掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.mtcomm.2023.107082

researchmap

出版者・発行元：International Journal of Advanced Manufacturing Technology  

In this study, an energy-saving and highly efficient high-density pulsed electric current (HDPEC) method was used to improve the formability of the aluminum alloy A6061 after T6 heat treatment (A6061-T6). An interrupted tensile test was performed, and the HDPEC treatment was applied after tensile deformation. The results showed that the ductility of A6061-T6 improved by approximately 33% after three HDPEC treatments. The Vickers hardness and residual stress were measured to investigate the effect of the pulsed electric current on formability, and they were recovered after HDPEC treatment. Furthermore, the microstructural morphology and dislocation density were investigated to understand the mechanism of formability enhancement. Detailed analysis shows that the formability enhancement of A6061-T6 after HDPEC treatment is mainly attributed to dislocation elimination, while grain size and crystalline orientation changes are side effects. In addition, the results of equivalent heat treatments demonstrate that the athermal effect of the HDPEC treatment plays a crucial role in the removal of dislocations. Thus, due to the contribution of the athermal effect, HDPEC treatment realizes the advantages of low consumption and high efficiency, and can be dedicated to green processing and manufacturing of metallic materials.

DOI： 10.1007/s00170-023-11841-z

Web of Science

Scopus

出版者・発行元：Engineering Failure Analysis  

This study quantitatively analysed the effect of an electric current on improving the fatigue life of the aluminium alloy A6061-T6. The effect of a high-density pulsed electric current (HDPEC) was investigated for non-prestrained and prestrained aluminium alloys because they are frequently exposed to plastic deformation. The results showed that the HDPEC contributed to increasing the fatigue life of both materials with and without prestrain, and those without prestrain increased significantly with the HDPEC effect. Local melting sites were observed at the fatigue crack tip on the fracture surface of the non-prestrained and prestrained cases treated with HDPEC. Fatigue crack growth tests confirmed the improved fatigue life of the HDPEC effect. The results pave the way toward enhancing the resistance of fatigue crack growth in welded joints.

DOI： 10.1016/j.engfailanal.2023.107230

Web of Science

Scopus

出版者・発行元：Materials Today Communications  

A novel high-density pulsed electric current (HDPEC) method is developed to modify the grain-scale microstructure of laser powder-bed fused Ni-based superalloy IN718, which has not been reported in other studies. Rapid micro-residual stress relief and micro-segregation alleviation were achieved without significant grain coarsening which is common in conventional heat treatment. This technique can be an alternative energy-saving post-treatment method for additively manufactured metallic materials, enabling rapid and efficient annealing and solution treatment.

DOI： 10.1016/j.mtcomm.2023.106892

Scopus

出版者・発行元：Engineering Fracture Mechanics  

This study aims to demonstrate the use of a novel treatment approach for fatigue crack healing. High-density pulsed electric currents, which have been widely used for fatigue crack healing of metals, can exert synergistic effects on fatigue crack healing by both compressive stress (owing to the Joule heating) and dislocation motion (owing to the electron wind force). However, these synergistic effects are sometimes weakened by temperature elevations owing to high current densities, failing to efficiently heal fatigue cracks owing to the thermal degradation of metals. In this study, type 316 austenitic stainless steel, which is the most common metallic material, was considered for investigating fatigue crack healing improvement under controlled crack tip temperature elevation owing to the Joule heating induced by multiple high-density pulsed electric currents. Appropriate current parameters such as current density and pulse number under fixed pulse duration were optimized. The results revealed microstructural modifications, such as crack closure with crack bridging, annihilation of slip bands, and material filling near the crack tips, which is promising for fatigue crack healing improvement. The results of fatigue crack growth tests validated these microstructure improvements.

DOI： 10.1016/j.engfracmech.2023.109235

Web of Science

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.1016/j.vacuum.2021.110855

DOI： https://doi.org/10.1016/j.vacuum.2021.110855

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.1016/j.ijfatigue.2021.106639

DOI： https://doi.org/10.1016/j.ijfatigue.2021.106639

出版者・発行元：International Journal of Fatigue  

This study evaluated the low-cycle fatigue (LCF) life of type 316 austenitic stainless steel to determine the effect of multiple high-density pulsed electric currents (HDPECs). Fatigue properties were analyzed with the fatigue crack growth (FCG) and LCF tests by considering different conditions of multiple HDPECs and its application. The HDPEC densities of 100, 150 and 200 A/mm2 with application numbers from 1 to 17 times were used. The LCF results were assessed by using fatigue models, and the effectiveness of the application methods was examined. Under the HDPEC density of 200 A/mm2, increasing the number of HDPECs during the period of crack propagation is the best way for delaying FCG. Multiple applications of HDPEC caused a decrease in the length and an increase in the depth of striations in the specimen's fatigue fracture surface, and the degree of ductility was increased thereby leading to the delay in FCG. The proposed conditions pave the way toward improving the LCF life of the material.

DOI： 10.1016/j.ijfatigue.2021.106639

Web of Science

Scopus

出版者・発行元：Vacuum  

The {101} texture of deformed face-centered cubic metals, such as 316 stainless steel and Ni-based alloy Inconel 718, was successfully alleviated by high-density pulsed electric current (HDPEC) treatment. Furthermore, the deformed grains recovered after the HDPEC treatment. The HDPEC induced the rapid dislocation motion and grain refinement that resulted in random grain orientation and equiaxed grain morphology, which led to anisotropy recovery in the deformed metals. This method provides a promising way to modify the microstructure of materials with short time and low cost, after forming or during service.

DOI： 10.1016/j.vacuum.2021.110855

Scopus

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.1299/mej.21-00178

DOI： https://doi.org/10.1299/mej.21-00178

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.2320/matertrans.MT-M2020333

DOI： https://doi.org/10.2320/matertrans.MT-M2020333