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Vol.48, No.4, 297 ~ 305, 2010
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| Title |
| Microstructures and Hardness of CO2 Laser Welds in 409L Ferritic Stainless Steel |
| 공종판 Jong Pan Kong , 박태준 Tae Jun Park , 나혜성 Hye Sung Na , 엄상호 Sang Ho Uhm , 김정길 Jeong Kim Kim , 우인수 In Su Woo , 이종섭 Jong Sub Lee , 강정윤 Chung Yun Kang |
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| Abstract |
| The microstructure and hardness of CO2 laser welds were investigated in the Ti-stabilized ferritic stainless steel 409L. The observed specimen was welded in a fully penetrated condition in which the power was 5 kW and the welding speed 5 m/min. The grain structure near the bond line of the laser welds was produced by epitaxial growth. The grain size was the largest in the fusion zone, and HAZ showed nearly the same grain size as that of the base metal. The HAZ microstructure consisted of subgrains and precipitates that were less than l00 nm in size and that were located along the subgrain boundaries. On the other hand, the hardness was the highest in the fusion zone due to the large amount of small precipitates present. These were composed of TiN, Ti(C,N) and TiO2+Ti(C,N). The hardness decreased continuously from the fusion zone of the base metal. The HAZ hardness was slightly greater than that of the base metal due to the existence of subgrains and precipitates in the subgrain boundary. (Received January 13, 2010) |
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| Key Words |
| alloys, welding, microstructure, scanning/transmission electron microscopy, STEM, hardness |
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