An assessment is made of the consequences from hydrogen absorbed during auto service, as AHSS become more widely used in auto construction.
The influence of hydrogen on the mechanical properties of some AHSS was studied using the linearly increasing stress test (LIST) combined (i) with hydrogen absorbed during corrosion, and (ii) with hydrogen from cathodic charging.
There is little hydrogen influence for MS980, MS1180, MS1300, MS1500, 980DP and 1200DP containing the highest possible hydrogen absorption during automobile service.
In contrast, electrochemical-hydrogen charging causes an influence. The main manifestations are a decrease in yield strength, and the introduction of hydrogen assisted micro-fracture modes during specimen fracture at the ultimate tensile strength when the specimen has become mechanically unstable in the load controlled LIST. Hydrogen Enhanced Macroscopic Ductility (HEMP) decreases the yield strength. Hydrogen Assisted Micro-fracture (HAM) decreases ductility.