| 引用本文: | 谌江涛,罗庸生,李一飞,李荣和,赵夙.超声喷丸对不同取向单晶高温合金组织与表面性能的影响[J].中国表面工程,2023,36(1):67~76 |
| CHEN Jiangtao,LUO Yongsheng,LI Yifei,LI Ronghe,ZHAO Su.Effect of Ultrasonic Shot Peening on Microstructure and Surface Properties of a Single Crystal Superalloy with Different Orientations[J].China Surface Engineering,2023,36(1):67~76 |
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| 摘要: |
| 超声喷丸作为一种有效改善疲劳性能的手段在单晶材料方面得到一定研究，但喷丸振幅对不同取向镍基单晶高温合金微观组织及表面性能的影响尚不清晰。采用生长方向为[001]的国产第三代镍基单晶高温合金为研究对象，利用显微硬度计、 SEM、TEM、XRD、EBSD 等研究超声喷丸振幅(22.5 μm、45 μm、60 μm)对不同第二取向([100]、[110])样品组织形貌及表面性能的影响。结果表明：振幅为 22.5 μm 喷丸处理后的样品保持单晶合金原有的 γ / γ组织形貌和原始取向，并在表面局部已经形成尺寸约为 10 nm 的纳米晶；[100]与[110]取向样品近表层硬度相比基体硬度分别最大提高 75% 和 68.5%。大振幅(45 μm、60 μm)喷丸样品的 γ / γ组织发生严重畸变；随着振幅的增大，原始取向强度逐渐减弱并产生新的择优取向， 样品近表层的取向偏转更加显著且沿滑移带附近产生大量小角晶界。通过分析两取向样品的近表层硬度及 EBSD 结果可知， 在相同振幅条件下，第二取向[100]样品的近表层应变硬化效果优于[110]取向样品。研究喷丸振幅对不同第二取向单晶高温合金性能及微观组织的影响，可为生产中合理控制单晶叶片第二取向及提高单晶的疲劳性能奠定理论基础。 |
| 关键词: 超声喷丸 单晶高温合金 第二取向 组织形貌 表面性能 |
| DOI：10.11933/j.issn.1007?9289.20220501003 |
| 分类号:TG172 |
| 基金项目:浙江省“领雁”研发攻关计划(2022C01114)、宁波市“3315 计划”创新团队(Y80929DL04)、宁波市自然科学基金(2021J221)、浙江省自然科学基金(LQ22E010011)和宁波材料所所长基金(2021SZKY0310)资助项目 |
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| Effect of Ultrasonic Shot Peening on Microstructure and Surface Properties of a Single Crystal Superalloy with Different Orientations |
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CHEN Jiangtao1,2, LUO Yongsheng1,2, LI Yifei2, LI Ronghe2, ZHAO Su2
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1.Faculty of Mechanical Engineering and Mechanics, Ningbo University, Ningbo 305211 , China;2.Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences,Ningbo 305201 , China
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| Abstract: |
| Nickel-based single-crystal superalloys are widely used to manufacture advanced aero-engines and gas turbine blades because of their excellent high-temperature properties. During the high-temperature service of the engine, the tenon is in a complex high-temperature alternating load state, which is prone to fatigue fracture. Therefore, the fatigue performance is an important performance indicator of single-crystal alloys. Ultrasonic shot peening has been studied as an effective process to improve the fatigue properties of single crystals. However, the effects of the shot peening amplitude on the microstructure and surface properties of nickel-based single-crystal superalloys with different orientations remain unclear. The influence of the ultrasonic peening amplitude (22.5 μm, 45 μm, and 60 μm) on the microstructure and surface characteristics of a third-generation nickel-based single-crystal superalloys with different second orientations ([100], [110]) was studied by a microhardness tester, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). The results show that the microhardness of the near-surface layer of the samples decreased in the order of peening with the amplitudes of 22.5 μm, 60 μm, and 45 μm. Compared with the microhardness of the matrix, the highest microhardness of the near-surface layer in the [100]-and [110]-oriented samples increased by 75% and 68.5%, respectively. With the same amplitude, the strain-hardening effect of the [100] samples was better than that of the [110] samples. The surface roughness of the [100] samples was smaller than that of the [110] samples after shot peening. The SEM and XRD results show that the samples with a small peening amplitude (22.5 μm) maintained the microstructure of cubic γ recipitates embraced in the γ-phase and initial orientation of the single crystal; the γ /γ structures of the samples with large amplitudes (45 μm, 60 μm) were severely deformed; and the initial orientation gradually weakened as the amplitude increased. For the [100] samples, the preferred diffraction peak changed from (200) to (111) with the increase in the shot peening amplitude. For the [110] samples, the preferred diffraction peak changed from (220) to (111) as the peening amplitude increased; (200) and (311) peaks appeared at the same time. TEM analysis revealed that nanocrystals were formed on the two oriented surfaces, and amorphous structures were locally formed on the surface of the [110] samples after peening with an amplitude of 22.5 μm. EBSD analysis showed that with the increase in the shot peening amplitude, the misorientation of the near-surface layer in these samples became more significant, and a large number of low-angle grain boundaries occurred near the slip bands. The plastic deformation depth of the two oriented samples first increased and then reached saturation with the increase in the peening amplitude. The deformation magnitude of the near-surface layer in the [100] samples continuously increased, while that of the near-surface layer in the [110] samples first increased and then gradually reached saturation as the amplitude increased. With the same amplitude, the plastic strain of the [100] samples is more significant than that of the [110] samples, which may be attributed to the smaller elastic modulus and greater number of activated ＜110＞{111} slip systems in the [100] samples compared with those in the [110] samples. By analyzing the effect of ultrasonic shot peening on the properties and microstructure of single-crystal superalloys with different orientations, a theoretical basis can be laid out for the production of single-crystal blades with a reasonable second orientation and the enhancement of the fatigue properties of single crystals. |
| Key words: ultrasonic shot peening single crystal superalloy second orientation microstructure morphology surface property |
