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Abstract The effect of Zr and Al acting as deoxidizer on the formation behavior of sulfides in micro-alloyed steel was studied by vacuum induction furnace experiment. The experimental results showed that sulfides appear mostly intergranular cluster-like distribution which were typically the typeⅡsulfides (most showed fan or chain-like distribution) in Al deoxidized steel . Lots of sulfide particles in Al deoxidized steel existed per unit， and most of them were smaller than 2.5 μm， a few were bigger. The sulfides in Zr deoxidized steel mainly appeared intergranular distribution which belonged to the typeⅡsulfides； Some precipitated in interdendritic regions， which fitted into the type III sulfides. Compared to the sulfides in Al deoxidized steel， the distribution of sulfides in Zr deoxidized steel had been much improved， mostly of them were chainlike distributed. And the number of sulfides per unit area was reduced， the size increased， and the number of sulfides whose size was bigger than 5 μm increased； According to the nonhomogeneous nucleation theory， the lattice disregistry between (001)MnS and (001)ZrO2 was 3.0， and the lattice disregistry between (111)MnS and (0001)Al2O3 was 26.9. Due to the low lattice disregistry between the MnS and ZrO2， a part of MnS precipitated on ZrO2 nuclei in advance， and grown into big inclusions (as type Ⅲ)， which made the precipitation amount of type Ⅱ MnS at the end of solidification reduces， the distribution of sulfides changed from fan-like to chainlike distribution， and the distribution of sulfides improved.
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Received: 23 March 2015
Published: 27 January 2016
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2016, Vol. 51 
