喷丸强度对FGH4113A高温合金微观组织的影响及定量表征

Effect of shot peening intensity on FGH4113A superalloy microstructure and quantitative analysis

摘要:

镍基粉末高温合金涡轮盘长期在高温高应力条件下服役，对其综合力学性能有着严苛的要求，而表面形态与微观组织对盘件性能有着至关重要的影响，通常需进行表面喷丸强化处理。基于此，本工作系统性的研究了不同喷丸强度下FGH4113A合金的表面和亚表层微观组织及变形情况，并探究了两者的定量关系。结果表明：经过喷丸处理后，合金亚表面产生位错塞积，诱发晶粒内形成变形孪晶，并且变形孪晶数量随喷丸强度的增大而增大。另外由于喷丸强化引入的位错使变形层存在大量的小角晶界，从而发生晶粒细化以提升合金硬化效果。随着喷丸强度的增大，合金表面粗糙度、表面残余亚应力、硬化层厚度以及表面显微硬度等特征呈现出不断增大的趋势，并且表现出较好的线性关系或幂指数关系。这一发现可为实际生产过程中喷丸强化参数的调控提供一定的数据支撑。

Abstract:

Powder metallurgy Ni-based superalloy turbine discs serve at high temperatures and high stress levels for a long time, and the comprehensive mechanical properties of the superalloy have stringent requirements, while the surface morphology and microstructure have a significant impact on the performance of the superalloy, which generally requires surface shot peening treatment. Based on this, this work systematically investigates the surface/subsurface microstructure and deformation of the FGH4113A superalloy at different shot peening intensities and explores the quantitative relationship between them. The result indicates that the dislocation pile-up occurs in the subsurface and induces the formation of deformation twins. Meanwhile, the number of deformation twins rises with the increase in shot peening intensity. Furthermore, the dislocations triggered by shot peening induce a large number of low angular grain boundaries in the deformed layer, which results in grain refinement to reinforce the superalloy hardening effect. In addition, with the increase of shot peening intensity, the characteristics of superalloy surface roughness, surface residual compressive stress, hardened layer thickness, and surface microhardness display an increasing trend and exhibit a good linear or power exponential relationship. This finding can provide data to support the regulation of shot peening parameters in the actual production process.