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| Hot Ductility of Niobium-Microalloyed High Strength Steel Q345C Slab |
| WANG Sheng-zhao1,ZHAO Gang1 ,BAO Si-qian1，SHI Hai-ning2,DENG Shen2,ZHANG Hai-zhou3 |
1. College of Material and Metallurgical Engineering, Wuhan University of Science and Technology, Wuhan 430081, Hubei, China
2. Technology Center, Liuzhou Iron and Steel Group Company, Liuzhou 545002, Guangxi, China
3. Alloy Materials Research Institute, Metallurgical Research Institute of Guangxi, Nanning 530023, Guangxi, China ） |
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Abstract Hot ductility of continuous casting Q345C slabs was tested by Gleeble-2000 thermal /strain simulation machine. Using scanning electron microscopy, metalloscopy and transmission electron microscopy, morphology characteristics and microstructure of fracture surface of tensile specimen in brittle temperature zone Ⅰ and Ⅲ were observed. Influences of dynamic recrystallization, phase change and precipitate on hot ductility of the niobium- microalloyed steel were analyzed. The results showed that: at the 1 × 10-3/s strain rate, there are two low ductility zones, namely brittle zone Ⅰ (1200-1300℃) and brittle zone Ⅲ (600-875℃)，the brittle zone Ⅱdoes not exist; the maximum ductility is around 1050℃ and area reduction （Z）reached 85.8%; in brittle zone Ⅲ, membranous lower tensile strength of ferrite along austenite grain boundaries, and the existence of inclusions and precipitates of micro-alloying elements in the grain boundaries is the main reasons for lower ductility of Q345C steel.
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Received: 26 September 2010
Published: 16 January 2012
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2012, Vol. 47 
