Hydrogen : What Is Hydrogen Cracking?

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Hydrogen Cracking

What is hydrogen cracking? It is probably the most talked about failure mechanism associated with the welding industry. It is also known as hydrogen induced cracking, (HIC); hydrogen assisted cracking, (HAC); cold cracking,(CC); delayed cracking, (DC); under-bead cracking, (UBC); and hydrogen embrittlement, (HE).


Hydrogen cracking of welds first became a major concern during the first part of the 20th century. Up until that time welding was experimented with, but not used in normal production. A few transmission pipelines were built using gas welding and arc welding was being used in shipbuilding on a limited basis.

World War I and World War II pushed the envelope as far as manufacturing technology and made welding a common manufacturing method. During a war it is very important to be able to manufacture very quickly and efficiently. Welding helped a great deal to win the wars.

But as welding was taking place in large volumes in many different manufacturing and fabricating industries, welding defects were also happening. Lack of penetration, lack of fusion, porosity, slag inclusions and cracking were some of the more common defects. Cracking was especially problematic because the cracks were sometimes visible on the surface of the weld and sometimes they were either under the weld beads or delayed for several hours after the weld was complete. The under bead and delayed cracking was especially dangerous because these cracks could

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