Pub Date : 2025-01-12DOI: 10.1016/j.addlet.2025.100268
Jinhu Liu , Feihong Wang , Dong Lu , Yongfeng Liang , Junpin Lin
Titanium alloys are widely regarded as ideal biomaterials due to their superior mechanical properties and resistance to corrosion. Additive manufacturing offers a novel approach for fabricating porous structures, enabling the production of titanium alloys with intricate geometries and varied dimensions. In this study, porous titanium alloys were produced using the Ti-6Al-2Zr-2V-1Mo alloy via electron beam selective melting (EBSM). Thin-wall structures with thicknesses ranging from 360 μm to 600 μm demonstrated exceptional mechanical performance near the forming threshold. An increase in porosity from 22 % to 32 % was observed, resulting in a reduction in tensile strength from 350 MPa to 250 MPa. Tensile testing and microstructural analyses revealed that precise control of the electron beam spot diameter facilitated effective metallurgical bonding between powder particles, with residual pores comparable in size to the original powder. This work highlights a promising strategy for fabricating titanium alloys tailored for biomedical applications.
{"title":"Fabrication of ultra-thin porous titanium alloys by electron beam selective melting: Porosity and mechanical properties","authors":"Jinhu Liu , Feihong Wang , Dong Lu , Yongfeng Liang , Junpin Lin","doi":"10.1016/j.addlet.2025.100268","DOIUrl":"10.1016/j.addlet.2025.100268","url":null,"abstract":"<div><div>Titanium alloys are widely regarded as ideal biomaterials due to their superior mechanical properties and resistance to corrosion. Additive manufacturing offers a novel approach for fabricating porous structures, enabling the production of titanium alloys with intricate geometries and varied dimensions. In this study, porous titanium alloys were produced using the Ti-6Al-2Zr-2V-1Mo alloy via electron beam selective melting (EBSM). Thin-wall structures with thicknesses ranging from 360 μm to 600 μm demonstrated exceptional mechanical performance near the forming threshold. An increase in porosity from 22 % to 32 % was observed, resulting in a reduction in tensile strength from 350 MPa to 250 MPa. Tensile testing and microstructural analyses revealed that precise control of the electron beam spot diameter facilitated effective metallurgical bonding between powder particles, with residual pores comparable in size to the original powder. This work highlights a promising strategy for fabricating titanium alloys tailored for biomedical applications.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"13 ","pages":"Article 100268"},"PeriodicalIF":4.2,"publicationDate":"2025-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143148820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The demands of high-performance industries such as aerospace, automotive, tool manufacturing, oil, and gas industries are driving the innovation in high-performance materials and their production methods. This study explores the impact of hybrid manufacturing, specifically the effect of the addition of tungsten carbide (WC/W2C) via Laser-Directed Energy Deposition (L-DED), on the hot workability, hardness, and microstructure of nickel-based superalloy Inconel 625 (IN625). IN625 is known for its high temperature and high corrosion resistance, and tungsten carbide for its high wear resistance and grain refinement effect. The integration of WC/W2C particles into the IN625 matrix, in addition to the use of the hybrid approach of additive manufacturing followed by a hot–forming process, significantly influences the microstructure and mechanical behavior of the material. Thus, while incorporation of the WC/W2C can strengthen the material and extend the mechanical limitations, its full impact, including any potential usages, should be thoroughly evaluated for the intended application of the materials. To understand the effect of WC/W2C, additive manufacturing of IN625 both with and without WC/W2C and isothermal hot compression was carried out. The objective is to analyze the differences in microstructure and properties between L-DED manufactured IN625, and WC-reinforced IN625, and their hot-forming behavior, focusing on the effects of WC addition and post-deformation on microstructure and mechanical properties. This work represents the first investigation into the effect of WC/W2C hard particles on the hot-forming process of additively manufactured Ni-based metal matrix composites.
{"title":"Hot forming behavior of tungsten carbide reinforced Ni-Based superalloy 625 additively manufactured by laser directed energy deposition","authors":"Gökhan Ertugrul , Aliakbar Emdadi , Angelika Jedynak , Sabine Weiß , Sebastian Härtel","doi":"10.1016/j.addlet.2025.100267","DOIUrl":"10.1016/j.addlet.2025.100267","url":null,"abstract":"<div><div>The demands of high-performance industries such as aerospace, automotive, tool manufacturing, oil, and gas industries are driving the innovation in high-performance materials and their production methods. This study explores the impact of hybrid manufacturing, specifically the effect of the addition of tungsten carbide (WC/W2C) via Laser-Directed Energy Deposition (L-DED), on the hot workability, hardness, and microstructure of nickel-based superalloy Inconel 625 (IN625). IN625 is known for its high temperature and high corrosion resistance, and tungsten carbide for its high wear resistance and grain refinement effect. The integration of WC/W2C particles into the IN625 matrix, in addition to the use of the hybrid approach of additive manufacturing followed by a hot–forming process, significantly influences the microstructure and mechanical behavior of the material. Thus, while incorporation of the WC/W2C can strengthen the material and extend the mechanical limitations, its full impact, including any potential usages, should be thoroughly evaluated for the intended application of the materials. To understand the effect of WC/W2C, additive manufacturing of IN625 both with and without WC/W2C and isothermal hot compression was carried out. The objective is to analyze the differences in microstructure and properties between <span>L</span>-DED manufactured IN625, and WC-reinforced IN625, and their hot-forming behavior, focusing on the effects of WC addition and post-deformation on microstructure and mechanical properties. This work represents the first investigation into the effect of WC/W2C hard particles on the hot-forming process of additively manufactured Ni-based metal matrix composites.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"13 ","pages":"Article 100267"},"PeriodicalIF":4.2,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143098795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01DOI: 10.1016/j.addlet.2024.100260
Peyton J. Wilson , Elaheh Azizian-Farsani , Mikyle Paul , Michael M. Khonsari , Shuai Shao , Nima Shamsaei
With the recent implementation of additively manufactured parts into industrial applications, there is a dire need for nondestructive evaluation methods to qualify if these components are fit for service due to their sensitivity to processing conditions. The Impulse Excitation Technique (IET) is applied to additively manufactured Ti-6Al-4V bending specimens to determine natural frequencies and damping properties in order to predict fatigue performance relative to specimens fabricated with different processing parameters. From the damping and natural frequency results, it was found that the specimens, fabricated with intentional underheating to induce lack of fusion defects, had the lowest damping value in the pristine condition and the highest natural frequency. For the three batches of specimens tested, it was determined that the underheated specimens had the best fully-reversed bending fatigue performance with the highest fatigue limit (297 MPa) and longest fatigue lives as compared to the other two batches, implying a relation of decreased fatigue life with increased material damping in the pristine condition. The theory of the IET related to materials is presented with damping and fatigue results, as well as microstructural analysis and fractography of three specimens batches fabricated with different processing parameters.
{"title":"On the damping and fatigue characterization of additively manufactured Ti-6Al-4V","authors":"Peyton J. Wilson , Elaheh Azizian-Farsani , Mikyle Paul , Michael M. Khonsari , Shuai Shao , Nima Shamsaei","doi":"10.1016/j.addlet.2024.100260","DOIUrl":"10.1016/j.addlet.2024.100260","url":null,"abstract":"<div><div>With the recent implementation of additively manufactured parts into industrial applications, there is a dire need for nondestructive evaluation methods to qualify if these components are fit for service due to their sensitivity to processing conditions. The Impulse Excitation Technique (IET) is applied to additively manufactured Ti-6Al-4V bending specimens to determine natural frequencies and damping properties in order to predict fatigue performance relative to specimens fabricated with different processing parameters. From the damping and natural frequency results, it was found that the specimens, fabricated with intentional underheating to induce lack of fusion defects, had the lowest damping value in the pristine condition and the highest natural frequency. For the three batches of specimens tested, it was determined that the underheated specimens had the best fully-reversed bending fatigue performance with the highest fatigue limit (297 MPa) and longest fatigue lives as compared to the other two batches, implying a relation of decreased fatigue life with increased material damping in the pristine condition. The theory of the IET related to materials is presented with damping and fatigue results, as well as microstructural analysis and fractography of three specimens batches fabricated with different processing parameters.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"11 ","pages":"Article 100260"},"PeriodicalIF":4.2,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143148337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01DOI: 10.1016/j.addlet.2024.100259
Benedikt Kirchebner , Kellen D. Traxel , Alexander E. Wilson-Heid , Eric S. Elton , Andrew J. Pascall , Jason R. Jeffries
Molten metal jetting (MMJ) is an additive manufacturing (AM) method where droplets of molten metal are used to build parts. Like most AM technologies, MMJ is typically used to build stand-alone parts rather than add onto existing parts. However, the droplet-wise deposition method of MMJ is inherently compatible with the ability to build on existing parts. Here, we utilize MMJ to “repair” machined damage on cast aluminum parts. A commercial MMJ system was used to fill in varied but defined groove geometries to find optimal shapes amenable to repair with MMJ. Subsequently, grooves were cut into tensile specimens and back-filled (repaired) using MMJ. Tensile tests indicate that MMJ repair restores significant strength to samples despite the distinct microstructure and void structures present in the repaired section. Repaired samples demonstrated tensile strengths ∼72 % of the as-received material, compared to UTS of ∼33 % for damaged samples. These results indicate that MMJ is a viable method to repair parts where other repair methods may be impractical.
{"title":"Molten metal jetting for repairing aluminum components","authors":"Benedikt Kirchebner , Kellen D. Traxel , Alexander E. Wilson-Heid , Eric S. Elton , Andrew J. Pascall , Jason R. Jeffries","doi":"10.1016/j.addlet.2024.100259","DOIUrl":"10.1016/j.addlet.2024.100259","url":null,"abstract":"<div><div>Molten metal jetting (MMJ) is an additive manufacturing (AM) method where droplets of molten metal are used to build parts. Like most AM technologies, MMJ is typically used to build stand-alone parts rather than add onto existing parts. However, the droplet-wise deposition method of MMJ is inherently compatible with the ability to build on existing parts. Here, we utilize MMJ to “repair” machined damage on cast aluminum parts. A commercial MMJ system was used to fill in varied but defined groove geometries to find optimal shapes amenable to repair with MMJ. Subsequently, grooves were cut into tensile specimens and back-filled (repaired) using MMJ. Tensile tests indicate that MMJ repair restores significant strength to samples despite the distinct microstructure and void structures present in the repaired section. Repaired samples demonstrated tensile strengths ∼72 % of the as-received material, compared to UTS of ∼33 % for damaged samples. These results indicate that MMJ is a viable method to repair parts where other repair methods may be impractical.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"11 ","pages":"Article 100259"},"PeriodicalIF":4.2,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143148355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01DOI: 10.1016/j.addlet.2024.100258
Tyler D. Smith , Chad Westover , Matthew D'Souza , Shenghan Guo , Dhruv Bhate
This study seeks an early prediction method of crack failure location and orientation due to low cycle fatigue in additively manufactured metallic cellular materials by leveraging experimentally observed accumulation of plastic deformation. To study this, a novel spatial-temporal approach for analyzing Infrared Thermographic (IRT) video was developed to detect heat generated by local plastic deformation. The method was validated experimentally by conducting fully reversed low cycle fatigue tests of Inconel 718 (IN718) honeycomb specimens manufactured using Laser Powder Bed Fusion (LPBF). Using the approach developed, results showed that localized heating due to plastic work could be detected and used for early prediction of the most probable path, and orientation of crack propagation. Furthermore, the method developed was found to be able to predict these results within the first 1.5 % of the total life of the specimen apriori to crack initiation.
{"title":"A spatial-temporal method for early prediction of fatigue crack region and orientation in metallic cellular materials using in-situ infrared thermography (IRT)","authors":"Tyler D. Smith , Chad Westover , Matthew D'Souza , Shenghan Guo , Dhruv Bhate","doi":"10.1016/j.addlet.2024.100258","DOIUrl":"10.1016/j.addlet.2024.100258","url":null,"abstract":"<div><div>This study seeks an early prediction method of crack failure location and orientation due to low cycle fatigue in additively manufactured metallic cellular materials by leveraging experimentally observed accumulation of plastic deformation. To study this, a novel spatial-temporal approach for analyzing Infrared Thermographic (IRT) video was developed to detect heat generated by local plastic deformation. The method was validated experimentally by conducting fully reversed low cycle fatigue tests of Inconel 718 (IN718) honeycomb specimens manufactured using Laser Powder Bed Fusion (LPBF). Using the approach developed, results showed that localized heating due to plastic work could be detected and used for early prediction of the most probable path, and orientation of crack propagation. Furthermore, the method developed was found to be able to predict these results within the first 1.5 % of the total life of the specimen apriori to crack initiation.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"11 ","pages":"Article 100258"},"PeriodicalIF":4.2,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143148338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-19DOI: 10.1016/j.addlet.2024.100257
L. Becker, P. König, J. Lentz, S. Weber
High-nitrogen martensitic stainless steels, such as X30CrMoN15 (0.3 to 0.5 mass% nitrogen), exhibit an excellent combination of strength and corrosion resistance, making them well-suited for applications in the medical technology and aerospace industry. The qualification of these steels for additive manufacturing (AM) could generate new application areas where AM, due to its process-specific advantages, could offer added value compared to conventional manufacturing methods. However, the laser powder bed fusion (PBF-LB/M) of high-nitrogen alloyed steels is challenging due to the high tendency for gas pore formation, resulting from the limited nitrogen solubility in the steel melt. In this work, a new process route for AM of a high nitrogen containing X50CrMoV15 martensitic stainless steel is presented, which consists of a process combination of powder nitriding, PBF-LB/M and subsequent hot isostatic pressing (HIP) with integrated quenching. Gas nitriding is used to achieve a nitrogen content in the starting powder that exceeds the maximum solubility in the melt. Although the nitrogen content decreases during the PBF-LB/M process, the high solidification and cooling rates prevent the melt from reaching equilibrium nitrogen levels, resulting in a nitrogen content above the solubility limit in the final PBF-LB/M state. The pores formed during the process are closed through HIP, which also allows hardening via integrated gas quenching. With an additional cryogenic treatment, the process produces a fully dense steel with 75% martensitic structure and 0.246 mass% nitrogen. Further optimization opportunities have been identified and are discussed.
{"title":"A new process route for the additive manufacturing of a high nitrogen containing martensitic stainless steel - A feasibility study","authors":"L. Becker, P. König, J. Lentz, S. Weber","doi":"10.1016/j.addlet.2024.100257","DOIUrl":"10.1016/j.addlet.2024.100257","url":null,"abstract":"<div><div>High-nitrogen martensitic stainless steels, such as X30CrMoN15 (0.3 to 0.5 mass% nitrogen), exhibit an excellent combination of strength and corrosion resistance, making them well-suited for applications in the medical technology and aerospace industry. The qualification of these steels for additive manufacturing (AM) could generate new application areas where AM, due to its process-specific advantages, could offer added value compared to conventional manufacturing methods. However, the laser powder bed fusion (PBF-LB/M) of high-nitrogen alloyed steels is challenging due to the high tendency for gas pore formation, resulting from the limited nitrogen solubility in the steel melt. In this work, a new process route for AM of a high nitrogen containing X50CrMoV15 martensitic stainless steel is presented, which consists of a process combination of powder nitriding, PBF-LB/M and subsequent hot isostatic pressing (HIP) with integrated quenching. Gas nitriding is used to achieve a nitrogen content in the starting powder that exceeds the maximum solubility in the melt. Although the nitrogen content decreases during the PBF-LB/M process, the high solidification and cooling rates prevent the melt from reaching equilibrium nitrogen levels, resulting in a nitrogen content above the solubility limit in the final PBF-LB/M state. The pores formed during the process are closed through HIP, which also allows hardening via integrated gas quenching. With an additional cryogenic treatment, the process produces a fully dense steel with 75% martensitic structure and 0.246 mass% nitrogen. Further optimization opportunities have been identified and are discussed.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"11 ","pages":"Article 100257"},"PeriodicalIF":4.2,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142702849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Simulation is one of the most widely used methods for process optimization towards improved part quality in Additive Manufacturing (AM), particularly for metal parts. However, due to the nature of the AM processes and the complex phenomena that occur, simulations that are capable of providing a detailed overview of the physical mechanisms demand considerable computational resources and time. In this study, a numerical approach is presented, which can be applied to any implicit numerical thermal simulation for AM, allowing for a significant decrease in computational time (higher than 70%) with minimal impact on accuracy. This is achieved by combining space partitioning, enabled by a boundary condition that was developed, with dynamic mesh adaptation in the x-, y-, and z-axis. The methodology is described in detail and both the decrease in computational time and the accuracy of the developed approach are validated in a computational case study, as well as using experimental results.
模拟是增材制造（AM）中最广泛使用的工艺优化方法之一，旨在提高零件质量，尤其是金属零件。然而，由于增材制造工艺的性质和发生的复杂现象，能够提供物理机制详细概述的模拟需要大量的计算资源和时间。本研究提出了一种数值方法，可应用于任何隐式热模拟 AM，从而大幅减少计算时间（超过 70%），并将对精度的影响降至最低。这是通过将空间分区与 x、y 和 z 轴的动态网格适应相结合而实现的。本文对该方法进行了详细描述，并通过计算案例研究和实验结果对计算时间的减少和所开发方法的准确性进行了验证。
{"title":"Additive manufacturing simulations: An approach based on space partitioning and dynamic 3D mesh adaptation","authors":"Panagis Foteinopoulos, Alexios Papacharalampopoulos, Panagiotis Stavropoulos","doi":"10.1016/j.addlet.2024.100256","DOIUrl":"10.1016/j.addlet.2024.100256","url":null,"abstract":"<div><div>Simulation is one of the most widely used methods for process optimization towards improved part quality in Additive Manufacturing (AM), particularly for metal parts. However, due to the nature of the AM processes and the complex phenomena that occur, simulations that are capable of providing a detailed overview of the physical mechanisms demand considerable computational resources and time. In this study, a numerical approach is presented, which can be applied to any implicit numerical thermal simulation for AM, allowing for a significant decrease in computational time (higher than 70%) with minimal impact on accuracy. This is achieved by combining space partitioning, enabled by a boundary condition that was developed, with dynamic mesh adaptation in the <em>x</em>-, <em>y</em>-, and <em>z</em>-axis. The methodology is described in detail and both the decrease in computational time and the accuracy of the developed approach are validated in a computational case study, as well as using experimental results.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"11 ","pages":"Article 100256"},"PeriodicalIF":4.2,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142702850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-13DOI: 10.1016/j.addlet.2024.100253
Nicolas Nothomb , Ignacio Rodriguez-Barber , María Teresa Pérez-Prado , Norberto Jimenez Mena , Grzegorz Pyka , Aude Simar
Only a limited aluminium material palette is currently available for L-PBF processing, especially for high strength aluminium alloy. Unmodified Al7075 suffers from hot cracking making it nearly impossible to process by L-PBF. Adding some grain refiner to Al7075 solves this issue of hot cracking. However, this alloy still presents difficulties to be processed with densities above 99.5%. In this study, the unconventional pre-sintering scanning strategy is applied to process 99.9% density Al7075+1.8%Zr. For this scanning strategy, each layer is scanned twice with different power, i.e. it is first scanned with half the power selected for the second scan. This specific strategy remelts potential defect generated by the first scan and reduces lack of fusion pores. These two phenomena lead to high density L-PBF Al7075+1.8%Zr and pave the way to higher densities for high strength aluminium alloys.
{"title":"Understanding the effect of pre-sintering scanning strategy on the relative density of Zr-modified Al7075 processed by laser powder bed fusion","authors":"Nicolas Nothomb , Ignacio Rodriguez-Barber , María Teresa Pérez-Prado , Norberto Jimenez Mena , Grzegorz Pyka , Aude Simar","doi":"10.1016/j.addlet.2024.100253","DOIUrl":"10.1016/j.addlet.2024.100253","url":null,"abstract":"<div><div>Only a limited aluminium material palette is currently available for L-PBF processing, especially for high strength aluminium alloy. Unmodified Al7075 suffers from hot cracking making it nearly impossible to process by L-PBF. Adding some grain refiner to Al7075 solves this issue of hot cracking. However, this alloy still presents difficulties to be processed with densities above 99.5%. In this study, the unconventional pre-sintering scanning strategy is applied to process 99.9% density Al7075+1.8%Zr. For this scanning strategy, each layer is scanned twice with different power, i.e. it is first scanned with half the power selected for the second scan. This specific strategy remelts potential defect generated by the first scan and reduces lack of fusion pores. These two phenomena lead to high density L-PBF Al7075+1.8%Zr and pave the way to higher densities for high strength aluminium alloys.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"11 ","pages":"Article 100253"},"PeriodicalIF":4.2,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142702920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-08DOI: 10.1016/j.addlet.2024.100255
Mohammad Salman Yasin , Kevin Stonaker , Shuai Shao , Nima Shamsaei
Deteriorated filter condition in laser powder bed fusion (L-PBF) systems may negatively impact shield gas flow, causing inadequate spatter particle/plume removal, leading to laser beam attenuation and reduction in melt pool depth, and potentially causing more frequent formation of volumetric defects. This work investigated the effects of filter condition and part location on the micro-/defect-structure and mechanical behavior, including tensile and fatigue, of Ti-6Al-4V parts fabricated by L-PBF. Interestingly, within the manufacturer recommended service intervals, no specific effect of filter condition could be observed on the micro-/defect-structure or the mechanical behavior of the fabricated parts. However, the parts’ defect-structures were affected by their location, with ones located near the center of the build plate having less porosity than the ones located away. Although these defects did not affect the tensile properties, they frequently observed to initiate fatigue cracks (the critical defects sizes were often in the range of a few tens of micrometers). Therefore, their sensitivity to location resulted in the location dependence of the fatigue behavior.
{"title":"Mechanical performance of laser powder bed fused Ti-6Al-4V: The influence of filter condition and part location","authors":"Mohammad Salman Yasin , Kevin Stonaker , Shuai Shao , Nima Shamsaei","doi":"10.1016/j.addlet.2024.100255","DOIUrl":"10.1016/j.addlet.2024.100255","url":null,"abstract":"<div><div>Deteriorated filter condition in laser powder bed fusion (L-PBF) systems may negatively impact shield gas flow, causing inadequate spatter particle/plume removal, leading to laser beam attenuation and reduction in melt pool depth, and potentially causing more frequent formation of volumetric defects. This work investigated the effects of filter condition and part location on the micro-/defect-structure and mechanical behavior, including tensile and fatigue, of Ti-6Al-4V parts fabricated by L-PBF. Interestingly, within the manufacturer recommended service intervals, no specific effect of filter condition could be observed on the micro-/defect-structure or the mechanical behavior of the fabricated parts. However, the parts’ defect-structures were affected by their location, with ones located near the center of the build plate having less porosity than the ones located away. Although these defects did not affect the tensile properties, they frequently observed to initiate fatigue cracks (the critical defects sizes were often in the range of a few tens of micrometers). Therefore, their sensitivity to location resulted in the location dependence of the fatigue behavior.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"11 ","pages":"Article 100255"},"PeriodicalIF":4.2,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-04DOI: 10.1016/j.addlet.2024.100254
Scott C. Bozeman, O. Burkan Isgor, Julie D. Tucker
Functionally graded materials are an emergent method for designing components with programmable site-specific material properties. These materials are typically fabricated using metal additive manufacturing tools by simultaneously feeding multiple wire and/or powder feedstocks at various rates to achieve spatial composition change. The wire-powder-directed energy deposition (WP-DED) technique is of particular interest for many functionally graded material applications by balancing the low raw materials cost of wire with the high resolution of powder. However, feeding wire and powder are inherently different processes since all extruded wire enters the melt pool, while much of the blown powder is scattered, which makes determining the composition of the build challenging. In this study, we devise a simple area-based measurement method for estimating the composition of WP-DED structures. WP-DED single beads are printed using 309L stainless steel wire and commercially pure Fe powder at five wire feed rates (0.5, 0.75, 1.00, 1.25, 1.50 mm/mm) and five powder feed rates (2, 4, 6, 8, 10 rpm). Characteristic defects including interface gaps and macrosegregation (lack of mixing) tendencies are examined. High powder feed rates (8, 10 rpm) result in interface gaps at all wire feed rates, but smooth deposition and complete mixing is achieved at low powder feed rates, particularly with lower wire feed rates as well. The area-based composition measurement method is within ±20% of energy dispersive x-ray spectroscopy measurements for all samples, showing its effectiveness as a rapid composition estimate for WP-DED materials development.
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