Official Answer
Answer
High-carbon steels like SAE 1070 to 1090 with hardness exceeding HRC 40 are highly susceptible to Hydrogen Embrittlement (HE). During the acid pickling or electroplating process, atomic hydrogen diffuses into the steel lattice and accumulates at grain boundaries and stress concentrators (the peaks of the waves). Under axial load, these hydrogen atoms promote brittle fracture. To mitigate this, a baking process is mandatory within 4 hours of plating. According to ASTM B633 or similar standards, the springs must be baked at 190°C to 220°C for 8 to 24 hours depending on the section thickness and strength level. Failure to bake results in sudden, catastrophic fracture during the first compression cycle or during static hold.
