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Ti-6Al-4 V/SUS316 L dissimilar joints were manufactured by a novel solid-state joining method named “pressure-controlled joule heat forge welding”. The microstructure and mechanical properties of the joints were systematically investigated. Both materials were homogeneously deformed by applying the pressure corresponding to the intersectional point of the temperature-dependent yield strength. Along the joint interface, the uniform hardness distributions in the center and periphery regions were obtained because the heat input generated by the joule heat was homogeneous from center to periphery. The welding temperature was able to be decreased to suppress the formation of the intermetallic compound (IMC) layers by applying the high pressure because the welding is accompanied and accomplished by the interfacial deformation and the high pressure affects the deformable temperature. As a result, when the applied pressure was increased from 300 MPa to 450 MPa, the width of the IMC layers was decreased to around 28 nm. As the upset increased, the interfacial area ratio to base material increased hence the interfacial defects were successfully suppressed, and the tensile strength increased by removing the ragged surface and the oxide layers existing on the surface of the base material. Eventually, the joint efficiency reached 98.5 % compared to the base material.
Yeongseok Lim; Yoshiaki Morisada; Huihong Liu; Hidetoshi Fujii. Ti-6Al-4V/SUS316L dissimilar joints with ultrahigh joint efficiency fabricated by a novel pressure-controlled joule heat forge welding method. Journal of Materials Processing Technology 2021, 298, 117283 .
AMA StyleYeongseok Lim, Yoshiaki Morisada, Huihong Liu, Hidetoshi Fujii. Ti-6Al-4V/SUS316L dissimilar joints with ultrahigh joint efficiency fabricated by a novel pressure-controlled joule heat forge welding method. Journal of Materials Processing Technology. 2021; 298 ():117283.
Chicago/Turabian StyleYeongseok Lim; Yoshiaki Morisada; Huihong Liu; Hidetoshi Fujii. 2021. "Ti-6Al-4V/SUS316L dissimilar joints with ultrahigh joint efficiency fabricated by a novel pressure-controlled joule heat forge welding method." Journal of Materials Processing Technology 298, no. : 117283.
This paper investigated the microstructure and mechanical properties of a friction-stir-welded beryllium-copper alloy, which is difficult to weld with conventional fusion welding processes. Friction stir welding (FSW) was successfully conducted with a tungsten-carbide (WC) tool. Sound joints without defects were obtained with a tool rotational speed of 700 RPM and tool travel speed of 60 mm/min. A post-weld heat treatment (PWHT) of the FSW joints was performed to analyze the evolution of the microstructure at 315 °C for a half, one, two, three, four, five and eight hours, respectively. The microstructures of the joints were observed using an optical microscope (OM), a scanning electron microscope (SEM) and a transmission electron microscope (TEM). Observed softening of microstructure is suggested to be due to the dissolution of the strengthening precipitates during the FSW process, whereas the strength of the joints was recovered via the formation of the CuBe (γ′) phase during the post-weld heat treatment. However, the strength was decreased upon an excessive post-weld heat treatment exceeding three hours. It is considered that the formation of the γ phase and the coarse γ′ phase contributed to the reduction in the strength.
Yeongseok Lim; Kwangjin Lee; Sangdon Moon. Effects of a Post-Weld Heat Treatment on the Mechanical Properties and Microstructure of a Friction-Stir-Welded Beryllium-Copper Alloy. Metals 2019, 9, 461 .
AMA StyleYeongseok Lim, Kwangjin Lee, Sangdon Moon. Effects of a Post-Weld Heat Treatment on the Mechanical Properties and Microstructure of a Friction-Stir-Welded Beryllium-Copper Alloy. Metals. 2019; 9 (4):461.
Chicago/Turabian StyleYeongseok Lim; Kwangjin Lee; Sangdon Moon. 2019. "Effects of a Post-Weld Heat Treatment on the Mechanical Properties and Microstructure of a Friction-Stir-Welded Beryllium-Copper Alloy." Metals 9, no. 4: 461.