Abstract：The influence of trace element Bi on MnS inclusions aspect ratio in S-Bi free-cutting steel was investigated through using Q500 image analyzer and JSM6480LV SEM. The results show that there are three existing forms of Bi in free-cutting steel: exist alone in steel, be packaged by sulfide and between steel and sulfide. The aspect ratio of MnS in S-Bi free-cutting steel ingot, with w（TO） = 0.032%, 0.022% and 0.024%, w(Bi) = 0.0002%, 0.0010% and 0.0020%, is during 1.0-1.6, which is lower than 1.2-3.2 in w（TO）=0.030% S free-cutting steel. The growth rate of inclusion aspect ratio is less than 1.0 when forging ratio is 2.25. Deformation rate MnS inclusions will decrease when Bi content rising up. It is found that Bi in steel can prevent MnS deformation during forging process.
林腾昌，朱荣，王成杰，李明钢. 微量铋合金对易切削钢中MnS形貌的影响[J]. 钢铁, 2013, 48(9): 77-80.
LIN Teng-chang,ZHU Rong,WANG Cheng-jie,LI Ming-gang. Effect of Trace Bi on Inclusion Morphology in Free-Cutting Steel. Iron and Steel, 2013, 48(9): 77-80.
2013, Vol. 48 
