Why to remove Hydrogen in Electroplating of Alloy Steel High Strength Fasteners?

Grade 10.9 /12.9 /14.99 high strength alloy steel fasteners are manufactured in chrome-manganese or chrome-molybdenum alloy steels, generally with a hardness between 42 and 52HRc. Because electroplating (surface treatment) process must be pickling activation treatment, hydrogen evolution hydrogen osmosis in the whole electroplating is inevitable, the hydrogen precipitated into electroplating, even into the substrate metal, coating hydrogen absorption is about 0.001%-0.100%, and iron carbon alloy hydrogen absorption is about 0.1%. Hydrogen in the metal lattice distortion, produce a great deal of internal stress, resulting in the reduction of mechanical properties, hydrogen evolution not only has an adverse effect on the coating performance, such as pinhole, pitting, bubbles and other defects, but also penetrate into the matrix metal, metal toughness is greatly reduced, resulting in brittle parts. Reasons for hydrogen evolution In addition to heat treatment, high heating temperature, hydrogen is easy to penetrate the parts stress concentration area, pickling and electroplating will occur hydrogen evolution.