Abstract
The internal friction and mechanical properties after quenching, tempering and isothermal transformation of a spring steel containing about 1% Cr and 1% Mn were measured. The internal friction measurements were carried out by using a transversal resonance vibrating method. The strain amplitude dependence of internal friction was not observed in the martensite structure, while it was revealed in the tempered structure. Along with various phenomena which occur in the course of tempering, the strain amplitude independent internal friction at a low amplitude underwent more sensitive changes than other mechanical properties.
Specimens transformed isothermally had a strain amplitude dependent internal friction, which was found to be the highest in a specimen transformed isothermally at 500°C at which the Charpy impact value was the lowest.
