Answer
High-carbon steels like SAE 1070-1090 are susceptible to Hydrogen Embrittlement (HE) during the acid pickling or electroplating process (e.g., zinc or cadmium plating). Atomic hydrogen diffuses into the grain boundaries of the steel, especially under high tensile stress areas like the wave crests. This leads to brittle fracture at loads significantly below the yield strength. To mitigate this, springs must undergo a 'baking' process immediately after plating—typically at $375^\circ F \pm 25^\circ F$ for at least 4 to 24 hours depending on the part thickness and hardness. Failure to bake within 1-4 hours of plating often results in irreversible damage. For critical aerospace components, mechanical plating or vacuum deposition is preferred to avoid hydrogen exposure entirely.
