GX4CrNi13-4铸钢非金属夹杂物的消除及其对性能的影响

The Improvement for the Non-Metallic Inclusions and Their Influence on the Properties of GX4CrNi13-4 Cast Steel

研究了非金属夹杂物对核电机组用铸钢GX4CrNi13-4材料冲击性能的影响。扫描电镜(SEM)观察和能谱分析(EDS)结果表明:GX4CrNi13-4铸钢中主要夹杂物为角状不规则的Al_2O_3和硫化物,其中单个Al_2O_3夹杂物的尺寸在5~20μm,数量较多。Al_2O_3夹杂物与硫化物形成复合夹杂并且聚集生长,分布范围为100μm左右。通过真空脱气、减少含铝脱氧剂的使用和脱渣处理,有效改善了铸件的夹杂物水平,使钢中Al_2O_3夹杂物数量下降,尺寸减小为5μm左右,GX4CrNi13-4铸钢冲击韧性由23.67 J/cm^2提高到128.33 J/cm^2,超出国家标准,为实现第三代AP1000 MW核电汽轮机大型核心铸钢件的国产化奠定了坚实的基础。

The influence of non-metallic inclusions on the impact properties of nuclear power cast steel GX4CrNil3-4 was studied. The analysis result of scanning electron microscopy and energy dispersive spectrometer show that the main inclusions in GX4CrNil3-4 steel were horn-shaped irregular Al2O3 and irregular sulfide. The size of single Al2O3 inclusions ranged from 5 to 20 μm. The Al2O3 inclusions formed duplex inclusions with sulfide inclusions and gathered together, the distribution of Al2O3 cluster ranged about 100μm. The content of inclusion in steel was decreased effectively by vacuum degassing, reducing the use of deoxidizer containing aluminum, removing the residue etc. After the improvement, the Al2O3 content in inclusion decreased and the size of inclusions decreased to 5 μm, the impact energy of GX4CrNi 13-4 cast steel is increased from 23.67 J/cm2 to 128.33 J/cm2. The performance of GX4CrNil3-4 cast steel is beyond the standard after the improvement and it has laid a solid foundation for the realization of the autonomy and localization of the large steel castings of the third generation ofAP 1000 MW nuclear power steam turbine core material.