Effects of Zr on acicular ferrite formation in HAZ of Ti-bearing low carbon steels with high heat input of weld thermal simulations  

作　　者：ZHU Kai YANG Jian WANG Ruizhi 

机构地区：[1]Metallurgical Process Division,Research Institute,Baoshan Iron&Steel Co.,Ltd.,Shanghai 201900,China

出　　处：《Baosteel Technical Research》2012年第2期39-43,共5页宝钢技术研究（英文版）

摘　　要：To research the effect of Zr addition on inhibiting austenite grain growth of Ti-bearing low carbon steels, two steels with different Zr contents were prepared using a laboratory vacuum induction furnace. The performance of HAZ under weld thermal simulations was investigated. The impact toughness, microstmcture and the second-phase particle performance of HAZ under weld thermal simulations were investigated. The HAZ toughness was improved from 13 J to 87 J by addition of 0.010 % Zr into the steel, with the fracture mechanism changing from cleavage fracture to toughness fracture, which was mainly attributed to the second-phase particles that were potent to nucleate acicular ferrite in HAZ during welding. It was concluded that the second-phase particles TiOx ＋ MnS, ZrO2 ＋ MIlS or TiO/＋ ZrO2 ＋ MnS were nucleated on ZrO2 or TiOx （x = 1.5,2）. This method can be applied to grain refinement by promoting the acicular ferrite formation and growth during large-scale welding, as in the cases of thick steel plates requiring higher heat inputs during welding.To research the effect of Zr addition on inhibiting austenite grain growth of Ti-bearing low carbon steels, two steels with different Zr contents were prepared using a laboratory vacuum induction furnace. The performance of HAZ under weld thermal simulations was investigated. The impact toughness, microstmcture and the second-phase particle performance of HAZ under weld thermal simulations were investigated. The HAZ toughness was improved from 13 J to 87 J by addition of 0.010 % Zr into the steel, with the fracture mechanism changing from cleavage fracture to toughness fracture, which was mainly attributed to the second-phase particles that were potent to nucleate acicular ferrite in HAZ during welding. It was concluded that the second-phase particles TiOx ＋ MnS, ZrO2 ＋ MIlS or TiO/＋ ZrO2 ＋ MnS were nucleated on ZrO2 or TiOx （x = 1.5,2）. This method can be applied to grain refinement by promoting the acicular ferrite formation and growth during large-scale welding, as in the cases of thick steel plates requiring higher heat inputs during welding.

关 键 词：low carbon steel ZIRCONIUM heat affected zone impact toughness microstructure 

分 类 号：TG457.11[金属学及工艺—焊接] TG142.31[一般工业技术—材料科学与工程]