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Vol.51, No.12, 883 ~ 893, 2013
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| Title |
| Microstructural Changes and Variations of Hot Deformation Stability with Homogenization Treatment of 1Cr-1.25Mo-0.25V Steel before Hot Forging |
| 권거영 Keo Young Kwon , 나영상 Young Sang Na , 서성문 Seong Moon Seo , 양재규 Jea Kyu Yang , 김양도 Yang Do Kim |
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| Abstract |
| In order to investigate the effects of homogenization treatment on microstructural change and high temperature deformation stability, a series of hot compression tests and homogenization treatment were conducted for as-cast and upset-forged 1Cr-1.25Mo-0.25V steels. Microstructural inhomogeneity like dendritic morphology and elemental segregation in as-cast steel was homogenized after 10 hours-holding at 1200 ℃, followed by the rapid grain coarsening up to about 700 μm after 20 hours-holding. However, upset- forged steel showed rapid grain coarsening even in the early stage of high temperature holding at 1200 ℃. Compression tests for the 1Cr-1.25Mo-0.25V steels showed that flow stresses of as-cast 1Cr-1.25Mo-0.25V steel were higher than those of the upset-forged at temperatures lower than 1000 ℃. By analyzing the compression test results based on a dynamic materials model, we concluded that the microstructural inhomogeneity diminished hot deformation stability of the as-cast 1Cr-1.25Mo-0.25V steel. It is clear that the microstructural homogenization of as-solidified steel prior to upset forging is essential for improving the hot deformation stability and soundness of hot forgings. |
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| Key Words |
| metals, homogenization treatment, hot working, microstructure, compression test |
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