2015 Volume 64 Issue 6 Pages 244-250
1400-MPa class high-strength PC wires are used for pre-stressed concrete structures. One of trusted hydrogen embrittlement tests for steel is a testing method that is provided in the FIP Report1) and defined in JSCE S 12013) for a test procedure. This test includes a constant load test in a 20% NH4SCN at 50ºC for up to 200 hours to measure the rupture time. The test examined corrosion behavior in the early stage of the test when hydrogen concentration in steel would show a rapid increase. It was recognized that dissolved oxygen accelerated a corrosion reaction in pure oxygen atmosphere, but a 6-hour immersion test showed no notable difference in corrosion rate and corrosion potential in air and deaerated atmosphere. Polarization measurements suggested that a cathodic reaction independent of dissolved oxygen exerted a profound effect on a corrosion reaction. The analysis of corrosion products and iron ion led to a presumption that the iron-sulfide and iron oxide would precipitate concurrently in the early stage of immersion in 20% NH4SCN.