Key Takeaways & Executive Findings
- •• A two-dimensional longitudinal simplified model of hole burnishing was developed to analyze surface roughness improvement and material accumulation mechanisms. • Increasing burnishing depth improves surface integrity (roughness, residual stress, hardness) but deteriorates structure shape (material accumulation, contour, roundness). • Optimal burnishing parameters (BD=0.20 mm, spindle speed=200 r/min, feed rate=0.2 mm/r) increased fatigue life of titanium alloy TB6 holes by 162%. • The study provides a parameter selection scheme for collaborative improvement of structure shape and surface integrity in hole burnishing.
Abstract
In the aerospace field, hole burnishing enhancement plays an essential role in improving the service performance of load-bearing holes. To satisfy the assembly accuracy and strength requirements, the structure shape and surface integrity must be considered simultaneously during the enhancement process. The current manufacturing process of hole burnishing has a relatively weak balance between the structure shape and surface integrity; therefore, it is necessary to analyze the mechanism and optimize the parameters to improve the strengthening effect of the holes. In this study, a two-dimensional longitudinal simplified model for the hole burnishing process was established, and the reasons for the surface roughness improvement of the hole wall and material accumulation on the upper surface were analyzed. Experiments were conducted to determine the influence of the burnishing parameters on the structure shape (material accumulation, shape contour, and roundness) and surface integrity (surface roughness, residual stress, and surface hardness), based on the opposite requirements of improving the structure shape and surface integrity for the burnishing depth (BD). The results showed that with an increase in the BD, the structure shape deteriorated, whereas the surface integrity improved. Fatigue behavior verification experiments were conducted, and parameter selection schemes for the collaborative improvement of the structure shape and surface integrity were discussed. For the holes of titanium alloy TB6 (Ti-10V-2Fe-3Al), the fatigue life can be increased by 162% when the BD, spindle speed, and feed rate were 0.20 mm, 200 r/min, and 0.2 mm/r, respectively.
1. Introduction
Titanium alloys are widely used to manufacture key components in various fields. The titanium alloy TB6 (Ti-10V-2Fe-3Al) is widely used in aerospace, owing to its excellent specific strength, fracture toughness, corrosion resistance, and thermal hardness [1, 2]. In aircraft, many key components are assembled through holes that bear significant stresses, strains, and impact loads during service [3, 4]. To satisfy the assembly accuracy and strength requirements, it is necessary to simultaneously consider the structure shape and surface integrity during hole processing. However, owing to its weak machinability, titanium alloy TB6 is likely to undergo deformation and surface defects during processing, making it prone to fatigue fracture under external loads [5–7]. Therefore, higher requirements have been put forward for the manufacturing quality of holes, including their structure shape and surface integrity.
Surface enhancement technology can improve the morphology, structure, and stress distribution of surface materials to achieve superior performance, compared with matrix materials. Shot peening is a commonly used enhancement method [8–10]. However, shot peening usually requires the surface to be exposed, which is unsuitable for small-diameter and deep holes. Moreover, shot peening generally leads to an increase in surface roughness [11, 12]. Expansion has a limited effect on surface roughness improvement, although it can introduce significant residual stress and surface hardening [13–15]. Feng et al. [16] found that the surface roughness of aluminum alloy holes remained after direct cold expansion, owing to the effect of lubricants. However, titanium alloy TB6 is sensitive to surface roughness. That is, higher roughness can lead to fatigue crack initiation and seriously affect the fatigue life [17, 18]. Burnishing is an efficient and reliable surface enhancement method with significant advantages in improving the surface roughness and quality, compared with other enhancement methods [19–23]. Cao et al. [24] found that the surface roughness of a magnesium alloy AZ31 plane was reduced from 1.95 to ...
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Jiahui Liu, Pingfa Feng, Zibiao Wang, Jianfu Zhang, Feng Feng, Xiangyu Zhang (2025). Collaborative Improvement of Structure Shape and Surface Integrity in Titanium Alloy Hole Burnishing. Chinese Journal of Mechanical Engineering. https://doi.org/10.1186/s10033-024-01164-9
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Frequently Asked Questions
What is the main objective of the study on titanium alloy hole burnishing?
The study aims to collaboratively improve the structure shape and surface integrity of titanium alloy TB6 holes during burnishing by analyzing the process mechanism and optimizing parameters.
How does burnishing depth affect the structure shape and surface integrity?
Increasing burnishing depth improves surface integrity (reduces roughness, increases residual stress and hardness) but deteriorates structure shape (increases material accumulation and shape deviation).
What were the optimal burnishing parameters for titanium alloy TB6 holes?
The optimal parameters were a burnishing depth of 0.20 mm, spindle speed of 200 r/min, and feed rate of 0.2 mm/r, which increased fatigue life by 162%.
Why is hole burnishing preferred over shot peening for titanium alloy holes?
Hole burnishing is preferred because shot peening is unsuitable for small-diameter and deep holes and tends to increase surface roughness, whereas burnishing effectively improves surface roughness and quality.
What is the significance of the two-dimensional longitudinal simplified model in this study?
The model helps analyze the mechanisms behind surface roughness improvement and material accumulation during hole burnishing, providing a theoretical basis for parameter optimization.
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