Evaluation of Hydrogen Embrittlement of High Strength Steel in the Atmospheric Environment

Abstract

High strength steels for automobiles should be concerned about hydrogen embrittlement. Therefore, we investigated the hydrogen embrittlement of 1500 MPa class high strength steel in atmospheric environment in the form of U-bend test piece. Cracks due to hydrogen embrittlement didn’t occur in 36 months of exposure to Choshi and 12 months of exposure to Miyakojima under the conditions of bending radius of 5 mm, 10 mm, 15 mm and stress of 1300 MPa, 1500 MPa. On the other hand, test pieces cracked after 20 months of exposure to Miyakojima. Corrosion test in Miyakojima showed that reduction of the steel thickness due to corrosion reached original test piece thickness after 24 months. Therefore, it is considered that cracks after 20 months of exposure to Miyakojima was mainly caused by corrosion.