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Cold Cracking

Cold cracking refers to cracks that appear immediately or within hours of welding, caused by the combination of hydrogen present in the weld, susceptible microstructures like martensite forming due to rapid cooling, and mechanical stresses. It can occur in carbon steel and some low-alloy steels at temperatures between -60 and 150 degrees Celsius, appearing as fine cracks in the weld or surrounding heat-affected zone. To prevent cold cracking, hydrogen content must be reduced through techniques like drying and proper filler selection, while preheating and post-weld heat treatment help eliminate cracks by modifying microstructure and residual stresses.

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211 views1 page

Cold Cracking

Cold cracking refers to cracks that appear immediately or within hours of welding, caused by the combination of hydrogen present in the weld, susceptible microstructures like martensite forming due to rapid cooling, and mechanical stresses. It can occur in carbon steel and some low-alloy steels at temperatures between -60 and 150 degrees Celsius, appearing as fine cracks in the weld or surrounding heat-affected zone. To prevent cold cracking, hydrogen content must be reduced through techniques like drying and proper filler selection, while preheating and post-weld heat treatment help eliminate cracks by modifying microstructure and residual stresses.

Uploaded by

7774R105
Copyright
© Attribution Non-Commercial (BY-NC)
We take content rights seriously. If you suspect this is your content, claim it here.
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COLD CRACKING

DEFINITION: Cold cracking, or hydrogen assisted cracking, is shown by the apparition of cracks, immediately or after a few minutes, sometimes even hours, after the welding is finished. These cracks can appear in the weld or in the heat affected zone (HAZ). CAUSES: Are needed the following factors: Hydrogen present in the weld material or in the HAZ. Susceptible microstructure (martensite). Mechanical stresses (thermal or residual stresses). MATERIALS: Carbon steel or low alloy steel. Some high alloy steel (for example 12% Cr). RANK OF TEMPERATURES: Between -60 and 150 C. DETECTION: In carbon steel and those steels with a low content in manganese or microalleated, cracks are very small (H micro cracks) and often those cracks r egroup. In high strength steels, cracks are generally bigger being able to cross the weld in transverse direction. The crack is observed radiologically as a black, fine and regular crack.

SOLUTION: In order to prevent cold cracking the content in H2 should be reduced, preheat or postwarm the piece to prevent the apparition of fragile microstructures and to decrease the residual stresses.

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