Abstract
Continued from 1st report, we studied influence of strain ageing upon fatigue strength of high-tension steel sheet (as rolled, 7mm thick).
Test specimens were strained 1-10% in tension, aged at 100°C or 250°C, and then these endurance limits were measurd under completely reversed plane bending by Upton-Lewis type fatigue testing machine. Here, in order to put these tests to condition of practical use, sheet surfaces of test specimens were as rolled and not finished.
These test results showed that endurance limits of high-tension steel decreased largely with incresing pre-strains, and changed slightly with progressing strain ageing.
