Abstract
The most important thing concerning the reinforcement steel rod of prestressed concrete isr to clarify the creep strength at room temperature. In this paper, we report on the results of creep tests at room temperature on mild and medium carbon steel rods induction-hardened which were manufactured as the reinforcement steel rod of prestressed concrete. The main object of the tests is to find the most suitable tempering temperature to make the creep strength maximum.
Specimens used were the round rod with 12mm diameter hardened by high frequency induction heating and tempered at 200°C, 300°C, 400°C and 500°C after induction hardening. Specimens were applied constant tensile stresses from 6mn to 100h at room temperature. The creep limit was determined according to DIN E 4227, that is, the creep limit is the critical stress which causes creep strain of 0.008% during 1-100h, but, in that case, the creep strain during 6mn-1h must not be more than 0.016%.
As the test results, the relation between creep limits and tempering temperature was obtained in both cases when the steels were induction through hardened and induction surface hardened.
