核电用304L奥氏体不锈钢等离子体源渗氮

Plasma source nitriding of 304L austenitic stainless steel for nuclear power plant

对核电用304L奥氏体不锈钢进行450℃×6 h等离子体源渗氮处理,对比研究了渗氮前后改性层的组织与性能。结果表明:304L奥氏体不锈钢渗氮后,表面获得了厚度约为15μm,峰值氮浓度可达25at%的单一面心结构的γ_Ν相改性层,其最大显微硬度高达1320 HV0.025,干摩擦条件下,γ_Ν相改性层的磨损体积由原始不锈钢的0.102 mm^3降低至9.26×10^(-3)mm^3,磨损机制由黏着磨损转变为氧化磨损,耐磨性能显著提高。在3.5%Na Cl溶液和p H=8.4硼酸溶液中,γ_Ν相改性层的自腐蚀电位比原始不锈钢分别提高了323 m V和75 m V,耐蚀性能明显改善。

304L austenitic stainless steel for nuclear power plant was plasma source nitrided at 450 ℃ for 6 h,and microstructure and properties of the modified layer before and after nitriding were studied. The results show that a single high-nitrogen face-centered-cubic phase（ γ_Ν） with a thickness of 15 μm and the peak nitrogen concentration of about 25at% is formed on the 304 L austenitic stainless steel surface,and has the highest microhardness about 1320 HV0. 025. The wear mechanism of the γ_Ν phase layer changes from the adhesive wear corresponding original stainless steel to oxidative wear in dry friction condition. The increased wear resistance of the γ_Ν phase layer is obtained with a decrease wear volume from 0. 102 mm^3 of original stainless steel to 9. 26 × 10（- 3）mm3. Compared with the original stainless steel,the self-corrosion potential of the γ_Ν phase layer in 3. 5% Na Cl solution and in boric acid solution with p H 8. 4 increase 323 m V and75 m V,respectively. The corrosion resistance of the γ_Ν phase layer is improved in comparison with that of original stainless steel.