石墨易切削钢是顺应易切削钢无铅、低硫这一发展趋势而提出的。具有亚共析组织的钢种其石墨化过程一直很难，因此该钢种开发的关键是促进其石墨化过程。基于增加石墨核心来加速石墨化过程进行了钢种的成分设计与研制。结果表明，正是开发钢中具有与石墨结构（简单六方）相同的BN成为了石墨的形核位置，从而有效促进了开发钢的石墨化过程。开发钢的组织由铁素体和石墨组成，其中，石墨的缺口效应和润滑效果赋予了开发钢较高的切削性能和冷成形性能。

Development of lowsulfur and Pbfree free cutting steel is significant because the use of S or Pb freecutting steel can result in serious pollution.The hypoeutectoid graphitized free cutting steel was proposed. The graphitization is difficult due to slow graphitization process,so it is crucial to accelerate the graphitization process. The composition design was based on the principle of increasing the number of graphite nucleus. The machinability of developed steel is improved by taking advantage of notch effect and lubrication action of dispersed fine graphite particles.