Temperature and Lubrication Dependence of Threaded Fastener Release

Effective lubrication of the release of threaded fasteners has been investigated much less than assembly lubrication. However, the lubrication of threaded fasteners during disassembly, especially after exposure to elevated temperatures, is important for integrity and maintenance of critical assets.Four anti-seize and assembly lubricant technologies were applied to A2-70 stainless steel fasteners. Fastener release torques were measured after exposure at various temperatures between 20 and 780 °C. The lubrication performance was correlated with the likely remaining composition inferred from thermal analysis (TGA/DSC).Release torque was low and consistent at or below 250 °C, when the lubricant base fluid was present, albeit sometimes as an oxidised residue. From 380-480 °C, release torque was higher, less consistent, and depended on the lubricating solids in the original formulation. Above 480 °C, the release torque was lower, due to the oxidation and mass loss of the lubricating solids: This, again, varied greatly with the lubricating solids present.