Effects of heat treatment process and niobium addition on the microstructure and mechanical properties of low carbon steel weld metal

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	Effects of heat treatment process and niobium addition on the microstructure and mechanical properties of low carbon steel weld metal
	S. P. Lu; S. T. Wei; D. Z. Li; Y. Y. Li
	2010
发表期刊	Journal of Materials Science
ISSN	0022-2461
卷号	45 期号:9 页码:2390-2402
摘要	The mechanical properties and microstructure were evaluated and analyzed by optical microscopy (OM) and transmission electron microscopy (TEM) for micro-alloy carbon steel weld metal with and without Nb addition, respectively, under different heat treatment processes including stress relief annealing, normalizing, and no treatment after welding. The strength and elongation of the weld metal without treatment after welding were improved with the addition of Nb element, and the impact toughness was not affected obviously with the Nb addition. After stress relief annealing, the strength decreased for the Nb-free weld metal, while the elongation and impact toughness increased. However, for the Nb-bearing weld metal, stress relief annealing improved the strength of the weld metal significantly, and deteriorated the elongation and impact toughness. In the case of normalizing treatment to the weld metal, it was shown that with the increase of the holding time at the normalizing temperature of 920 A degrees C, for both the weld metals with and without Nb addition, the microstructure of the columnar grain zone (CGZ) was transformed from one of columnar grain into one of equiaxed grain. The grain size of the equiaxed grain zone (EGZ) increased initially, then remained almost unchanged with the prolonging of the holding time. The mechanical properties of the weld metal with and without Nb addition showed no obvious change with the increasing holding time. With the increase of the normalizing temperature, the strength of the Nb-bearing weld metal increased, while the elongation and impact toughness decreased significantly. OM and TEM analysis found that the fine NbC particles were precipitated at the normalizing temperature of 920 A degrees C, which refined the grains of the weld metal and increased the impact toughness. With the increase of the normalizing temperature, the content of widmanstatten ferrite (WF) in the Nb-bearing weld metal increased, whereas the quantity of the NbC particles decreased, which improved the strength and lowered the impact toughness.
部门归属	[lu, shanping; wei, shitong; li, dianzhong; li, yiyi] chinese acad sci, inst met res, shenyang natl lab mat sci, shenyang 110016, peoples r china.;lu, sp (reprint author), chinese acad sci, inst met res, shenyang natl lab mat sci, 72 wenhua rd, shenyang 110016, peoples r china, peoples r china;shplu@imr.ac.cn weist2003@yahoo.com.cn
关键词	Nb-microalloyed Steels Continuous Cooling Transformation Similar Yield Strength Pipeline Steel Impact Toughness Mn Behavior Precipitation Kinetics Vanadium
URL	查看原文
WOS记录号	WOS:000275442500018
引用统计	被引频次：19[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.imr.ac.cn/handle/321006/31345
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	S. P. Lu,S. T. Wei,D. Z. Li,et al. Effects of heat treatment process and niobium addition on the microstructure and mechanical properties of low carbon steel weld metal[J]. Journal of Materials Science,2010,45(9):2390-2402.
APA	S. P. Lu,S. T. Wei,D. Z. Li,&Y. Y. Li.(2010).Effects of heat treatment process and niobium addition on the microstructure and mechanical properties of low carbon steel weld metal.Journal of Materials Science,45(9),2390-2402.
MLA	S. P. Lu,et al."Effects of heat treatment process and niobium addition on the microstructure and mechanical properties of low carbon steel weld metal".Journal of Materials Science 45.9(2010):2390-2402.