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압축 가공된 비용접 배관의 소성변형 거동에 미치는 내압의 영향
서위걸,이문수,손수지,최시훈 한국소성∙가공학회 2019 소성가공 : 한국소성가공학회지 Vol.28 No.4
In this study, compression process is performed on the seamless E235 pipe using the newly developed compression technology for seamless pipe. Experimental analysis on the heterogeneity of microstructures and mechanical properties of the deformed seamless pipe is conducted. As a result, the correlation between microstructures and mechanical properties are determined. The spatial distribution of effective stress and effective strain developed in the seamless pipe deformed through compression is analyzed using the finite element method (FEM) based on different inner pressure conditions. From the results of the FEM, the impact of the inner pressure on effective stress and effective strain of the seamless pipe deformed through compression can be understood theoretically.
Zn-Al-Mg 합금의 압출 시 미세조직 변화에 관한 연구
서위걸,Khushahal Thool,이희남,양동주,박순균,최시훈 한국소성∙가공학회 2023 소성가공 : 한국소성가공학회지 Vol.32 No.6
The use of Zn-Al-Mg alloy coatings for enhancing the corrosion resistance of steel sheets is gaining prominence over traditional Zn coatings. There is a growing demand for the development of thermal spray wires made from Zn-Al-Mg alloys, as a replacement for the existing wires produced using Al and Zn. This is particularly crucial to secure corrosion resistance and durability in the damaged areas of coated steel sheets caused by deformation and welding. This study focuses on the casting and extrusion processes of Zn-2Al-1Mg alloy for the fabrication of such spray wires and analyzes the changes in microstructure during the extrusion process. The Zn-2Al-1Mg alloy, cast in molds, was subjected to a heat treatment at 250 °C for 3 hours prior to extrusion. The extrusion process was carried out by heating both the material and the mold up to 300 °C. Microstructural analysis was conducted using FE-SEM and EDS to differentiate each phase. The mechanical properties of the cast specimen were evaluated through compression tests at temperatures ranging from 200 to 300 °C, with strain rates of 0.1 to 5 sec-1. Vickers hardness testing was utilized to assess the inhomogeneity of mechanical properties in the radial direction of the extruded material. Finite Element Analysis (FEA) was employed to understand the inhomogeneity in stress and strain distribution during extrusion, which aids in understanding the impact of heterogeneous deformation on the microstructure during the process.