Effects of sulfur addition methods and Ca-Si treatment on the microstructure and properties of 30MnVS

Guo-zhong Li1,2), Fu-ming Wang1), Rong Hui2), and Wen-kui Cao2) 1) School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China 2) Jiangyin Xingcheng Special Steel Co. Ltd., Jiangyin 214400, China

摘 要：The effects of sulfur addition methods and Ca-Si treatment on the microstructure and properties of free-cutting non-quenched and tempered steel 30MnVS were investigated by using optical microscopy, SEM and tensile test methods. The results show that sulfur addition methods influence the morphology of sulfides and the properties of 30MnVS slightly. Ca-Si treatment is beneficial for the formation of complex sulfides which normally have oxide cores, therefore, improving the distribution of sulfides in the tested steel and enhancing its toughness. The two methods, pyrite addition during LF process and S wire feeding during VD process, slightly influence the morphology and distribution of sulfides and the properties of 30MnVS; Ca addition not only promotes the nucleation of sulfides on the cores of calcium aluminate inclusions, but also creates modification effect on MnS, reducing the relative plasticity and hot deformability of sulfides during hot rolling process, thereby reducing the length/width value of sulfides and improving their distribution, and significantly enhancing its mechanical properties, in particular, the impact toughness increased by 30%.

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