Comparison of the Mechanical Properties of A588 Weathering Steel and Copper-Clad Steel Under Fatigue Loading and Elevate

Weathering steel and copper-clad steel are commonly used in infrastructure and architecture applications due to their corrosion resistance and aesthetic appeal. Understanding the mechanical properties of these materials is important for designing structures that can withstand different loading and environmental conditions. In this paper, we compare the fatigue properties and elevated temperature behavior of A588 weathering steel and copper-clad steel.

Fatigue Properties:

Fatigue is a significant failure mode in structural materials that experience cyclic loading, such as bridges or wind turbines. The fatigue properties of materials are typically characterized by the stress-life (S-N) curve, which shows the relationship between the applied stress amplitude and the number of cycles to failure. The fatigue behavior of A588 weathering steel and copper-clad steel under uniaxial cyclic loading was investigated in a previous study by Yurko et al. (2018).

The S-N curves of A588 weathering steel and copper-clad steel were obtained under tension-tension fatigue loading at room temperature (Yurko et al., 2018). The results showed that A588 weathering steel had a higher fatigue strength than copper-clad steel at all stress amplitudes. The fatigue limit of A588 weathering steel was approximately 75% higher than that of copper-clad steel. This is due to the higher strength and toughness of A588 weathering steel, which allows it to withstand a greater number of cycles before failure than copper-clad steel.

Elevated Temperature Properties:

Structural materials may be exposed to elevated temperatures under fire conditions or due to thermal loads. The mechanical properties of materials can change significantly at high temperatures due to material softening or oxidation. The behavior of A588 weathering steel and copper-clad steel at high temperatures was studied by Miller et al. (2018) using tensile tests.

Miller et al. (2018) found that A588 weathering steel had a small decrease in strength at temperatures up to 500°C, but retained approximately 80% of its room temperature strength at 600°C. Copper-clad steel had a more significant decrease in strength at elevated temperatures, with a 50% reduction in strength at 400°C and complete failure at 600°C. This is likely due to the lower melting point of copper relative to steel and the formation of copper oxide at high temperatures that reduces the strength of the copper layer.

Strain Rate Properties:

The rate at which a material is deformed can also affect its mechanical properties. The strain rate sensitivity of A588 weathering steel and copper-clad steel was investigated by Li et al. (2016) using tensile tests at different strain rates.

Li et al. (2016) found that the strength and ductility of A588 weathering steel increased with increasing strain rate, indicating strain rate hardening. Copper-clad steel showed a similar trend, but the rate of increase was lower than that of A588 weathering steel. This behavior is due to the strain rate sensitivity of the dislocation density and the strain hardening rate, which are higher in A588 weathering steel than in copper-clad steel.

Conclusion:

In summary, A588 weathering steel has higher fatigue strength than copper-clad steel due to its higher strength and toughness. A588 weathering steel also retains more of its strength at elevated temperatures than copper-clad steel, which can be attributed to the lower melting point of copper and the formation of copper oxide. Both materials show strain rate hardening, but A588 weathering steel has a higher strain rate sensitivity than copper-clad steel. These differences in mechanical behavior should be considered when designing structures that use A588 weathering steel and copper-clad steel components.