Four types of Implant test specimens were used to study the hydrogen induced cracking of steel weldments. Two types of the specimens had a shallow notch with a depth of 0.5 mm but different diameters, one type had a 2 mm deep notch and one type a helical notch with M6-threads. The specimen with the deep notch had many advantages over specimens having the helical or shallow notch. The advances are mainly seen in "mild" tests in which hydrogen cracking may occur only at stress levels considerably above the yield stress of the parent metal. The results with the deep notch specimen can, therefore, be applied to real joints welded under high level of restraint.