Answer
Hydrogen embrittlement occurs in high-carbon steel (SAE 1070-1090) wave springs during the acid pickling or electroplating process. Atomic hydrogen $(\text{H}^+)$ diffuses into the crystal lattice, concentrating at grain boundaries and areas of high tensile stress. Under load, these hydrogen atoms impede dislocation movement, leading to brittle fracture at stresses well below the yield strength. Post-failure analysis typically reveals a 'cleavage' or intergranular fracture surface under a Scanning Electron Microscope (SEM), with little to no macroscopic plastic deformation. To prevent this, plated springs must be 'baked' at approximately $375^{\circ}F$ ($190^{\circ}C$) for 4-24 hours within 1 hour of plating to drive out the trapped hydrogen.
