稀土Ce对SUS444铁素体不锈钢夹杂物及力学性能的影响

Influence of Rare Earth Ce on Inclusions and Mechanical Properties of SUS444 Ferrite Stainless Steel

通过金相显微镜、扫描电子显微镜、拉伸和冲击试验等分析测试手段,研究了稀土Ce含量对SUS444铁素体不锈钢夹杂物及室温力学性能的影响。结果表明,添加0.008wt%~0.015wt%Ce可改变夹杂物的种类、形态和尺寸,可将大尺寸、不规则形状的SiO_(2)变质为小尺寸球形的Ce_(2)O_(3)夹杂物,添加0.008%Ce不足以使SiO_(2)完全变质,但添加0.015%Ce可实现夹杂物的完全变质。稀土Ce可细化不锈钢的显微组织,随Ce含量增加,不锈钢的抗拉强度提升,拉伸断口由韧-脆结合断裂完全转变成韧性断裂;冲击韧性显著提升,最高可提升至未添加Ce的4.9倍,冲击断口由脆性断裂向韧性断裂转变。综合考虑夹杂物和力学性能,不锈钢中Ce最优含量为0.015wt%。

The effects of rare earth Ce content on the inclusions and room temperature mechanical properties of SUS444 ferritic stainless steel were studied by means of metallographic microscopy,scanning electron microscopy,tensile and impact tests.The results show that adding 0.008%-0.015wt%Ce can change the type,shape and size of inclusions,and the large size and irregular shape SiO_(2) can be modified into small size spherical Ce_(2)O_(3)inclusions.The added 0.008%Ce is not enough to complete the modification of SiO_(2),but adding 0.015%Ce can realize the complete modification of inclusions.The rare earth Ce can refine the microstructure of the stainless steel,and the tensile strength of stainless steels increases with the increase of Ce content.The tensile fracture completely changes from ductile-brttleness to ductile fracture.The impact toughness is significantly improved,up to 4.9 times of that of the steel without Ce,and the impact fracture is transformed from brittle fracture to ductile fracture.Considering the inclusion and mechanical properties,the optimal content of Ce in stainless steel is 0.015wt%.