1. Department of Mechanical Engineering, Islamic Azad University, Khomeinishahr Branch, Khomeinishahr 84175119, Isfahan, Iran 2. Department of Materials Engineering, Islamic Azad University, Najafabad Branch,Najafabad 8514143131, Isfahan, Iran 3. Department of Metallurgy Physique, Material Transformation Unit, University of Lille 1 USTL, F-59655 Villeneuve d��Ascq Cedex, Lille, France
Formation of AlN Nano Particles Precipitated in St-14 Low Carbon Steel by Micro and Nanoscopic Observations
1. Department of Mechanical Engineering, Islamic Azad University, Khomeinishahr Branch, Khomeinishahr 84175119, Isfahan, Iran 2. Department of Materials Engineering, Islamic Azad University, Najafabad Branch,Najafabad 8514143131, Isfahan, Iran 3. Department of Metallurgy Physique, Material Transformation Unit, University of Lille 1 USTL, F-59655 Villeneuve d��Ascq Cedex, Lille, France
ժҪ In low carbon steels, dissolution and precipitation of the second phases such as carbides and nitrides during annealing cycles can affect the final structure and properties of the materials. The interaction of above processes depends on parameters such as reheating temperature, heating rate, annealing temperature, soaking time and finishing temperature in hot rolling stage before cold rolling. The effects of heating rate and annealing temperature on the microstructure and hardness were investigated. Two heating rates for annealing temperatures of 550, 610 and 720 �� were applied on cold-rolled specimens and St-14 low carbon steel, which were immediately quenched after isothermal annealing. The intercept method was used to measure average grain sizes. However, resulted microstructures are different for the two heating rates. While pancaked structures were observed in specimens annealed with low heating rate, in samples annealed with high heating rate, equiaxed microstructures were observed. Vickers micro-hardness values decreased at all temperatures, which were more significant at higher temperatures. At longer annealing time, signs of increase of hardness values were detected. All results and observations consistently suggest that a precipitation process has occurred concurrently with restoration processes during annealing. In addition, the energy dispersive spectroscopy analysis resulted from transmission electron microscopic micrographs have proved that the nano particles precipitated in grain boundaries are AlN.
Abstract��In low carbon steels, dissolution and precipitation of the second phases such as carbides and nitrides during annealing cycles can affect the final structure and properties of the materials. The interaction of above processes depends on parameters such as reheating temperature, heating rate, annealing temperature, soaking time and finishing temperature in hot rolling stage before cold rolling. The effects of heating rate and annealing temperature on the microstructure and hardness were investigated. Two heating rates for annealing temperatures of 550, 610 and 720 �� were applied on cold-rolled specimens and St-14 low carbon steel, which were immediately quenched after isothermal annealing. The intercept method was used to measure average grain sizes. However, resulted microstructures are different for the two heating rates. While pancaked structures were observed in specimens annealed with low heating rate, in samples annealed with high heating rate, equiaxed microstructures were observed. Vickers micro-hardness values decreased at all temperatures, which were more significant at higher temperatures. At longer annealing time, signs of increase of hardness values were detected. All results and observations consistently suggest that a precipitation process has occurred concurrently with restoration processes during annealing. In addition, the energy dispersive spectroscopy analysis resulted from transmission electron microscopic micrographs have proved that the nano particles precipitated in grain boundaries are AlN.
ͨѶ����:
E. Karamian
E-mail: Ebkaramian91@gmail.com
����:
Amirsalar Khandan,Ebrahim Karamian,Mojdeh Faghih,Allain Bataille. Formation of AlN Nano Particles Precipitated in St-14 Low Carbon Steel by Micro and Nanoscopic Observations[J]. �й������ڿ���, 2014, 21(9): 886-890.
Amirsalar Khandan,Ebrahim Karamian,Mojdeh Faghih,Allain Bataille. Formation of AlN Nano Particles Precipitated in St-14 Low Carbon Steel by Micro and Nanoscopic Observations. Chinese Journal of Iron and Steel, 2014, 21(9): 886-890.
2014, Vol. 21 
