高氧增材制造IN718镍基高温合金的蠕变性能
Role of high oxygen content on creep property of additive manufactured IN718 nickel-based superalloy
巩俐 1史慧文 2杨博威 1孙美慧 1刘文月 1郭呈宇1
作者信息
- 1. 鞍钢集团北京研究院有限公司,北京 102209
- 2. 煤炭科学技术研究院有限公司,北京 100013
- 折叠
摘要
氧作为高温合金冶炼过程中难以去除的杂质元素,氧质量分数仅仅为0.000 1%～0.001 0%就会显著降低高温合金的疲劳与蠕变性能.增材制造技术由于其在难切削合金与复杂构件上的制造优势,已被广泛应用于高温合金的制造.然而,由于粉末的比表面积大,增材制造高温合金的氧质量分数为传统铸造的10～100倍,致使其疲劳与蠕变性能大幅下降.基于此,充分利用了选区激光熔化工艺的特点,开展了高氧含量气氛中IN718合金的打印.采用了打印室氧质量分数分别为0.001%与0.100%的环境,制备了高、低2种氧含量合金.650℃/550 MPa的蠕变与 650℃/690 MPa的持久测试显示,高氧含量制造的合金的蠕变与持久寿命为低氧含量制造的合金的 2倍,同时具有更好的塑性.结合光镜、扫描电镜与能谱仪,对2种合金的显微组织进行表征.结果显示,氧含量增高并未引起打印过程的烧损,且高氧含量与低氧含量制造的合金具有相同的致密度与显微组织特征,2种合金均显示出良好的冶金结合,没有明显的打印缺陷.在热处理之后,2种合金均发生了晶粒回复与再结晶,在晶界处析出了几乎同样尺寸和含量的碳化物与δ相.通过透射电镜发现高氧含量合金中具有弥散分布的Al2O3 颗粒,尺寸为15～30 nm,且其附近遍布位错网.这些纳米氧化物结构稳定,可以有效阻碍位错运动,从而提升了合金的蠕变性能.详细分析了该纳米氧化物在选区激光熔化过程中的形成机制.提出利用激光增材制造特性制备含纳米氧化物合金的思路,该方法可以有效避免氧对合金损害,提升合金的性能.
Abstract
Oxygen,as an impurity element that is difficult to remove in the smelting process,will significantly reduce the fatigue and creep properties of superalloys with only a oxygen mass percent of 0.000 1%-0.001 0%.Additive manufacturing technology has been widely used in the manufacture of superalloys due to its advantages in the manufacturing of hard-to-cut alloys and complex components.However,due to the large specific surface area of powders,the oxygen content of additively manufactured superalloys is 10-100 times higher than that of traditional casting,resulting in a significant decrease in fatigue and creep performance.Therefore,this paper made full use of the characteristics of selective laser melting process to carry out the additive manufacturing of IN718 alloy in the atmosphere with high oxygen content.In this work,the printing chamber had oxygen contents of 0.001%and 0.100%to prepare alloys with high and low oxygen content.The creep test at 650℃/550 MPa and rupture test at 650℃/690 MPa showed that the creep and rupture lives of alloys manufactured with high oxygen content were twice than those of alloys manufactured with low oxygen content.Combined with optical microscope,scanning electron microscope and energy dispersive spectrometer,the microstructures of two kinds of alloys were characterized.The results showed that the increase in oxygen content does not cause burn-off during the printing process,and the alloy manufactured with high oxygen content has the same density and microstructure characteristics as the low oxygen content one,both alloys showing good metallurgical bonding without obvious printing defects.After heat treatment,grain recovery and recrystallization occurred in both alloys,and the carbides and δ phases precipitated at grain bound-aries had almost the same size and content.Through transmission electron microscopy it was found that Al2O3 par-ticles with a size of 15-30 nm dispersedly distributed in the alloys with high oxygen content,with dislocation net-works around them.These nano-oxide structures are highly stable and can effectively hinder the dislocation move-ment,thereby improving the creep performance of the alloy.The formation mechanism of these nano-oxides during selective laser melting was analyzed in detail.An idea of using the characteristics of laser additive manufacturing to prepare nano-oxides dispersed alloys was put forward,which can effectively avoid oxygen damage and improve the performance of alloys.
关键词
选区激光熔化/镍基高温合金/高氧含量/纳米氧化物/蠕变性能Key words
selective laser melting/nickel-based superalloy/high O content/nano-oxides/creep property引用本文复制引用
基金项目
国家自然科学基金(52101144)
中国博士后科学基金(2022T150342)
博士后国(境)外交流资助项目(YJ20210129)
出版年
2024
NETL
NSTL
万方数据