Pub Date : 2025-02-01DOI: 10.1016/j.jmatprotec.2024.118709
Mert Efe, Kate Rader, Nicole Overman, Wahaz Nasim, Angel Ortiz, Ayoub Soulami, Kyoo Sil Choi
This paper introduces a novel thermo-mechanical process to modify the local formability and hardness of 6xxx aluminum (Al−Mg−Si−Cu) alloy sheets in T4 and T6 tempers. In this process, two pairs of rollers travel along the length of a sheet while locally bending and unbending it so that the final shape and thickness of the sheet remains unchanged. It is possible to apply local deformation and/or heating with the process and control the properties separately. Room temperature bending/unbending (B/U) produces a deformation gradient through thickness and local hardening in both T4 and T6 sheets (with 38 % and 15 % greater Vickers hardness, respectively). High temperature B/U performed at ∼ 500 °C via induction heating, produces T4-temper-level bendability (bend angles of ∼ 150°) within the high temperature B/U processed zones of T6 sheets, without disturbing the T6 temper in the remainder of the sheet. T4 sheets benefit from the B/U deformation more than the T6 sheets, and the process offers increased local hardness of T4 sheets without significant loss in formability mainly due the heterogenous microstructure development and the weakened Cube texture through thickness. Individual control of local bendability and hardness in both tempers can enable downgauging and increase their usage in automotive applications.
{"title":"Optimizing bendability and hardness of age-hardenable aluminum sheets through local thermo-mechanical processing","authors":"Mert Efe, Kate Rader, Nicole Overman, Wahaz Nasim, Angel Ortiz, Ayoub Soulami, Kyoo Sil Choi","doi":"10.1016/j.jmatprotec.2024.118709","DOIUrl":"10.1016/j.jmatprotec.2024.118709","url":null,"abstract":"<div><div>This paper introduces a novel thermo-mechanical process to modify the local formability and hardness of 6xxx aluminum (Al−Mg−Si−Cu) alloy sheets in T4 and T6 tempers. In this process, two pairs of rollers travel along the length of a sheet while locally bending and unbending it so that the final shape and thickness of the sheet remains unchanged. It is possible to apply local deformation and/or heating with the process and control the properties separately. Room temperature bending/unbending (B/U) produces a deformation gradient through thickness and local hardening in both T4 and T6 sheets (with 38 % and 15 % greater Vickers hardness, respectively). High temperature B/U performed at ∼ 500 °C via induction heating, produces T4-temper-level bendability (bend angles of ∼ 150°) within the high temperature B/U processed zones of T6 sheets, without disturbing the T6 temper in the remainder of the sheet. T4 sheets benefit from the B/U deformation more than the T6 sheets, and the process offers increased local hardness of T4 sheets without significant loss in formability mainly due the heterogenous microstructure development and the weakened Cube texture through thickness. Individual control of local bendability and hardness in both tempers can enable downgauging and increase their usage in automotive applications.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"336 ","pages":"Article 118709"},"PeriodicalIF":6.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143168494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.jmatprotec.2024.118702
J. Rodrigues Da Silva , Z. Hamouche , A.-L. Helbert , T. Baudin , F. Coste , P. Peyre
The geometries, microstructures, and mechanical properties of vertically built Inconel 625 Laser Powder Bed Fusion (L-PBF) struts were investigated in this study. The influence of strut size (between 0.2 mm and 2 mm) and scan strategy was more specifically addressed. As-built struts exhibit satisfactory geometry and porosity rates, whatever the strut size and scan strategy. Classical columnar grains oriented parallel to the build direction (BD) were obtained, with a < 001 > // BD fiber texture only for the smaller struts (0.2 mm to 0.5 mm), due to the formation of a unique circular melt pool on the whole strut surface. At a smaller scale, the influence of the build strategy is also visible on solidification cells, whose average diameter decreases for outside-in strategies and larger hatching area ratios. The tensile strengths and hardness values are lower for the smaller diameter (0.3 mm) struts and for the inside-out strategies, suggesting the important role played by a finer sub-grain structure and a smaller crystallographic texture on the strengthening of Inconel 625 struts.
{"title":"Influence of diameter and scan strategy on the geometrical, microstructural, and mechanical properties of small Inconel 625 L-PBF struts","authors":"J. Rodrigues Da Silva , Z. Hamouche , A.-L. Helbert , T. Baudin , F. Coste , P. Peyre","doi":"10.1016/j.jmatprotec.2024.118702","DOIUrl":"10.1016/j.jmatprotec.2024.118702","url":null,"abstract":"<div><div>The geometries, microstructures, and mechanical properties of vertically built Inconel 625 Laser Powder Bed Fusion (L-PBF) struts were investigated in this study. The influence of strut size (between 0.2 mm and 2 mm) and scan strategy was more specifically addressed. As-built struts exhibit satisfactory geometry and porosity rates, whatever the strut size and scan strategy. Classical columnar grains oriented parallel to the build direction (BD) were obtained, with a < 001 > // BD fiber texture only for the smaller struts (0.2 mm to 0.5 mm), due to the formation of a unique circular melt pool on the whole strut surface. At a smaller scale, the influence of the build strategy is also visible on solidification cells, whose average diameter decreases for outside-in strategies and larger hatching area ratios. The tensile strengths and hardness values are lower for the smaller diameter (0.3 mm) struts and for the inside-out strategies, suggesting the important role played by a finer sub-grain structure and a smaller crystallographic texture on the strengthening of Inconel 625 struts.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"336 ","pages":"Article 118702"},"PeriodicalIF":6.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143168496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.jmatprotec.2024.118701
Peng Han, Wen Wang, Jingyu Deng, Ke Qiao, Kai Zhou, Jia Lin, Yuye Zhang, Fengming Qiang, Kuaishe Wang
Titanium and its alloys hold significant industrial importance due to their potential for superplastic formability. However, most titanium and its alloys require high temperatures and low strain rates to achieve superplasticity. Friction stir processing, severe plastic deformation technology, offers an effective approach to achieve low-temperature or high-strain-rate superplasticity in fine-grained titanium alloys. Herein, the effect of rotation speed on the microstructure of the friction stir processed Ti-4.5Al-3V-2Mo-2Fe titanium alloy was investigated for the first time. An ultra-fine-grained Ti-4.5Al-3V-2Mo-2Fe titanium alloy was achieved, exhibiting an average grain size of only 0.26 μm at a rotation speed of 100 r/min and a processing speed of 80 mm/min. Subsequently, the superplastic tensile tests were conducted at temperatures ranging from 550°C-800°C, at an interval of 50°C, and strain rates of 3 × 10−4 s−1, 1 × 10−3 s−1, 3 × 10−3 s−1, and 1 × 10−2 s−1, respectively. The results demonstrated that the ultrafine-grained titanium alloy exhibited excellent superplasticity, achieving an elongation of 1808 ± 52 % at 650°C and 3 × 10−3 s−1. This large elongation was the highest reported value in the field of severe plastic deformed titanium alloys. The superior superplasticity was attributed to the fine grains (＜2 μm), a relatively high proportion of β phase (∼20 %), and a high proportion of high-angle grain boundaries (＞80 %) in the α and β phases during superplastic deformation. The primary superplastic deformation mechanism included dislocation slip and grain rotation coordinated with α/α, β/β grain boundary sliding, and α/β phase boundary sliding. Finally, a model correlating temperature, strain rate, and superplastic elongations was developed using backpropagation neural networks and support vector regression algorithms. The correlation coefficient between the predicted and the actual values was higher for support vector regression (0.93) compared to backpropagation neural networks (0.81), indicating that support vector regression was more suitable for predicting the superplastic elongations. This study offers a novel method for achieving superplasticity in SP700 titanium alloy components.
{"title":"Achieving excellent superplasticity and predicting the elongations in ultrafine-grained Ti-4.5Al-3V-2Mo-2Fe titanium alloy prepared by friction stir processing","authors":"Peng Han, Wen Wang, Jingyu Deng, Ke Qiao, Kai Zhou, Jia Lin, Yuye Zhang, Fengming Qiang, Kuaishe Wang","doi":"10.1016/j.jmatprotec.2024.118701","DOIUrl":"10.1016/j.jmatprotec.2024.118701","url":null,"abstract":"<div><div>Titanium and its alloys hold significant industrial importance due to their potential for superplastic formability. However, most titanium and its alloys require high temperatures and low strain rates to achieve superplasticity. Friction stir processing, severe plastic deformation technology, offers an effective approach to achieve low-temperature or high-strain-rate superplasticity in fine-grained titanium alloys. Herein, the effect of rotation speed on the microstructure of the friction stir processed Ti-4.5Al-3V-2Mo-2Fe titanium alloy was investigated for the first time. An ultra-fine-grained Ti-4.5Al-3V-2Mo-2Fe titanium alloy was achieved, exhibiting an average grain size of only 0.26 μm at a rotation speed of 100 r/min and a processing speed of 80 mm/min. Subsequently, the superplastic tensile tests were conducted at temperatures ranging from 550°C-800°C, at an interval of 50°C, and strain rates of 3 × 10<sup>−4</sup> s<sup>−1</sup>, 1 × 10<sup>−3</sup> s<sup>−1</sup>, 3 × 10<sup>−3</sup> s<sup>−1</sup>, and 1 × 10<sup>−2</sup> s<sup>−1</sup>, respectively. The results demonstrated that the ultrafine-grained titanium alloy exhibited excellent superplasticity, achieving an elongation of 1808 ± 52 % at 650°C and 3 × 10<sup>−3</sup> s<sup>−1</sup>. This large elongation was the highest reported value in the field of severe plastic deformed titanium alloys. The superior superplasticity was attributed to the fine grains (＜2 μm), a relatively high proportion of β phase (∼20 %), and a high proportion of high-angle grain boundaries (＞80 %) in the α and β phases during superplastic deformation. The primary superplastic deformation mechanism included dislocation slip and grain rotation coordinated with α/α, β/β grain boundary sliding, and α/β phase boundary sliding. Finally, a model correlating temperature, strain rate, and superplastic elongations was developed using backpropagation neural networks and support vector regression algorithms. The correlation coefficient between the predicted and the actual values was higher for support vector regression (0.93) compared to backpropagation neural networks (0.81), indicating that support vector regression was more suitable for predicting the superplastic elongations. This study offers a novel method for achieving superplasticity in SP700 titanium alloy components.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"336 ","pages":"Article 118701"},"PeriodicalIF":6.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143169451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.jmatprotec.2024.118680
Zhubin He , Yi Xu , Bingao Wang , Gaoning Tian , Haimin Zhang
Due to the inherent brittleness of lightweight NiAl alloys, conventional manufacturing methods are inadequate for producing large-sized NiAl sheets with excellent mechanical properties. This paper presents an alternative approach, employing Ni nets and Al foils as raw materials to fabricate a NiAl sheet via hot-press sintering in a vacuum furnace. The sheet exhibited a three-dimensional network structure, wherein small-sized grains enveloping larger grains within the net. The network structure is controlled by Ni nets used and the sintering parameters. A nearly fully dense sheet with a density of 99.98 % and a thickness of 1 mm was achieved under sintering conditions of 1400 ℃/20 MPa/0 min. The hardness distribution within the NiAl sheet exhibited a three-dimensional wavy surface profile with distinct peaks and valleys. The hardness in the high-hardness regions exceeded 600 HV0.05, while the hardness in the low-hardness regions ranged from 500 to 550 HV0.05. Tensile test results indicate that, at an initial strain rate of 0.001, the NiAl sheet exhibits brittle fracture at 900 °C, while displaying ductile fracture behavior at 950 °C and 1000 °C. The ultimate tensile strength exceeds 100 MPa at 900 °C but declines sharply as the deformation temperature increases. During tensile testing, cracks propagate along the fine-grain regions, and the fracture surface exhibits a multi-peak morphology. The study provides a new method for the preparation of heterogeneous NiAl alloy sheets and provides new ideas for the microstructure design and performance optimization of NiAl alloys.
{"title":"Fabrication and mechanical properties of the NiAl sheet with a 3-dimensional network structure prepared by Ni nets and Al foils","authors":"Zhubin He , Yi Xu , Bingao Wang , Gaoning Tian , Haimin Zhang","doi":"10.1016/j.jmatprotec.2024.118680","DOIUrl":"10.1016/j.jmatprotec.2024.118680","url":null,"abstract":"<div><div>Due to the inherent brittleness of lightweight NiAl alloys, conventional manufacturing methods are inadequate for producing large-sized NiAl sheets with excellent mechanical properties. This paper presents an alternative approach, employing Ni nets and Al foils as raw materials to fabricate a NiAl sheet via hot-press sintering in a vacuum furnace. The sheet exhibited a three-dimensional network structure, wherein small-sized grains enveloping larger grains within the net. The network structure is controlled by Ni nets used and the sintering parameters. A nearly fully dense sheet with a density of 99.98 % and a thickness of 1 mm was achieved under sintering conditions of 1400 ℃/20 MPa/0 min. The hardness distribution within the NiAl sheet exhibited a three-dimensional wavy surface profile with distinct peaks and valleys. The hardness in the high-hardness regions exceeded 600 HV0.05, while the hardness in the low-hardness regions ranged from 500 to 550 HV0.05. Tensile test results indicate that, at an initial strain rate of 0.001, the NiAl sheet exhibits brittle fracture at 900 °C, while displaying ductile fracture behavior at 950 °C and 1000 °C. The ultimate tensile strength exceeds 100 MPa at 900 °C but declines sharply as the deformation temperature increases. During tensile testing, cracks propagate along the fine-grain regions, and the fracture surface exhibits a multi-peak morphology. The study provides a new method for the preparation of heterogeneous NiAl alloy sheets and provides new ideas for the microstructure design and performance optimization of NiAl alloys.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"336 ","pages":"Article 118680"},"PeriodicalIF":6.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143168416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.jmatprotec.2024.118694
Lv-Yi Cheng , Kai-Shang Li , Run-Zi Wang , Xue-Lin Lei , Jia-Sheng Chen , Ning Yao , Cheng-Cheng Zhang , Xian-Cheng Zhang , Shan-Tung Tu
The premature fatigue failure of hole structures poses a critical challenge in aviation components. This study introduces an end-to-end integrated paradigm, utilizing the cold expansion process (CEP) as a technological carrier to simultaneously improve both fatigue life and stability in the IN718 hole structures. Integrated process technology gains better performance than the isolated ones, where IP-CEP achieves a 2.76-fold improvement in fatigue life. This paradigm further advances to a 4.87-fold fatigue life improvement with reduced dispersions by actively integrating drilling, reaming, cold expansion, reaming, and polishing, breaking through the upper limits of CEP-series. The fatigue life improvement mechanisms are elucidated through advanced surface integrity analysis and fatigue fracture characterization. The results show that the cold expansion process induces substantial maximum compressive residual stress (CRS) and gradient plastic deformation layer, while reaming and polishing effectively improve the surface quality of cold expansion holes. Finally, a clear link between surface integrity and high-temperature fatigue life is established. The consistent enhancement in the fatigue life of the hole structure was primarily attributed to the synergistic effects of CRS, the plastic deformation layer, and superior surface quality. This study proposes an active anti-fatigue paradigm with flexible stages, providing a unified framework to balance multiple objectives for high-temperature structural applications.
{"title":"A novel end-to-end integrated process paradigm for fatigue life improvement in nickel-based superalloy hole structures","authors":"Lv-Yi Cheng , Kai-Shang Li , Run-Zi Wang , Xue-Lin Lei , Jia-Sheng Chen , Ning Yao , Cheng-Cheng Zhang , Xian-Cheng Zhang , Shan-Tung Tu","doi":"10.1016/j.jmatprotec.2024.118694","DOIUrl":"10.1016/j.jmatprotec.2024.118694","url":null,"abstract":"<div><div>The premature fatigue failure of hole structures poses a critical challenge in aviation components. This study introduces an end-to-end integrated paradigm, utilizing the cold expansion process (CEP) as a technological carrier to simultaneously improve both fatigue life and stability in the IN718 hole structures. Integrated process technology gains better performance than the isolated ones, where IP-CEP achieves a 2.76-fold improvement in fatigue life. This paradigm further advances to a 4.87-fold fatigue life improvement with reduced dispersions by actively integrating drilling, reaming, cold expansion, reaming, and polishing, breaking through the upper limits of CEP-series. The fatigue life improvement mechanisms are elucidated through advanced surface integrity analysis and fatigue fracture characterization. The results show that the cold expansion process induces substantial maximum compressive residual stress (CRS) and gradient plastic deformation layer, while reaming and polishing effectively improve the surface quality of cold expansion holes. Finally, a clear link between surface integrity and high-temperature fatigue life is established. The consistent enhancement in the fatigue life of the hole structure was primarily attributed to the synergistic effects of CRS, the plastic deformation layer, and superior surface quality. This study proposes an active anti-fatigue paradigm with flexible stages, providing a unified framework to balance multiple objectives for high-temperature structural applications.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"336 ","pages":"Article 118694"},"PeriodicalIF":6.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143169449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.jmatprotec.2024.118681
Qingyun Zhu , Zhengxin Lu , Hui Li , Yaowu Hu
Room-temperature laser shock peening without coating (RT-LSPwoC) is the mainstream method for surface strengthening, yet it induces tensile residual stress on the surface during rapid heating and cooling. Warm LSPwoC, combining the benefits of dynamic strain aging and LSPwoC, exhibits higher performance than RT-LSPwoC. However, overall high-temperature is time- and resource-consuming, and it is prone to causing thermal stress relaxation during processing, making it unsuitable for large-scale applications. In this paper, a novel localized heating assisted LSPwoC (LHA-LSPwoC) method, utilizing a continuous wave laser for local heating, is proposed. Additionally, the deep physics-informed neural network model, embedded with physical formulas, is designed for process optimization. It enables rapid and accurate responses for an extensive number of cases (40 cases with an average deviation below 1 %), overcoming the drawbacks of traditional numerical simulations that are time-consuming and difficult to efficiently handle numerous cases. Compared to RT-LSPwoC, LHA-LSPwoC samples have higher dislocation density and higher grain refinement, demonstrating higher hardness and residual stress, particularly superior fatigue performance. The mechanism of LHA-LSPwoC is discussed, and thermally coupled finite element simulations and molecular dynamics calculations are conducted to provide theoretical support. The proposed method is cost-effective and flexible, showing outstanding potential for industrial applications.
{"title":"Localized heating assisted laser shock peening without coating enhances mechanical properties of Ti6Al4V alloys","authors":"Qingyun Zhu , Zhengxin Lu , Hui Li , Yaowu Hu","doi":"10.1016/j.jmatprotec.2024.118681","DOIUrl":"10.1016/j.jmatprotec.2024.118681","url":null,"abstract":"<div><div>Room-temperature laser shock peening without coating (RT-LSPwoC) is the mainstream method for surface strengthening, yet it induces tensile residual stress on the surface during rapid heating and cooling. Warm LSPwoC, combining the benefits of dynamic strain aging and LSPwoC, exhibits higher performance than RT-LSPwoC. However, overall high-temperature is time- and resource-consuming, and it is prone to causing thermal stress relaxation during processing, making it unsuitable for large-scale applications. In this paper, a novel localized heating assisted LSPwoC (LHA-LSPwoC) method, utilizing a continuous wave laser for local heating, is proposed. Additionally, the deep physics-informed neural network model, embedded with physical formulas, is designed for process optimization. It enables rapid and accurate responses for an extensive number of cases (40 cases with an average deviation below 1 %), overcoming the drawbacks of traditional numerical simulations that are time-consuming and difficult to efficiently handle numerous cases. Compared to RT-LSPwoC, LHA-LSPwoC samples have higher dislocation density and higher grain refinement, demonstrating higher hardness and residual stress, particularly superior fatigue performance. The mechanism of LHA-LSPwoC is discussed, and thermally coupled finite element simulations and molecular dynamics calculations are conducted to provide theoretical support. The proposed method is cost-effective and flexible, showing outstanding potential for industrial applications.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"336 ","pages":"Article 118681"},"PeriodicalIF":6.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143169441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.jmatprotec.2024.118696
Yuxiang Hong , Jiaxing Gao , Kai Lin , Shengyong Li , Baohua Chang , Dong Du
The molten pool behavior and weld formation in ultra-thin (thickness ≤ 0.3 mm) sheets edge welding is extremely sensitive to the variation of thermodynamic conditions, due to its unique heat transfer conditions and molten pool dynamics caused by special joint form and extremely small molten pool size. In this paper, micro-plasma arc source was applied to join the edge joint composed of two 0.12 mm thickness 304 stainless steel diaphragms. The typical molten pool bridging behavior was observed by a high-speed microphotography system. In addition, the formation mechanism of lack of fusion (LOF) defects was analyzed. The experimental results showed that common disturbances could affect the continuity and symmetry of melting process. Due to the instability raised by this melting process, the liquid bridge fails to form or to maintain, which is the major cause for undesirable weld and defects. Unlike sound weld formation process, the molten pool behaviors in LOF defects formation process could be classified into three states: temporarily discontinuous bridging (TDB), cyclically discontinuous bridging (CDB), and not only cyclically discontinuous but asymmetric bridging (CDAB). Comparing the TDB state, the backflow of molten pool under the CDB state tends to be more intense, leading to the occurrence of defects in succession. During the CDAB process, the molten pool is subject to lateral misalignment due to the gravitational component, resulting in asymmetric weld with defects. This study offers a comprehensive insight into molten pool behavior and weld formation process, which can enhance the understanding of ultra-thin sheets edge welding.
{"title":"Bridging behavior of molten pool and its effect on defects formation in ultra-thin sheets edge welding by micro-plasma arc","authors":"Yuxiang Hong , Jiaxing Gao , Kai Lin , Shengyong Li , Baohua Chang , Dong Du","doi":"10.1016/j.jmatprotec.2024.118696","DOIUrl":"10.1016/j.jmatprotec.2024.118696","url":null,"abstract":"<div><div>The molten pool behavior and weld formation in ultra-thin (thickness ≤ 0.3 mm) sheets edge welding is extremely sensitive to the variation of thermodynamic conditions, due to its unique heat transfer conditions and molten pool dynamics caused by special joint form and extremely small molten pool size. In this paper, micro-plasma arc source was applied to join the edge joint composed of two 0.12 mm thickness 304 stainless steel diaphragms. The typical molten pool bridging behavior was observed by a high-speed microphotography system. In addition, the formation mechanism of lack of fusion (LOF) defects was analyzed. The experimental results showed that common disturbances could affect the continuity and symmetry of melting process. Due to the instability raised by this melting process, the liquid bridge fails to form or to maintain, which is the major cause for undesirable weld and defects. Unlike sound weld formation process, the molten pool behaviors in LOF defects formation process could be classified into three states: temporarily discontinuous bridging (TDB), cyclically discontinuous bridging (CDB), and not only cyclically discontinuous but asymmetric bridging (CDAB). Comparing the TDB state, the backflow of molten pool under the CDB state tends to be more intense, leading to the occurrence of defects in succession. During the CDAB process, the molten pool is subject to lateral misalignment due to the gravitational component, resulting in asymmetric weld with defects. This study offers a comprehensive insight into molten pool behavior and weld formation process, which can enhance the understanding of ultra-thin sheets edge welding.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"336 ","pages":"Article 118696"},"PeriodicalIF":6.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143169454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.jmatprotec.2024.118691
Jiageng Jin , Yuxuan Liao , Jiachang Qin , Yuanna Xu , Guangyao Li , Junjia Cui , Hao Jiang
Ultrahigh-strength steel (UHSS) is a promising material that can decrease sheet thickness and increase automobile safety. However, joining UHSS with aluminum alloys poses significant challenges to existing joining processes, such as self-piercing riveting (SPR), which often leads to rivet upsetting owing to the high strength of UHSS. This study proposes a novel joining process called electromagnetic self-pierce-upsetting riveting (ESP-UR). This method combines the piercing of a semi-hollow rivet leg in SPR with the upsetting of a rivet shank in traditional riveting, utilizing a novel rivet designed for high-strength and low-ductility steel. The effectiveness of the ESP-UR process was validated through riveting experiments involving 1.5-mm-thick 22MnB5 UHSS and 2.0-mm-thick 5052 aluminum sheets. A numerical experimental analysis and microstructural characterization were performed to characterize the joint formation mechanism. The results indicated that small protrusions created by the short rivet leg embedded in the lower sheet were compensated for by rivet cavities, resulting in a flat bottom surface of the joint. Furthermore, the hole diameter positively influenced the strength of the ESP-UR joint, with joints featuring a hole diameter of 5.8 mm exhibiting an 8.5 % increase in shear strength compared to those with a 5.6-mm diameter under a stroke of 5.0 mm. Additionally, the failure modes were analyzed and discussed. These findings provide theoretical guidance for optimizing stroke and hole diameter designs in future engineering applications.
{"title":"A novel electromagnetic self-pierce upsetting riveting with flat die for joining ultra-high strength steel and aluminum structures","authors":"Jiageng Jin , Yuxuan Liao , Jiachang Qin , Yuanna Xu , Guangyao Li , Junjia Cui , Hao Jiang","doi":"10.1016/j.jmatprotec.2024.118691","DOIUrl":"10.1016/j.jmatprotec.2024.118691","url":null,"abstract":"<div><div>Ultrahigh-strength steel (UHSS) is a promising material that can decrease sheet thickness and increase automobile safety. However, joining UHSS with aluminum alloys poses significant challenges to existing joining processes, such as self-piercing riveting (SPR), which often leads to rivet upsetting owing to the high strength of UHSS. This study proposes a novel joining process called electromagnetic self-pierce-upsetting riveting (ESP-UR). This method combines the piercing of a semi-hollow rivet leg in SPR with the upsetting of a rivet shank in traditional riveting, utilizing a novel rivet designed for high-strength and low-ductility steel. The effectiveness of the ESP-UR process was validated through riveting experiments involving 1.5-mm-thick 22MnB5 UHSS and 2.0-mm-thick 5052 aluminum sheets. A numerical experimental analysis and microstructural characterization were performed to characterize the joint formation mechanism. The results indicated that small protrusions created by the short rivet leg embedded in the lower sheet were compensated for by rivet cavities, resulting in a flat bottom surface of the joint. Furthermore, the hole diameter positively influenced the strength of the ESP-UR joint, with joints featuring a hole diameter of 5.8 mm exhibiting an 8.5 % increase in shear strength compared to those with a 5.6-mm diameter under a stroke of 5.0 mm. Additionally, the failure modes were analyzed and discussed. These findings provide theoretical guidance for optimizing stroke and hole diameter designs in future engineering applications.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"336 ","pages":"Article 118691"},"PeriodicalIF":6.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143169458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-31DOI: 10.1016/j.jmatprotec.2025.118751
Lei Li , David Garcia , Tianhao Wang , Julian D. Escobar , Mayur Pole , Kathy Nwe , David M. Brown , Kenneth A. Ross , Matthew J. Olszta , Keerti S. Kappagantula , Donald R. Todd , Neil J. Henson , Erin I. Barker , Eric Smith , Ayoub Soulami
Friction stir processing (FSP) is a promising solid-phase microstructural modification technique that can repair and enhance damaged stainless steel surfaces exposed to harsh environments. The quality of the repaired material is closely correlated to the recrystallized grain size in the stir zone (SZ), which is influenced by the thermomechanical conditions dictated by FSP process parameters. Thus, establishing a reliable relationship between these parameters and recrystallized grain size in the SZ is crucial for optimizing repair quality. However, existing experimental approaches often rely on indirect temperatures measured far from the SZ, along with rough strain rate estimations, which are imprecise and time-consuming. Meanwhile, existing mesh-based modeling methods usually face numerical challenges when dealing with the large material deformations inherent in FSP. To address these issues, this study introduces a meshfree process model for FSP based on the smoothed particle hydrodynamics (SPH) method, aimed at predicting process conditions under different parameters. The model is validated using experimental data from 11 combinations of tool traverse and rotation speeds on 316 L stainless steel. Correlations between process parameters, material flow, temperature, strain, strain rate, and recrystallized grain size are revealed through SPH simulations and electron backscatter diffraction (EBSD) imaging. The results show that in situ SZ temperatures range from 1071 to 1322°C, which exceed the tool temperature by over 300°C. Furthermore, SZ temperature, strain rate, and grain size increase monotonically with higher tool temperature and faster traverse speed. A relationship is then established between the model-predicted Zener-Hollomon parameter and the recrystallized grain size based on EBSD data, expressed as . This relationship exhibits satisfactory accuracy with errors of less than 26.9% in predicting grain sizes at various SZ locations, which offers valuable insights for optimizing FSP repair processes for 316 L stainless steel.
{"title":"Meshfree simulation and prediction of recrystallized grain size in friction stir processed 316L stainless steel","authors":"Lei Li , David Garcia , Tianhao Wang , Julian D. Escobar , Mayur Pole , Kathy Nwe , David M. Brown , Kenneth A. Ross , Matthew J. Olszta , Keerti S. Kappagantula , Donald R. Todd , Neil J. Henson , Erin I. Barker , Eric Smith , Ayoub Soulami","doi":"10.1016/j.jmatprotec.2025.118751","DOIUrl":"10.1016/j.jmatprotec.2025.118751","url":null,"abstract":"<div><div>Friction stir processing (FSP) is a promising solid-phase microstructural modification technique that can repair and enhance damaged stainless steel surfaces exposed to harsh environments. The quality of the repaired material is closely correlated to the recrystallized grain size in the stir zone (SZ), which is influenced by the thermomechanical conditions dictated by FSP process parameters. Thus, establishing a reliable relationship between these parameters and recrystallized grain size in the SZ is crucial for optimizing repair quality. However, existing experimental approaches often rely on indirect temperatures measured far from the SZ, along with rough strain rate estimations, which are imprecise and time-consuming. Meanwhile, existing mesh-based modeling methods usually face numerical challenges when dealing with the large material deformations inherent in FSP. To address these issues, this study introduces a meshfree process model for FSP based on the smoothed particle hydrodynamics (SPH) method, aimed at predicting process conditions under different parameters. The model is validated using experimental data from 11 combinations of tool traverse and rotation speeds on 316 L stainless steel. Correlations between process parameters, material flow, temperature, strain, strain rate, and recrystallized grain size are revealed through SPH simulations and electron backscatter diffraction (EBSD) imaging. The results show that <em>in situ</em> SZ temperatures range from 1071 to 1322°C, which exceed the tool temperature by over 300°C. Furthermore, SZ temperature, strain rate, and grain size increase monotonically with higher tool temperature and faster traverse speed. A relationship is then established between the model-predicted Zener-Hollomon parameter and the recrystallized grain size based on EBSD data, expressed as <span><math><mrow><mi>ln</mi><mrow><mrow><mfenced><mrow><mi>d</mi></mrow></mfenced></mrow><mo>=</mo><mtext>-</mtext><mn>0.364</mn><mi>ln</mi><mrow><mfenced><mrow><mi>Z</mi></mrow></mfenced></mrow><mtext>+</mtext><mn>14.673</mn></mrow></mrow></math></span>. This relationship exhibits satisfactory accuracy with errors of less than 26.9% in predicting grain sizes at various SZ locations, which offers valuable insights for optimizing FSP repair processes for 316 L stainless steel.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"337 ","pages":"Article 118751"},"PeriodicalIF":6.7,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143175409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-30DOI: 10.1016/j.jmatprotec.2025.118749
Ryan Welch, Sumner Gubisch, Saniya LeBlanc
Silicon germanium alloys are high-temperature thermoelectric materials that convert heat to electricity at ∼1000 °C. Yet, the current application of silicon germanium-based thermoelectric devices is limited to niche areas due to unwieldy manufacturing processes that limit the shape of thermoelectric materials to simple cuboids and thus limit power generation potential. Laser powder bed fusion of thermoelectric materials offers the potential to fabricate freeform shapes and induce nano- and microstructures favorable for thermoelectric energy conversion. Here, we successfully fabricated undoped Si50Ge50 and Si80Ge20 parts using laser powder bed fusion and investigated the resulting structure and properties. The undoped Si80Ge20 alloy had a maximum thermoelectric figure of merit, ZT, of 0.06 at 400 °C. The laser manufactured parts exhibited p-type behavior with a measured Seebeck coefficient that changed based on the stoichiometry. Si50Ge50 reached a Seebeck coefficient of 588 µV/K at 50 °C while Si80Ge20 reached 513 µV/K at 400 °C. Oxidation during processing contributed to balling and lack-of fusion defects and was alleviated in single melt lines by washing the powder in hydrofluoric acid prior to laser processing. Processing related defects remained in bulk samples fabricated with acid treated powder, suggesting that the processing atmosphere is a primary cause of processing-induced defects. This work advances the processing of silicon germanium alloys for thermoelectric devices by uncovering the structures and thermoelectric properties of silicon germanium processed via laser-based additive manufacturing.
{"title":"Nano/microstructures and thermoelectric properties of silicon germanium manufactured using laser powder bed fusion","authors":"Ryan Welch, Sumner Gubisch, Saniya LeBlanc","doi":"10.1016/j.jmatprotec.2025.118749","DOIUrl":"10.1016/j.jmatprotec.2025.118749","url":null,"abstract":"<div><div>Silicon germanium alloys are high-temperature thermoelectric materials that convert heat to electricity at ∼1000 °C. Yet, the current application of silicon germanium-based thermoelectric devices is limited to niche areas due to unwieldy manufacturing processes that limit the shape of thermoelectric materials to simple cuboids and thus limit power generation potential. Laser powder bed fusion of thermoelectric materials offers the potential to fabricate freeform shapes and induce nano- and microstructures favorable for thermoelectric energy conversion. Here, we successfully fabricated undoped Si<sub>50</sub>Ge<sub>50</sub> and Si<sub>80</sub>Ge<sub>20</sub> parts using laser powder bed fusion and investigated the resulting structure and properties. The undoped Si<sub>80</sub>Ge<sub>20</sub> alloy had a maximum thermoelectric figure of merit, <em>ZT</em>, of 0.06 at 400 °C. The laser manufactured parts exhibited p-type behavior with a measured Seebeck coefficient that changed based on the stoichiometry. Si<sub>50</sub>Ge<sub>50</sub> reached a Seebeck coefficient of 588 µV/K at 50 °C while Si<sub>80</sub>Ge<sub>20</sub> reached 513 µV/K at 400 °C. Oxidation during processing contributed to balling and lack-of fusion defects and was alleviated in single melt lines by washing the powder in hydrofluoric acid prior to laser processing. Processing related defects remained in bulk samples fabricated with acid treated powder, suggesting that the processing atmosphere is a primary cause of processing-induced defects. This work advances the processing of silicon germanium alloys for thermoelectric devices by uncovering the structures and thermoelectric properties of silicon germanium processed via laser-based additive manufacturing.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"337 ","pages":"Article 118749"},"PeriodicalIF":6.7,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143174390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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