Effect of Bending Speed on Zinc-Coating Microcracking in Electrogalvanized Steel during Forced V-Bending

Danang Supriyanto (Universitas Sebelas maret)
Sukarman Sukarman (Universitas Buana Perjuangan Karawang)
Khoirudin Koirudin (Universitas Buana Perjuangan Karawang)
Dodi Mulyadi (Universitas Buana Perjuangan Karawang)
Amir Amir (Universitas Buana Perjuangan Karawang)
Karyadi Karyadi (Universitas Buana Perjuangan Karawang)
Nana Rahdiana (Universitas Buana Perjuangan Karawang)

Jurnal Teknik Mesin Mechanical Xplore
Vol. 7 No. 1 (2026): Jurnal Teknik Mesin Mechanical Xplore (JTMMX)

Electrogalvanized (EG) steel is widely used in sheet components. However, bending deformation can damage the Zn coating and affect its protective properties. This study investigated the effect of punch speed on the deformation response and coating microcracking of EG steel during forced V-bending. Sheets with a thickness of 0.65 mm were bent using a 1.0 mm punch radius and a 30° V-die angle at speeds of 20, 30, and 40 mm/min. The punch force and displacement were recorded, and coating damage was examined using scanning electron microscopy and quantitative image analysis. Finite element analysis (FEA) was used to evaluate the deformation response. The results showed a transition from springback at 20 and 30 mm/min to spring-go at 40 mm/min. The maximum punch force changed only slightly, whereas the mean microcrack dimension increased from 5.61 ± 0.67 µm at 20 mm/min to 7.86 ± 1.18 µm at 40 mm/min. These findings indicate that a higher bending speed promoted more pronounced microcracking in the Zn coating.