What is hydrogen-induced cracking and which steels are most at risk?

What is hydrogen-induced cracking and which steels are most at risk?

• A. Hydrogen-induced cracking occurs during heating only.
• B. Hydrogen-induced cracking occurs during cooling when hydrogen diffuses into steel.
• C. Hydrogen-induced cracking is unrelated to hydrogen content.
• D. Hydrogen-induced cracking occurs during bending only.

Answer: (C)

Hydrogen-induced cracking happens when hydrogen atoms diffuse into steel under tensile stress and gather at defects or grain boundaries, causing cracks to form and propagate. The presence of hydrogen weakens the metal’s ability to carry a load, so cracking can occur even in steels that are normally ductile if hydrogen levels are high and there is applied or residual stress. The steels most at risk are high-strength steels, especially those that have been quenched and tempered or are martensitic/bainitic in structure. These steels have high hardness and low ductility, making them more susceptible to hydrogen embrittlement when hydrogen is present—such as during welding, electroplating, pickling, or exposure to hydrogen-rich environments (like sour gas conditions). Hydrogen-induced cracking is not limited to heating, cooling, or bending alone, and it is indeed related to hydrogen content. It can occur during processing or in service whenever hydrogen is present and stresses can drive crack growth.

Hydrogen-induced cracking happens when hydrogen atoms diffuse into steel under tensile stress and gather at defects or grain boundaries, causing cracks to form and propagate. The presence of hydrogen weakens the metal’s ability to carry a load, so cracking can occur even in steels that are normally ductile if hydrogen levels are high and there is applied or residual stress.

The steels most at risk are high-strength steels, especially those that have been quenched and tempered or are martensitic/bainitic in structure. These steels have high hardness and low ductility, making them more susceptible to hydrogen embrittlement when hydrogen is present—such as during welding, electroplating, pickling, or exposure to hydrogen-rich environments (like sour gas conditions).

Hydrogen-induced cracking is not limited to heating, cooling, or bending alone, and it is indeed related to hydrogen content. It can occur during processing or in service whenever hydrogen is present and stresses can drive crack growth.