser paths on complex metal parts. A strategy for selecting the overlap rate for multi-track cladding is proposed, based on the key parameters of surface curvature, mass conservation, and the profile of single-track coatings. A multi-track overlap model is developed, expressing the relationship between coating morphology and the overlap rate. The optimal spacing value is determined to achieve the goal of high-quality coating remanufacturing. To verify the effectiveness of this method, nickel-based powder was used for laser forming on the surface of metal gears. The results showed that the surface of the cladding layer was smooth and flat, further demonstrating that this model helps improve the repair quality and overall performance of curved metal parts. Thus, it provides valuable guidance for the remanufacturing of failed metal parts.
{"title":"Laser Cladding Path Planning for Curved Metal Parts","authors":"Jinduo Liu, Zhiyong Ba, Da Shu","doi":"10.3390/met14091055","DOIUrl":"https://doi.org/10.3390/met14091055","url":null,"abstract":"In depositing multiple layers on the surface of failed metal parts, the overlap rate is a critical factor in determining the surface smoothness and uniformity of the coating thickness. Therefore, special attention must be given to the spacing between adjacent melt tracks when planning laser paths on complex metal parts. A strategy for selecting the overlap rate for multi-track cladding is proposed, based on the key parameters of surface curvature, mass conservation, and the profile of single-track coatings. A multi-track overlap model is developed, expressing the relationship between coating morphology and the overlap rate. The optimal spacing value is determined to achieve the goal of high-quality coating remanufacturing. To verify the effectiveness of this method, nickel-based powder was used for laser forming on the surface of metal gears. The results showed that the surface of the cladding layer was smooth and flat, further demonstrating that this model helps improve the repair quality and overall performance of curved metal parts. Thus, it provides valuable guidance for the remanufacturing of failed metal parts.","PeriodicalId":18461,"journal":{"name":"Metals","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Peng Zhang, Yue Wang, Pizhi Zhao, Zhengyi Jiang, Yinbao Tian, Yang Yang, Jian Han
In this study, as a vital part of the production of Mn-increased 5083 Al alloy, i.e., homogenization annealing before hot rolling, the target states of key Al6Mn precipitation, including the dispersed, initial coarsening and intensive coarsening states, were designed, and the corresponding precipitates formed via the control of the temperature and holding time in the annealing process. By means of metallographic corrosion and nitric acid mass loss tests (NAMLT) for assessing the intergranular corrosion (IGC) resistance, temperatures ranging from 175 °C to 225 °C were determined to induce a transition from sensitization to stabilization for this innovative 5083. At a temperature of 175 °C for a duration of up to 24 h (2 h, 4 h, 8 h, 16 h, 24 h), the results show that when the soak time is 24 h, the sample with initially coarsened Al6Mn phases has a lower degree of sensitization (DOS) compared to the samples with Al6Mn phases in both the dispersed and intensive coarsening states, and its NAMLT is reduced by 11% and 15%, respectively. Subsequently, transmission electron microscopy (TEM) analysis has investigated that for the sample with the best IGC resistance, i.e., that with initially coarsened Al6Mn phases, plate-like Al6Mn particles (200~500 nm) can act as heterogenous nucleation sites for β phases, driving their preferential precipitation on Al6Mn particles and resisting their precipitation along grain boundaries, ultimately improving the IGC resistance of 5083 Al alloy after homogenization annealing.
{"title":"Study of Intergranular Corrosion Behaviors of Mn-Increased 5083 Al Alloy with Controlled Precipitation States of Al6Mn Formed during Homogenization Annealing","authors":"Peng Zhang, Yue Wang, Pizhi Zhao, Zhengyi Jiang, Yinbao Tian, Yang Yang, Jian Han","doi":"10.3390/met14091053","DOIUrl":"https://doi.org/10.3390/met14091053","url":null,"abstract":"In this study, as a vital part of the production of Mn-increased 5083 Al alloy, i.e., homogenization annealing before hot rolling, the target states of key Al6Mn precipitation, including the dispersed, initial coarsening and intensive coarsening states, were designed, and the corresponding precipitates formed via the control of the temperature and holding time in the annealing process. By means of metallographic corrosion and nitric acid mass loss tests (NAMLT) for assessing the intergranular corrosion (IGC) resistance, temperatures ranging from 175 °C to 225 °C were determined to induce a transition from sensitization to stabilization for this innovative 5083. At a temperature of 175 °C for a duration of up to 24 h (2 h, 4 h, 8 h, 16 h, 24 h), the results show that when the soak time is 24 h, the sample with initially coarsened Al6Mn phases has a lower degree of sensitization (DOS) compared to the samples with Al6Mn phases in both the dispersed and intensive coarsening states, and its NAMLT is reduced by 11% and 15%, respectively. Subsequently, transmission electron microscopy (TEM) analysis has investigated that for the sample with the best IGC resistance, i.e., that with initially coarsened Al6Mn phases, plate-like Al6Mn particles (200~500 nm) can act as heterogenous nucleation sites for β phases, driving their preferential precipitation on Al6Mn particles and resisting their precipitation along grain boundaries, ultimately improving the IGC resistance of 5083 Al alloy after homogenization annealing.","PeriodicalId":18461,"journal":{"name":"Metals","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bo Qiu, Longxia Jia, Heng Yang, Zhuoyu Guo, Chuyun Jiang, Shuting Li, Biao Sun
ZG25MnCrNiMo steel samples were prepared by squeeze casting under pressure ranging from 0 to 150 MPa. The effects of pressure on the microstructure, low-temperature toughness, hardness, and impact wear performance of the prepared steels were experimentally investigated. The experimental results indicated that the samples fabricated under pressure exhibited finer grains and a significant ferrite content compared to those produced without pressure. Furthermore, the secondary dendrite arm spacing of the sample produced at 150 MPa decreased by 45.3%, and the ferrite content increased by 39.1% in comparison to the unpressurized sample. The low-temperature impact toughness of the steel at −40 °C initially increased and then decreased as the pressure varied from 0 MPa to 150 MPa. And the toughness achieved an optimal value at a pressure of 30 MPa, which was 65.4% greater than that of gravity casting (0 MPa), while the hardness decreased by only 6.17%. With a further increase in pressure, the impact work decreased linearly while the hardness increased slightly. Impact fracture analysis revealed that the fracture of the steel produced without pressure exhibited a quasi-cleavage morphology. The samples prepared by squeeze casting under 30 MPa still exhibited a large number of fine dimples even at −40 °C, indicative of ductile fracture. In addition, the impact wear performance of the steels displayed a trend of initially decreasing and subsequently increasing across the pressure range of 0–150 MPa. The wear resistance of samples prepared without pressure and at 30 MPa was superior to that at 60 MPa, and the wear resistance deteriorated when the pressure increased to 60 MPa, after which it exhibited an upward trend as the pressure continued to rise. The wear mechanisms of the samples predominantly consisted of impact wear, adhesive wear, and minimal abrasive wear, along with notable occurrences of plastic removal, furrows, and spalling.
{"title":"Study on the Effect of Pressure on the Microstructure, Mechanical Properties, and Impact Wear Behavior of Mn-Cr-Ni-Mo Alloyed Steel Fabricated by Squeeze Casting","authors":"Bo Qiu, Longxia Jia, Heng Yang, Zhuoyu Guo, Chuyun Jiang, Shuting Li, Biao Sun","doi":"10.3390/met14091054","DOIUrl":"https://doi.org/10.3390/met14091054","url":null,"abstract":"ZG25MnCrNiMo steel samples were prepared by squeeze casting under pressure ranging from 0 to 150 MPa. The effects of pressure on the microstructure, low-temperature toughness, hardness, and impact wear performance of the prepared steels were experimentally investigated. The experimental results indicated that the samples fabricated under pressure exhibited finer grains and a significant ferrite content compared to those produced without pressure. Furthermore, the secondary dendrite arm spacing of the sample produced at 150 MPa decreased by 45.3%, and the ferrite content increased by 39.1% in comparison to the unpressurized sample. The low-temperature impact toughness of the steel at −40 °C initially increased and then decreased as the pressure varied from 0 MPa to 150 MPa. And the toughness achieved an optimal value at a pressure of 30 MPa, which was 65.4% greater than that of gravity casting (0 MPa), while the hardness decreased by only 6.17%. With a further increase in pressure, the impact work decreased linearly while the hardness increased slightly. Impact fracture analysis revealed that the fracture of the steel produced without pressure exhibited a quasi-cleavage morphology. The samples prepared by squeeze casting under 30 MPa still exhibited a large number of fine dimples even at −40 °C, indicative of ductile fracture. In addition, the impact wear performance of the steels displayed a trend of initially decreasing and subsequently increasing across the pressure range of 0–150 MPa. The wear resistance of samples prepared without pressure and at 30 MPa was superior to that at 60 MPa, and the wear resistance deteriorated when the pressure increased to 60 MPa, after which it exhibited an upward trend as the pressure continued to rise. The wear mechanisms of the samples predominantly consisted of impact wear, adhesive wear, and minimal abrasive wear, along with notable occurrences of plastic removal, furrows, and spalling.","PeriodicalId":18461,"journal":{"name":"Metals","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, a near-net discrete clamp motion path control (SF-CMPC)-based stretch-forming method is proposed as a solution for the low-cost high-quality machining of highly curved surfaces. In this approach, the clamps are discretized, the motion paths are designed to control deformation distribution and avoid forming defects, the stretch-forming transition zone can be effectively reduced, the material utilization rate can be increased, and the near-net formation of large surfaces can be achieved. To investigate this method’s feasibility, the conventional stretch-forming (SF-C) and SF-CMPC processes are numerically analyzed. The results indicate that, upon increasing the transition zone length via SF-CMPC, the maximum thickness reduction and strain value are reduced by 0.010 mm and 0.0249, respectively, with the dependence of the forming quality on the transition zone length being significantly reduced compared to SF-C. In the formation of surfaces with large curvatures, SF-CMPC’s crack risk is lower than SF-C’s crack risk, with better adaptability. Through controlling the contact process with a die, the sheet metals’ constraint state is improved, the transverse compressive strain can be effectively reduced via friction, and the wrinkling defects can be suppressed. A stretch-forming experiment was carried out on a spherical surface, using self-developed equipment. The feasibility of achieving surfaces’ near-net stretch forming by controlling the clamps’ motion paths was hereby proven.
{"title":"Research on Discrete Clamp Motion Path Control-Based Stretch-Forming Method for Large Surfaces","authors":"Zhen Yang, Qian Tang","doi":"10.3390/met14091046","DOIUrl":"https://doi.org/10.3390/met14091046","url":null,"abstract":"In this paper, a near-net discrete clamp motion path control (SF-CMPC)-based stretch-forming method is proposed as a solution for the low-cost high-quality machining of highly curved surfaces. In this approach, the clamps are discretized, the motion paths are designed to control deformation distribution and avoid forming defects, the stretch-forming transition zone can be effectively reduced, the material utilization rate can be increased, and the near-net formation of large surfaces can be achieved. To investigate this method’s feasibility, the conventional stretch-forming (SF-C) and SF-CMPC processes are numerically analyzed. The results indicate that, upon increasing the transition zone length via SF-CMPC, the maximum thickness reduction and strain value are reduced by 0.010 mm and 0.0249, respectively, with the dependence of the forming quality on the transition zone length being significantly reduced compared to SF-C. In the formation of surfaces with large curvatures, SF-CMPC’s crack risk is lower than SF-C’s crack risk, with better adaptability. Through controlling the contact process with a die, the sheet metals’ constraint state is improved, the transverse compressive strain can be effectively reduced via friction, and the wrinkling defects can be suppressed. A stretch-forming experiment was carried out on a spherical surface, using self-developed equipment. The feasibility of achieving surfaces’ near-net stretch forming by controlling the clamps’ motion paths was hereby proven.","PeriodicalId":18461,"journal":{"name":"Metals","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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