To provide a method for preventing hydrogen embrittlement cracking from occurring in a steel material when the steel material has been subjected to chemical treatment such as pickling and subsequently to a working process.
This prevention method comprises the steps of: preparing a steel material having a tensile strength of 690 MPa or higher; subjecting the steel material to the chemical treatment; subjecting the chemical-treated steel material to the pre-working treatment which includes leaving it in the atmosphere or heat-treating it; and subjecting it to working treatment. The chemical-treated steel material is left in the atmosphere preferably at 10C or higher and for a period of 1 day or longer; and is heat-treated preferably at 40 to 100C and for a period of 10 minutes or longer. This prevention method also comprises the steps of: sampling a test material of the steel material before shipping; subjecting the test material to chemical treatment corresponding to chemical treatment which will be carried out after shipping; subjecting the test material to the pre-working treatment of leaving the test material in the atmosphere in a predetermined condition or heat-treating the test material in a predetermined condition, while considering the situation before it will be subjected to the working treatment and the condition of the working treatment; then, working it in a condition which simulates the working treatment that will be carried out after shipping; examining the damaged state of the test material; and determining whether the hydrogen embrittlement cracking occurs or not in the test material in the working treatment, while comparing the state with the damaged state of an untreated test material which has not been treated with a chemical solution.
HASHIMOTO YUJI
KAWABATA YOSHIKAZU
TOYODA SHUNSUKE
ARAYA MASATOSHI
SUZUKI KOJI
SATO AKIO
GUNJI MAKIO
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