Alloy steel high strength fastener electroplating why to remove hydrogen?

Grade 10.9 /12.9 /14.99 high strength alloy steel fasteners are made of chrome-manganese or chrome-molybdenum alloy steel, and the hardness is generally between 42-52HRc. Because the electroplating (surface treatment) process must be pickling activation treatment, hydrogen evolution hydrogen infiltration in the entire electroplating is inevitable, the precipitated hydrogen can penetrate into the electroplating, even into the base metal, the hydrogen absorption of the coating is about 0.001%-0.100%, and the iron carbon alloy hydrogen absorption is about 0.1%. Hydrogen in the metal lattice distortion, resulting in a large amount of internal stress, resulting in reduced mechanical properties, hydrogen development not only has an adverse effect on the performance of the coating, such as pinholes, pitting, bubbles and other defects, but also penetrate into the matrix metal, the 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 stress concentration area of the part, pickling and electroplating will occur hydrogen evolution.