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过程工程学报 ›› 2023, Vol. 23 ›› Issue (3): 451-459.DOI: 10.12034/j.issn.1009-606X.222126

• 研究论文 • 上一篇    下一篇

微量镁对Incoloy825耐蚀合金力学性能的影响

李秋寒， 龚伟*， 姜周华， 王鹏飞   

  1. 东北大学冶金学院，辽宁 沈阳 110819
  • 收稿日期:2022-04-11 修回日期:2022-05-28 出版日期:2023-03-28 发布日期:2023-03-28
  • 通讯作者: 龚伟 gongw@smm.neu.edu.cn
  • 作者简介:李秋寒，硕士研究生，研究方向为冶金工程，E-mail: 957529785@qq.com；通讯联系人，龚伟，副教授，研究方向为冶金工程，E-mail: gongw@smm.neu.edu.cn
  • 基金资助:
    国家自然科学基金资助项目;中央高校基本科研业务专项基金资助项目

Effect of trace magnesium on mechanical properties of Incoloy825 corrosion resistant alloy

Qiuhan LI,  Wei GONG*,  Zhouhua JIANG,  Pengfei WANG   

  1. School of Metallurgy, Northeastern University, Shenyang, Liaoning 110819, China
  • Received:2022-04-11 Revised:2022-05-28 Online:2023-03-28 Published:2023-03-28
  • Contact: Wei Gong gongw@smm.neu.edu.cn

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摘要： Incoloy825合金作为一种耐蚀合金应用于海洋工程、石油气等行业，由于此类行业环境较为恶劣，不仅需要材料具有出色的耐蚀性能，对力学性能也有较高的要求。本工作利用25 kg真空感应炉冶炼4炉镁含量分别为0wt%, 0.0012wt%, 0.0030wt%和0.0065wt%的Incoloy825合金，使用金相显微镜、扫描电子显微镜和能谱仪，分别对合金中非金属夹杂物的尺寸、数量进行统计，对夹杂物的形貌和成分进行观察和分析，同时对组织和碳化物进行观察，并对合金进行室温拉伸实验和室温冲击实验，结合实验结果揭示了微量镁改善Incoloy825合金力学性能的机理。研究结果表明，镁的加入使合金中氧和硫的含量减少，夹杂物数量减少，夹杂物成分得到改善，合金洁净度提高，减小了夹杂物对力学性能的影响，同时，晶粒得到细化。合金的屈服强度、抗拉强度、断面收缩率和伸长率均有一定程度的提高，即夹杂物和组织的改善提高了合金的强度和塑性。研究还发现，镁的加入可以将Cr, Fe和Mo等元素从合金的晶界处驱逐，从而减少了晶界处硬脆性碳化物M23C6的析出，显著提高合金的冲击韧性。与未加入镁的合金相比，镁含量达到0.0065wt%时，合金的脱硫率为37.19%，脱氧率为15.71%，单位面积夹杂物数量由75降低至53，大尺寸块状的Al2O3转化为小尺寸的镁铝尖晶石和二维形貌为近圆形的MgO，合金的冲击功由262.5 J提升至384.7 J，提升幅度高达46.55%。杂质元素减少、夹杂物数量减少、晶粒细化、碳化物尺寸减小和晶界碳化物数量减少的综合作用提高了合金的力学性能。

关键词: Incoloy825耐蚀合金, 镁处理, 夹杂物, 碳化物, 力学性能

Abstract: As a corrosion-resistant alloy, Incoloy825 alloy is used in marine engineering, LPG, and other industries. Due to the harsh environment of such industries, it is necessary not only for the material to have excellent corrosion resistance, but also to have high mechanical properties. In this work, 4 furnaces of Incoloy825 alloy with Mg content of 0wt%, 0.0012wt%, 0.0030wt%, and 0.0065wt% were smelted in a 25 kg vacuum induction furnace. Utilizing a metallographic microscope, scanning electron microscope, and energy dispersive spectrometer, the size and quantity of non-metallic inclusions were counted, the morphology and composition were observed and analyzed, and the microstructure and carbide were observed. Room temperature tensile test and room temperature impact test were carried out on the alloy. Combined with the experimental results, the influence mechanism of magnesium on the mechanical properties of Incoloy825 was revealed. The results showed that the addition of magnesium reduced the content of oxygen and sulfur in the alloy, reduced the number of inclusions, improved the composition of inclusions, improved the cleanliness of the alloy, reduced the influence of inclusions on mechanical properties, and refined the grains of the alloy. The yield strength, tensile strength, reduction of area and elongation of the alloy were improved to a certain extent, that was, the improvement of inclusions and microstructure improved the strength and plasticity of the alloy. It was also found that the addition of magnesium can expel Cr, Fe and Mo from the grain boundary of the alloy, thus reducing the precipitation of hard and brittle carbide M23C6 at the grain boundary and significantly improving the impact toughness of the alloy. Compared with the alloy without magnesium addition, when the Mg content increased to 0.0065wt%, the sulfur content and oxygen content in the alloy decreased by 37.19%, 15.71%, number density of inclusions decreased from 75 to 53 pcs, the large-sized bulk Al2O3 was transformed into small-sized MgO?Al2O3 and MgO with nearly circular 2D morphology, and the impact absorbing energy was increased from 262.5 J to 384.7 J, with an increase range of 46.55%. The mechanical properties of the alloy were improved by the comprehensive effects of the reduction of impurity elements, the number of inclusions, grain refinement, the size of carbides and the number of carbides at grain boundaries.

Key words: Incoloy825 corrosion resistant alloy, magnesium treatment, inclusions, carbides, mechanical property