Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing addit...Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.展开更多
为探讨ARC菌肥对提高花生产量和降镉的可能性,本研究以阜花40为试验材料,采用小区试验,以单独施用复合肥为对照,分析ARC菌肥不同施用量对花生产量和降镉效果的影响。结果表明,随着ARC微生物菌肥施用量的增加,花生产量增幅15.84%~25.31%,...为探讨ARC菌肥对提高花生产量和降镉的可能性,本研究以阜花40为试验材料,采用小区试验,以单独施用复合肥为对照,分析ARC菌肥不同施用量对花生产量和降镉效果的影响。结果表明,随着ARC微生物菌肥施用量的增加,花生产量增幅15.84%~25.31%,且A3(每亩施用6 kg ARC菌肥)和A4(每亩施用8 kg ARC菌肥)处理产量最高,但两处理间差异不显著。在花生籽仁镉含量的测定中发现,A3和A4处理降镉效果最好,但2处理间差异不显著。综上所述,A3处理是本试验条件下兼顾花生产量提升和降镉效果的最优处理方案,该处理不仅能够有效提高花生产量,还能显著降低花生籽仁镉含量,达到理想的降镉效果,同时在成本控制方面具有明显优势,适合在花生生产中推广应用。展开更多
0 INTRODUCTION Serpentinite has high contents of water(up to~12 wt.%)and other volatiles(Pettke and Bretscher,2022).Dehydration of subducted serpentinite transfers massive water into the sub-arc mantle wedge and induc...0 INTRODUCTION Serpentinite has high contents of water(up to~12 wt.%)and other volatiles(Pettke and Bretscher,2022).Dehydration of subducted serpentinite transfers massive water into the sub-arc mantle wedge and induces fluxmelting to generate arc magmas.However,characterizing the role of serpentinite-derived fluids in arc magmatism is not easy,as serpentinite is depleted in incompatible elements compared to other subducted components(e.g.,altered oceanic crust(AOC)and sediments).展开更多
In this study,the rotary movement of the tungsten needle in gas tungsten arc welding(GTAW)process was realized by direct current motor.The arc characteristics,the flow of molten pool and the microstructure and propert...In this study,the rotary movement of the tungsten needle in gas tungsten arc welding(GTAW)process was realized by direct current motor.The arc characteristics,the flow of molten pool and the microstructure and properties of the weld bead were studied.The results showed that the rotary motion of the tungsten needle transferred circumferential momentum to the arc as well as the molten pool,thereby conferring the latter with rotating fluid flow characteristics.Under the action of a relatively spiraling shielding gas,arc constriction occurred,and molten pool width dropped considerably.A finer and more uniform precipitated phase in the matrix,as well as a fewer large-medium pores,were achieved in the 5A06 aluminum alloy weld metal using this modified GTAW process,which noticeably increased the bending strength and tensile strength of weld metal and the microhardness of fusion zone.展开更多
Arc motion and splitting of vacuum arc at intermediate frequency（400-800 Hz） were investigated under transverse magnetic field（TMF）.The experiment was performed on cup-type TMF contacts with contact diameter of 40...Arc motion and splitting of vacuum arc at intermediate frequency（400-800 Hz） were investigated under transverse magnetic field（TMF）.The experiment was performed on cup-type TMF contacts with contact diameter of 40 mm and a contact gap of 4 mm in a single-frequency circuit.With high-speed photography we characterized the arc appearance at different arc currents from 3.3 kA-rms to 10 kA-rms at intermediate frequencies.As arc current increases from3.3 kA-rms to 10 kA-rms the arc appearance changes obviously.When current value is 3.3 kArms（current frequency 400-800 Hz）,there is almost no splitting arc;when the current exceeds5 kA-rms（current frequency 400-800 Hz）,the arc rotates at a speed above 20 m/s,accompanied by an observable splitting arc.The splitting arc could be observed at different frequencies and the arc-voltage had no noises when splitting occurred.The motion direction and the velocity of arc column were studied.Finally,the formation of a split arc was discussed.展开更多
基金National Key Research and Development Program of China(2022YFB4600902)Shandong Provincial Science Foundation for Outstanding Young Scholars(ZR2024YQ020)。
文摘Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.
文摘为探讨ARC菌肥对提高花生产量和降镉的可能性,本研究以阜花40为试验材料,采用小区试验,以单独施用复合肥为对照,分析ARC菌肥不同施用量对花生产量和降镉效果的影响。结果表明,随着ARC微生物菌肥施用量的增加,花生产量增幅15.84%~25.31%,且A3(每亩施用6 kg ARC菌肥)和A4(每亩施用8 kg ARC菌肥)处理产量最高,但两处理间差异不显著。在花生籽仁镉含量的测定中发现,A3和A4处理降镉效果最好,但2处理间差异不显著。综上所述,A3处理是本试验条件下兼顾花生产量提升和降镉效果的最优处理方案,该处理不仅能够有效提高花生产量,还能显著降低花生籽仁镉含量,达到理想的降镉效果,同时在成本控制方面具有明显优势,适合在花生生产中推广应用。
基金supported by the National Natural Science Foundation of China(Nos.42122019 and 42288201)the Fundamental Research Funds for the Central Universities(No.2652023001)the State Key Laboratory of Geological Processes and Mineral Resources,China。
文摘0 INTRODUCTION Serpentinite has high contents of water(up to~12 wt.%)and other volatiles(Pettke and Bretscher,2022).Dehydration of subducted serpentinite transfers massive water into the sub-arc mantle wedge and induces fluxmelting to generate arc magmas.However,characterizing the role of serpentinite-derived fluids in arc magmatism is not easy,as serpentinite is depleted in incompatible elements compared to other subducted components(e.g.,altered oceanic crust(AOC)and sediments).
基金supported by National Natural Science Foundation of China(52175305)National Natural Science Foundation of China(U22B20127)Taishan Scholars Project(tstp20230618).
文摘In this study,the rotary movement of the tungsten needle in gas tungsten arc welding(GTAW)process was realized by direct current motor.The arc characteristics,the flow of molten pool and the microstructure and properties of the weld bead were studied.The results showed that the rotary motion of the tungsten needle transferred circumferential momentum to the arc as well as the molten pool,thereby conferring the latter with rotating fluid flow characteristics.Under the action of a relatively spiraling shielding gas,arc constriction occurred,and molten pool width dropped considerably.A finer and more uniform precipitated phase in the matrix,as well as a fewer large-medium pores,were achieved in the 5A06 aluminum alloy weld metal using this modified GTAW process,which noticeably increased the bending strength and tensile strength of weld metal and the microhardness of fusion zone.
基金supported by Special Scientific and Research Funds for Doctoral Specialty of Institution of Higher Learning of China(No.200800060004)National Natural Science Foundation of China(No.50877002)the Innovation Foundation of BUAA for Ph.D Graduates of China
文摘Arc motion and splitting of vacuum arc at intermediate frequency（400-800 Hz） were investigated under transverse magnetic field（TMF）.The experiment was performed on cup-type TMF contacts with contact diameter of 40 mm and a contact gap of 4 mm in a single-frequency circuit.With high-speed photography we characterized the arc appearance at different arc currents from 3.3 kA-rms to 10 kA-rms at intermediate frequencies.As arc current increases from3.3 kA-rms to 10 kA-rms the arc appearance changes obviously.When current value is 3.3 kArms（current frequency 400-800 Hz）,there is almost no splitting arc;when the current exceeds5 kA-rms（current frequency 400-800 Hz）,the arc rotates at a speed above 20 m/s,accompanied by an observable splitting arc.The splitting arc could be observed at different frequencies and the arc-voltage had no noises when splitting occurred.The motion direction and the velocity of arc column were studied.Finally,the formation of a split arc was discussed.
