Hydrogen embrittlement of DP-1000 flat steel sheet: Influence of mechanical properties, specimen geometry, pre-damaging and electrolytically zinc galvanizing.

Studies towards the impact of solute hydrogen on the mechanical properties of ultra-high strength sheet steel grades (UHSS) for the automotive industry have been increasingly conducted in the past years. This paper focuses on the pre-damaging of a dualphase DP-1000 automotive sheet steel, as found in the manufacturing of automotive body parts, in connection with hydrogen embrittlement. It is shown that the kind of pre-damaging of the specimens has a severe influence on the occurrence of hydrogen embrittlement. Hydrogen embrittlement resistance under corrosive conditions was determined through constant load tests. Tensile specimens, manufactured from electrolytically zinc galvanized DP-1000 steel, were immersed in a 5% sodium chloride solution. The impact of material properties, pre-damaging and specimen geometry are critically discussed. Furthermore a discussion is given about the material testing methods most suitable to indicate high or low hydrogen embrittlement resistance if constant load testing is performed. [ABSTRACT FROM AUTHOR]