Fatigue test results: 6000-series vs 7000-series aluminum trekking pole

When it comes to choosing trekking poles, the material is crucial, and aluminum alloys are popular for their balance of strength, weight, and affordability. Among aluminum alloys, the 6000-series and 7000-series are commonly used in trekking pole manufacturing. A comprehensive fatigue test was conducted to evaluate the performance differences between these two series, providing valuable insights for outdoor enthusiasts and manufacturers alike.​

Material Composition and Properties​

The 6000-series aluminum alloy, primarily composed of aluminum, magnesium, and silicon, is known for its good corrosion resistance, moderate strength, and excellent formability. This makes it relatively easy to shape into the slender tubes required for trekking poles. On the other hand, the 7000-series aluminum alloy contains a higher percentage of zinc, along with magnesium and copper, which endows it with significantly higher strength and hardness, making it one of the strongest aluminum alloys available. However, this enhanced strength comes at the cost of reduced formability and higher production costs.​

Fatigue Test Setup​

The fatigue test aimed to simulate the repeated stress that trekking poles endure during outdoor activities, such as hiking on uneven terrain. A total of 20 samples (10 from each series) were tested under identical conditions. The poles were subjected to a cyclic loading pattern with a constant amplitude. The test setup involved a three-point bending mechanism, where the poles were fixed at both ends, and a load was applied at the midpoint, mimicking the bending stress experienced when supporting a hiker's weight on slopes or rough surfaces. The load was set at 80N, a value representative of the typical stress a trekking pole might encounter during heavy-duty use. The frequency of loading was maintained at 2Hz, simulating the regular footsteps of a hiker.​

Test Results​

The results of the fatigue test were revealing. The 7000-series aluminum trekking poles demonstrated remarkable durability, with an average fatigue life of 150,000 cycles before failure. Failure was typically characterized by catastrophic fracture, indicating the high strength of the material until its breaking point. In contrast, the 6000-series poles showed an average fatigue life of 110,000 cycles. Instead of sudden fractures, they often exhibited visible deformation and the development of multiple micro-cracks before reaching their limit.​

Upon microscopic analysis of the failed samples, it was found that the 7000-series poles had a more uniform grain structure, which contributed to their superior resistance to crack propagation. The 6000-series poles, while having a lower fatigue life, showed better ductility, allowing them to deform gradually under stress rather than breaking immediately. This characteristic could be advantageous in certain situations, as it provides a warning sign before complete failure.​

Practical Implications​

For avid hikers who frequently tackle challenging terrains, such as rocky mountains or steep slopes, the 7000-series aluminum trekking poles are the preferred choice. Their higher fatigue resistance ensures greater reliability and safety, reducing the risk of pole failure in critical moments. However, these poles are generally more expensive and slightly heavier, which might be a consideration for long-distance backpackers who prioritize minimizing weight.​

The 6000-series aluminum trekking poles, on the other hand, offer a more budget-friendly option without sacrificing too much on performance. They are suitable for casual hikers or those who engage in less strenuous outdoor activities. Their good corrosion resistance and moderate strength make them reliable for everyday use, and their ability to deform before breaking can be a safety feature in some cases.​

Conclusion​

In conclusion, the fatigue test clearly shows that both 6000-series and 7000-series aluminum trekking poles have their own strengths and weaknesses. The 7000-series excels in terms of fatigue resistance and overall strength, making it ideal for demanding outdoor conditions. The 6000-series, with its balance of cost, formability, and ductility, caters to a wider range of users with different needs and budgets. When choosing a trekking pole, hikers should consider their specific usage scenarios, budget constraints, and personal preferences to make an informed decision.