Selecting Filler Metals: Low Hydrogen

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This is part two in a series on selecting filler metals. When selecting filler metals, the specifier may elect to require "low hydrogen electrodes." Such electrodes may be required to minimize the possibility of hydrogen related cracking. In some cases the engineer may specify low hydrogen electrodes because he believes these electrodes will also provide weld deposits exhibiting a high minimum level of notch toughness. While this may be true, it can not be assumed. This article will address specifying filler metals that resist hydrogen related cracking while also providing good mechanical properties.The term "low hydrogen" has been around for about 60 years. It was first introduced to differentiate this classification of shielded metal arc welding (SMAW) electrode (e.g., E7018) from other non-low hydrogen SMAW electrodes (e.g., E6010). They were created to avoid hydrogen cracking on high strength steels, such as armor plate.1 Figure 1. "Fish-eyes" on an all-weld-metal tensile specimen fracture surface.  http://gewc.ahlamontada.com/montada-f1/topic-t94.htmEXPERIENCE MAKES SENSE