Diffusible hydrogen content for electrodes used with quenched and tempered steels is specified in which unit?

Diffusible hydrogen content for electrodes used with quenched and tempered steels is specified in which unit?

• A. ml per kilogram of weld metal
• B. ml per cubic centimeter weld metal
• C. ml per 100 g of weld metal
• D. liters per 100 g of weld metal

Answer: (C)

Diffusible hydrogen content is the amount of hydrogen that can diffuse out of the weld metal and potentially cause hydrogen-induced cracking. To compare this consistently for welds of different sizes, it is expressed as a volume of hydrogen per a fixed mass of weld metal. The standard unit is milliliters of hydrogen per 100 grams of weld metal. This mass-based normalization makes it practical for specifying and evaluating hydrogen content across electrodes and welds, especially for quenched and tempered steels where low diffusible hydrogen is critical. Other units would complicate comparisons or aren’t the convention used in welding specifications, so the correct unit is ml per 100 g of weld metal.

Diffusible hydrogen content is the amount of hydrogen that can diffuse out of the weld metal and potentially cause hydrogen-induced cracking. To compare this consistently for welds of different sizes, it is expressed as a volume of hydrogen per a fixed mass of weld metal. The standard unit is milliliters of hydrogen per 100 grams of weld metal. This mass-based normalization makes it practical for specifying and evaluating hydrogen content across electrodes and welds, especially for quenched and tempered steels where low diffusible hydrogen is critical. Other units would complicate comparisons or aren’t the convention used in welding specifications, so the correct unit is ml per 100 g of weld metal.