稀土改性42CrMoS易切削钢中的硫化物夹杂分析

利用光学显微镜和能谱仪研究了42CrMo钢中分别添加S(0．09wt％)和S—RE元素后，钢中夹杂物的组成、形态和变形能力，并分析了硫化物夹杂对钢的力学性能的影响。结果表明，单独加S元素时，钢中主要存在MnS夹杂，MnS在高温具有强的塑性变形能力是导致锻件力学性能各向异性的重要原因；加入RE(0．076％)元素后，钢中出现的稀土硫化物具有较强的抗塑性变形能力，改善了钢的横向力学性能，其横纵向冲击韧度比值由单一加S元素的0．2提高到0．5，从而为钢的实际应用提供了理论依据。

Analysis on Sulphide Inclusions in Free-cutting 42CrMoS Steel Modified by Rare Earth Elements

The composition,morphology,deformation of the inclusions and their influence on mechanical properties of 42CrMo steels respectively added with S(0.09wt%)and S-RE elements were investigated by means of optical microscope and energy spectrum analysis.The results show that the inclusions existing in the steel only added with S element are MnS mainly.As a result of the high deformability of MnS at high temperatures,the mechanical properties of the steel exhibit anisotropy.When rare earth elements(0.076wt%) is added into the 42CrMo steel,the (Mn,RE)S inclusions possess strong anti-deformability so that the mechanical properties in transverse section are improved.The ratio of the impact toughness in transverse section to the ones in longtitudinal section increase from 0.2 to 0.5 which make it possible to put the steel into the industrial use.