ժҪ Effects of Mg on the chemical component and size distribution of Ti��bearing inclusions favored grain refinement of the welding induced coarse��grained heat affected zone (CGHAZ), with enhanced impact toughness in Ti��killed steels, which were examined based on experimental observations and thermodynamic calculations. The results indicated that the chemical constituents of the inclusions gradually varied from the Ti��O+Ti��Mg��O compound oxide to the Ti��Mg��O+MgO compound oxide and the single��phase MgO, as the Mg content increased from 0��002 3% to 0��006%. A trace addition of Mg (approximately 0��002%) led to the refinement of Ti��bearing inclusions by creating the Ti��Mg��O compound oxide and provided favorable size distribution of the inclusions for acicular ferrite transformation with a high nucleation rate in the CGHAZ, and a high volume fraction of acicular ferrite was obtained in the CGHAZ with enhanced impact toughness. Otherwise, a high content of Mg (approximately 0��006%) produced a single��phase MgO, which was impotent to nucleate an acicular ferrite, and a microstructure comprised of a ferrite side plate and a grain boundary ferrite developed in the CGHAZ. The experimental results were confirmed by thermodynamic calculations.
Abstract��Effects of Mg on the chemical component and size distribution of Ti��bearing inclusions favored grain refinement of the welding induced coarse��grained heat affected zone (CGHAZ), with enhanced impact toughness in Ti��killed steels, which were examined based on experimental observations and thermodynamic calculations. The results indicated that the chemical constituents of the inclusions gradually varied from the Ti��O+Ti��Mg��O compound oxide to the Ti��Mg��O+MgO compound oxide and the single��phase MgO, as the Mg content increased from 0��002 3% to 0��006%. A trace addition of Mg (approximately 0��002%) led to the refinement of Ti��bearing inclusions by creating the Ti��Mg��O compound oxide and provided favorable size distribution of the inclusions for acicular ferrite transformation with a high nucleation rate in the CGHAZ, and a high volume fraction of acicular ferrite was obtained in the CGHAZ with enhanced impact toughness. Otherwise, a high content of Mg (approximately 0��006%) produced a single��phase MgO, which was impotent to nucleate an acicular ferrite, and a microstructure comprised of a ferrite side plate and a grain boundary ferrite developed in the CGHAZ. The experimental results were confirmed by thermodynamic calculations.
CHAI Feng;YANG Cai��fu;SU Hang;ZHANG Yong��quan;XU Zhou. Effect of Magnesium on Inclusion Formation in Ti��Killed Steels and Microstructural Evolution in Welding Induced Coarse��Grained Heat Affected Zone[J]. �й������ڿ���, 2009, 16(1): 69-0.
CHAI Feng;YANG Cai��fu;SU Hang;ZHANG Yong��quan;XU Zhou. Effect of Magnesium on Inclusion Formation in Ti��Killed Steels and Microstructural Evolution in Welding Induced Coarse��Grained Heat Affected Zone. Chinese Journal of Iron and Steel, 2009, 16(1): 69-0.
2009, Vol. 16 
