Both aluminum alloy and steel motorcycle frames will undergo some changes in their microstructures over time, even if they are kept still without use. These changes are primarily driven by environmental factors and material properties.
Aluminum Alloy Frames: Aluminum alloys used in motorcycle frames can undergo a process called precipitation hardening or age hardening. This involves heat treatment to optimize the material's strength. Over time, even without use, aluminum can experience natural aging, which can result in slight changes in its mechanical properties. These changes are generally minimal and may not significantly affect the frame's overall strength or performance.
Steel Frames: Steel motorcycle frames can also undergo changes over time due to environmental factors. Steel is susceptible to corrosion, especially if exposed to moisture or certain chemicals. If the frame's protective coating or paint is compromised, it can accelerate the onset of corrosion. While corrosion doesn't necessarily alter the microstructure of steel, it can weaken the material and compromise its structural integrity if left unaddressed.
Heat treatments for steel frames, such as during the manufacturing process, are typically designed to improve the material's strength and durability. If the frame is exposed to excessive heat over time, it can potentially lead to a loss of mechanical properties. However, under normal storage conditions, heat treatments are unlikely to significantly weaken the frame over the years.
Overall, the extent of microstructural changes in both aluminum alloy and steel frames during storage without use will depend on various factors, including the specific materials, environmental conditions, and the presence of protective coatings. Regular maintenance, including proper storage, corrosion prevention, and periodic inspections, can help preserve the structural integrity of motorcycle frames over time.